rodsatheart
Member
- Joined
- Oct 2, 2012
- Messages
- 17
OK. Duh !!!!!!!!!!
Thickness of main cup is .380"=9.652mm.
Thickness of main cup is .380"=9.652mm.
Overseas Jack Rebuild Help Tutorial.
- Thread starter Hiball
- Start date
For Hiball
I tried one 24 x 40 x 8 urethane u-cup made by KASTAS. I tested it both on the Michelin and on one Craftman 4 ton which uses the same pump. On both, the seal was a tight fit.
The seal you show on your photos was used in the way early version of the Michelin jack. The seal you show is made out of nitrile. Although it is not shown in the photos posted, I believe that in another early thread you posted similar photos of the Michelin u-cup and in one of those photos, the top of the u-cup could be seen. If I remember right, because I have seen the Michelin early version's u-cups before, that u-cup have ribs connecting both the outer and the inner lips. And as we can see in the photos you posted now, that u-cup also has a step on the botton or the heel of the cup. These two are a design characteristic of nitrile u-cups. PLease correct me if I am wrong about the ribs.
Since the nitrile u-cup wasn't as strong as an urethane u-cup for this particular application, they had to connect the lips to give it strenght and stability. Many early mini jacks, like the ones made by MVP and PROLIFT, made by Shinn Fu use the same design, without the ribs but with the step, as shown in your photos, but smaller in size, of course, and all of them are made of nitrile. You can be sure that any u-cup with that particular step on the heel is a nitrile u-cup. I don't recall ever seeing an urethane u-cup, whether OEM, or aftermarket, with a step on the botton or the heel, and I have seals catalogs from many companies and I have accessed the websites of many seals manufacturing companies and there is not a single one with a step. Even the OEM urethane seals that come with other brands of jacks do not have the step. There are some urethane u-cups, that come with a backup ring ( not washer) already attached ( permanently) to them, that do have the step but this is not one of those. We are refering here to the standard, or common, type of u-cup were you have to use a separate back up.
There is a reason for the step in the nitrile u-cup and the taller side of its back up washer. Because nitrile is slightly more flexible and not as strong as urethane, the nitrile u-cup requires more protection from extrusion of the u-cup bottom than the urethane u-cup. Therefore to provide this extra protection, the manufacturers of these nitrile u-cups gave them a backup washer with a tall side, which required to make a step on the u-cup, just to contain the bottom of the u-cup inside the back up washer. Look at that seal you posted, see that the bottom of the u-cup is inside the back up washer. Since the urethane material is stronger than nitrile it can resist extrusion better and using only a flat back up washer. No need to trap the bottom of an urethane u-cup inside the back up washer. Therefore no need for a step on the bottom of an urethane u-cup. Easier and cheaper to make also. Urethane u-cups can sit happily on top of its back up washer all day long.
As a matter of fact, manufacturers recommend nitrile u-cups to be used only in pneumatic or low to medium pressure hydraulic applications. They are not to be used in high pressure applications. Using them in floor jacks requires the use of a tall side back up washer and not a flat BU washer. It is like a trick they are trying to perform with the tall sided back up washer, like trying to enhance the performance of nitrile u-cups for an application they are not recommended.
The later versions of that Michelin jack, also made by Shinn Fu, use a blue urethane u-cup without the step and with a flat backup washer. Most of the Michelin jacks I have repaired in the last four or five years have had the blue urethane u-cup. They had to change from nitrile to urethane because the nitrile was not strong enough for a 3.5 ton rated jack. Maybe for a 2 ton rated jack the nitrile could had been adequate. As you might know, nitrile u-cups are rated at about 1000 to 1500 psi with a back-up, while urethane u-cups are rated from 4000 to 6000 psi with a back up, a big difference! By the way, both versions of the Michelin look exactly alike.
I measured the urethane u-cup in the later versions of the Michelin and they are almost a millimeter smaller than a 24 x 40 x 8 u-cup on the outside diameter, measured at the heel or bottom of the u-cup. And if you compare them size for size, back to back, you will see that there is a noticeable difference in size AND THAT'S THE REASON AN AFTERMARKET 24 X 40 X 8 U- CUP IS A TIGHT FIT FOR THE LATER VERSION MICHELIN. It is not because the back up washer outside diameter is bigger as you implied or because it has expanded over time as the Walker, Lincoln, Hein Werner heel plates do. Compounding the problem, the aftermarket u-cups have a more aggressive lip design that the OEM, meaning that they are wider at the top than OEM u-cups which have much less flare on the lips.
I do know that a 24 x 40 x 8 u-cup fits the early version of the Michelin, the one with the nitrile u-cup, without being a tight fit. I know because I have tried that. But it simply does not fit well the later version of the Michelin. Has to be the manufacturer changed the inside diameter of the cylinder slightly when they changed to an urethane u-cup. These Michelins were supposed to be economical (cheap ) jacks so the quality of some parts, like the casters, was not the best. I bet Shinn Fu also saved some money by using nitrile, a less desirable material for an u-cup, instead of the better urethane. After a while, they had no choice but to switch to urethane but they never used better casters.
That you show the early black nitrile MICHELIN u-cup and, apparently, do not know about the change of material and shape, can only mean that you have not repaired a Michelin in the last four or five years or that you have only gotten the early versions.
By the way, there were more of the later versions of the Michelins made than the early versions because the strengt issue of the nitrile u-cup.
In my early post (#265) were I mentioned the 24 x 40 x 8 u-cups I did mention that there was a better fitting u-cup for the Michelin. This u-cup size in metric is 23.8 x 39.68 x 9.52 . This cup is also available in inches and the size is 15/16 x 1 - 9/16 x 3/8 which just happens to be the same size as the metric u-cup. This is the size I use when repairing the later version of the Michelin 3.5 ton jack as it is close in size to the OEM blue urethane u-cup that comes with the Michelin jack. I never mentioned that I was actually using the 24 x 40 x 8 to repair the later version Michelins.
Since you have shown a tendency of doubting what I say, you are probably going to say that these sizes mentioned above do not exist, but let me tell you I bought them from MFPseals.com in Houston, Texas, USA! That you don't know about them does not mean that these do not exist. In an effort to keep my knowledge up to date, I have spent many hours searching (and researching) through the many seal manufacturer's websites, wanting to know what they offer and also reading the excellent technical information about seals and related hydraulic topics many of these sites offer. I hope you are doing the same. And if you don't, please google " hydraulic seals" and start reading.
If you still want to believe that the u-cup in the photo is made out of urethane, well, be my guest, but remember an old saying : "what you don't know can hurt you".
By the way, Canadian Tyre shows a new, and different version, of the blue 3.5 ton Michelin floor jack.
Also, in another new thread, there is shown a black 4 ton (early?) Craftman which is different from the one currently sold by Sears, as seen on their web site, ( the one that shares the same pump with the Michelin). I do not know if this different 4 ton jack uses the same size u-cup as the early Michelin although the size 24 x 40 x 10 is mentioned on that thread, but from the photo posted, I can see it is also a nitrile u-cup, like the one in your photo, but in the photos of this new thread the ribs between the lips and the step in the heel are shown. Maybe a 24 x 40 x 10 u-cup will fit this (early?)Craftman 4 ton without being a tight fit. The title of this new thread is "Craftman 4 ton floorjack rebuild".
I tried one 24 x 40 x 8 urethane u-cup made by KASTAS. I tested it both on the Michelin and on one Craftman 4 ton which uses the same pump. On both, the seal was a tight fit.
The seal you show on your photos was used in the way early version of the Michelin jack. The seal you show is made out of nitrile. Although it is not shown in the photos posted, I believe that in another early thread you posted similar photos of the Michelin u-cup and in one of those photos, the top of the u-cup could be seen. If I remember right, because I have seen the Michelin early version's u-cups before, that u-cup have ribs connecting both the outer and the inner lips. And as we can see in the photos you posted now, that u-cup also has a step on the botton or the heel of the cup. These two are a design characteristic of nitrile u-cups. PLease correct me if I am wrong about the ribs.
Since the nitrile u-cup wasn't as strong as an urethane u-cup for this particular application, they had to connect the lips to give it strenght and stability. Many early mini jacks, like the ones made by MVP and PROLIFT, made by Shinn Fu use the same design, without the ribs but with the step, as shown in your photos, but smaller in size, of course, and all of them are made of nitrile. You can be sure that any u-cup with that particular step on the heel is a nitrile u-cup. I don't recall ever seeing an urethane u-cup, whether OEM, or aftermarket, with a step on the botton or the heel, and I have seals catalogs from many companies and I have accessed the websites of many seals manufacturing companies and there is not a single one with a step. Even the OEM urethane seals that come with other brands of jacks do not have the step. There are some urethane u-cups, that come with a backup ring ( not washer) already attached ( permanently) to them, that do have the step but this is not one of those. We are refering here to the standard, or common, type of u-cup were you have to use a separate back up.
There is a reason for the step in the nitrile u-cup and the taller side of its back up washer. Because nitrile is slightly more flexible and not as strong as urethane, the nitrile u-cup requires more protection from extrusion of the u-cup bottom than the urethane u-cup. Therefore to provide this extra protection, the manufacturers of these nitrile u-cups gave them a backup washer with a tall side, which required to make a step on the u-cup, just to contain the bottom of the u-cup inside the back up washer. Look at that seal you posted, see that the bottom of the u-cup is inside the back up washer. Since the urethane material is stronger than nitrile it can resist extrusion better and using only a flat back up washer. No need to trap the bottom of an urethane u-cup inside the back up washer. Therefore no need for a step on the bottom of an urethane u-cup. Easier and cheaper to make also. Urethane u-cups can sit happily on top of its back up washer all day long.
As a matter of fact, manufacturers recommend nitrile u-cups to be used only in pneumatic or low to medium pressure hydraulic applications. They are not to be used in high pressure applications. Using them in floor jacks requires the use of a tall side back up washer and not a flat BU washer. It is like a trick they are trying to perform with the tall sided back up washer, like trying to enhance the performance of nitrile u-cups for an application they are not recommended.
The later versions of that Michelin jack, also made by Shinn Fu, use a blue urethane u-cup without the step and with a flat backup washer. Most of the Michelin jacks I have repaired in the last four or five years have had the blue urethane u-cup. They had to change from nitrile to urethane because the nitrile was not strong enough for a 3.5 ton rated jack. Maybe for a 2 ton rated jack the nitrile could had been adequate. As you might know, nitrile u-cups are rated at about 1000 to 1500 psi with a back-up, while urethane u-cups are rated from 4000 to 6000 psi with a back up, a big difference! By the way, both versions of the Michelin look exactly alike.
I measured the urethane u-cup in the later versions of the Michelin and they are almost a millimeter smaller than a 24 x 40 x 8 u-cup on the outside diameter, measured at the heel or bottom of the u-cup. And if you compare them size for size, back to back, you will see that there is a noticeable difference in size AND THAT'S THE REASON AN AFTERMARKET 24 X 40 X 8 U- CUP IS A TIGHT FIT FOR THE LATER VERSION MICHELIN. It is not because the back up washer outside diameter is bigger as you implied or because it has expanded over time as the Walker, Lincoln, Hein Werner heel plates do. Compounding the problem, the aftermarket u-cups have a more aggressive lip design that the OEM, meaning that they are wider at the top than OEM u-cups which have much less flare on the lips.
I do know that a 24 x 40 x 8 u-cup fits the early version of the Michelin, the one with the nitrile u-cup, without being a tight fit. I know because I have tried that. But it simply does not fit well the later version of the Michelin. Has to be the manufacturer changed the inside diameter of the cylinder slightly when they changed to an urethane u-cup. These Michelins were supposed to be economical (cheap ) jacks so the quality of some parts, like the casters, was not the best. I bet Shinn Fu also saved some money by using nitrile, a less desirable material for an u-cup, instead of the better urethane. After a while, they had no choice but to switch to urethane but they never used better casters.
That you show the early black nitrile MICHELIN u-cup and, apparently, do not know about the change of material and shape, can only mean that you have not repaired a Michelin in the last four or five years or that you have only gotten the early versions.
By the way, there were more of the later versions of the Michelins made than the early versions because the strengt issue of the nitrile u-cup.In my early post (#265) were I mentioned the 24 x 40 x 8 u-cups I did mention that there was a better fitting u-cup for the Michelin. This u-cup size in metric is 23.8 x 39.68 x 9.52 . This cup is also available in inches and the size is 15/16 x 1 - 9/16 x 3/8 which just happens to be the same size as the metric u-cup. This is the size I use when repairing the later version of the Michelin 3.5 ton jack as it is close in size to the OEM blue urethane u-cup that comes with the Michelin jack. I never mentioned that I was actually using the 24 x 40 x 8 to repair the later version Michelins.
Since you have shown a tendency of doubting what I say, you are probably going to say that these sizes mentioned above do not exist, but let me tell you I bought them from MFPseals.com in Houston, Texas, USA! That you don't know about them does not mean that these do not exist. In an effort to keep my knowledge up to date, I have spent many hours searching (and researching) through the many seal manufacturer's websites, wanting to know what they offer and also reading the excellent technical information about seals and related hydraulic topics many of these sites offer. I hope you are doing the same. And if you don't, please google " hydraulic seals" and start reading.
If you still want to believe that the u-cup in the photo is made out of urethane, well, be my guest, but remember an old saying : "what you don't know can hurt you".
By the way, Canadian Tyre shows a new, and different version, of the blue 3.5 ton Michelin floor jack.
Also, in another new thread, there is shown a black 4 ton (early?) Craftman which is different from the one currently sold by Sears, as seen on their web site, ( the one that shares the same pump with the Michelin). I do not know if this different 4 ton jack uses the same size u-cup as the early Michelin although the size 24 x 40 x 10 is mentioned on that thread, but from the photo posted, I can see it is also a nitrile u-cup, like the one in your photo, but in the photos of this new thread the ribs between the lips and the step in the heel are shown. Maybe a 24 x 40 x 10 u-cup will fit this (early?)Craftman 4 ton without being a tight fit. The title of this new thread is "Craftman 4 ton floorjack rebuild".
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Jesus Edgar..... Where to start.
1. First I was only trying to assist you in your excess drag issue.... And since you failed to answer my question on "how you remedied replacing the oem seal (with the step)" ill give you some friendly advice... If you slap a normal ucup on that shaft without first machining that step off or modifying that backup into a normal heel plate it will cause the backside of the ucup to flare ever so slightly and I think that is where yor drag Is coming from. I've used a 24 x 40 x 8 many of times on these jacks (after machining the step down) And have never encountered a iissue.
2. I've never seen a quick lift/magic lift/speedy lift 3/3.5 ton jack use anything other than the cup/backup that I pictured earlier. It's a possibility that the New models use a normal ucup, unfortunately I can't verify because I haven't encountered one. It may very wellbe a nitrile cup, I've never tried to find it nor is it easy to tell the difference between a "used" nitrile witha 90 durometer and a urethane with a 95. I agree... A urethane seal is the proper choice versus the oem seal I pictured earlier, I've encountered many of them that had lip failures.
3. I've been buying seals for along...... Time from MFP.... I deal with Michigan branches.
4. I don't doubt that you research seals, it seems you insist on quoting there catalogs word for word here on a regular basis.
5. I've been to numerous hydraulic shop throughout the US, from Texas to Ny.. I know of no "reputable" rebuilder who hasn't been stumped at least once or twice (Maybe your the exception, doubtful but maybe).. Please don't feel the need to impress me with your copy/paste skills... It may work for the community, but hydraulic seals haven't changed that much over the last 20 years and its getting reduntant.
1. First I was only trying to assist you in your excess drag issue.... And since you failed to answer my question on "how you remedied replacing the oem seal (with the step)" ill give you some friendly advice... If you slap a normal ucup on that shaft without first machining that step off or modifying that backup into a normal heel plate it will cause the backside of the ucup to flare ever so slightly and I think that is where yor drag Is coming from. I've used a 24 x 40 x 8 many of times on these jacks (after machining the step down) And have never encountered a iissue.
2. I've never seen a quick lift/magic lift/speedy lift 3/3.5 ton jack use anything other than the cup/backup that I pictured earlier. It's a possibility that the New models use a normal ucup, unfortunately I can't verify because I haven't encountered one. It may very wellbe a nitrile cup, I've never tried to find it nor is it easy to tell the difference between a "used" nitrile witha 90 durometer and a urethane with a 95. I agree... A urethane seal is the proper choice versus the oem seal I pictured earlier, I've encountered many of them that had lip failures.
3. I've been buying seals for along...... Time from MFP.... I deal with Michigan branches.
4. I don't doubt that you research seals, it seems you insist on quoting there catalogs word for word here on a regular basis.
5. I've been to numerous hydraulic shop throughout the US, from Texas to Ny.. I know of no "reputable" rebuilder who hasn't been stumped at least once or twice (Maybe your the exception, doubtful but maybe).. Please don't feel the need to impress me with your copy/paste skills... It may work for the community, but hydraulic seals haven't changed that much over the last 20 years and its getting reduntant.
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rodsatheart
Member
- Joined
- Oct 2, 2012
- Messages
- 17
Here's a big THANK YOU to ..... BOTH ..... Hiball and Edgar for all the educating you've been doing to us greenhorns when it comes to dismantling and fixing hydraulic jacks.
Stumbled on this thread and now have confidence to tear into nice long handle floor jack I've owned for 15 years but never used because it had leak down issues!!! Thanks again for helping us get these jacks back in service.
Stumbled on this thread and now have confidence to tear into nice long handle floor jack I've owned for 15 years but never used because it had leak down issues!!! Thanks again for helping us get these jacks back in service.
Your very welcome.... That was my Goal. There is nothing difficult about rebuilding a hydraulic jack, some are a bit trickier than others but all use basically the same principle. It's a common practice of hydraulic shops to make things out to be worse than they are or use big words to try and persuade the average individual from undertaking the task there self. If you have any questions or are unable to source the parts locally. Give me a shout and ill point you in the right direction.
Steven
Jeeper
Well-known member
That is my thread.
The measurement of the cup that i listed is approximate. The actual measurements are 24.2mmx39.34mmx9mm. That is WITHOUT the backing washer. If helpful i can post some more photos of just the washers.The other thread for clickablity ease.
http://www.garagejournal.com/forum/showthread.php?t=168840
That is my thread.
The other thread for clickablity ease.
http://www.garagejournal.com/forum/showthread.php?t=168840
Should be the same seal that I posted in #279
Hiball
The only way to replace the nitrile OEM u-cup with the step is with a u-cup without the step because the ones with the step are not available in the aftermarket. You would need to get a repair kit from Shinn Fu, assuming that these are available.
Of course you have to shave or file away, the backup washer to make it a flat washer to be able to mount a modern stepless u-cup. If you don't it won't fit properly. That goes without saying. Thank you for your "friendly advice" but that info is very, very old news to me. It reflects on you if you think I am so stupid not to have known that.
If you have used the 24 x 40 on those jacks with no issue that means that you have only worked on the early versions of the Michelin jack. Even your photo says that you were not aware of the production change fron a nitrile cup to a stepless urethane cup, otherwise you would have also shown a photo of the late version u-cup.
These stepless seals in the quick lift have been around for more than six or seven years maybe even more. They are also found on the Omegas, made by Shinn Fu. That you have never encountered them is beyond my comprehension. Are you only fixing Weavers and Lincolns?
I was not stumped with the change of u-cup from nitrile to urethane because I realized right away that there was also a slight difference in size between them, something you will realize the day you finally get to fix one the later versions of Michelins. And what are you going to do then? Because you are only relying on the 24 x 40 u-cup and you did not know about the other size I mentioned in my post. You would be stumped!
I do not quote and paste here, I keep myself informed with the latest about hydraulics from the peolple that have knowledge about this issues, namely the manufacturers of u-cups and other types of seals. Perhaps you think they are a bunch of chumps?
That you make fun of my research means that you have never done any research about hydraulic seals. There is a lot of good info in these websites and you would have known about it if you had done even a little research on your own.
You are only relying in what you learned 20 years ago. So you are relying perhaps on outdated info? I see that you have over 7000 post on GJ. Perhaps you should use some of that computer time to keep up to date by doing some research about hydraulic seals.
Please, before challenging someone else knowledge, be certain that you know what you are talking about. The community here may think that you are a "guru" but without good, updated knowledge, you are just an "also ran". I can see through the smoke screen...others not.
For example, you did not know about tapping new valve balls to seat them properly. EVERYBODY IN THE BUSINES OF HYDRAULIC REPAIR KNOWS THAT. How come you don't know it.
I do not need to impress you or anyone else here. I only have interest in learning and knowing things that can help me do better job. Apparently, you don't.
The only one who always try to impress people here is you because you never miss an opportunity to mention that you have been doing this for 20 years. Just because you have been doing this for 20 years doesn' t make you an expert if you don't do any research or keep up to date with the changes that happens with hydraulic seals and equipment.
I do not claim to know everything there is to know about hydraulics, as you do, and that is why I do the research, not to impress anyone but to know what I am talking about. If I don't know something I would say it right away and not make up things or excuses, I have no problem with that. How about you, Hiball?
I do not negotiate with terrorist, Mr. "All high and mighty guru of jacks".
The only way to replace the nitrile OEM u-cup with the step is with a u-cup without the step because the ones with the step are not available in the aftermarket. You would need to get a repair kit from Shinn Fu, assuming that these are available.
Of course you have to shave or file away, the backup washer to make it a flat washer to be able to mount a modern stepless u-cup. If you don't it won't fit properly. That goes without saying. Thank you for your "friendly advice" but that info is very, very old news to me. It reflects on you if you think I am so stupid not to have known that.
If you have used the 24 x 40 on those jacks with no issue that means that you have only worked on the early versions of the Michelin jack. Even your photo says that you were not aware of the production change fron a nitrile cup to a stepless urethane cup, otherwise you would have also shown a photo of the late version u-cup.
These stepless seals in the quick lift have been around for more than six or seven years maybe even more. They are also found on the Omegas, made by Shinn Fu. That you have never encountered them is beyond my comprehension. Are you only fixing Weavers and Lincolns?
I was not stumped with the change of u-cup from nitrile to urethane because I realized right away that there was also a slight difference in size between them, something you will realize the day you finally get to fix one the later versions of Michelins. And what are you going to do then? Because you are only relying on the 24 x 40 u-cup and you did not know about the other size I mentioned in my post. You would be stumped!
I do not quote and paste here, I keep myself informed with the latest about hydraulics from the peolple that have knowledge about this issues, namely the manufacturers of u-cups and other types of seals. Perhaps you think they are a bunch of chumps?
That you make fun of my research means that you have never done any research about hydraulic seals. There is a lot of good info in these websites and you would have known about it if you had done even a little research on your own.
You are only relying in what you learned 20 years ago. So you are relying perhaps on outdated info? I see that you have over 7000 post on GJ. Perhaps you should use some of that computer time to keep up to date by doing some research about hydraulic seals.
Please, before challenging someone else knowledge, be certain that you know what you are talking about. The community here may think that you are a "guru" but without good, updated knowledge, you are just an "also ran". I can see through the smoke screen...others not.
For example, you did not know about tapping new valve balls to seat them properly. EVERYBODY IN THE BUSINES OF HYDRAULIC REPAIR KNOWS THAT. How come you don't know it.
I do not need to impress you or anyone else here. I only have interest in learning and knowing things that can help me do better job. Apparently, you don't.
The only one who always try to impress people here is you because you never miss an opportunity to mention that you have been doing this for 20 years. Just because you have been doing this for 20 years doesn' t make you an expert if you don't do any research or keep up to date with the changes that happens with hydraulic seals and equipment.
I do not claim to know everything there is to know about hydraulics, as you do, and that is why I do the research, not to impress anyone but to know what I am talking about. If I don't know something I would say it right away and not make up things or excuses, I have no problem with that. How about you, Hiball?
I do not negotiate with terrorist, Mr. "All high and mighty guru of jacks".
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Please stop cluttering up my thread with your pointless posts.... Where on earth are you getting your info? Don't know how to reseat ball seat? Its not rocket science and i also have the proper hand cutting dies if its boogered up too much. What are you talking about? And yes I primarily I only work on the higher end jacks.. Mainly because most customers don't want to invest the money to fix the lower priced jacks. Why would a seal size stump me? Even if the seal is beyond measurable, all the hard parts are still there. Smoke screen? Humerous...to say the least..... Just because I don't type novels to get my point acrossed, doesn't mean I don't know what I'm talking about.
In regards to my 7000 posts... What exactly do I need to research about hydraulic seals? Most of today's jacks utilize piston style ucups. Are you trying to memorize the entire MFP catalog? Yes I know there are some hybrid cups that can be used in both a rod/piston application along with loaded cups. I will say this.... If I've been bluffing my way through all this hydraulic stuff with "smoke screens", I'm a bad mofo... 3 years, prob answered 3k+ Pm's and countless threads. Guess I've been lucky..?
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Jeeper
Well-known member
That looks like the one. Can you get me one? PM with price if you don't mind.
Have a 25+ year old jack, made in Taiwan. 4400lb. Nice little jack. Was leaking badly, but worked OK. Would bleed down over time with a load on it.
The pump mechanism is very similar to this one:
www.youtube.com/watch?v=uSms24ZqG1Q&feature=related
I replaced the O-rings in the pump shaft bore: one that goes around the shaft and one that seals the bottom of the screw in fitting that the pump shaft goes in. It has one ball below the pump shaft, just like in the youtube video.
The first time I tried the jack it worked fine, lifting about 500 lb. When I tried it again the jack goes up on the pump stroke and then back down when I move the handle down for another pump stroke. The fluid level was a little low so I filled it. Pumped it with the filler plug out and release on and off to bleed air. Still got same result.
What could be wrong?
The pump mechanism is very similar to this one:
www.youtube.com/watch?v=uSms24ZqG1Q&feature=related
I replaced the O-rings in the pump shaft bore: one that goes around the shaft and one that seals the bottom of the screw in fitting that the pump shaft goes in. It has one ball below the pump shaft, just like in the youtube video.
The first time I tried the jack it worked fine, lifting about 500 lb. When I tried it again the jack goes up on the pump stroke and then back down when I move the handle down for another pump stroke. The fluid level was a little low so I filled it. Pumped it with the filler plug out and release on and off to bleed air. Still got same result.
What could be wrong?
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GeorgiaHybrid
Well-known member
Edgar,
Most of the people on here repair old, American made jacks. If one of us has a newer made, Shinn Fu jack, Hiball has still helped them with a kit. I have noticed several things about your posts though; you tend to be long winded, wordy, have to win any argument and seem to have an issue with needing to get the last word in.
Back off and smell the hydraulic fluid for a while and let your blood pressure come down. As it stands right now, I wouldn't trust you with a jack of mine because of your “I’m right and everyone else is wrong, know it all, attitude".
Most of the people on here repair old, American made jacks. If one of us has a newer made, Shinn Fu jack, Hiball has still helped them with a kit. I have noticed several things about your posts though; you tend to be long winded, wordy, have to win any argument and seem to have an issue with needing to get the last word in.
Back off and smell the hydraulic fluid for a while and let your blood pressure come down. As it stands right now, I wouldn't trust you with a jack of mine because of your “I’m right and everyone else is wrong, know it all, attitude".
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Lift Arm feedback that follows the Handle is normally a indication that Valve has a Ball that isnt seating properly. This can be caused by Debris that has made its way through the system, Components installed Wrong or Lastly a Damaged seat/Ball. On the Extreme side of things it could also be a Catastropic failure of the Main Ram seal, This scenario would probably also show some Leakage around the Tank Seal/Nut.
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I suspect the ball that seals the high pressure in the pump during the pump backstroke.
This parts breakdown should be similar to mine:
images.harborfreight.com/manuals/36000-36999/36119.PDF
Looks like that ball (item 6, page 14) is in the cylinder side, so I need to pull the oil chamber and cylinder off. Does that sound like what I need to do?
Tried with my pipe wrench but wouldn't budge. May try to find a 1-3/4" socket.
If this were my cheap chinese $25 jack I might not mess with it. But this old Taiwan jack is a jewel compared to the chinese one, so I'm determined now to fix it.
Thanks Hiball.
Pete
You would be better served by removing that tank nut, this way you can evaluate the system looking for problem areas at could be allowing seal parts to be ingested I to the system. I think it's uphill business trying to flush the system without opening up all ports. What have you tried so far to remove the tank nut? Have you tried adding leverage?
I tried a big pipe wrench with a cheater pipe. Also tried hitting the wrench with a big hammer to shock it loose. Next I will try to find a 1-3/4" socket to put on the 3/4" drive impact wrench at work.
Thanks,
Pete
theoldwizard1
Well-known member
First, you have to make certain the pump body is SECURELY attached to something that is not going to move when you apply massive amounts of torque !
Second, for a "cheater" I actually used the full handle to my floor jack ! Because the hole in the handle was not big enough to insert the pipe wrench, I lashed it to my pipe wrench using 1/8" braided nylon rope.
That was a problem using my home vice. But the work vice is much better. Or, I may reinstall the pump back in the jack frame, and secure the frame.
Pete
It helps sometimes to support the end of the unit (the portion that pertrudes outside the vise) I have some special steel bars made to accomidate different jacks. This way when you do get chippy on the cheater, it doesn't allow the unit to give in the vise.
Hi HiBall,
Your post got me motivated to rebuild my Craftsman 3.5 ton professional jack. I used the seal kit from an Omega MagicLift 25030 (http://www.shinnfuamerica.com/ProductDetails/Omega_Lift_Equipment/Magic_Lift_Service_Jacks/25030/360) because the power unit cross referenced to be the same and was able to replace the cracked u-cup and most of the o-rings to bring the jack back to life.
However, there is one small annoyance after the rebuild. When I lower the jack with no load on it, the arm comes down in steps as if its sticking rather than smoothly like it originally did. I tested the jack by lifting a corner of my car and it lifts and holds. So I have been reviewing my rebuild in my mind particularly on the release valve but I couldn't figure out why.
One thing I may have done incorrectly is I placed the tiny ball under the release needle valve (as shown in the owner's manual diagram) in the bottom passage (there is one on top that leads to the release valve and one at the bottom that I don't know where it leads to) that leads away from the hole where the quick lift tube is seated because I thought that's where it came out when I disassembled it. Even with that, I couldn't imagine how that would cause the ram not to retract smoothly.
Any thoughts? Or is the new u-cup simply tighter causing the ram to stick a little?
Thanks
Eddy
Your post got me motivated to rebuild my Craftsman 3.5 ton professional jack. I used the seal kit from an Omega MagicLift 25030 (http://www.shinnfuamerica.com/ProductDetails/Omega_Lift_Equipment/Magic_Lift_Service_Jacks/25030/360) because the power unit cross referenced to be the same and was able to replace the cracked u-cup and most of the o-rings to bring the jack back to life.
However, there is one small annoyance after the rebuild. When I lower the jack with no load on it, the arm comes down in steps as if its sticking rather than smoothly like it originally did. I tested the jack by lifting a corner of my car and it lifts and holds. So I have been reviewing my rebuild in my mind particularly on the release valve but I couldn't figure out why.
One thing I may have done incorrectly is I placed the tiny ball under the release needle valve (as shown in the owner's manual diagram) in the bottom passage (there is one on top that leads to the release valve and one at the bottom that I don't know where it leads to) that leads away from the hole where the quick lift tube is seated because I thought that's where it came out when I disassembled it. Even with that, I couldn't imagine how that would cause the ram not to retract smoothly.
Any thoughts? Or is the new u-cup simply tighter causing the ram to stick a little?
Thanks
Eddy
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Hello Eddy, first off you reference a "needle valve", does your release stem have a "cone" shaped tip or a flat stem with a upper seat for a ball? If it has the "Needle/cone" style it won't use a ball in the release galley. The reason there are 2 holes in the release hole is because 1 of them (center) shuts the oil off from leaving the cylinder and the 2nd one (normally on the side) is the path back to the reservoir. The studdering upon the release can be a few things, yes it could be a obstruction from the cylinder to the reservoir as discussed earlier, it could also be a improper sized main ram seal (Did the new cup and the old one look the same?), binding linkages and lastly.. It could be simply you don't have enough oil in the reservoir and are ingesting air into the system and its causing problems on the release. Have you tried to cycle the jack completely while under load?
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Hi Hiball,
The release valve has a conical tip which one reason I couldn't figure what the tiny ball i found both in the unit and in the diagram was for. Maybe the ball I put back in there is not really needed and its obstructing the release of oil.
I didn't mic the u-cup but visually it looked the same shape and size and the fit was good on the rod and just snug back into the cylinder.
I did make sure I bled the air after filling the oil reservoir by pumping it with the release open and the oil covering the inner cylinder after bleeding. But I have only cycled the jack under load maybe 2-3 times. Perhaps I need to use it a few times to break it in?
Thanks again.
Eddy
The release valve has a conical tip which one reason I couldn't figure what the tiny ball i found both in the unit and in the diagram was for. Maybe the ball I put back in there is not really needed and its obstructing the release of oil.
I didn't mic the u-cup but visually it looked the same shape and size and the fit was good on the rod and just snug back into the cylinder.
I did make sure I bled the air after filling the oil reservoir by pumping it with the release open and the oil covering the inner cylinder after bleeding. But I have only cycled the jack under load maybe 2-3 times. Perhaps I need to use it a few times to break it in?
Thanks again.
Eddy
Eddy, if your release stem is in the shape of a cone/needle it does NOT use a ball to seat and if you installed a ball it probably dinged it up a bit. Could you post a picture of the release stem just to confirm what style you have?
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Hi HiBall,
The release is definitely a cone/needle valve. The extra ball however was never placed into the release valve cavity so I am positive the valve seat wasn't damaged by the ball.
It's a bit difficult to describe and I didn't take a picture but I actually found the ball in the cavity where the most inner tube sits.(the tube that goes inside the ram that provides the quick lift function) In that cavity, there are 2 galleys, one goes up to the release needle valve and one goes down. I saw the ball fall out of the bottom galley (though I am not 100% sure as it could've fallen out of the top galley into the bottom galley and back out into the center of the cavity) so that's where I put it back.
At this point, the jack is lifting and coming back down so it's just slightly annoying that it's studdering when it's coming down.
Thanks.
Eddy
The release is definitely a cone/needle valve. The extra ball however was never placed into the release valve cavity so I am positive the valve seat wasn't damaged by the ball.
It's a bit difficult to describe and I didn't take a picture but I actually found the ball in the cavity where the most inner tube sits.(the tube that goes inside the ram that provides the quick lift function) In that cavity, there are 2 galleys, one goes up to the release needle valve and one goes down. I saw the ball fall out of the bottom galley (though I am not 100% sure as it could've fallen out of the top galley into the bottom galley and back out into the center of the cavity) so that's where I put it back.
At this point, the jack is lifting and coming back down so it's just slightly annoying that it's studdering when it's coming down.
Thanks.
Eddy
As long as your happy, Im happy... I guess i misunderstood what you where saying earlier. Who Knows.. It might loosen up after a few cycles
but, I Know of none of those jacks that utilizes a ball "Inside" the Main cylinder or the quick lift stem, hopefully it won't make it's way into one of the passages.. Good Luck..
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Hey hiball--- my jack is almost exactly like the one in the original thread....how does one put the pieces back together and bleed it??? My jack only moves the same distance as the handle....then back down when I raise the handle... Seems like such a simple fix but I am stumped----
AMT jack ?
I have an AMT jack made in Taiwan that I am trying to fix . Is this brand one you are familiar with Hiball? The u cup is shot. It is a 3 ton floor Jack. Id .85in od 1.4 in .33height are the dimensions of the piston and cylinder. I paid 20 dollars for it and 4 jackstands and a bottle jack . Can take pictures if you care to see them . Seems worth fixing . Thanks in advance
I have an AMT jack made in Taiwan that I am trying to fix . Is this brand one you are familiar with Hiball? The u cup is shot. It is a 3 ton floor Jack. Id .85in od 1.4 in .33height are the dimensions of the piston and cylinder. I paid 20 dollars for it and 4 jackstands and a bottle jack . Can take pictures if you care to see them . Seems worth fixing . Thanks in advance
Lift arm feedback that mimics the handle is a indication of a valve issue, double check the working valve assembly order.
I'm out of town, ill contact you via Pm when I get home..
Hiball--- i can not thank you enough--took her apart--cleaned everything---the two balls in one of the chambers were stuck---anywho---works like a champ now-- she's not the best jack in the world, but get's the job done---thanks again--- no way i could have done it without this feed!!! THANKS!!!!!!!!!
GeorgiaHybrid
Well-known member
Contact member hiball for a kit and do a search for a rebuild thread on Walker jacks.
Hey Hiball, I found this post when my jack quit. Great post! My jack is a little different because it has a speedy lift function. It is beefier than the newer China jacks and I would like to save it. Like you, I don't like throwing anything away.
Here's what I know:
It is a Penske Speedy Lift 3 Ton, about 10 years old, made by MVP. I took it apart and replaced the pump and valve seals, put it back together and it did nothing, NADA. I checked my photo and checked to see if I had it all back correctly, then I found a checkball on the floor that must have fell off magnet when dissassembling. I have no idea where this ball goes and quite certain that's the problem. Mine has an extra control valve not shown in your post. I'm including photos, one of my dissassembly and another of the power unit.
If you have a diagram for this type jack, it would help me get that "extra" ball back where it belongs. Thanks for considering my dilema.
Here's what I know:
It is a Penske Speedy Lift 3 Ton, about 10 years old, made by MVP. I took it apart and replaced the pump and valve seals, put it back together and it did nothing, NADA. I checked my photo and checked to see if I had it all back correctly, then I found a checkball on the floor that must have fell off magnet when dissassembling. I have no idea where this ball goes and quite certain that's the problem. Mine has an extra control valve not shown in your post. I'm including photos, one of my dissassembly and another of the power unit.
If you have a diagram for this type jack, it would help me get that "extra" ball back where it belongs. Thanks for considering my dilema.
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Hey Hiball, I found this post when my jack quit. Great post! My jack is a little different because it has a speedy lift function. It is beefier than the newer China jacks and I would like to save it. Like you, I don't like throwing anything away.
Here's what I know:
It is a Penske Speedy Lift 3 Ton, about 10 years old, made by MVP. I took it apart and replaced the pump and valve seals, put it back together and it did nothing, NADA. I checked my photo and checked to see if I had it all back correctly, then I found a checkball on the floor that must have fell off magnet when dissassembling. I have no idea where this ball goes and quite certain that's the problem. Mine has an extra control valve not shown in your post. I'm including photos, one of my dissassembly and another of the power unit.
If you have a diagram for this type jack, it would help me get that "extra" ball back where it belongs. Thanks for considering my dilema.
Navy man, your pictures aren't showing up, but here is a link to a 3 valve speedy,quick/magic lift jacks. There are a few variations of theses jacks ( this link is for the vertical pump, versus the angled) but the majority use the same hydraulic system, so disregard the aesthetics and pay attention to the valve order and parts list.
http://www.shinnfuamerica.com/Temp/2352.PDF
Anyone know what brand of jack this is? Appears to be a walker/lincoln design but the rear wheels are welded and look different than what I've seen? Very old one?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290811582907&ssPageName=ADME:B:SS:US:1123
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290811582907&ssPageName=ADME:B:SS:US:1123