Lube for Bronze Bushing?

[kartracer55]

Ok, I know bronze bushings, especially the ones with graphite in them are supposed to be self lubricating, but apparantly they arnt at very high speeds.

The application is the kart clutch (again). This bushing usually wont see speeds over 10,000 rpm, but it sees maybe 175*-200*.

Right now, I use white lithium grease during assembly, and after a run on the track I spray some tri-flow in there. I cant pull it apart after every run to grease it, so I need an aero-sol spray.

I was wondering if you guys could maybe help me out. I dont quite think Tri-flow is intended to handle the high speeds/temps like this. I mean, I dont have a problems with the bushings failing (at least not quite like the bearings) but When I pull the clutch I will see bronze sludge if you will that is sort of caked on the shaft. When I clean it off and reinstall the clutch the drum has alot of play because the bushings have worn more than they should.

Im looking for a way to keep this from happening. I mean, some guys lube them with wd40, but im looking to extend the life of the bearing. I dont think I need anything quite like krytox grease or other extremely high end greases, the white lithium grease (you know the stuff... in the yellow tub... everybody's got it!) seems to be ok, but Im looking for an aerosol lube that will stand up to the high speeds better than tri-flow will. I just dont think it was intended to. Im placing an MSC order tommorow so If you guys can recommend a product that would be good. I know bronze bushings really should be oiled (correct?) but I need an aerosol spray that I can use a little straw with due to the location.


Im looking at the super-lube line actually. I have a little tube of grease they make for fishing reels and its good stuff, but fishing reels dont really see too extreme of an environment lol

Thoughts? would I be better off just getting a decet grease and not worrying about having to relube it? What do you think? Its a pain to have to keep pressing in new bushings, they are simply wearing out too fast. Should I consider a dry-graphite lube? The bronze bushings have little pockets with graphite in them already.

What do you guys think?

Jim

 

[cc_rider]

Can you replace the bushing with a ball or roller bearing? I know it's drastic, but it would eliminate the issue.

c.

 

[kartracer55]

Yes, but youd be surprised. The needle bearings are actually more prone to failure and when they fail they start to eat up the shaft. I ordered an aftermarket component designed to use a bushing in it

Jim

 

[neblinc]

I use spray on white lithium grease in my fishing reels. It come with the little red spray tube to get into those tight spots.

Randy

 

[CraigFL]

...

The application is the kart clutch (again). This bushing usually wont see speeds over 10,000 rpm, but it sees maybe 175*-200*.

...

Jim

Are you saying the max speed is only 200RPM? Usually, clutches on the engine will see engine RPM (>10,000) or if they are axle clutches, maybe 1200RPM.

 

[kartracer55]

Sorry, I meant Temperature is usualy under 200*


Are axle clutches even legal? I want one!!

 

[W-Cummins]

more likey he can't do this

190° 210° etc....

William....

BTW ° is alt 0176 on the numeric key pad for unicode and the Veranda font ( the default here)

 

[kartracer55]

Ahhh thanks. Yeah, I wasnt sure had to do that


Jim

 

[CraigFL]

I get it.... Anyway, this what I call not your typical application. Bronze is used because it fails slowly as opposed to a needle bearing setup which would fly apart when it failed. Hopefully, you will see the wear and replace it before it becomes a major problem. That kind of bearing would normally be designed for a maximum surface speed-- RPM, diameter(circumference). I'm sure the application is way over the acceptable limits.
The only thing I see to prolong the life at that RPM is a drip oiler and even that wouldn't give you much. I would just face it that you will need to change it often. It's like the wear board on a Formula 1 car..-- the one that throws a shower of sparks when they hit a bump.

 

[MXtras]

I would suggest using a high temp, molybdenum disulphide grease. Maybe you could find a way to seal it just a little to help with contamination and retention - like positioning a few O-rings on the shaft?

Moly grease would be a good choice for this application in my opinion - something like Mobiltemp SHC100.

Scott

 

[kartracer55]

Thanks guys,

Craig, Thats kinda what Im thinking as well. I am just trying to avoid it ya know? They are only a few $ each so its not so much the cost, but I mean, Other than that, I have no need to spend the 45 minutes tearing down the clutch and putting it all back together. I can get 6-8 races out of a set of friction disks. Its just a pain to have to do it, ya know?

Scott, Ill hae to look into that stuff. Do you know if it comes in a tube or is it cartridge only?

Thanks

Jim

 

[MXtras]

It does not come in a spray can - like you were looking for. I believe it is in a tub or a tube only. Sorry.

Scott

 

[Tim240Z]

Try this:
Put the bushing on the palm of your hand (just below the thumb, on the meaty part of your hand). Place it upright so that the bushing is now a cup with your palm as the bottom of the cup. Pour in some motor oil (synthetic tends to work best as it is less viscous). Fill it as much as possible so that the miniscus of the oil is actually above the rim of the bushing. Use your other hand (same location, the meaty part under the thumb joint), and 'close' the cup and squeeze the oil into the bushing. Keep squeezing until you can see the oil seeping through the outside of the bronze. Don't know if it will help at those speeds, but we always did this with gearbox inputshaft bushings (the ones that go into the flywheel of the engine of a car/truck). It keeps the bushing lubricated for a long time.
Tim

 

[kartracer55]

Tim, Ill give that a shot as well. I have plenty of bushings and a buh of races left so Ill have aalot of time to experiment. Somebody on another board said I might consider a heavy weight synthetic, like a 20-50.

What does your kart run in the clutch drum? Your not Direct Drive right?

Thanks

Jim

 

[CraigFL]

Try this:
Put the bushing on the palm of your hand (just below the thumb, on the meaty part of your hand). Place it upright so that the bushing is now a cup with your palm as the bottom of the cup. Pour in some motor oil (synthetic tends to work best as it is less viscous). Fill it as much as possible so that the miniscus of the oil is actually above the rim of the bushing. Use your other hand (same location, the meaty part under the thumb joint), and 'close' the cup and squeeze the oil into the bushing. Keep squeezing until you can see the oil seeping through the outside of the bronze. Don't know if it will help at those speeds, but we always did this with gearbox inputshaft bushings (the ones that go into the flywheel of the engine of a car/truck). It keeps the bushing lubricated for a long time.
Tim

My guess is that the bushing is not sintered and is just solid bronze. This means it would not be porous and allow for oil impregnation. Sintered bronze bushings are fairly brittle and non-forgiving of shock loads like you would experience in a clutch drive.

 

[Tim240Z]

Jim,
The Rotax FR125 uses a caged needle bearing (unless running a 11 tooth drive gear, then it uses a bushing). I run a 12 tooth driver.

Craig,
Yes, granted, if it isn't a sintered bushing, that will not work.
I don't know which type it is, so I just threw it out there.

I wonder if cutting some grooves longitudinally inside the bushing would help to retain some lubrication. You would just have to be careful to deburr it afterwards.

 

[CraigFL]

When you cut grooves, it's a toss-up between the extra lube space and the decreased surface area which would cause more wear. I don't think you could effectivly lubricate the bushing without some sort of seal. Like you said, the real problem is that with only 11 teeth, there is no room for a needle cage...

P.S. I'm an ex-Kart racer too...from 35 years ago!!

 

[kartracer55]

Thanks guys

Tim, your running #219 right? I think the horstman guys need to take a lesson from whoever designed the rotax clutch.

Get this...

10tooth (what I run) uses a needle bearing, but the aftermarkets use a bushing. The 11 tooth drums use a bushing from the factory, and the 12 tooths go back to using a bearing... but its the same exact bearing as the 10 tooth drums. I dont get it!

Jim

 

[Tim240Z]

Jim,
Yes, I'm running a 219 chain.
Tim

 

[kartracer55]

Then Why the hell cant horstman make a 219 sprocket to accept a bushing?????


jeeze!

And by the way, you know your a die-hard kart racer when you break in an engine during hurricane Errrrnesto. Haha It better be a powerhouse tommorow after what I sat through today!!

Jim