Bearing Failure... Help!

[kartracer55]

Ok, so I am having a problem with a bearing. The OEM ones are Made in Japan IKO BA95Z... shelled needle bearings. This one had less than an hour of run time before it was whipped! They are for a clutch drum on my kart, normally they use bushings but this is a special drum. Anyway, I use special machined spacers to keep endplay to a minimum, and there is hardly any axial? load on it. The problem is they encounter two things bearings dont like... High speeds and high temps.

They see pretty high temps... too hot to touch with your hand without getting seriously burned. And they see regular speeds of as much as 9000 RPMS, but On occasion they can get even higher.

Anyway, I called a bearing place and they had a few in stock, so I ordered a couple.

What can I do to keep these things "Alive" so to speak? What sort of lube should I be using? I was thinking wheel bearing grease because of the high speed and temp, but would it be too thick for this application? I had a long conversation with the guy on the phone about this but I want more opinions for you guys.

And No, I cant really switch to a different kind of bearing, because of the tight space... only maybe a different style of needle bearing...

THanks

Jim

 

[REFLEXX]

Perhaps dry ceramic bearings or "Air" bearings?

Are your bearings seeing just RPMs and temp or vibration also???

At those speeds, any lube just gets flung out. Perhaps a system of oiling the bearing while in use? You cannot be the ony one with that problem?!?

as for tight space, can you machine out for a bigger bearing?

 

[DynoDave]

"At those speeds, any lube just gets flung out. Perhaps a system of oiling the bearing while in use? You cannot be the ony one with that problem?!?"

This was my thinking as well. Is this a sealed bearing to retain the grease?

 

[CraigFL]

My opinion FWIW....

At 9K rpm, this should be a oil lubed, caged needle bearing. You may have to live with shortened life (a single race + practice) unless you change bearings. It is unlikely that a different manufacturer would have a bearing with a higher rating for the same size. It would be interesting to know why the bearings are failing. I'm assuming this is on your centrifugal clutch hub and it's spinning until your clutch locks up?

 

[MXtras]

The needle rollers are not all that well suited for high speeds. I would not recommend a needle roller for such an application - especially without oil bath lubrication. They are also extremely sensitive to contamination.

If you are stuck with this bearing then try Krytox grease - made by DuPont. If it fails to survive then you are really in a pickle because nothing comes close to the performance of this lubricant. Obtaining a peak running temp would help you select the appropriate lube.

Scott

 

[MXtras]

Jim -

When I first read this topic, one individual immediately came to mind. This guy posts on www.cnczone.com as "NC Cams" and worked in bearing engineering for many years. He is Johnny-on-the-spot with many critical, high accuracy, demanding bearing questions and fields such topics with substantial authority. I took the liberty of asking his opinion on this and here is his response:

I'm not that familiar with that brand of bearing BUT needles fall into 2 categories - full complement or caged type.

Caged tend to have better high speed performance (the rollers don't rub against each other thus stripping off lube) but they don't have the radial capacity of a full complement.

The first thing you need to know is whether or not the bearings have the necessary capacity. Many times guys package stuff and don't consider loads involved and some NEVER do life calcs - not even with SWAG loads.

Assuming (bad assumption) that the bearings have adequate capacity (probably not), the next thing to look at is execution. Is the housing round, are the finishes proper, is the raceway smooth, round, properly clearanced (as in measured and not feel) ???

Final and most common issue that causes problems is lubrication (lack thereof or contamination thereof).

The most common cause of ANY bearing failure is contaminated lube.

Next common cause is assembly damage.

Next is poor housing/shaft geometry and next is insufficient capacity.

If somebody says "I checked it all and everything is right...", he clearly didn't or else it would work.

Hope this helped

 

[kartracer55]

Thanks guys! Im not sure of the temp, but I cant see it being over 500* but it is much too hot to touch, and you can get burned if you touch it right off the track. I run about 460* measured right at the seat of the sparkplug, but Id imagine the bottom end is cooler.

Craig, your correct... this is the hub bearing. I can get pics tommorow if you guys are interested. I just got 10 direct replacement bearings for it, same brand and everything, but now im looking for longevity. The problem Is I cant get an oil bath in there. Before I was trying to lube from the side because pulling the clutch during the raceday is something I avoid. It takes about 15 minutes to get it off, another 15 to get everything deglazed, aligned, lapped etc, then another 15 to get it setup, plus 5 new 10-32 screws each time. Its too much to do as regular maintenance on a raceday. I was thinking about drilling a hole in line with the oil hole on the shell but the drum is hardened steel and id be drilling on a slope.

Reflexx & Dave... I was kinda of thinking the same thing but I was hoping a grease would stay in better than a sort of liquid, and it has an outer shell. These things are notorious for having problems, but this is a first as far as I know.

Scott, I appreciate that! ******** that krytox grease is expensive!!!!! lol

Id imagine the housing is pretty round, there is no play that I can feel. The pin it rides on isnt exactly smooth, fairly close though. The one problem that these cranks have is that they are relativly soft (I hate yamaha) for a so called "hardened" crank, and apparantly needle bearings dont fair very well on non-hardened pins.

These are caged needle bearings, which are what the bearing guy told me seemed to be the best for this application.

What it comes down to is lube Id imagine. I am just at a loss because of the temp, load and speed. Id love to get a bushing like I used on the other drums with different size drivers, but for soem reason they only use bearings on these.

I might have to go for that krytox, any other stuff out there that might work?

THis is a pain in the ***... Im so tempted to go Direct drive to avoid this damn clutch haha

Thanks!

Jim

 

[Tim240Z]

Direct drive gets very 'interesting' when you stick the engine, especially when it seizes in the apex of a fast, banked, right hander......I speak from experience

 

[OctaneMotorsports]

Your engine runs 460F on the CHT? Holy ****...the Maxter I run runs between 300-350F. That's insane, lol.

Yeah man, get an ICA or convert your KT100 to direct drive.

 

[katit]

Better yet get water cooled Leopard TaG (if class available in your area)
Much cheaper in a long run. I had no single problem with mine for whole year.
Or get stock shifter. Will be more reliable that crappy air cooled KT

 

[kartracer55]

Octane... A guy I know hit 490 by the end of a 30 lapper he ran the day before this particular bearing incident. I hottest I got was 476, but I usually try to get it between 425-460 for CHT. CHT is a bad way to tune though, because ambient temp and air flow has a big effect. Also, it takes a while for the heat to transfer through the aluminum head. EGT is ideal because its instant.

Katit... I want one! We have a TaG heavy and A TaG light around here. I also runa margay limo chassis in the kt100 heavy class but alot of guys do quite well with these chassis in TaG. As you said the Leopard seems to be one of the best engines around. I definetly want one but its the kt100 for the rest of this season.


Ill get some pics up later for everybody else to see the exact application.

Jim

 

[katit]

Katit... I want one! We have a TaG heavy and A TaG light around here. I also runa margay limo chassis in the kt100 heavy class but alot of guys do quite well with these chassis in TaG. As you said the Leopard seems to be one of the best engines around. I definetly want one but its the kt100 for the rest of this season.

I had Monza with extention kit (tall guy as well )

If you have stock shifter class - I strongly suggest it if you can afford additional expense on chassis. Stock shifter motor cost about the same as TaG 125cc

Honda/Yamaha more reliable then Parilla, you will have much more fun. I had shifter but without much help on a track decided to go TaG. Phew

 

[kartracer55]

Ok... Pictures..



Side view of the clutch... these bearings sit between the sprocket and the black plate to the left of the tan disk closest to the engine.... talk about hard to get too





This is where the bearing fits in... you can see how it spun inside, but the new bearings seem to fit fine.



whats left of the old... and the new ones


Ok, so thats what Im workin' with here. I was told similar dry clutches can see between 4-500* if they are slipping too much (IE too many slow pace laps)

Katit, this track used to run ICC and Moto, but they combined the classes, and alot of Moto guys left because most of the moto engines couldnt keep up on the straights with the gearing. Of course there are a few who do VERY well, but other than that its mostly ICC around here.

Jim

 

[Charles (in GA)]

I'm thinking you need one of those Infrared Digital Themometers. The handheld type with a laser aiming device and in this case you need a fairly high temp range. Most of the cheap ones either don't go high enough temp (about 400f seems to be common on the cheap ones) or they don't have the laser aim point and or the ability to measure a small area. This Grainger/Westward model goes to 788F but no laser and measures a 1 inch circle at 8 in distance, and is under a $100.

http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1612840858

Charles

 

[kartracer55]

I'm thinking you need one of those Infrared Digital Themometers. The handheld type with a laser aiming device and in this case you need a fairly high temp range. Most of the cheap ones either don't go high enough temp (about 400f seems to be common on the cheap ones) or they don't have the laser aim point and or the ability to measure a small area. This Grainger/Westward model goes to 788F but no laser and measures a 1 inch circle at 8 in distance, and is under a $100.

http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1612840858

Charles

I kinda have one. I say kinda because... there are a few of us who pit together and we found it one day. It isnt really anybody's in particular it just gets passed around. The problem is I didnt know the bearing was whipped until the other night when I went to go through the clutch and relube the bearing. I cant get it up to normal operating temp until the weekend, but Ill definetly try to get some accurate measurements on it for you guys.

Did I mention I hate this sport yet?

Jim