Shimming Airhead wheel bearings

[woody's wheel works]

Originally Posted by El Hombre

Thanks for the quick reply, I thought it might have something to do with pinching the bearings. Have you noticed any difference in the name brand SKF, etc. and the cheaper ones? I ordered two of the SKF for the back wheel, and going to try two of the cheaper ones up front.

you are right,,, it has to do with ''pinching the bearings''

as far as saying which brand is ''better'',,truth be told ,,we have probably installed every brand name out there ,,properly set-up and lubricated they have all worked...we don't buy discount bearings,,,nor do we patronize iffy sources,,,

what i've noticed is that there's a bunch of counter-fitting going on and every brand name manufacturer is addressing the issue....so if you are getting an SKF that sells for $10-20 over the counter and you find em advertised somewhere for $2-3 well caveat emptor...

i wouldn't be surprised that even ''brand'' names are made in china or some third world country,,, outsourcing has it's tentacles everywhere.....whoever can get it done for less,,,,hence,,,when ya can't squeeze any more juice out of the lemon,,well then your next profit source is packaging the junk in some recognized high end brand name's box,,the ultimate ''plastic fuzzy''
w

[pommie john]

I don't see how a correctly shimmed tapered roller bearing can be pinched by over tightening the wheel nut.
If over tightening the wheel nut squeezes the bearing so much that it seizes, surely the thing hasn't been shimmed right in the first place?

[woody's wheel works]

Originally Posted by pommie john

I don't see how a correctly shimmed tapered roller bearing can be pinched by over tightening the wheel nut.
If over tightening the wheel nut squeezes the bearing so much that it seizes, surely the thing hasn't been shimmed right in the first place?

well,, it's real easy to check if that is happening..if BWOE the spec is xxinch /lbs of torque/resistance at 30 ft/lbs of axle nut torque ...you can actually feel what that reading is by twisting either the axle or turning the hub....put 60 lbs of torque on it and i bet you'll feel the difference,,,same sorta thing happens over on the F800gs rear bearing disintegrates thread....properly speced bores feel smooth when ya turn the bearing ,,undersized bores make the bearing ever harder to turn...

i know in a perfect world the bmw set-up does work when everything is perfekt... and their is not much room for fudging if ya miss any of the steps [cept having it be a little looser thus erring in a safer direction]

my rule of thumb was no end play and very little drag when turning the axle

your notion works if there would be zero compression of the inner spacer assy

BWOE,,take all the old harley stuff,,they ran their tapered set ups quite loose ,,partly because of the chintzy /flimsy spacer material,,you get one of those big bruisers and a 16'' wrench ,,they tightened those axle nuts to 75 ft/lbs and then some ,,i'd need a 4' cheater bar to break the axle nuts loose...my custom spacer set-ups were made of beefy machine grade steel tubing ,,,it didn't give
w

[El Hombre]

Originally Posted by pommie john

I don't see how a correctly shimmed tapered roller bearing can be pinched by over tightening the wheel nut.
If over tightening the wheel nut squeezes the bearing so much that it seizes, surely the thing hasn't been shimmed right in the first place?

You understand it, if you have it shimmed so the roller bearings are just kissing the inner races or a slight pre-load, then cranking on the axle nut won't screw it up.

Took me a while to understand what was going on with the bearing stack; eventually I could visualize how the squeeze from the axle nut goes thru the axle spacers, inner races, inner spacer and wedding ring, and pulls everything up tight without crushing the bearings. Get the wedding ring too big, lots of slop. Too small, crush the bearings.

All of this is why I'm going to ball bearings, just get the inner bearing spacer the correct length, once, and it's a done deal with no more lubing or adjusting.

[pommie john]

Originally Posted by El Hombre

.....

....All of this is why I'm going to ball bearings, just get the inner bearing spacer the correct length, once, and it's a done deal with no more lubing or adjusting.

Yeah, once they're set up they work well, but strictly speaking, a tapered roller bearing is more suitable for the forces that a wheel experiences.

[El Hombre]

Originally Posted by pommie john

Yeah, once they're set up they work well, but strictly speaking, a tapered roller bearing is more suitable for the forces that a wheel experiences.

I've read the tapered roller bearings were used by BMW because of the side thrust you get with a sidecar. Without a sidecar, all the load is straight down into the races. Which ball bearings handle quite nicely. The ball bearings I'm using are a deep groove race, those are able to withstand some sideloads, not as much as a tapered roller, but enough.

All of the rear wheel drive cars I worked on had roller bearings in the front axle. But all the front wheel drive cars had ball bearing hubs, usually double row. So the industry has been changing over to ball bearings for some time. I decided to join them....And Woody's experience with them, gives me confidence they'll work fine.

[mark1305]

Luckily, the tapered bearings in my R80 ST are shimmed spot-on and with a little care and feeding they should outlive me.

For single row ball bearings, I've read recommendations in both the Ducati communities I hung out in and in the F650 community that routinely replacing wheel bearings and if applicable, sprocket carrier bearings at about 15K mile intervals as preventive maintenance is good practice. Good quality bearings like SKF and FAG are cheap enough at my local bearing jobber that I try to keep to that and usually have the next set already on the spares shelf.

[supershaft]

Originally Posted by pommie john

I don't see how a correctly shimmed tapered roller bearing can be The pinched by over tightening the wheel nut.
If over tightening the wheel nut squeezes the bearing so much that it seizes, surely the thing hasn't been shimmed right in the first place?

Within reason they don't. The rear axle nut especially almost never gets a torque wrench for the muffler being in the way. I have seen that nut get over tightened by hand literally hundreds of times over wrenching at dealerships and whatnot. If the bearings are set up right to start with, they can handle it NO problem.

[supershaft]

Originally Posted by pommie john

Yeah, once they're set up they work well, but strictly speaking, a tapered roller bearing is more suitable for the forces that a wheel experiences.

I would say "theoretically" they are better because strictly speaking about practical use the sealed ball bearing hold up tens time better.

[supershaft]

Originally Posted by mark1305

Luckily, the tapered bearings in my R80 ST are shimmed spot-on and with a little care and feeding they should outlive me.

For single row ball bearings, I've read recommendations in both the Ducati communities I hung out in and in the F650 community that routinely replacing wheel bearings and if applicable, sprocket carrier bearings at about 15K mile intervals as preventive maintenance is good practice. Good quality bearings like SKF and FAG are cheap enough at my local bearing jobber that I try to keep to that and usually have the next set already on the spares shelf.

I would ask why? They have almost NO problems. Most sprocket carriers have them doubled up to handle the radial load perfectly. Other than that they last almost forever.

Early F650's had some wheel bearing issues because they had junk Russian made bearings in them but BMW quit using that brand.

[woody's wheel works]

Originally Posted by El Hombre

I've read the tapered roller bearings were used by BMW because of the side thrust you get with a sidecar. Without a sidecar, all the load is straight down into the races. Which ball bearings handle quite nicely. The ball bearings I'm using are a deep groove race, those are able to withstand some sideloads, not as much as a tapered roller, but enough.

All of the rear wheel drive cars I worked on had roller bearings in the front axle. But all the front wheel drive cars had ball bearing hubs, usually double row. So the industry has been changing over to ball bearings for some time. I decided to join them....And Woody's experience with them, gives me confidence they'll work fine.

thanks for pointing that out regarding the tapered bearings and their enhanced ability to take side-loads... like in side-car and trike applications....however regular motorcycle applications do experience some lateral loads ,obviously within the abilities of current ball bearings design parameters.

...and that's why you should opt for the appropriate ball/tapered bearing for each application,,, motorcycles with tapered bearings are IMHO leftovers from the days when people bought a lot of sidecars,,,even HD has gone mainstream as of circa 2000 and switched to ball bearings ,,,BMW quit circa 1980.

w

[pommie john]

Originally Posted by El Hombre

Without a sidecar, all the load is straight down into the races. Which ball bearings handle quite nicely..

So long as you never turn a corner

[mark1305]

Originally Posted by supershaft

I would ask why? They have almost NO problems. Most sprocket carriers have them doubled up to handle the radial load perfectly. Other than that they last almost forever.

Early F650's had some wheel bearing issues because they had junk Russian made bearings in them but BMW quit using that brand.

Apparently both communties experienced enough bearing failures, or early failure symptoms (I'm talking 1990s bikes in all these cases) to come up with the idea of preemptive replacement at roughly those intervals.

In my case, my 95 M900 had a notchy wheel bearing at about 13K miles. My 99 F650 had a notchy sprocket carrier bearing at pretty close to the same mileage, give or take 1-2K miles.

Since my Ducatis spent about equal miles on the street and track, and my F 650 was my long haul bike and I wouldn't want to have a bearing go out at a track 500-700 miles from home(especially at speed) nor on a trip to a rally that far or farther away, it is a simple choice for me. That's my why. I've spent a lot of years in a career where risk management got you home. It's carried over into my recreational life too. Ain't preaching it as gospel, just mentioning it as food for thought.

[supershaft]

Originally Posted by mark1305

Apparently both communties experienced enough bearing failures, or early failure symptoms (I'm talking 1990s bikes in all these cases) to come up with the idea of preemptive replacement at roughly those intervals.

In my case, my 95 M900 had a notchy wheel bearing at about 13K miles. My 99 F650 had a notchy sprocket carrier bearing at pretty close to the same mileage, give or take 1-2K miles.

Since my Ducatis spent about equal miles on the street and track, and my F 650 was my long haul bike and I wouldn't want to have a bearing go out at a track 500-700 miles from home(especially at speed) nor on a trip to a rally that far or farther away, it is a simple choice for me. That's my why. I've spent a lot of years in a career where risk management got you home. It's carried over into my recreational life too. Ain't preaching it as gospel, just mentioning it as food for thought.

I wonder if Ducati was using the same junk bearings? After the F650GS came out and BMW quit putting the junk bearings in SOME of their F650, they never had any problems just like almost all sealed roller ball wheel bearings. The F650 bearings got checking the sealed ball wheel bearings during tire changes a mandated shop ritual. After the GS came out, we went back to never finding any to replace again. We changed a LOT of tires there!

[El Hombre]

Originally Posted by pommie john

So long as you never turn a corner

I don't know how they do it down under, but up here we lean the bike into a corner. And that puts the bearings directly inline with the load. In a car, rip thru a turn and you feel your ass wanting to slide sideways on the seat. Do the same on a bike, it just pushes you harder into the saddle. But when you antipodian's come up here, you seem to pick up the leaning in turns thang pretty good; Mladin, et al.