WHERE DOES THIS PART GO????

[PITAPan]

Wow.......no end to the good info coming.......another complete procedure........I am surprised that someone hasn't made some tools for reading the axel torque for sale??? I'm guessing that my standard inch pound torque wrench isn't a fine enough calibration for these tiny bearings......does any mfg. make a small grams type torque wrench???
I agree with the above that the string pull method would seem iffy because of the "starting torque" verses the running torque. I felt that the original author covered that objection well, in mentioning the use of a really long string to get the measurement stable after the beginning of the pull.
In truth, I am a reasonably qualified tech, being a retired ASE Master truck tech.
I feel reasonably confident that I could set these up reasonably well just by hand feel. I have already ordered the grams scale.....so I'll give it a try and see what I get. As for the seals, I have those on order from MAX as well. I'll install them last after the pre load is obtained.

I'm having a wonderful time now, trying to see how close to "on spec" I can come in learning about the proper properties for the grease.
The SKF spec is so outdated (Shell Grease: Shell Retinax A, Filling degree (For BT1), Basic oil type Mineral, Basic oil viscosity 220 mm2/s at 40 degrees C and 16 mm2/s at 100 degrees C, Thickener Li, Temperature range -20/+110 degrees C, Consistency NLGI=2 ; special grease quantity for TRB's) ...........that I can not find any reference anywhere as to the updated modern shell product. I was very interested in the 220 & 16 mm2/s specs. I found at least 1 grease that has slightly higher numbers Castrol Blue grease) and a lot of greases that have lower numbers. Can I assume that in this case the slightly higher viscosity numbers would be preferable to slightly lower numbers????
As a side note: Personally, in forums, I do my best to stay "on Topic", consider everyone's point equally, and never try to be in "controversy". I consider it to be a place to Learn, not a place to argue.
Rgards, Ibjman

I use whatever Moly EP grease is in the gun, and a lot of it w/ a bearing flusher/packer. But I'm known to be a complete hack and the antithesis of the "precious" airhead owner. I pour the good oil I use into Kmart house brand bottles just to disturb visitors. Keep the torque wrench wound up so it's handy as a breaker bar, etc.

For the /7, the wheel bearing preload spec is 15-30 Ncm. ie, 22.5 Ncm +-7.5

The radius of the jig Snowbum is using is 1.905cm.

7.5Ncm/1.905cm=3.93701 N = 401.46...grams-force

The Ohaus 8004 MA has a 2000 gram range and a 50 gram readability. Take the readability out of the 401g tolerance and call that 350 grams. 17.5% of full scale. Might do that. Ohaus is mighty mum on the matter---but I would want to check it and if I need a weight for that, why do I need another scale? (besides I'd have to buy one, MSRP $16 + shipping)

There are arguments and arguments, and I mentioned. I come from a very long line of people who are very fond of arguing---but even more fond of truth. I think of arguments as honest and dishonest---it's sort of instinctual. Do they cleave to tradition or not?

[ME 109]

What I found out was that both of the wedding band spacers I had on hand were too short and the bearing preload was way too high. So high that sliding the string to the end of the beam didn't do it, I would have had to make up a bigger weight. So, I tried decreasing the torque on my axle nut. I think I backed off 15lb-ft or something, don't really remember. But that got me pretty close. So I said screw it and just greased up the bearing and installed the wheel on the bike---not tightening the axle nut as much as I would have otherwise.

So your bearing preload is determined by the axle nut torque? Wrong. The axle nut has nothing to do with 'setting' preload properly. I suspect that you know that, and that you're just being slack. Like me.

There is not a wide range of torques available.
Preload on a trb for a bmw wheel is precise. Too tight (as in your case) = smoked bearings.
Too loose = a flooppy wheel.
Neither of these situations will give you 1 million miles.

[barryh]

I understand that using axle torque to set the bearing pre-load is not the right thing to do but I consider it acceptable within limits at least on the front wheel where the axle is clamped both sides. I'd be quite happy using say 20ft/lb instead of 35 ft/lb. In any case unless you get lucky the standard 0.002" increments of wedding band spacer don't allow for that precise a pre-load setting without some variation of the torque.

Obviously if all play goes away at 5ftlbs you have to shim it. That's how my rear wheel came from the factory though and it survived the first 6000 miles without problem. I'm less happy about using too low a torque on the rear wheel as the axle is only clamped on one side so I go to some trouble to shim it as close to spec as I can. It's probably not necessary but if you want to be anal enough get it spot on I found that meant working to half a thou on the shims. If someone has never set bearing pre-load before and they are indoctrinated in to the view that it must be spot on there's a fair chance they are going to be frustrated by just using the available range of wedding bands.

[PITAPan]

What I found out was that both of the wedding band spacers I had on hand were too short and the bearing preload was way too high. So high that sliding the string to the end of the beam didn't do it, I would have had to make up a bigger weight. So, I tried decreasing the torque on my axle nut. I think I backed off 15lb-ft or something, don't really remember. But that got me pretty close. So I said screw it and just greased up the bearing and installed the wheel on the bike---not tightening the axle nut as much as I would have otherwise.

So your bearing preload is determined by the axle nut torque? Wrong. The axle nut has nothing to do with 'setting' preload properly. I suspect that you know that, and that you're just being slack. Like me.

There is not a wide range of torques available.
Preload on a trb for a bmw wheel is precise. Too tight (as in your case) = smoked bearings.
Too loose = a flooppy wheel.
Neither of these situations will give you 1 million miles.

Umm...methinks one of us should read the instructions again (hint: not me). The bearing preload cannot be set by any method unless the axle nut it torqued to specification. If thouest doubt, then just set the axle torque to 0, that is take it off. Now lets see you set the preload. It follows that the nut must be torqued to some non-zero, non-negative number. So what value will you choose?

The preload isn't precise. There was rather a nice page on that. I found the results surprising but someone went to the trouble to graph the bearing preload against the life expectancy using standard equations--and there it was.

There is such a thing as too loose and too tight. There is also too big and too small, too green and too red, too hot and too not-hot. But these are qualitative statements and meaningless in this context. If you don't get quantitative what you are saying means exactly nothing (zero is one of the more precise of the numbers). You can tighten by feel, which is a semi-qualitative method, and them measure what you have done, which is fully quantitative.

I apologize for the big words. I'm working on the new heated grips and at the last moment I remembered I had some rolls of PTFE glass cloth tape good for 400F with a silicone adhesive on it. So I can sandwich my wiring in that rather than the grey silicone goop and butter cloth routine I was going to do. I amaze myself sometimes----anyway I came in to warm up and figured I was on a roll...


NB, the same bearing in the headset application is far more critical. The method of setting it is different that wheel bearings and the setting is as-tight-as-you-can-get-it-and-still-have-completely-free-movement-of-the-bars.

[ME 109]

If someone has never set bearing pre-load before and they are indoctrinated in to the view that it must be spot on there's a fair chance they are going to be frustrated by just using the available range of wedding bands.

It is indeed a dark art Barry. And a bloody stupid idea for an every day machine that gets played with by a lot of people.
The concept of a trb is excellent, the reality of that concept in this situation ain't so smart.
Once the preload is right, and the same brand bearing is used as a replacement each time, there's little problem.
That's the problem.

[Ken in Oklahoma]

I understand that using axle torque to set the bearing pre-load is not the right thing to do but I consider it acceptable within limits at least on the front wheel where the axle is clamped both sides. I'd be quite happy using say 20ft/lb instead of 35 ft/lb. In any case unless you get lucky the standard 0.002" increments of wedding band spacer don't allow for that precise a pre-load setting without some variation of the torque.

Obviously if all play goes away at 5ftlbs you have to shim it. That's how my rear wheel came from the factory though and it survived the first 6000 miles without problem. I'm less happy about using too low a torque on the rear wheel as the axle is only clamped on one side so I go to some trouble to shim it as close to spec as I can. It's probably not necessary but if you want to be anal enough get it spot on I found that meant working to half a thou on the shims. If someone has never set bearing pre-load before and they are indoctrinated in to the view that it must be spot on there's a fair chance they are going to be frustrated by just using the available range of wedding bands.

When you think about it, using the axle nut to set bearing preload (sans wedding band) is essentially the same as setting the preload on the front spindle of millions of cars. The big difference is that there's no cotter pin to ensure that the nut stays in place on the axle. (Of course that little consideration can be handled by boring a hole in the axle and using your handy dandy milling machine to make a castellated nut. (Or I guess you could use your angle grinder to make the castellated nut.

On the other hand, for the front axle, I would be very nervous because you would be counting on the fork slider pinch bolts to keep the adjustment you set. (I regard airhead front forks as being pretty springy.)

Ken

[PITAPan]

I understand that using axle torque to set the bearing pre-load is not the right thing to do but I consider it acceptable within limits at least on the front wheel where the axle is clamped both sides. I'd be quite happy using say 20ft/lb instead of 35 ft/lb. In any case unless you get lucky the standard 0.002" increments of wedding band spacer don't allow for that precise a pre-load setting without some variation of the torque.

Obviously if all play goes away at 5ftlbs you have to shim it. That's how my rear wheel came from the factory though and it survived the first 6000 miles without problem. I'm less happy about using too low a torque on the rear wheel as the axle is only clamped on one side so I go to some trouble to shim it as close to spec as I can. It's probably not necessary but if you want to be anal enough get it spot on I found that meant working to half a thou on the shims. If someone has never set bearing pre-load before and they are indoctrinated in to the view that it must be spot on there's a fair chance they are going to be frustrated by just using the available range of wedding bands.

Well, screwing with your axle nut torque to adjust the preload is a bit flaky. But even on the rear, I got enough torque on the nut so it isn't falling off (or hasn't yet) and clamping the axle on one end is rather thorough. Try to pull it out with the tommy bar and cam.

Lapping the wedding bands is STOP. Piece of 400 grit paper on a flat surface and a light hand while keeping it dead flat. It takes very little---one should be careful not to remove to much which is surprisingly easy to do. I never had any problem nailing the preload on the /6 removo-stacks. The thing is done by feel but it's an easy feel. It snap clicks or it don't. But you can also work those both ways, which is nice if you make it too tight.

I think someone tried shimming mine (/7) with some sort of goop. It didn't work and with the stuff removed, the bearing was too tight. But it was close enough I couldn't use a feeler gauge to measure for the wedding band I needed. I'll just have to measure the band, get the next size up and walk it in by lapping.

I know I have variation in the torque because I'm not using a torque wrench when I put my wheels on. So I want to check what my wrist is doing on various days. Some days I screw the caps back on the soda bottles so tight I need a wrench to get them off, but I'm not aware of doing it.

[barryh]

When you think about it, using the axle nut to set bearing preload (sans wedding band) is essentially the same as setting the preload on the front spindle of millions of cars. The big difference is that there's no cotter pin to ensure that the nut stays in place on the axle. Ken

The other big difference is that many cars specify end float of say 1 or 2 thou. My understanding of a possible reason they do that is not because they really want or must have end float. A little pre-load would be OK too. They do it because it's not hyper critical and end float is easy to measure and set for the average mechanic either with a dial indicator or by a knowledge of the thread pitch. Pre-load on the other hand is not at all easy to measure even when it's possible. Having a very small amount of end float on a bike would not be the end of the world (think ball race wheel bearings which have some fraction of a thou) but it's not desirable even on a car. I'm reminded of taking my old Merc for it's annual inspection which I've been doing for 20 years. They kept giving me an advisory notice for slight play in the steering joints. I reduced the wheel bearing end float from the specified couple of thou to as near zero as I could get it and no more advisory notices. I used to reset bearing end float after the inspection but gave up on that once I'd got to grips with Airhead wheel bearings.

It's interesting to ponder on the fact that setting end float to exactly zero is impossible. Maybe that's one reason why they specify either a little end play or a little pre-load.

[PITAPan]

When you think about it, using the axle nut to set bearing preload (sans wedding band) is essentially the same as setting the preload on the front spindle of millions of cars. The big difference is that there's no cotter pin to ensure that the nut stays in place on the axle. Ken

The other big difference is that many cars specify end float of say 1 or 2 thou. My understanding of a possible reason they do that is not because they really want or must have end float. A little pre-load would be OK too. They do it because it's not hyper critical and end float is easy to measure and set for the average mechanic either with a dial indicator or by a knowledge of the thread pitch. Pre-load on the other hand is not at all easy to measure even when it's possible. Having a very small amount of end float on a bike would not be the end of the world (think ball race wheel bearings which have some fraction of a thou) but it's not desirable even on a car. I'm reminded of taking my old Merc for it's annual inspection which I've been doing for 20 years. They kept giving me an advisory notice for slight play in the steering joints. I reduced the wheel bearing end float from the specified couple of thou to as near zero as I could get it and no more advisory notices. I used to reset bearing end float after the inspection but gave up on that once I'd got to grips with Airhead wheel bearings.

It's interesting to ponder on the fact that setting end float to exactly zero is impossible. Maybe that's one reason why they specify either a little end play or a little pre-load.

A ball bearing is a different animal, even an angular contact type. The end fload or "preload" actually changes the geometry of the balls in the races (less so on angular contact). On the 16007 C3 (crank front bearing, standard cardan ball bearing) the C3 specifies a larger internal clearance. You can feel it (just) with the bearing in hand. They won't take any end load so they run bit sloppy in that direction. (or they better!).

On the tapered roller (30203x) once the rolling elements are in contact the geometry doesn't change. But if there is the slightest play they brinnell quickly, and if they are too tight there isn't clearance for lubrication and they burn. So you set to zero play and then a bit tighter for CYA.

Same bearing in the headset and any play is a problem much faster because the loading is mostly axial. I lost the headset bearings on my first bike (/5) by not knowing to set them accurately. On replacement I did it correctly and they lasted 20+ years. But at the same time if they are even a bit too tight the steering is compromised. You really want as close to zero play with minimal preload as you can get.

I think the R65 had ball bearings on the front. Don't know the setting Procedure for those.

A fixed torque screwdriver will go down to the values used for the peload spec on the wheels, and it's quick. But they are costly and you still have to work out a coupling. In the factory manual they call this a "Torsiometer" and it looks like a variable torque screwdriver to me. They couple to the axle nut with a socket. They also show the Push-with-thumb method for the removable stacks.

It occurs to me if I put a stop collar on my torque beam to locate it in the axle hole, and an encircling weight (lead spoke wheel weight?) on the beam rather than the weight and string, I would have a very quick to use go/no-go tester for the preload. If I'm thinking about it right, the math wouldn't be too ugly.

[ibjman]

This is the failed bearing inner race taken from the left rear (1982 R100rs) 26,000 miles. Right side looked great, outer race looked good with the exception of the expected "dents & marks" caused by running over the flakes from the failed inner race. 2 of the rollers were just starting to flake away