Roller Wheel Bearing Adjustment

[problemchild]

Perhaps someone could explain the correct procedure for adjusting the front wheel bearings on a car with the roller bearings. Thanks!

[grimes34]

Are you kidding?

[problemchild]

No.

[hardingfv32-1]

This is an interesting question. The old myth with ball bearings is to set then loose, but is this in fact correct if you want low drag? This is what Timken does for the NASCAR teams, maybe there is something to be learned: http://machinedesign.com/ContentItem/62 ... track.aspx

Brian

[cendiv37]

Greg,

I've been using roller bearings for most of my time racing FV's. In that time, I've always used spacers and a shim pack between the inner races. I shim to .001" - .003" end play (cold) measured with a dial indicator and mag base. This is true end play, not rocking of the drum. I've never measured the end play hot, but they always spin very freely once the grease is warmed up.

I don't think we need any preload for stability since the loads aren't that great, especially compared to a high CG, 3500# cup car running on high banked ovals at 180 mph. I've never had any sense of instability that wasn't traceable to another source (loose link pins, worn or displaced trailing arm bushings, etc.). I use Red Line synthetic WB grease and though I fully pack the roller assembly, I always give the grease a place to go, i.e. I don't pack the drum cavity and dust cover, but just coat them for corrosion resistance.

I'm not sure how I'd adjust them if I wasn't using the spacers since the inner races wouldn't always run as true to each other. Still, I'd start with a small amount of free play and adjust around from there to see what seemed to work best. The bearing sizes (and spacing?) are a bit different on the ball joint spindles so that might change things a bit.

my $.02

[brian]

On roller bearings I was taught to eliminate free play, then preload 1/8 of a turn. This centers the rollers in the cage. On VW ball bearings the key is the washer behind the outside bearing. Tighten the bearings until the washer just barely moves when flexed with a screwdriver. If you can't move the washer, it's too tight, if the washer flops around, it's too loose.

[problemchild]

Thankyou Gentlemen. I know there had been discussion in the past but could not recall the details.

[CitationFV21]

[quote="brian"]On roller bearings I was taught to eliminate free play, then preload 1/8 of a turn. [/quote]

Preloading rollers is usually a bad idea. With disc brakes the rollers heat up and expand and since they have no where to go they end up binding and failing. Now on a FV with drum brakes we probably never get that hot. A FFirst might.... I have half and half, a roller on the inside and a ball on the outside, but my last vee had both rollers. I have used the "washer" method and it seemed to work well. (.000 endplay) Going to my old "Stokel" repair manual, they say rollers need .001 to .003 end play (drum) and .001 - .000 (disc) and ball bearings can tolerate .000 or a slight preload (ball bearings can deflect slightly). I like the preloaded spacers inbetween the races. I think Mike P. has a kit that I may want to try in order to reduce stress on the spindle.

ChrisZ

[hardingfv32-1]

"I was taught...." by who? Timpken? Fag? Where is the science or test data for any of these adjustment recommendations? I have not been able to fined anything myself.

Brian

[brian]

Most of what I have been taught came from professional mechanics I have worked with over the past 50 years. The preload concept came from the realization that freshly packed bearings can loosened up in the first few miles and a loose bearing will cause rocking and premature wear. Side load often is determined by the application and so a single procedure is not relevant. I've seen industrial applications that call for very high torque to establish a ton of preload.

[wroché29]

I'm not sure how applicable it is to F Fiist, but here's a whole crap-load of stuff from Timken...

http://www.timken.com.mx/es-es/solution ... fault.aspx

[clubford00]

Brian is right, I was tought by the boys ate DRE when i worked for them ( and set up a ton of front ends ) that basically set your nuts (old school)( or the new single lock with the allen set ) so that when everything is clamped tight, you can put a standard screwdriver between the hub and the thrust washer. If you can move the washer with the screwdriver (with resistance) it should be correct. picture setting your valves with heavy drag. Thats about the feel your looking for.

[cendiv37]

I also learned the "twisting the screw driver can move the thrust washer with some resistance" adjustment method. I seem to recall there WAS a difference between ball and roller bearing adjustment methods. I'm guessing the screw driver blade method was/is the "stock" ball bearing adjustment method.

I just checked my Haynes 1954 to 1979 VW Beetle repair manual's recommendation. It also brought back memories on the adjustment procedure that I was taught back then (overtighten and then back off to displace any excess grease and seat the bearing assemblies).

It reads:

"Tighten the nut by hand until all loosness and freeplay is gone. Now tighten the nut an additional 1/4 turn to create a very slight preload, then back it off about 1/8 turn. The acceptable amount of endplay is 0.001 to 0.003 inch."

I'd recommend rotating the drum/hub while tightening the nut to allow the rollers to seat properly and not mar the races.

I don't recall using the manual as the reference for my inner spacer setting but I might have. Mostly I targeted the least slop I thought reasonable while still "guaranteeing" (in my mind anyway) minimum drag due to preload.

Again, I have never had any sense of instability nor have I seen unusual wear on the races. The races eventually develop nice even, roller width wear bands where the rollers run. I only replace the bearings when I lose a spindle in an accident or something.

Just my $.02. Take or leave as you see fit

[brian]

Thanks Bruce, sounds like we're on the same channel. 1/4 turn in less 1/8 out equals 1/8 preload.

[cendiv37]

Brian,

The math does add up as you say, however, they are targeting .001" to .003" endplay which I would not call "preload". The 1/4 turn overtighten is to move the grease and bearings around to make sure everything's metal to metal. THEN you back off to a small amount of endplay.

Just semantics? Maybe.