Wheel bearing preload help

[rodorico83]

Hi guys.
Im trying to understand how to do the preload on a lola b99 wheel bearings.
I have this info from the manual, But im uncapable of understand the drawing !!! Im new on this I hope somebody can help me on how to use this preload jig.

[Fred Michael]

You need to determine the distance between the inner and outer bearings as they are mounted in the upright, then you will need to grind the spacer to a dimension that results in .0025" of pre-load.

[rodorico83]

You need to determine the distance between the inner and outer bearings as they are mounted in the upright, then you will need to grind the spacer to a dimension that results in .0025" of pre-load.

I Understand the concept, what i do not fully get i how to place the jig in the upright, the drawing is not quite clear to me. but ok i took some measurements, and the base plate of the jig should fit into the upright down to the base of one bearing.
Also it was not clear not me if I should put only inner race of both.

In any case i would prefer to NOT manufacture this jig and set preload by torque with a spring weight scale, it will be cheaper and easier i can measure torque to rotate hub,

There is a way to convert dimensional preload into torque preload base on lets say bearing diameter ???

Anyway i feel that even on bearing rebuild (no parts replaced) preload needs to be done again ??, i have the feeling that torque needed to turn hub is different between the 4, actually 3, cos for one i have to replace bearing and preload is gone,

instead of making new longer spacer can i handle this with a range of shims between 0.02 and 0.1 mm i guess ??

Anybody have some values for this torque preload, i read in some places that preload can not be measure with torque but from my point of view it can. any disagree ?

[Bob L.]

There is a way to convert dimensional preload into torque preload base on lets say bearing diameter ???

Probably not, reliably. Torque is too subject to factors such as lubrication to be a good "tool"....you also, have breakaway vs. steady state values to consider. Physical stackup is best.

As to doing it with shims: should be fine, just keep them thick enough so they don't extrude or fall out of place and are easy to handle. Perhaps make a shorter spacer, assemble, measure the float, do the math, either cut new spacer to fit or grind the shim(s) to use with your shorter spacer.....

Bob L. (dare say ME/PE?)

(I also, found the diagrams hard to read/follow...think the axle centerline lable threw me, if I got what they showed correct....perhaps I still missed meaning?)

[rodorico83]

There is a way to convert dimensional preload into torque preload base on lets say bearing diameter ???

Probably not, reliably. Torque is too subject to factors such as lubrication to be a good "tool"....you also, have breakaway vs. steady state values to consider. Physical stackup is best.

As to doing it with shims: should be fine, just keep them thick enough so they don't extrude or fall out of place and are easy to handle. Perhaps make a shorter spacer, assemble, measure the float, do the math, either cut new spacer to fit or grind the shim(s) to use with your shorter spacer.....

Bob L. (dare say ME/PE?)

(I also, found the diagrams hard to read/follow...think the axle centerline lable threw me, if I got what they showed correct....perhaps I still missed meaning?)

breakaway vs. steady state values to consider ? can you explain ?
yep lubrication i thought about that, difficult to solve that but imagine that same amount of grease has been applied to all bearings.
I guess if doing it with Physical stackup bearing should not be lubricated on the measurements.

[Hardingfv32]

....imagine that same amount of grease has been applied to all bearings.

Was the right amount of grease used during the last rebuild? What viscosity grease?

The main purpose of preload is to reduce friction.

Brian

[R. Pare]

Actually, no.

Preload is there to make sure that the bearings rollers are adequately loaded under all conditions to keep the rolling elements from skidding or chattering, among a host of other necessities:

https://www.skf.com/binary/12-299896..._12-299896.pdf

[Lotus7]

Actually, no.

Preload is there to make sure that the bearings rollers are adequately loaded under all conditions to keep the rolling elements from skidding or chattering, among a host of other necessities:

https://www.skf.com/binary/12-299896..._12-299896.pdf

Exactly! And in the case of split-inner race ball bearings (not so common in our cars), it ensures the balls don’t experience triple-point contact down at the split line. There is no alternative to accurate measuring and shims/spacers.

[Bob L.]

Not sure I've the time or best words to explain, so, let me point you here:

https://en.wikipedia.org/wiki/Friction

Basically 2 levels of force needed...first to get motion started (breakaway), 2nd to keep it going (dynamic)... lubrication, normal load, and coefficient of friction..are the main factors.... Not sure you can back (properly) to a torque number when given preload values for "specs".

Pare is right...need load to make rollers, roll...not skid...

As to lube when doing stack up....just use stuff that comes on brgs, or clean and put light coat of oil on rollers to get measurements. Do any grease on final assy....

Sorry, to be short, but trying to get out door to go racing in Sav. this weekend... cold, wet, windy...OH BOY!

Bob L.

[R. Pare]

Don't know if they are still doing it, but DANA used to measure their differential preload with the torque drag method. Never understood why, since they had such horrible bearing life in so may rear ends. Using torque drag as your goal is subject to way too many things that can affect it, giving wildly different drag numbers at the same actual measured length of crush.

[Bob L.]

Don't know if they are still doing it, but DANA used to measure their differential preload with the torque drag method. Never understood why, since they had such horrible bearing life in so may rear ends. Using torque drag as your goal is subject to way too many things that can affect it, giving wildly different drag numbers at the same actual measured length of crush.

sort of an aside...

ran into this when building my steel bldg. Local inspector wanted to have all structural bolted joints "torqued" and certified..... Told, I could certify, what values did he need? Didn't know, told me I should if I was able to "certify".... So I went looking for values only to discover the AISC/others listed torque values for about 2 yrs back in the early 50's before giving up and going to strain....Goal: wanted the joint to be clamped with proper force, They found: only good way was to look at strain (stretch) in fasteners..use a crush sleeve that collasped at given load, or finally to hand tighten, then go so far in further revolution (axial distance down thread) to get right "stretch".... NO ONE USED or ACCEPTED TORQUE in those applications...well you could/can, but had to have a supremely regulated calibration program, which was beyond the blush for cost...so no one (global use of term) does it... ARP does this on their fasteners, too...

(edit...added)....

Not saying torque doesn't have it's place on our race cars.... just isn't best to get exact levels of load....I still torque the heads, rods, mains, flywheel, wheels, and more... just do so with a bit more appreciation... my old mechanic buddy showed me not to just go to the click, rather go till the joint stops moving...then check again!

Okie

[Fred Michael]

I Understand the concept, what i do not fully get i how to place the jig in the upright, the drawing is not quite clear to me. but ok i took some measurements, and the base plate of the jig should fit into the upright down to the base of one bearing.
Also it was not clear not me if I should put only inner race of both.

In any case i would prefer to NOT manufacture this jig and set preload by torque with a spring weight scale, it will be cheaper and easier i can measure torque to rotate hub,

There is a way to convert dimensional preload into torque preload base on lets say bearing diameter ???

Anyway i feel that even on bearing rebuild (no parts replaced) preload needs to be done again ??, i have the feeling that torque needed to turn hub is different between the 4, actually 3, cos for one i have to replace bearing and preload is gone,

instead of making new longer spacer can i handle this with a range of shims between 0.02 and 0.1 mm i guess ??

Anybody have some values for this torque preload, i read in some places that preload can not be measure with torque but from my point of view it can. any disagree ?

If you replace a bearing you will have to re-measure. Bearings are not all the same dimension, You will most likely need to grind a new spacer to the proper dimension.
As far as the jig goes, you do not necessarily need one but you need some way of accurately measuring the distance between the bearings.
Measuring torque is not a good way to go about it, far too many variables.
Just for reference, my primary job between races is servicing uprights.

[Hardingfv32]

Preload is there to make sure that the bearings rollers are adequately loaded under all conditions to keep the rolling elements from skidding or chattering, among a host of other necessities.

Which are the source of friction or energy loss through heat.

Brian