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I buttoned my Cooper S front brakes up for what I was hoping would be the last time today, but I've got some play on the left side that has me a bit concerned. The right side feels perfect, but there is a definite 'clunk, clunk' when I grab the rotor at the 6 and 12 o'clock position, and try to rock it. There doesn't appear to be any measurable end-float, but the rotor, and drive flange are able to rock about the axle centerline. It's difficult to measure, but I would say the outer edge of the rotor rocks in and out by about 0.005-0.008".

This is a completely new set-up that i bought from MiniSpares about 10-12 years ago, and has never been put in use. The bearings are all Timken brand parts, and the distance pieces were kept with the bearings as a set. The castellated nut had been torqued to 150 ft-lbs.

It seems to me that the distance piece may be a few thou too long, but I don't know. Has anyone else dealt with this, and how did you go about troubleshooting it?

Thanks very much.

I had a similar thing a few years ago and all i had done was put one half of the bearing in the wrong way round . Working late at night it was a simple mistake to make . On the plus side simple to put right .

I found this quite often on new cars especially noticable on the 13" wheel sport pack cars. It was the spacer between the bearing that varied in size. I have a drawer full of spacers all different sizes !
If its a used cooper S set up it could also be the integral hub spacer is worn or the splines on the drive flange worn.

IAIN wrote:If its a used cooper S set up it could also be the integral hub spacer is worn or the splines on the drive flange worn.

All brand new parts. I also think the spacer seems to be the most likely suspect.

Is the hub itself new ?

its worth checking the bores of the hub (when the bearing is removed with a bore gauge as its quite common that they are worn due to old bearings shuffling around or spinning.

ive seen loads where a new bearing outer will rock in the hub and cause all sorts of play

its a particular p[problem on the lh hub as the cv nut is always doing its best to unwind, so everything is/can be a lot looser than on the rh side

Guys,

These are ALL NEW PARTS.

Time to thin your spacer down i reckon! A small amount at a time should the free play disappear.

Get someone to hold the steering wheel tightly and try putting your hands at 3 & 9 o'clock. If you can't feel the same play this way it's not the wheel bearing. What have you torqued the hub nut up to ?

Thats not a lot of free play if it was me I would take it for a run to bed everything in and then retorqe the hub nut and check again. If the play is still excessive then think about shaving the spacer. The bearings are fine with a small amount of free-play but NOT WITH BEING COMPPRESSED be carefull of the amoount you shave off the spacer, your looking for zero play but obviously this is a difficult figure to achive without being at -figures!

Benny wrote:Guys, These are ALL NEW PARTS.

I am with everyone that says to thin down the spacer...

There are LOTS of tolerances here:
One inner/spacer thickness,
The other inner/spacer thickness,
One outer race diagonal to butt-face measurement,
The other outer race diagonal to butt-face measurement,
The diameters of all the rollers,
The thickness of the centre-web in the hub...
Possible small/unidentified piece of rust/crap between the bearing inners...

I could go on, but won't - If you end up with a set of tolerances
that are all in the wrong direction, this can, and DOES happen,
and maybe more often than you think!

Thought for the day:

"I once bought a wheel bearing kit and found that one bearing had
'Made in Japan' stamped on it and the other had 'Made in China'"

Tell me that this was a carefully matched set and I'll eat my hat....

If it is a genuine matched Timken Bearing set, I'd say it's the hub. I've had one that was undersize.

The bearing register is very difficult to measure accurately, however, if you can, they should be 10.00 mm wide. Yes, it is a metric size.

minimans wrote:Thats not a lot of free play if it was me I would take it for a run to bed everything in and then retorqe the hub nut and check again. If the play is still excessive then think about shaving the spacer. The bearings are fine with a small amount of free-play but NOT WITH BEING COMPPRESSED be carefull of the amoount you shave off the spacer, your looking for zero play

Thanks, I'll give it a drive before worrying about it much more. I've always erred on the side of having wheel bearings looser rather than tighter....as you say, they don't tolerate being tight for very long.

MGB front wheel bearings are set with spacers and shims, and I think the factory spec is something like 0.004-0.005" end float, so there is a 'clunk' there even when set to spec. This play probably wouldn't have bothered me too much if the other side hadn't come out so perfectly!

They should have 0.004" pre-load.



Without pre-load, the brake pedal will be lower than otherwise should be and the bearing life is reduced.

Here's some more reading on preload;-

http://www.timken.com/en-us/solutions/a ... ol6No3.pdf

http://www.timken.com/en-us/solutions/a ... ol5No4.pdf

Yes a small amount of preload is good IF you have the means to accuratly measure it, I'm not sure that Benny has the dial gauges, micrometers and skill available to measure and calculate the correct preload. So as I stated a small amount of freeplay or 0 tolerance is good given the equipment and skill level available. Timkins will not tolerate a tight clearence for long and given the habit of bearings spinning in the hubs I think 0 is a good figure to aim for...........Paul

After reading the links to the Timken documents, the ideal preload appears to be 0.001" not 0.004". According to the graph in the second link the ideal preload is about 0.025mm which is about 0.001". 0.004" is about 0.1mm which, according to the same graph would lead to a very very short bearing life.

Given the shape of the graph it is always better to err on the side of less or no preload rather than even slightly too much.

Kelley