Hub bearing clearance question

Series 1.

Replacing a rear hub bearing With the spacer I ordered I have a fat 001 on my dial indicator. The manuals all say .002-.006. But some people have opined that .001 or less is good.

So, what sayeth the experts?

Thanks, Alan

I would use the setting in the manual. Other people’s opinions are just that.

Others have managed to burn up those bearings. I think it’s not worth the risk with too small of a float.

When I set mine up, I read every post I could find here by using the search function. At the time, it was stated the spec did change on later Jags with the same set up. IIRC it is / was now considered better to
be zero at most or a few thousands of pre load.
A search of the archives should help your decision.

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I set mine with a bit of preload, been doing it for about 10 years. I started because I autocross the cars and found that I was having problems with the inner, inner race rotating on the hub.The fix required a new hub, and bearing. I got tired of it, started setting it up with preload and so far so good. Differential bearings, which are tapered needle rollers use preload so I figured why not on the hub…

The manual calls for the front wheel bearings to be set up with a slight float as well, 0.003 to 0.005. I was advised to, and set mine up with a slight preload. Every other car I’ve owned and replaced or packed wheel bearing on specified a wheel bearing preload.

Just did this job on my SIII XJ.
Same conundrum… I decided to go with a very slight preload.
Did the same on the front bearings as well.

Best,
Aristides

Hello Terry,
Its a fact that Tapered Roller Bearings prefer Pre-load rather than Clearance (End Play) and can better tolerate a slightly greater degree of Pre-load than optimal, than a greater degree of End Play without affecting the life of the bearing.

However, the Inner Race ID of the Inner Bearing of an E Type Rear Hub has a substantial interference fit with the OD of the Hub where it sits. If the Inner Bearing were to spin on Hub Bearing Journal, there is an initial problem with the dimensions of the Inner Bearing Race ID and, or the OD of the Hub Bearing Journal. There is no engineering evidence that supports pre-loading the bearing will help stop it from rotating on its Bearing Journal; in fact it will exacerbate the situation.

Front Stub Axles are made so that the Inner Bearing is a slight running fit on the shaft. They are generally made this way so that when the hub is removed for other reasons than to replace bearings and seals (replace rotors for example), the Inner Bearing and Seal come with it and not left on the shaft requiring a puller to remove the bearing. Just about every car that has the same bearing configuration as an E Type (and other Jaguars), that I’ve stripped the front bearing system, show a pronounced groove at 6 o’clock on the Stub Axle. This is caused by the Inner Bearing spinning on the Stub Axle.

I manufacture Front Stub Axles in two forms for the various Jaguars using this bearing system. One with Bearing Journal dimensions that results in an interference fit of the Bearing Inner Race; the other form uses a spacer between the Inner and Outer Bearing inner races so that an axial load can be applied to the Inner Races of the bearing to lock them in place. Correct Pre-load is achieved through the use of shims in conjunction with the spacer.

Regards,

Bill

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When I first set mine up, I tried to do it to spec - a few thou of slop. But, once on the car, it ended up being more - enough that there was noticeable movement when pulling/pushing on the top/bottom of the wheel. This appeared to accentuate any slight imbalance in that wheel. I pulled the stub axle, measured the shim, and machined one a bit thinner. This one provided no discernable slop, but the axel still turned easily. Were I to do the whole process again, I would go for slight pre-load.

On the fronts, I do basically the same - use a socket to tighten the bearing until it starts to drag, then back off to the closest notch on the castle nut. If it’s too far away, I shave a few thou off the back of the nut, and try to get it to where with the cotter pin in, there is still some small pre-load. Never had a problem.

Regards,
Ray L.

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Thanks Bill – this is good information to know. I went through two sets of rear hubs over a couple of years, because the inner, inner bearing was rotating on the hub. I doubt if it’s the bearing that’s miss sized, so perhaps the size of the aftermarket hubs was incorrect, and/or I got unlucky and got some undersized production variance. Certainly the inner race had to be pressed on in all cases. On the last redo, again with new hubs, I locked the inner bearing on with green bearing retainer. So far so good.

I’m familiar with the inner front wheel bearing rotating on the stub axle and the wear it causes. Had some axles chromed and ground a few years ago, on the E Type I vintage raced, to try and deal with the wear. It turned out that it would have been a lot cheaper to buy new axles! Could have used your stuff a few years ago when I was racing.

The humble little MGB has this arrangement as standard. The owners of Triumphs and Mustangs go to great expense to add it to their cars for racing, as they claim it prevents brake pad “knock back” from stub axle deflection.

Ironically, about 75% of MGB owners seem to have thrown the shims and spacers in the bin, as they consider the 10 minutes of set-up time to be too bothersome.

Hello Ben,
To each their own. Even if it did take 10 minutes and I doubt that its ever taken me that long, just how often do you have to spend that time? I would rather amortize that minuscule period over a number of years and not have to worry about the bearing spinning on the Stub Axle, as clearly it will without some step taken to prevent it happening.

Regards,

Bill

Thanks to everyone for the replies. Much appreciated and very helpful!
I found the general/theoretical discussion very interesting.

And, in fact the archive search was a huge help.

In the end, since my technical knowledge is lacking; I’m going with the authorities. Small preload seems to be the optimal. Dick Maury agrees…conclusive for me.

OTOH, Wiggy’s empirical input from his years of experience and his own car, says up .006 is okay; and that comports with the manual. My conclusion is that .001 will work, and since I’m already there I’ll call it good.

Again thank you, Alan

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Yes, that was my point. It’s a false “economy” to throw away a well designed system for a few mins of time saving.

Our 928 Porsche has a very odd set up for the front wheel bearings (per the manual, anyway). You tighten the nut until you can turn the large washer under the nut. At that point it wouldn’t have preload, but - I guess - in the German way it would be “perfect”?