Rear hub shim thickness

Probably a stupid question, but if I need to INCREASE the end float of the hub, would I need a thinner or thicker spacer? I’m thinking thinner ??

Simple answer…Thicker

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The thicker spacer holds the inner and outer bearings further apart, increasing end float.

Somewhat related question; In grabbing top and bottom of the tire and rocking (wheel off the ground) should ANY movement be felt? Would the bearing end float, up to .006", cause a barely perceptible movement?


Im assuming from your question that your hub is already assembled and you now want more endfloat…increasing the spacer wont do this as the bearing is already pressed tighter on to the hub…you will have to pull the inner bearing and start again with the bearing set up procedure

Yes if your endfloat is in the correct range there is noticeable side to side movement in the wheel.

I took some measurements with a dial indicator gauge recently on the hub carrier. With 5 thou endfloat I was able to measure 13 thou of in and out movement at the top of the hub carrier.

Thanks for the reply. I asked as the car just failed the VT annual inspection because of “play in the rear wheels”. I suggested that the amount of allowable play was somewhat subjective, but was told no play is allowable. There is only about 30K miles on the car since restoration, and I don’t want to go through the somewhat onerous job of replacing the bearings only to have it fail again.


I used the Churchill special collar to install the inner race but must not have taken an accurate measurement, as I have no endfloat with the .139" spacer I used. I guess I’ll have to borrow the tool from JCNA again and reinstall. But back to my question, does a thinner spacer produce less or more endfloat? I would think less, as it would allow the inner race to be pulled in farther when tightening the nut on the half shaft.

Thanks for your assistance.

BTW, I’m using new hubs which I assume are manufactured by a third party and may not have identical specs to the originals.

I had the same issue for my RHR a few years ago. Got off promising a fix for next year, which I did. I turned my spacer down progressively - after about three trial and error fits I was happy.

I took my 69 E in for a 4W alignment, ( a long time ago). The proprietor called me over and did the top & bottom rock. A “S” load of rocking!
It seems the diff output flange ball bearings were in the process of…how does Wiggy say it? Perishing!
Just in case you have a 69 with that NOA bearing, I’d add that info. Figure out where the movement is coming from.

…and don’t forget the half-shaft UJs as a source of play, as well as the fulcrum shaft bearings. As David says, you need to monitor closely what is moving relative to what to determine the source of any rear wheel rocking movement. Hopefully, there is only one source. If you have more than one problem you have my sympathy…

If the problem is that your wheel bearing spacer is too thick (giving excessive end float), you don’t need to get the special Churchill tool again. Just measure the end-float with you current shim. The difference between that measured end-float and the end-float you desire is the amount THINNER that you want your spacer to be compared to the one you have.

Hi AJ11…Thicker shims give more endfloat…thinner shims reduce endfloat…with the Special tool it has the equivelant of a 150th spacer machined on the end …when you press on the inner bearing…this will give quite a bit if end play…which you measure with a dial guage…you then calculate the shim size required which will be smaller than the 150th…useing this calculated shim to assemble will then pull the inner bearing more onto the hub when you tighten…thus reduceing the endfloat…
As i said previously becaus you are tight already you need to dismantle and start again…look at the outer race of the inner bearing…it might not be pressed in fully…hope this helps…Steve

. I’ll start over again. I’ve only assembled one of the hubs so far, so I’ll only have to redo that one. Thanks Steve

Before tearing the first hub apart, I’m double checking the second hub. I tapped the hub down to make sure it is fully seated, then set my dial gauge to zero. Prying up with two screwdrivers, I consistently get .013" endfloat. So I’m thinking I subtract .004" and arrive at .009", then subtract that from .150" to arrive at a spacer thickness of .141". Does that sound right?

You say double checking your second hub…is this one that you have put new bearings in etc…or havent you done anything to it yet…the calculations you make are correct if setting up a hub…useing the tool that has the 150th spacer machined into it then measureing 13th float deducting 4 to give you a spacer requirement of 141th

I was double checking one that is a new hub with new bearings installed with the J15 tool, but I have not installed the half shaft yet. I’m not sure why I have no endfloat on the first one. I must have measured wrong. Thanks

Hello AJ,
Are you using the actual JD15 Tool in your above test, or the existing spacer? If using the JD15 Tool, then the base dimension of 0.150" is correct. If you have measurable End Float with an Existing Spacer, then the base dimension to use in the calculation will be the measured thickness of the Existing Spacer.

Also, the End Float range specified in the Service Manual is 0.001" to 0.003", giving a nominal value of 0.002", not 0.004". Accordingly, using the measured End Float of 0.013" stated in your Post above and the Spacer Thickness of 0.150", simulated by the JD15 tool, if used, the spacer thickness you require is derived as follows:

0.150 - (0.013 - 0.002)
= 0.139"

If the End Float is measured using an Existing Spacer, transpose 0.150" in the above algorithm with the measured thickness of the Existing Spacer.

Tapered Roller Bearings like Pre-load better than End Float and will tolerate minimal, in excess Pre-load better than minimal in excess End Float, in terms of bearing longevity. Although this is not a recommendation to depart from the End Float specified by Jaguar, I set Rear Hub and Front Wheel bearings with pre-load.



if you end up with a set of good used bearings on hand, it makes life so much easier to hone them up as a “setup” tool,

that way, if the endfloat is not satisfactory, just slip-fit them on/off, till its correct, press the new bearings on when you are sure

Hi Bill…the endfloat shown in my Jaguar Service manual is .002-.006 and nominal as .004 …Steve