Hi All,

I've just removed rear o/s hub on my 1994 XJS, and pressed in new bearing cups. Greased new roller bearings up and installed them in the cups. Now, after putting it all back together on the car, I have quite a bit of play between the roller bearings and wishbones.

I read the factory manual for my car (later arrangement where as far as I can tell, shims have to go between the bearing outer grease seal and wishbone on either side), but I'm pretty confused about how to set the preload. Can I do it on the car or do I have to remove hub again? Don't really understand what the manual is saying about how to set preload.

Guess I can't use some new 'washers' I have (?!). I'll have to order some special Jaguar shims? What size should I start with? When I took it apart there were no shims. Is that not a bit odd?

Thanks for your help.

 

The manual is a bit vague. Mine (for an X300, but it's the same arrangement) simply says "used equal size shims to give .003" pre-load"

Well, anyway.....

First measure how much free play you have without any shims. For conversation let's say it's 0.303".

So, to remove all free play you'd need a 0.303" shim/washer.

But, since spec calls for .003" pre-load, you'd need a 0.306" shim/washer.

Since you need equal sized shims on both sides, you'd use two shims of 0.153" each, part number MHC3397AA1

In reality you may not be able to get the exact spec but I seriously doubt that the car will care much if the bearings have .002" pre-load or .004" pre-load or if there's a .001" difference between the two shims.

It IS odd that you found no shims. Makes me wonder if someone has been in there before you.

Cheers
DD

 

Doug,

You're an absolute star! Thank you so much for your reply, which is extremely helpful. Now I understand what I'm doing.

Many thanks indeed.

 

You're welcome

Cheers
DD

 

Doug,
Can he measure the float with feeler gauges somewhere or will he need to use a dial test indicator (DTI)?

 

I'd certainly prefer using a dial inidcator. If nothing else, it would be faster and easier. Depending on the terrain, so to speak, it might be the only way.

If the opposing surfaces have have broad enough faces to properly accomodate a feeler gauge (hope that makes sense), that would work also.

Years ago I did the same job on the older style "inboard brake" IRS using feeler gauges. I recall it being a bit awkward. It was difficult getting the feeler blades cleanly into the area to be measured, if you know what I mean

Cheers
DD

 

In either event I'd guess he needs to be careful to pull axially to 'feel' the bearing sits square since rocking it will give a falsely high reading.

 

Thanks guys. Used feeler gauge today, after ensuring bearings were really nicely seated firmly against the races with the assistance of a broad-bladed screwdriver. Using Doug's helpful advice, I'll be ordering two 0.07" shims tomorrow, which includes 0.03" preload in total. I'm sure it'll last longer this time as there were no shims in there and the old bearing was loose and rusted in there just rattling around! I've really enjoyed doing this job. Used a 20 tonne press and taught myself to mig weld to get the old races out.

 

Far out!

Sounds to me like you're well on your way to earning your "Jag-Man" stripes

Cheers
DD