Quick questions about S3 IRS rebuild

[NorfolkJohn]

Hello, I am helping a friend rebuild his S3 E type . We are at the point where we will rebuild the IRS shortly. I am fairly happy but have a few questions - looking for pointers and helpful comments from others who have done this ..

1/ the wheel bearings are supposed to have between 2 and 6 thou free play according to the manuals we have. I am normally accustomed to putting taper rollers in with a preload.( admittedly this is on FWD cars).. Is this because the carriers are aluminium - and the differential expansion needs to be accommodated. When it gets up to running temp the free play goes? or is there some other reason?

2/ We separated the water throwers from the back of the hubs. Now it seems impossible to get them to snap back on the retaining step on the hub. Anyone have a good method to achieve this ? I am not sure If heating them will work? Has anyone used this method successfully? or is there another method...

I am sure we will hit other issues and no doubt be back for tips and advise.. Many thanks for any help..

[mgcjag]

Hi John....welcom to the forum...im sure you will find it very usefull......The spec for the rear wheel bearings is as specified in the service manual.....however there has been lots of discussion on this on various forums and many are convinced that they should be set with preload as per your thoughts....however others are adamant that the service manual is correct and should be adheated to..personaly i sat on the fence and set mine in the middle at 0.....no endfloat and no preload.....no answer for the water thrower im affraid...im sure others will join in...Have a look here....Steve http://forum.etypeuk.com/viewtopic.php? ... 9f#p130196

[Joes66]

Hi John
I recently re built my IRS
And like you have always preferred a bit of pre load
Problem is with the shim that goes behind the bearing is that you need a very accurate Guage to measure it
But aside from this
When you fit new bearings in my experience they need a period of bedding in which can only be done by assembling and using the car for a short period
Then re adjust
What I did and I am not saying its any sort of best method was to re assemble with the original shims after going through the workshop manuals description of setting them up
I checked end float once I fully tightened them up for any excessive play or bearing over tightness
Mine were in my opinion ok and safe for a short bit of driving before re checking them
Both had no end float but also were not tight to turn
After 10 miles or so driving I re checked them
One side now had play and the other not
I replaced the spacer in the slight play one untill it had no play and after double checking left the other one as was
I have now done around 150 miles in the car and re checked them last weekend
Both had no play and all seemed well
That was my method anyways
Joe

[angelw]

John Wrote:

1/ the wheel bearings are supposed to have between 2 and 6 thou free play according to the manuals we have. I am normally accustomed to putting taper rollers in with a preload.( admittedly this is on FWD cars).. Is this because the carriers are aluminium - and the differential expansion needs to be accommodated. When it gets up to running temp the free play goes? or is there some other reason?

2/ We separated the water throwers from the back of the hubs. Now it seems impossible to get them to snap back on the retaining step on the hub. Anyone have a good method to achieve this ? I am not sure If heating them will work? Has anyone used this method successfully? or is there another method...

Hello John,
As Steve alluded to, there are those that are astonished that anyone would question the Jaguar engineers of the day. But many specifications relating to end float and pre-load have been varied during the production time of the E Type and shortly thereafter. For example, the amount of pre-load used with the Differential Pinion bearings (measured using a lb/in torque wrench) has increased from a mean of 10lb/in for early E Types to circa 26lb/in for the XJS.

The temperature of the aluminum hub carrier does indeed affect the amount of end float, or pre-load of the rear wheel bearings and I suspect that on a long run, the last specified end float of rear wheel bearings would disappear. Accordingly, I would go a little shy of the correct pre-load of tapered roller wheel bearings, as used in the E Type, but in a more stable thermal expansion environment.

The spindle bearing of CNC machines are invariably installed with substantial pre-load and a Machining Centre running 24/7 at 12,000 RPM spindle speed (quite common on big die work finishing) will equal the revs of the rear wheel bearing of an E Type running at 160km/hour, 24/7 for fifty years, in five.

The other thing that is questioned by me and many of my engineering colleagues, is the amount of grease many think is necessary. Again, using the CNC machine spindle bearings as an example, the correct amount of grease to use when assembling these is 10% of the available air space within the confines of the bearing race. Accordingly, for a wheel bearing, I fill the bearings with grease by hand and assemble. No further grease is used and I've not had any issues with God knows how many wheel bearings I've assembled over the years.

As, you have probably worked out, removing the water slingers is not necessary. However, heat does help in their refitting, but often, after they have been removed and refitted you will have to stake them to ensure they stay in place.

Regards,

Bill

[NorfolkJohn]

Thank you all for your replies. We managed to use a dial gauge and pre-assembled the bearings measured the free play and did the calcs. We await the correct shims now,. I expect as you suggest its worth checking after some miles. We did things really fastidiously - but obviously there is always room for slips.. Once gain really appreciate the advice.. cheers !!

[NorfolkJohn]

Oh, forgot to mention the water slingers - we heated and then had to knock them on around the periphery also, they are now once again a firm fit....
Thanks again