Differential advice

[mgcjag]

Lots of great info there from Bill.....Al have a look at your diff where iv put the arrow....stampings can sometimes identify the year of the diff....possibly you whole diff is a replacement....Steve

[angelw]

Steve Wrote:

possibly you whole diff is a replacement

Hello Steve,
I read through Al's post again, and I had missed that the diff ratio is 2.88 to 1, and that
Al Wrote:

One other point is that my diff preload looks as though it's done by shims between diff case and the inside face of the diff bearing. Totally different to the workshop manual I have. Is this right for a type 2 or is it a type 3!

I wrongly comprehended that when I made my previous post, thinking that the pre-load was via shims between the face of the output shaft bearing housing, and the diff housing.

His diff is actually the next generation on from the Type 3 and is NOT a Type 2 diff. His differential is most likely out of an early XJS, and is definitely a replacement for his original diff, which would have been a 3.07 ratio.

This would explain the 2.88 ratio, the one piece output shafts, and the collapsible spacers for pre-loading the output shaft bearings.

Regards,

Bill

[tim wood]

I thought that the car in question was an automatic which from my memory means a 2.88 diff.
Happy to be corrected

Tim

[angelw]

Hello Tim,
Actually, you're correct. A 2.88 ratio was used with the 2+2, which is what Al has. However, the fact that pre-load of the diff centre bearings is made via shims under the bearings, and taper roller bearing used for the output shafts, makes it a later model than a Type 3.

Regards,
Bill

[alunwill]

Many thanks for the input so far.

Having bought a partial restoration, I'm not sure if this diff has ever been fitted to this car. That's what you get for picking a job up part way.

I cleaned everything up this morning because I'm still chasing the source of the debris,

Bill, the spring I mentioned is the one around the top of the inner output bearing, photo attached.


This diff has had a hard life. Traces of overheating and a gear which is showing signs of having crunched something up.










Steve, The number you refer to is 90E 83496, is that 1983?

Al

[mgcjag]

Hi Al...90E I think is 1990 so S3 xj6..the spring is probably fron an oil seal....are you aware that diff mount brackets are specific to E types..so if this diff was just in a box of parts the mounts may also be xj6....how about the irs cage, driveshafrs, wishbones etc...do you have larger xj6 parts or E type parts....Steve

[angelw]

Al Wrote:

the spring I mentioned is the one around the top of the inner output bearing, photo attached.

Hello Al,
That spring is not a part of a Taper Roller Bearing and is most likely as suggested by Steve.

When you get to the point of setting the pre-load of the diff centre bearings and gear backlash, you will end up assembling and removing the bearing cones from the diff centre a number of times. These bearings are easily damaged due to typical difficulty removing the bearings. To avoid this, I use a set of bearing cones that I've honed the bore of the inner race to be a close running fit on the diff centre bearing journals.

Because the bearings are made within a tolerance range, I use the bearing cups that are going to be used in the repair, and measure the height difference between my trial set of cones and the new bearing cones that will ultimately used. To do this, I:
1. place the bearing cup on a flat surface and place the Trial Cone in the cup
2.sweep the top surface of the bearing inner race with a dial indicator and set it to zero.
3. repeat step 2 using the bearing cone that will be ultimately used in the assembly.
3. note the difference between step 2 and 3 above, and use this amount when calculating the required shims to use to obtain correct bearing pre-load.

As Steve has pointed out, the IRS Cross Member mounting brackets that attach to the differential are unique to the E Type, therefore, you need to determine in your's are correct before you go much further. They are quite hard to find, but if your's are not correct, I can help you with these parts.

Regards,

Bill

[alunwill]

Looking at the spring you're correct, although how that popped so neatly around that bearing is another thing!

Steve, I have a new irs cage from one of the usuals. It came with the car and it is for etypes.

The mounting brackets as you say are something else. Is there a specific measurement regarding the differences I can check. If not I'll get the cage out tomorrow and physically check it.

Any views on the gear wear and the overheating - just running with low oil?

Would you trust it or change it.

You've got me thinking about the rest of the rear axle bits although I do recall checking them against my spare cobra bits which are xj6 and noticing these were shorter.

Al

[mgcjag]

Plenty of info on the mounts/dog bones if you search... here is one viewtopic.php?f=3&t=10004&hilit=Dog+bones as re diff condition the gears dont look great to me plus whatever else needs doing....I would be looking around.....are you keeping the car auto or converting to manual?.....Steve ps you could just look at fitting one of the new LSD units keeping your crown wheel and pinion and o/p shafts

[alunwill]

Bill,

Thanks for the offer of the feet but I've just checked mine against the irs cage and everything aligns.

[angelw]

Hello Al,
For the amount of work required in refurbishing your current diff, plus the work involved to getting at the diff for a second time after you get to the point of car being derivable, I would be replacing the gear set.

If you get another complete diff, and it happens to be a Type 3 with the Double Row, Angular Contact Output Shaft Bearings, retain your current Output Shaft assemblies, for the opposing Taper Roller Bearings system is far better than using the alternative angular contact bearing and spacers being supplied by regular Jaguar parts suppliers. Your output shaft assemblies will fit a Type 3 diff housing without any modification whatsoever.

Regards,

Bill