Differential numbers

[Grant]

Hi Wise ones

I’ve been offered a differential that I’m told is a 3.071
But naturally it’s hard to know if this is the original dif in the car , I’ve been sent a picture of the numbers on it , attached

Does this confirm it ?

Thank you in advance as always

[Robbiee]

Hi
There’s usually a little metal tag with the diff ratio on it held under a set screw that’s holds on the rear diff cover
Robbie

[Grant]

Hi Robbie
This is the ones on there



Thakyou

Grant

[mgcjag]

Hi Grant,....as Robbie says above look for a small tab attached to one of the bolts holding the rear cover on.....at the bottom...it will have the ratio stamped on it ..43/14 for a 3.07.....however the only way to be really sure is turn the i/p and count the o/p..or remove rear cover and see whats stamped on the crown wheel.....your photo just shows casting numbers and not whats fitted inside.......the tag will also have PL if its a LSD But best to remove rear cover to see what your buying...3.07 LSD or 3.07 standard.......Steve
Edit..your photo of tag is 3.53 diff........46 ÷13

[Grant]

Hi Steve

Thank you that’s as I feared , the person selling said it was a 3.07 but they should of know about the stamped and apparently didn’t ,
So thank you very much for the advise

Much appreciated

Grant

[christopher storey]

There's a typo in Steve/Mcjag's post . 3.07 is 43:14

[mgcjag]

Thanks Christopher...typo corrected i hope

[Grant]

Hi All Again

Just wondering apart from the numbers 43/14 for a 3.07 is there any other way of identifying which will fit a 1969 series 2 ots ?

Thank you

Grant

[Tom W]

All the diffs from the Jag IRS, from the E-type through to the end of the XJS and Aston DB7 are superficially similar. Whether they all fit your E-type depends on how many other parts you want to change. The main external differences are the brake calipers mounting points (or sometimes lack of on really late diffs). Find one with the same style of calipers mounts as your current diff and you should be ok for a straight swap. The next choice is ratio, then powerlock or open diff. These are personal preferences, the diff will physically fit, but may not give the driving characteristics you’re after. Finally, there are subtle internal differences with shins and bearings etc. Not all the bits seem to be available to overhaul every spec of diff. Something to be aware of if your planning on rebuilding the new diff.

[mgcjag]

Hi Grant...note that the diff mounting brackets..the two on the bottom that the inner fulcrum shaft mounts to are specific to E type....so you will have to use the existing ones on yours (if you have one)...they mount the diff at a different angle to other jags.......Steve

[Grant]

Hi Tom and Steve


Thank you both for your very useful replies as always .

Much appreciated

Grant

[E600]

Hi Grant...note that the diff mounting brackets..the two on the bottom that the inner fulcrum shaft mounts to are specific to E type....so you will have to use the existing ones on yours (if you have one)...they mount the diff at a different angle to other jags.......Steve

Steve, I think the angle the diff sits in the cage is determined by the top of the diff and cage interface. You are correct in that the lower brackets are E Type specific as they align the inner fulcrum pivots to the cage.

Pat

[mgcjag]

Hi Pat.....if incorrect brackets were used then the diff would sit at a different angle on the base tie plate......then when you fit the cage it would not sit square on the top of the diff.....I suppose it could be possible to fit the top 4 bolts but the cage would probably distort.........so yes the brackets do determine the angle that the diff sits in the IRS..........haveing said that...with the correct brackets fitted the top of the diff before fitting the cage is actually level when checked with a bubble guage....(4.2 not sure on the 3.8).. .Steve
Just to make it easier with a photo.....the tie plate is level and so is the top of the diff

[288gto]

Also bear in mind that the brackets must be shimmed so that the fulcrum shaft lines up properly. This is done with small shims that fit between the brackets and the diff casing. These align the brackets with the holes in the IRS cage that the fulcrum shaft passes through. Failure to do this can distort the fulcrum shaft.
It's all in the service manual and I think there is a description in the Haynes Manual too.



Simon

[angelw]

Hello Grant,
Further to Tom's comments, the better differential to use is from a Series 2 XJ6 onward, or a Salisbury Diff from an XJS. XJS also used a Danna Diff, easily recognizable by the lack of a drain plug.

The correct bearing for the Output shafts of the Series 1 XJ6 and most S2 E Types is no longer available. The original bearing was a Double Row, Angular Contact ball bearing race that had a split centre race. When pressure is applied to the centre race (tightening the nut that hold the bearing in place on Output shaft), the bearing is put under pre-load.

The available replacement is a Double Row, Angular Contact ball bearing race, but without the facility to pre-load it. It is 2mm narrower (27mm) than the original, thus requiring two 2mm spacers (one for outer race, one for inner race).

S2 XJ6 onward Diffs used opposing taper roller bearings with a spacer between them to adjust the pre-load. XJS Salisbury Diffs used the flawed (in my opinion) collapsible spacer system in place of the solid spacer of the XJ6. However, the collapsible spacer in the XJS system can be replaced with a solid spacer. Taper Roller bearings for these Diffs are readily available and is an all round good system.

Regards,

Bill

[E600]

Hi Pat.....if incorrect brackets were used then the diff would sit at a different angle on the base tie plate......then when you fit the cage it would not sit square on the top of the diff.....I suppose it could be possible to fit the top 4 bolts but the cage would probably distort.........so yes the brackets do determine the angle that the diff sits in the IRS..........haveing said that...with the correct brackets fitted the top of the diff before fitting the cage is actually level when checked with a bubble guage....(4.2 not sure on the 3.8).. .Steve
Just to make it easier with a photo.....the tie plate is level and so is the top of the diff

Steve I am away from my reference material at the moment, but I thought the sequence for fitting was the diff to the cage first, meaning the pinion angle is fixed. The bottom brackets being used to secure it to the cage. I may be wrong, but notwithstanding the bottom brackets are e type specific as you pointed out.
Reds
Pat

[mgcjag]

Hi Pat...yes you are correct....on the assembly proceduer in the service manual the diff does mount into the irs first..and this will set the angle that the diff fits in the cage.....but with the wrong brackets fitted the fulcrum shafts and base tie plate would not fit correctly and something will distort.........My main point to the original poster was that he needs the correct brackets...which we both agree....Steve