I want to put in taller gears in my etype…preferable 2.88’s (vs. 3.08?) since I do almost all highway driving everyday. I have found some used differentials from various used Jags, but the one question I cannot get a handle on is the issue of the ‘posi-trak’. My understanding (or lack thereof) is that the etypes did have this feature? Or was it an option? I believe that 2+2 automatics may have come with the 2.88 gearing…if all etypes have the posi-trak feature, then it (in theory) should just bolt right in. I know there is the 5-speed option as well as the 3.08? option, but I do want the easiest way to do the swap.
I appreciate comments/thoughts…
michael
1970 etype OTS
1908 REO Model G
Any decent off-road shop can swap out your ring and pinion for a 2.88. It’s the same Dana 44 gear set used in millions of Jeeps over decades. The necessary gears and other parts are about $400.
Regards,
Ray L.
If I find a 2.88-posi from an XJS…does it just bolt right is or will there be other adjustments (axles, driveshaft, brakes, etc) that need to be made. I prefer to take out the original (nothing wrong with it at all) and put in something that looks original
thanks…now I need to go find the unit…
My suggestion is if you find the right on, have it rebuilt with new seals even if it reportedly works fine. Not a lot of money compared to having to drop the rear suspension and so it later!
Dennis 69 OTS
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Thanks for the responses…I will report on my progress.
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I went for easy though my choice would not be for everyone.
Coventry West sold (and possibly still sells) a rebuilt diff from a XJ6 auto (?) that has a ratio of 3.058, not PowerLoc.
Dick Maury was of the opinion that this unit is stronger than the 3.08 (52/17 vs 43/14).
Installation was simple as everything else was fine - just took the IRS to bits and reassembled it around the new diff:
At that time (4 years ago) it was $900 incl shipping.
Agreed: unless one never encountered a hill of any size, the 3.07 and the OE 4-speed works great.
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X3 - The Oil Leak starts seem to usually involve me crossing Arizona & Nevada. The combination of the 3.08 (really that 3.058) and cruise control make those long driving days a breeze.
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Contact Dick Maury at Coventry West. IIRC, he had a quantity of 2.88 diffs. Positraction or not? You’d have to ask him.;
I second the notion of rebuilding while you have the chance. Here is one of the friction plates from mine. No symptoms - yet - but a disaster waiting to happen.
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Didn’t Dick M. give us all a tutorial recently on rear gearing? Might be worth a search. I thought the 2.88 required a different gear carrier than a 3.07, but I could be wrong. My 2cents is make sure you '70 diff doesn’t have ball bearings in the output shafts. Changed back to rollers in 70, but if you’re in there changing seals make sure…I put XJS output flange parts in my diff as a tip.
Wide ratio S2 first gear is great with taller gears.
I can slip the clutch at idle with 3.07 at take off. Big oem flywheel, 65 series tires as a caveat. A good running XK can pull a 2.88 easily. Fun on the highway, I’ll bet.
If you replace your diff make sure you retain and use the mount brackets from your E type…the E type brackets position the diff at a different angle to XJ or XJS brackets…Steve
I am a bit confused, are you suggesting an XJS back axle complete will fit an E Type?
From my experience the cage is much to wide, doesn’t have the brake caged nuts, the absorbers mounts are in the wrong place, the shafts and wishbones are too long and the diff mounting brackets have the wrong angle.
The diff itself can be used, there maybe some retro work required regarding calliper mounts.
Gottcha . (20 characters)
You will need to address your speedometer. Since the take off is in front of the rear end, Jaguar listed 8 different speedometers in 1970, one for each of the 4 diff ratio they supplied as well as KPH and MPH. Most of the speedometers can be found used.
Richard Liggitt
Can you expand further on how the brackets are different. I had two sets, one from my 3.54 and one from the 2.88 I bought. I put it together and I’m not sure I used the correct brackets. Can you supply a measurement so I can check? Thanks
Hi Bill,
Pardon me for chiming in. They change the pinion angle is the short answer.
They are also paired with mounting plates captive on the underside of the top of the cage.
The set from your 3.54 should bring the inner fulcrum shafts into alignment with the cage.
Hi Bill…see attached photo…top is xke bottom xj6 distance between center holes xke approx 2in and xj6 2 7/8 in
Is there a way to assemble it wrong? It looks like the hole spacing is different so that you couldn’t put it together incorrectly?
Hi Bill…what i posted previously was to ensure that you use the correct bracket for an E type… as i explained useing the wrong bracket will positions the diff (pumpkin) at a different angle…the two brackets might look very different but they both can be used on the same diff…brackets only use 2 holes to bolt to the diff…from the photo above the outer left and inner right(left side of car)…the measurement between these 2 holes is the same on both brackets…hope this helps…Steve