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I’ve got a jag IRS rear end that came out of a Sand Rocket Sandrail. I’m wondering if someone can help me identify the rear end. It came with some old brake calipers and rotors. From the research I’ve done, it looks like a 72-87 xj6/xj12 but I’m not savy in the jag world. The gear ratio is 2.88. Im trying to get a new set of calipers and rotors for it. My brake guys said these calipers looked like they were like 57-61 XK series but he was puzzled from the diameter of the rotors. OE xj6 rotors are 10.75 inches diameter and these ones Ive got are 10 even. Long story short I want to be able to put some new rotors and calipers on this rear end but I need to know what I’ve got.
Also, I am putting some 4.88 gears in it and was told to get a Dana 44 carrier and gears and they will fit just fine in the xj6 rear end. Is this the case? Thanks!
Wow, those calipers are OLD ! The Jaguar IRS system was first introduced with the E-type and also the Mark 10 saloon in 1961. Then later, the same suspension was used in the S-type saloon of 1963. Later on, the XJ6 used the same IRS, but with uprated brakes. I assume you want to replace those with something a lot better and also easier to maintain. What you've got looks like the early brake calipers and the IRS is from one of those cars I listed. At some point Girling took over production to the same design. Certainly those brakes are not from an XJ6 even an early one. The original brake cylinders have a pad retraction mechanism built inside them. That sort of thing is not done that way now. Clever brake engineers worked out that you could do the retraction via the brake piston seal, which when the brakes are applied distorts slightly and then when the brakes are taken off, relaxes and retracts the piston.
The XJ6 from 1968 used a much better caliper and SNG Barratt sell these as a pair. However, you'll likely need the larger diameter discs to match them. They also sell a kit to convert the brakes to a modern design. Maybe worth asking them what your options are. You can, of course, buy aftermarket cylinders to the original design but this will probably cost more. All the parts for the handbrake caliper attached to the hydraulic caliper are also available if you need them. These parts are common to all the IRS brakes.
Damn cool sand rail, with a damn cool rear end! Those look like my '67 e-type brake calipers on a later pumpkin and I see no reason why later calipers can't be bolted on for cheap money.
Also if you desire a lower final drive than that relatively tall 2.88, there are several good options probably explained in those links above. Btw... I have used those calipers with good results.
You won't find the calipers themselves anymore, but you can get replacement cylinders. Also note that if these are the original fasteners on the Dunlop brakes, they are all Whitworth sizes, not the usual SAE sizes.
For the diff, if you are changing ratio the carrier is different for 2.88 and numerically lower than the 3.07 and higher. So if you wanted to change to a different ratio other than 2.88, you would need a different carrier, as the offset is different. Standard E Type ratio for the USA was 3.54, but other ratios available were 3.07 and 3.31. Jaguar did offer 3.77 and 4.55 in other cars, but I'm not sure if the 4.55 would fit that housing. 3.77 is likely the lowest you will find in the IRS, which came in S Types and the Mark 2.The Mark 2 is live axle, but I believe the ring and pinion interchange.
JB, wouldn't that diff be later with the 5 bolt axle housing covers? And it's an open diff, I suspect a limited slip would more suit a sand rail? Lots of choices, I still say it's a lot cheaper and less complicated to put two later rebuilt calipers on.
The diff could be later with early brakes. With that ratio, I wouldn't be surprised if it's from an XJ6. Agree, I'd put on new wheel cylinders and call it good.
Jag IRS Differential Identification questions
Those look like my '67 e-type brake calipers on a later pumpkin and I see no reason why later calipers can't be bolted on for cheap money.
