Bought a full set of rebuild kit from eBay, but found that the new seal ring for the rear caliper is much smaller than the original one (48mm). Seller said his kits are for ATE calipers. Mine (1995) are originals which I believe were made by ATE. I just did a search on past discussions on this site about calipers and am not that sure now. Did Jaguar use calipers made by different manufacturers for XJR's and non-XJR, or different calipers were used for 1995 and later models?

 

The XJ40 also used ATE calipers (In addition to Girling), the seals could be for those. I just pulled apart an 87 XJ40 and the rear calipers pistions are noticeably smaller than X300. I didn't measure though.

 

More findings to share here.

First, factory front and rear brakes of the X300 and XJR are single-piston calipers made by ATE to work with rotors of 305mm. If yours are not ATE, the previous owners may have replaced them with same or bigger brake calipers and/or rotors of other makes.

Second, the diameter of the ATE piston seal of the rear calipers of my 1995 XJR is 48mm, not 36mm as indicated in some of the eBay offerings (some do have 48mm). A member in another UK Jaguar forum too bought a wrong rebuild kit a that had a smaller seal of 36mm. X300 rear brake caliper rebuild trouble

Third, the diameter of the front ATE caliper is 60mm.

 

[Corrections to my earlier post highlighted in red below]

More findings to share here.

First, factory front and rear brakes of the X300 and XJR are single-piston calipers made by ATE to work with rotors of 288mm (Front) and 305mm (Rear). If yours are not ATE, the previous owners may have replaced them with same or bigger brake calipers and/or rotors of other makes.

Second, the diameter of the ATE piston seal of the rear calipers of my 1995 XJR is 48mm, not 36mm as indicated in some of the eBay offerings (some do have 48mm). A member in another UK Jaguar forum too bought a wrong rebuild kit that had a smaller seal of 36mm. X300 rear brake caliper rebuild trouble

Third, the diameter of the front ATE caliper piston seal is 60mm.

 

Late XJS with outboard brakes are ATE calipers, and have a different diameter to X300. That was to preserve the braking balance between the old style front calipers. They had 295mm rear rotors.

 

Here is more on rebuilding the brakes. It turns out that not all X300s are the same. Factory new ABS Sensors #LJA2226AA that claim to suit all four corners actually only fit later models from 1997 (from VIN 810672). Earlier models have unique sensor-cable setup. Parts No.# are LNA2220AB (FR), LNA2221AB (FL), LNA2222AB (RR), LNA2223AB (RL). Such parts are hyper-expensive, each costing over GBP220. So before deciding to find used or new parts, I have to be certain whether and which ones on the car is/are faulty. Would have to defer to the scanner tools as an aid.

 

As a "quick and dirty" test, with the sensor in place hook a multi meter across the plug end and give the wheel a spin. You should be seeing AC voltage, probably only a few volts.

Sometimes just cleaning the sensor tip and the tone ring can do the job. Note that the gap needs to be very small between the sensor and ring, I think the maximum is about 0.050". They are also sensitive to orientation, 90 degrees out and they won't pick up anything.

 

I discovered the difference in speed sensors also between my 96 daily Driver and my 97 donor. Both Sovereigns. If I remember rightly, the 97 sensors are longer and won't fit flush into the hub

 

Qvhk ,

Any suggestions on a broken sensor that I can't remove and passed over to leave alone for higher priorities . Tried heat , penetrate oil , and leverage from the inside of the hub . I had popped the top off and may be able to repot or refill the top cavity with epoxy and leave it alone . Will have to put a meter on it in the morning to see if it was bad as I was pulling them out to ensure they wouldn't be stuck in service and to clean the tips .
a
Right Rear VIN # 755681 / LNA2223AB (RL)

Thanks , Parker

 

Pals here did it before. The pre-1997 X300s' ABS sensors belong to the old design, and are a pig to remove. Check out this thread "Rear ABS Sensor Removal". New ones cost a fortune, so with luck you might find some good used ones.