XJS and the ABS system that has failed. 1992Model with 56000 miles

No more questions and thanks so much for all the advice and answers. I have spent a lot of time and that of others trying to make sense of an over-designed and overly complicated brake system that for the most part I will never need. I realize that many changes and modifications would be in order to change the entire system back to a normal, vacuum boosted system, and if the car were in better condition, it might make sense. When one considers sourcing a pedal box, and the relatively inexpensive assortment of new parts needed, I have to ask myself if it is worth the effort. The answer comes up the same; no, not to do it. The car has a great engine, and that is it’s true value, and my feeling is that it could go to a needy soul and car and serve a higher purpose. Again, my thanks to all the contributors for their time and patience.

When you get a quote for repair of the Teves III master cylinder, you might change your mind.

I guess I don’t understand that statement. Just remove pedal box, master cylinder, pump and accumulator and toss it over the hedge, bolt in the pedal box, master cylinder, and vacuum booster from earlier model. No cutting or welding involved, it’s all bolt-in. Gotta bend a few brake lines, that’s about it. As improvements go, one of the simplest. It does require a pre-1989 XJ-S pedal box, but that shouldn’t be that difficult.

A pre-89 example? OK, and I will do a search, and expect to have to buy an entire car to get everything I need. I am sure they are out there, and still don’t know if I want to do it to this car, but I have good mechanics who could do it for me for little money. I was told the XJ6’s would not work, so it has to be an XJS.

/[quote=“Kirbert, post:2, topic:393609, full:true”]

When you get a quote for repair of the Teves III master cylinder, you might change your mind.

I guess I don’t understand that statement. Just remove pedal box, master cylinder, pump and accumulator and toss it over the hedge, bolt in the pedal box, master cylinder, and vacuum booster from earlier model. No cutting or welding involved, it’s all bolt-in. Gotta bend a few brake lines, that’s about it. As improvements go, one of the simplest. It does require a pre-1989 XJ-S pedal box, but that shouldn’t be that difficult.
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Question? If I pull the master and booster, will the pedal box come out from the engine side? Or do I have to get inside and wrestle it loose?

The pedal box will only come out from the engine side.

You may have 3 options - XJS pre ABS pedal box & Pedal set up, or, Teves IV Pedal Box & pedal. setup (no ABS, or with ABS).

or, the Teves IV way:

Thanks for the info on the pedal box removal. I have found the whole setup on an earlier car. It is about two hours from me, and the engine and trans are gone. They wish to sell the whole car, but I am hoping they will part with just the brake system.

The Teves setup is for another person on another day, as I have no use for it and have had my share of troubles with trying to diagnose the ills mine exhibits. I am going to retrofit the earlier non-ABS system and drive the car to see if I want to keep it. Once accomplished, someone may get the deal of their lives on one. It all depends upon what I think of the car after it is operational. thanks for the photos showing me what all is involved.

You may have missed my point - the Teves IV components (Pedal box with pedal, Vacuum Booster, and Master Cylinder) can be installed without the ABS Controller Module, and function as a totally reliable simple vacuum boosted system with brakes at all four corners working as they did in the pre ABS days. Very simple brake line changes - all up front - using existing brake lines and fittings.

I did the full conversion to Teves IV ABS over a year ago to my wife’s '92 XJS. It has been totally problem free, and not 1 drop of fluid needing to be added, and ABS works perfectly.

Yes, the Teves IV pedal box will work for a non-ABS retrofit. I didn’t mention it because I presume they’d be a bunch harder to source than the pre-1989 pedal box.

And yes, you could retrofit the entire Teves IV ABS system. That’s another way to go. It’s probably a bunch more work, because you have to install the ABS ECU and associated wiring. I dunno if the wheel sensors from the Teves III will work with the Teves IV; I presume they do, but if they don’t you’ll have to upgrade wheel sensors.

You might even pick up a couple of brake lines while you’re at it. That’d save you from having to rebend the ones you have, and possibly having to change the fittings on the ends.

In general I agree with those sentiments, and I wouldn’t bother with the Teves IV either. I will comment, though, that IMHO the difference between Teves III and Teves IV is night and day. The Teves III is dangerous, should have been banned by NHTSA. The Teves IV is excellent, everything an ABS system should be.

My understanding is that a new teves 4 system would be very expensive, and finding one used is just rolling the dice; again. Nope, I will proceed with the vacuum booster/master brake cylinder and older pedal box, if I do it at all. Hate to buy another car to get the parts.

You wouldn’t be the first. I think there are guys on here with three or four parts cars to keep one car running. And a couple who discovered that the car they just bought for parts was in better shape than the one they were driving!

Yes, the current sensors and coax cables from the T3 work and tested out with the proper ohms, no shorts of the center conductor or shield to ground. The cables from the rear sensors to the T3 ABS over the left rear wheel arch can be brought forward under the carpet along the driveshaft tunnel to reach the T4 ABS Module placed where the T3 Pump / Accumulator were. Likewise the front wheel ABS cables can be shortened to connect to the T4 ABS module. Obviously, the coax cables have to be carefully separated from the old T3 wire bundles carefully so they are not damaged and remain useable. The power points of the T4 use the same two 30 amp fused supplies that the T3 did.for the control module solenoids and pump. There is an ignition switched 5 amp power supply to the “brain” of the T4 ABS Module. The existing brake lines were used and bent as necessary to complete the hydraulic portion. I only needed to supply about an 8" section of tubing and one coupling. All remnants of the T3 system are gone - except some electrical wires from the T3 system that pass behind the evaporator to the fuse panel on the right side. Do I need to explain why I didn’t go there to remove unused wires?
That’s the short version of the T4 ABS install.
Obviously, the non-ABS install of the T4 (pedal box/pedal, vacuum booster, and master cylinder / reservoir is much simpler and easier and faster if you choose to leave the T3 stuff in place. Mostly a plug and play with some simple revisions of the brake lines.
The components you see in my pictures are all used parts purchase in 2014. There are a lot more T4 XJS’s showing up in yards now that there were back in 2014. I can give good souces to anyone that wants them.

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Well, an early car popped up just two hours away, less engine and trans for $400, and I guess I am going to take a look. I priced out all the parts I would need and it comes to about the same amount. I really don’t need another car sitting there, taking up room. I have called all my local junk yards for about 60 miles around, and nothing to be had.