I got my 93 XJS registered today, which I found out meant that I had to get insurance for it first, and had my new tires installed! I took them off and put them in the truck, not wanting to trust an untested car for an across town trip. I got home and put it all together and decided to take it on it first real road test! I drove it around the neighborhood 3 times just to verify it first, I had the top down, then of course, it started raining so I put the top up. I pulled out onto the main road and it seemed ok! I got to the stop sign in town, behind a newer truck and when I hit the brakes it acted a little funny, and the abs light flickered. Ok I didnāt like that, but the pedal felt fine, so I decided to continue up the other main road to the one side road. I went to turn there and when I hit the brakes it was very spongey and it took a little longer to get slowed down. Drrrrrrrr! I said ok Iām just going to take it home. I went slowly and when my next turn came up I had a car behind me, but I had slowed to 15mph. I hit the brakes and the pedal went to the floor and I rolled past the road! I pulled to the side and put on my hazards. Everyone went around and then I backed up and took the turn, running my hazards the whole time. I came to my next turn, and absolutely no brakes! I drove up the road until there was a little place to pull over and it was raining steady at that point. I called the wife and let her know what was going on. When the rain slowed I got out and looked around, but didnāt see anything wrong! I got back in and someone pulled up and asked if I was ok, then he said āyeah I had a triumph in the 80s! Brakes were horrible in it!ā Then a guy buzzed through between us and he said āpeople that have never owned a British car just donāt understandā lol 
. I had pumped the brakes a little and they felt like they had pressure again so I figured Iād try for home. With the hazards on of course, and riding 2nd lol. I made it home safe! I donāt see any leaks, bit did notice that my right front wheel was smoking hot, so I figure the caliper may be locked. Drrrrrrr! Any ideas? Both the brake, and abs light would come on when I held the brakes in if it helps
Boiled brake fluid?
Low brake fluid?
Start with the basics- wheels off for a thorough visual inspection in front and under the car for the rear. You might see the problem outright.
What the history of the car?
When I buy (or work on) any 20-25-30 year old car I assume that a full brake system overhaul will be called for unless thereās proof of recent work.
Cheers
DD
PS- not to nit-pick but using paragraphs makes a long posting much easier to read !
Brake fluid is dirty, but full. I wondered if it may have gotten too hot, but thought the other brakes would have still worked if one got too hot.
I donāt see anything that jumps out as looking bad, no leaks that I can see. As for the history of the car, I bought it last September in a non running start. The last inspection was 2014. I had driven it around my neighborhood a couple of times before and everything seemed ok then. The rear was redone by the previous previous owner in 2014, which included brakes. He died and the kids sold it.
Just checked and if I pump the pedal 25 times or so, then turn on the ignition, the pump runs for about 15-20ish seconds. With the car running, when I hit the brakes it runs for a second or so.
Dirty brake fluid screams boiling, if one boils then it will affect the brakes. For very low cost one can purchase a fluid tester;
https://www.gearbest.com/other-car-gadgets/pp_1832572.html
Sounds like you need to pull the callipers and check that that are all free of rust and crud around the pistons. I would also suggest you go for DOT 5.1 brake fluid.
It sounds like the pump is working as it should.
Yeah as hot as the right front wheel and caliper was, Iām guessing itās at least sticking.
Unfortunately you also have ABS system that needs looking at.
My 88 that sat for 7 years and had dirty yellow brake fluid was simple - new master cylinder and brake bleeding and new rear pads, brakes now work great.
I would read Kirbyās book about whichever Teves system you have.
If the front calipers have never been overhauled before you can be 90% sure they have dubious pistons. Quite easy to split the calipers, although the bolts are mighty tight.
You should be able to buy the new seals and S/S pistons at reasonable cost.
Done that to both my XJ-Ss many years ago, and the 1988 convertible calipers were leaking when i bought it in 2007. The pistons were bad so at 19 years of age they were past their use by date.
I actually ordered new rubber brake lines, a reman caliper and new brake pads and sliders. Weāll see how it goes. I do plan on checking a few things Iāve read about, including testing the solenoids, tomorrow. I wouldnāt doubt if theyāre gunked up.
My guess: Your RF caliper is seized, dragging, which is generating heat big time. The fluid boiled, which means the front brakes wonāt work ā itās just like having a brake circuit full of air. You have the Teves III brake system, which means if the front brakes donāt work, the rear brakes donāt work either. Pedal goes to floor, panic ensues.
Iāve said it before and Iāll say it again: The Teves III is dangerous. If you had had the pre-ABS vacuum-assisted power brakes, a seized front caliper would have disabled the front brakes but the rears would have kept right on working. Same with the later Teves IV system. I suggest tossing the Teves III in the dumpster where it belongs and upgrading to either the pre-ABS or Teves IV systems. Your life may depend on it.
Iāve been reading forum posts and have seen people talking about upgrading to either the older or newer setup, but Iāve yet to see anyone say āyes Iāve done it, and hereās what I didā. Most of what Iāve seen is āwouldnāt it be niceā. Believe me, Iād much rather have brakes that have a better chance of working constantly lol
Chances are unless the remanufactured caliper specifically says āS/S pistonsā, it will not have them.
At least you will get 15 years minimum out of them.
Would you like to imagine what state the other side caliper is in ?
As Kirbert says, this is not a fail safe braking system. If you are going to the trouble of fitting a new caliper on one side, then draining all the old fluid and replacing and bleeding, you may as well fix the other side and be safe - well, more or less safe.
I have the dangerous Teves on the 1988 convertible. I am very conscious of any sign of braking performance being different to the norm. It is not so easy to find wrecked early XJ-Ss in this part of the world to extract the vacuum system pedalbox and other parts. I do have a spare V12 being rebuilt in no hurry for the car. If one day I change the engine then for sure I will go to the trouble of changing the brakes.
Caveat. Always work on brakes as pairs, NEVER only do one side.
As in never: I had a couple customer cars, that were relatively low mileage, but, natch, out of warranty, that had one front caliper or wheel cylinder leak.
ALWAYS replace/rebuild in pairs.
I didnāt even think about stainless vs regular pistons, and youāre right, it is a good chance the other side may be the same, unless it was swapped out at some point in its life. I will at least go through the left side. I am very interested in the possibility of swapping to the later style, but I have to find some more detailed information about the job
OK, someone has to be contrarian so it might as well be me ! 
I always replace friction material in pairs. But I see no compelling necessity to replace calipers or wheel cylinders in pairs. If a caliper or wheel cylinder is functioning properly, why replace it? Iāve done so many times. If something horrible is supposed to happen, Iāve never seen it, felt it, or heard it.
Example. Three or four years ago I replaced all calipers on my car. A few months ago I determined one was dragging. I replaced the one caliper, not two. Allās well. No problems.
On the flip side, there have been many times where I have replaced both sides, or all four calipers, even though only one was actually giving problems at the moment. This is typically when the system is obviously in rough shape and I make the assumption that the other three calipers/cylinders are likely to give trouble soon. And the car will probably get new brakes hoses and master cylinder as well. All under the guise of do it all, do it once, do it rightā¦and be done with it. Itās easier, in the long run, than the alĆ” carte approach.
āAlwaysā and āneverā can be troublesome words. Absolutism is not always required.
Cheers
DD
You make fair points: let me clarify.
Friction materialā¦ trueā¦BUT, thereās no guarantee that if you change out a single side of brake fluid-soaked friction material, while the other side is perfectly dry, youāre going to get the same friction coefficient in those new friction materials.
Secondly, if, say, I install a net axle set of calipers/ cylinders, and 18-2000 miles later, one side pops, then Iād would do (have done) a single-side replacement.
Thirdly, a real-world example: when I got Tweetles back OTR, one of the original Dunlop calipers was partially frozen, while the other side was quite functional: both calipers had had ~150,000 miles/~30 years use: would it have been prudent to just repair/replace one side?
Not on YOUR bippy!!!
Call me tort-shy, but on a customer carā¦ especially now?
NEVER.
There, I saidāand reasonably justifiedāan absolute.
Your serve!!!
Under those circumstances I would do just the same; replace both. And probably more.
Consumerism and litigation-ism have made cowards of us all. In many cases it encourages over-repair and discourages case-by-case evaluation of whatās really needed for a good result.
What Iām advocating is just that: case-by-case evaluation rather than āalwaysā and āneverā
Iāll add that urban legends, and admonishments passed down through generations, can create some always-never scenarios that leave me scratching my head
Cheers
DD
Oh well, jeez, there ya go again, with the āreasonableā DD.
Oh, MEGAdittos, and, TBH, one of the deciding factors for me to exit the mechanic bidness, stage right.
Ok so I checked and all of my solenoids click when 12 volts are applied, so that might be ok. I have parts ordered, just have to wait on them. One of the biggest drawbacks of a Jaguar! I canāt ājust go getā what I need. Smh! And on that note, I was looking into something that I saw in a picture I took yesterday before my ride, and noticed that it looks like my subframe mounts separated on the ride! Argh! The wifeās not going to be happy! First pic is from yesterday, I wanted to check the āgapā at the front mount. Second pic is from today. Smh!
