1991 Jaguar XJ-S

[AKROVER]

Yesterday and the day before were my two most intense workdays on this car so far. I worked 6 hours yesterday and 8 on Monday. I wasn’t expecting so many challenges in assembling things.

My first struggle was with the lower control arms. The bearings on the pivots want to fall apart. There is an inner sleeve that is wider than the pivot point. On either side of each pivot point, there are three concentric rings that rest on the edges of those sleeves. The inner ring is basically a washer. The outer ring is just a metal ring. The in-between ring is a rubber grease seal. These four sets (two pivot points per arm and two sets of rings per pivot point) balanced precariously as I tried to slowly insert the heavy assembly into the housing. There are also large washers that go outside of those seals while the 16” axle gets inserted through both pivot points. It is a job for someone with six hands. I managed to hold one side reasonably together, squeezed in the big washers and inserted the axle. The other side had to be reassembled in a tight space. Luckily there is some flex in the housing that allowed me to pry open some room while I gently inserted the concentric ring assembly, a tedious process requiring about a dozen tries before achieving success. When I moved to the second control arm, I saran wrapped the assemblies together. I am not sure I got all the saran wrap out, but I don’t think that will present a problem.

After that, I was able to motor along, bolting the axles down which sandwich the rotors. The next step was installing the new springs/struts. I realized that I was going to have to turn the assembly sideways on my dolly as the arms drop down too low for the way I had things oriented. This means I will have to slide the stationary wheels of the dolly sideways to move the assembly under the car, but the weight is mostly on the smaller pivoting wheels so I can probably just pick up the back of the dolly with the jack and roll the entire thing sideways. I suspected this was going to be necessary, but I wasn’t sure until I started to put on the springs.

Luckily, I realized that prior to pushing the pivot axle for the springs forward, I had to install the new radius arms. Those cannot be tightened until they are fully connected to the car and the car is sitting level, but the bolt has to go in before the front spring, another of those crazy thoughtless bolting details. There were a few washers in the mix of all these pivots that I wasn’t entirely sure about, but the number and sizes worked out logically. If you look in the picture below, you can see the radius arm (bungeed up to keep from scraping on the concrete) pivots are tucked behind those front springs.

Yesterday was supposed to be an easy day. I just needed to fabricate a few brake lines and install the calipers and handbrakes. Installing the calipers turned out to be a nightmare, even worse than taking them off. I think one problem is that the holes did not precisely align with the mounting bracket holes (I’ll blame the Chinese calipers for that). I was able to force the first one together, but that meant that the bolts were tight the entire way, a quarter turn at a time. Over half the turns had to be done with an open-end wrench because there was no clearance for a box wrench. I am glad I didn’t buy that set of Gear Wrenches I looked at the other day as those were too thick to fit in there until the end. I had two box wrenches of the right size in my collection and only the thinner one was really useful. I opened up the hole a little on the second caliper, but then ran into another problem. I managed to get the lower bolt to engage, but then the caliper wouldn’t rotate far enough to line up the second hole. I ended up grinding off a part of the caliper housing that was bottoming out and then finally jammed the bolt into the hole and repeated the quarter-turn-at-a-time joy of the first one. If you look at the picture, the mounting bolts are on the inside of the calipers behind the cylinder. The work is jammed between the caliper and the differential. There is so little room to work in there that the bolt cannot be removed until the caliper is pulled out.

I really didn’t understand how the handbrakes work until I began to assemble them. The first thing I ran into, though, was the realization that the stupid routing originally used for the driver’s side brake line was because of the handbrake lever. I now have to fabricate a new brake line for that side. I looked at the two points and chose the easiest routing, a foolish mistake. It seems every line I have fabricated has required repeating the process. The first set of crossover lines couldn’t be re-used with the new longer fittings because the first bend was too close to leave room for the flare tool (flare before bending).

The handbrakes are weird, for sure, but they aren’t as bad as I thought. They were merely a minor hassle to assemble and I think there is a chance that they might work OK. I didn’t want to adjust them too tightly, but they do seem to open on both sides when the tension on the arm is released. The old springs aren’t actually terrible, but they do need to be tightened up so I will probably try to bend those to tighten them. If they break, I can buy some new springs and fabricate them to the correct length.

With as much cleanup as I have done, I thought the assembly work would be relatively clean, but I seem to always grab a dirty spot that I missed. The anti-seize didn’t help me stay clean either, especially when I dropped a small bolt into the jar and had to fish it out. My hands are raw from constant washing and my Gojo is running low.

[AKROVER]

The car is sitting on its own wheels right now, although the wheels will be coming off for the final steps. Everything went really well this afternoon. I fabricated the last brake line and then stood there wondering what else needed to be done. I greased a couple of fittings, but then decided it was time to roll this thing back under the car. That worked exactly as planned. I was able to angle the dolly under the car and then rotate it to start the IRS into the gap. Once the dolly was north/south on the car and the IRS was about halfway in, I slid the jack under the dolly and picked up the big stationary wheels. Then I was able to roll the complete mess perpendicular to the car using the jack and the two swivel wheels on my dolly.

I hope I lucked out on the speed sensor. The one tab broke off at an angle so the broken piece actually engages with the main body of the sensor and provides some downward push. The other bolt tab was fine and probably would have been adequate by itself. The way it is sitting there with both bolts and both tabs in place, you couldn’t tell it was broken without removing a bolt. I think I dodged a bullet there as I could not find a replacement for that online. I think that is the speedometer feed so I will find out soon enough.

I next attached the ABS sensors to each wheel and installed the new cable guide screws that I found in my hoard. They worked perfectly. I then tried to tackle the handbrake cable. I got one side in, but the cable isn’t long enough with the new pads. I tried loosening the adjusting screws inside the car, but the cable doesn’t seem to be sliding out further. I decided that wouldn’t be any more difficult to address with the IRS mounted so I left it with the one end connected but the other end loose.

The next step was the big part of the plan, jacking up each side to align the mounting bolt holes and sliding the mounting bolts in. Before starting, though, I slid the jack under the dolly and was able to lift the IRS assembly up by putting the jack head between the rails of the dolly. That allowed me to slip another 2X8 under the IRS so that it sat a little higher on the dolly. Then I only needed to jack each side a little to get the mounting bolts inserted. It was some elegant one-person material handling with a very heavy assembly.

Once the IRS was bolted up, I put the jack back under it as that is the proper way to jack the entire rear of the car to put it up or take it off the stands. It also adds some safety when working underneath. The car was still resting on the stands, but the jack was there as a backup as I crawled underneath. I first inserted the exhaust pipes. Those went in easier than they came out, but I think I had the car sitting quite a bit higher this time. The pipes are resting on their support inside the IRS. One of the rear mufflers is already loosely attached and resting in its support. I need to buy a couple of new clamps and some new flange bolts to finish the exhaust. The next challenge was the driveshaft. It was awkward, but it all went together nicely with brand new hardware.

I thought about quitting at that point, but there was still some time left before dinner, and I was already a filthy mess so I decided to get the radius arms connected. I had reset the jackstands after removing the old radius arms so those had to be moved, first. I decided that the easy way of putting some load on the springs to level out the arms was to simply put the wheels back on and lower the car, getting the jackstands completely out of the picture. The radius arms required a little help from the jack to slide into place. I had to re-use some old crusty bolts, but after cleaning them up and adding a little anti-seize, they went in easy and clamped down solidly on the radius arms.

Replacing rear springs on a 34-year-old car is expected to alter ride height. They should settle a little after a few miles, but right now the look is quite different. The car looks like it is heading downhill, and the rear bumper looks like it is way up in the air. The springs are soft as the car bounces easily and settles immediately with the new struts. The surprising thing about the way it looks is that when I measure the actual gap between the top of the tire and the wheel arch, the front and rear are less than a half inch in difference. I think the problem with older cars is that nobody really knows or remembers what they looked like new. Most of these today are probably running around on saggy old springs so we end up thinking that is the ‘right’ attitude. The picture below does a decent job of showing the similar wheel arch gap front and rear and if you look at some of my older pictures you can see how squished down the back was. I suppose the bigger question for me will be any differences in handling and ride quality, but it takes some getting used to when your car’s attitude changes.

The final steps should be getting the exhaust buttoned up, tightening the rear radius arm bushings, and bleeding the brakes. I will take a closer look at that handbrake cable, as well, but that is not a high priority. If all goes well, I might even park it downtown on the fourth as part of the local car show.

[GMJohnny]

After reading this, I’m amazed at the engineering that went into the IRS on
your Jag. It seems a bit over complicated to me, but the majority of the cars
that I’ve worked on are very basic- almost tractor-like so anything different
seems complex. The struts don’t look too horrible to remove from the car with
the IRS assembly in place, so if you hate the new ride height, I’m sure you
could do something to adjust the springs. I’m a stickler for the “correct” height
(whatever my mind gets stuck on) and I can remember going out and measuring
my spring work almost daily after a spring install to see if gravity had helped
my situation out… most of the time, I’d lose about 1/2” height after it was all
said and done. Hopefully, it will settle to a height you’re happy with!

GM

[Basement Paul]

I expect it will take hundreds of miles and several months of gravity to chill those springs out to their natural height. A couple bags of ballast while it's sitting or even during your next few drives would speed up the process. I never once doubted your ability to tackle this project, but damn, like Dave mentioned before, this would make me question ever owning one myself. This thing is definitely overengineered for what the cars general purpose was, a nice grand tourer. Good work!

-BP

[MostMint]

My first thought is - front sprints had to have settled also over all that time so you might want to change those out also. I also wonder how well aftermarket springs meet the factory specifications for loading/spring rate.

[AKROVER]

I am not done yet. Yesterday’s work started well, but before getting to work I was buying more tools. As I contemplated the tasks ahead of me, I realized that tightening the radius arm rear bolt was going to require a tool I did not have, an 11/16 box end wrench. I took it apart with an open-end wrench which didn’t work well because the bolt only has 5 normal flats instead of six. The sixth one is cut way down because some engineer put the pivot point for the springs in the way (this also precludes using a socket). Any bolt will go in on an angle, but once there is a radius arm inserted, the bolt can only go in straight, and a normal hex head bolt will hit the nipple on the lower control arm. I can just imagine the conversation when the assembly team asked the engineer how they were supposed to put that together. Removing that bolt with an open end was silliness as I had to skip that flat spot whenever it came around, but it was easy enough with the wheel off. To tighten the bolt, I had to have a box wrench as I would be working behind a tire in a nearly blind and awkward position (the suspension has to be loaded before tightening these bolts). I was finally just going to buy a complete good set of wrenches, but that would give me quite a few duplicates, so I pulled the trigger on a set of the ratchet style as those are a meaningful complement to my toolset. That did make quick work of those radius arm bolts, quicker than a box wrench would have been. I also bought a marriage saver tool, a vacuum brake bleeding kit. I am getting no joy out of buying tools, but the wrenches are nice (I bought Craftsman).

After tightening the radius arms, the car went back on stands for the final few tasks. I bolted up both exhaust lines, although I had to re-use an old crusty clamp because the store only had one clamp in stock. It worked well enough for a pipe that connects to the rear muffler as that does not really need a perfect connection.

The last task was bleeding the brakes. It was a disaster. I am not sure how many leaks I have. The big one is on the line leading to the driver’s side caliper. I think my crossover lines are fine, but there was enough fluid up there to make it uncertain. I tried tightening, but had no luck. I took that leaky line out and fabricated a new one. It leaked just as badly. I tried even harder at tightening, even cycled the tightening, but no luck. Interestingly, the leak was small enough that I had a really firm pedal. With frustration and exhaustion building, and a margarita calling my name, I put the wheels back on, backed the car out of the garage, spun it around, and backed into the garage and up onto ramps. That will give me better access to those brake lines. The brakes felt good the entire time, but the stripe of brake fluid in my path tells a different story.

I began deeper research and came to two conclusions. First, my flaring tool sucks, particularly since the caliper connections are all bubble flares, and not even a standardized bubble flare. Regardless, my flaring tool really isn’t for bubble flares, although most Jaguar enthusiasts swear by simply doing the first step of a double flare to make a Jaguar compatible bubble flare. The problem with my double flaring tool is that the first step isn’t particularly bubbly, more flattened than rounded. The second conclusion is that I don’t like the fittings I have. The original fittings were not threaded all the way to the end and my fittings are showing some thread damage at the bottom which might mean I am running out of threads before fully compressing my flattened bubbles.

If you have no idea of what I am talking about, there are DIN (primarily metric) bubble flares and SAE double flares. In the past, British companies used something called a Girling bubble flare which is not the same as the modern DIN bubble flare, more of a hybrid between the double and the bubble. As you might imagine, a 1991 British car in its seventeenth year of production is a mess of SAE and metric stuff. Each brake fitting is anybody’s guess. In general, when working with soft brake lines (non-stainless), the precise shape of the fitting and flaring really don’t matter that much, but my flares are likely bad enough that I can’t compress the material better to get it to seal. The good news in all of this is that most of my connections did not leak and did not require some gorilla level of torque.

I don’t yet have a plan. I think I will talk to the parts store to see if they have a better flaring tool. They might even sell me bubble-flared lines with fittings that I can bend into the correct shape. The crossovers were only 10.5” of line and the other one is about 9”. In a worst case, I have picked out another flaring tool that looks a lot better for bubbling.

So the Jag did not go to the show today. I did walk down there, and it was a bigger show than I expected for our small town. I kept looking in the engine bays and realizing just how simple a pre-emissions carbureted car is to work on. I really am enjoying my challenges, but peaking underneath at a basic 9” rear end put some perspective to this interesting task I have taken on. I am 3 weeks into this mess. The car can sit a while now as I plan my next step. I have a few other things to take care of before getting back to this.

[AKROVER]

While in North Carolina visiting my family last week, I ordered some new brake lines. I found a supplier who had short sections of “British” brake line with bubble flares on both ends and the correct 3/8-inch threads on the fittings. I bought two 12” lines to replace my crossovers on each caliper. I bought one 8” line to replace the line going into the driver’s side caliper. This was cheaper than buying a better flaring tool. Those lines arrived today. I bent them into shape and installed them. This would have been a lot easier with the IRS still out, but it was achievable with the rear of the car sitting on ramps. It is a long way to roll under there from the back of the car, but the creeper is low enough that I can slide right under the differential and get access to the lines from the front side. It is all back together, and I have not found a single leak, but the bleeding procedure is not straightforward for the rear brakes. I really need to check the book more as the procedure is in there and it is nothing like what I was doing. At least that explains why I was getting almost no fluid to come out the bleeders. The rear brakes are fed by the ABS system pressure, so it has to be pressurized during the bleeding procedure. I think my losses of fluid throughout this process has also triggered the need to bleed the ABS system, a separate procedure covered by my book. I might need to buy more fluid.

While I was under there, I also managed to get the handbrake cable into place. I barely had enough cable to get it installed with the new thick pads. It took some prying and a turnbuckle to pull the levers together as far as possible. I was proud of that creative solution. I hope I never have to take that cable off again, although it would be easier if the pads were worn down. I haven’t adjusted the cable yet, but I already know that it is loose enough that I don’t have the brakes dragging. I also reinstalled the circlip on the driveshaft u joint that I mistakenly removed during disassembly. I think I am nearing the end of this ordeal.

[AKROVER]

On the road again.



Finishing was easier than I expected. Yesterday, my dashboard was lit up with brake warning lights, but reading the procedures for bleeding the brakes explained what the two warning lights mean. The first thing I did this morning was just turn the key to the run position. When I did this, I heard the ABS pump motor running. When it shut off and the warning lights all disappeared, I knew I had pressure in the system. I ran to the store and got some additional brake fluid to top off the reservoir. I then used my vacuum bleeder on the one caliper that was giving me nothing yesterday. With a little pressure in the system, I was able to see fluid rising in the tube with an occasional bubble. When the bubbles stopped, I took a chance. After lunch, I carefully pulled out of the garage. The brake pedal felt perfect. I decided to take a little ride. The first step was heading down my steep driveway, a terrifying first step after doing a brake job, but the car remained in control. I have since put on over 80 miles.

I also bought some wire as several of the bolts have holes through them for safety wires. I put wires on the two main radius arm bolts and the four caliper bolts even though I am pretty sure those four will never back out on their own.

While under there, I noticed that my rear mufflers weren’t centered. In fact, one of them was up against the sheet metal. I loosened the clamps and rotated them slightly to center them up. I later had to repeat that as they looked quite asymmetrical from the rear. They still are not perfect, but at least they are hanging reasonably.

I washed all the dust and fingerprints off the car and then took a nice long drive through some fast curvy roads. The handling is different. The car rides a little firmer, as expected. I used to have some clunks at times before, but now the suspension seems completely quiet over the bumps. The picture above is with a nearly full tank of gas and a little settling time for the new springs. I think it actually looks right now, even though I was used to the sagging rear. The car still feels confident in the curves, but it feels slightly less stable over bumps on the curves. I suspect that the change in angles with the higher ride height is giving me more rear steering that I will need to get used to. It is effectively a passive rear steering design. The brakes are wonderful, smooth and easy to modulate. The car was motoring along nicely on my high-speed cruise. I even managed to squeal my tires pulling away from a stop sign. I am not sure what that was about, but perhaps that seized caliper was inhibiting my starts before.

I can’t believe this project is finally done. It is certainly one of the more involved projects I have ever taken on with a car. I spent a total of 79 hours working on this, more if you count the hours spent on the internet buying parts and researching solutions. The total bill was just short of $1600, but the car has new calipers, rotors, radius arms, struts and springs, along with countless other minor pieces like hardware and brake lines. I also ended up spending over $400 on tools and supplies during this project. While a professional mechanic would certainly finish this job a lot quicker, particularly one who is familiar with Jaguars, it is frightening to think what it would cost to pay someone to do this work. Hopefully this will all last another 34 years. I am pretty sure I will not be doing the next rebuild on the IRS.

[MostMint]

What is the factory spec for camber and toe in and how close is the car to spec? If you have too much camber it can load more weight on less of the tire which would make it easier to chirp. There are probably other possibles like weight distribution due to higher ride height.

[Basement Paul]

Good work, Tim. That was a doozy. I suspect that rear will come down at least another inch by winter. Might be interesting to put a tape on it and see how much it drops in the next six months.

-BP

[AKROVER]

What is the factory spec for camber ...?

That was a good thought. It was a concern of mine during this project. The only alignment adjustment is for camber. One interesting thing about the Jaguar IRS is that the individual axle shafts are one of the links in the suspension. The adjustment for camber is therefore simply spacers between the axle shaft flange and the brake rotor. I put a micrometer on my new rotors and compared them to my old rotors. They were all extremely close in thickness. I was diligent about keeping the spacer packs for driver and passenger sides separated, but I hadn’t yet measured camber. I don’t exactly have a good setup for such measurements, but I was able to get a decent measurement. The specification is 3/4° ± 1/4. I measured both sides and they both appear to be closer to 1/2°, but still within specification. With the ride height difference, though, I don’t know what I had before and it could be different, potentially leading to both changes in contact patch and in handling in general. My goal was simply to not mess it up, but in retrospect, I should have measured what I had to begin with.

[AKROVER]

Might be interesting to put a tape on it and see how much it drops in the next six months.

-BP

I don’t know that I care, but it is a fun suggestion. Currently sitting in the garage with about ¾ tank of gas, I measure 22.5” from the ground to the point on center of the rear bumper where it begins to roll (sharp line there, easy to measure). Being a bumper height measurement in a car with a relatively long overhang, it should show the most change, but I suspect with that soft suspension, it is highly susceptible to load changes, including gas tank level. I also measured the roof height, which is something that I measured when I first got the car. The car currently sits just slightly under 50” at the high point on the roof. My previous measurement was 49.25”.

[MostMint]

if the rears are at 1/2 degree negative (further in at the top) with the weight on the rear tires, that is at the bottom end of acceptable range but should actually be the best contact patch at rest the factory spec allows.

It might be interesting to read some reviews from when this car was new to see if it had the same kind of chassis response then.

If it was out of spec prior maybe it was at 0.