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Hi all.
Been a while since I last posted but guess what I have a problem. The rear NS brake calliper has decided to start leaking so it looks like the rear cage will have to come out to overhaul the rear brakes. The car us up on stands and as far as I can see I have the following to undo / remove. Over axel exhaust pipes, trailing arms at the body mount, brake hose to the cage, ABS sensors, prop shaft then the 8 mounting bolts. After all this lower it down on a jack then out from under the car. Any tips would be gratefully received. My plan is to see what the callipers are like with regard to rebuilding or replacing. The discs will be renewed along with anything else I find worn.
My experience is on a ‘88- disconnect the parking brake cable in addition to what you have listed. If you block the brake pedal down with a piece of lumber between it and the seat, you will limit brake fluid loss. The over the axle pipes can be difficult to snake out it the car isn’t high enough; if so, lower the cage with them tangled in there. The pipes come out easily if the half shafts are out (applicable if you are doing the output shaft seals at the same time).
Now is the time to replace the output shaft seals if not totally dry; and if replacing the seals you should probably replace the bearings which requires new collapsible spacers ( and a way to measure rotation torque to set up the new bearings).
I cut a piece of 3/4” plywood to fit the reinforcement plate on the bottom of the cage, and attached a plumbing flange to it to fit into my floor jack, mounted on the fore/aft centerline, 3” forward of the axle centerline. This is the approximate balance point. I jacked from the side and rolled it out the side. Probably took me longer to type this than to remove the cage assembly.
Occasionally the thought has crossed my mind that Brit engineers made things as complex as possible to provide employment security to factory workers and maintenance mechanics.
Occasionally the thought has crossed my mind that Brit engineers made things as complex as possible to provide employment security to factory workers and maintenance mechanics.
It takes 10 minutes to remove a Corvette caliper.
Doug
True, but the question is what do you want, the ability to easily change a caliper, or the priceerformer supercar of its time? (1975). Comparing apples with apples and eras with eras, a 1975 Corvette would be outcornered and outrun by a 1975 XJS and would have 5% of its refinement. The inboard brakes (as I am sure you know) are to reduce unsprung weight and thus enhance the suspension's optimum performance. So do you want a cart sprung rear or the best axle available at that time, is the question!
Now as one who has struggled with all this, I also acknowledge that an inboard braked axle that could have the calipers removed without dropping the axle would be ideal! But the design heralds from an era where ease of maintenance was not a consideration.
Hi all. Thanks for all your replies. I forgot about the handbrake cable now noted. The only thing I’m concerned with is if the rear of the car is high enough so I can roll it out backwards on the jack. Not going to rush to get it done as the car is on sorn until the spring.
But the design heralds from an era where ease of maintenance was not a consideration.
Was ease/cost of maintenance not a consideration, or was it engineers that never even gave it a thought (closely related, but never even giving it thought is a sign of a poor engineer), or was it to make more work for the labor union people? Maybe management didn't care and told the engineers to just design something that works per requirement and not worry about repair difficulty?
The damn Italians were just as bad. The coolant temp sensor on a 308 is buried on the underside of the cross over pipe between the heads. There is room it could have been mounted horizontally, making it easy to remove, but no, when it is under neath, you have to remove two of the four Webers carbs and then re-synch them after reinstall, to change that $10 sensor. Several hours works instead of what could be an hours work. The same questions I asked above crossed my mind about that design tidbit.
I guess its a moot point, 35-50 YO cars,The questions I ask are rhetorical, the engineers that designed them have probably all retired, but I still curse them when I have to deal with something that could have been made easier to work on, without sacrificing performance. But, as an engineer myself, I would have fired anybody who came up with maintenance nightmares like these.
I just did this on my 1987! I removed the cage to replace the output seals. I also used 3/4" plywood routed to fit the ties plate. Top tip: I used an ATV jack - not a regular floor jack. The ATV jack has a much larger lifting surface so minimizes chance of the cage toppling over. As you can see, I didn't raise the car very high so it was too low to remove the exhausts. As suggested already, I removed them with the cage and extracted the cage sideways. I lifted the assembly with an engine crane so I could get it high enough to remove the exhausts. FWIW, I found the most stubborn part was re-fitting the handbrake cable.
The goal was to build the most refined and best riding and handling car available while providing value for money. Consider when the XJS came out it was the fastest car in the world you could by with an automatic transmission. While cheap compared a Rolls Royce or Ferrari, these were not cheap cars to buy when new, typically 3 times the price of a large Ford/Chevy sedan. If you could afford the purchase price, you afford to take it to the dealer and pay whatever it cost to get the car serviced. These were specialist cars, not taxi's. Cheap repairability was a much lower design priority than excellence of the ride. The original owners were not the type to create a spreadsheet and buy a car based on the projected cost per mile to operate them!
Consider that pads are easy and fast to change on these cars with a hoist. Replacing calipers is not a usual maintenance operation. On a hoist, even the rotors are not bad to do. Jaguar used a high quality material in the rear rotor and they last a lot longer than other cars.
The main designer of the rear suspension was an excellent engineer, and also later became Managing Director of the company ( basically president). Management and Engineering were basically the same thing for much of the 1950's to 1980's.
Not to mention that Jaguar had a good design from the post ‘61 models, including the E Type, that could be carried over. Money and time saved, why reinvent the wheel? I don’t feel any task on theXJ-S is particularly difficult compared to similar vehicles, just different.
Occasionally the thought has crossed my mind that Brit engineers made things as complex as possible to provide employment security to factory workers and maintenance mechanics.
It takes 10 minutes to remove a Corvette caliper.
Doug
Yeah, Corvette calipers are a breeze; the older Corvettes are generally easy to repair. OTOH, dealing with the rear hub bearings on the C2/C3 cars is a real PITA which I dread. Same with behind-the-dashboard work on C3s.
But, really, whatever the car you become accustomed to the repairs, right?
I think we can all share stories of xxx-car and xxx-design which were unusually hard (or time consuming) to repair. It's helps, sometimes, to vent a little
Many are daunted by the V12 Jags. All the "stuff" under the hood, right? But, really, it's just a matter of working patiently. And after you've been elbow-deep a couple of times you begin to see that Jaguar left "just enough" room to do what needs to be done.
My TR6 earn top marks of ease-of-repair. Except perhaps an old VW Beetle or MGB it would be hard to find a simpler, easier-to-repair car. But, OTOH, it ain't no Jaguar (or Corvette!) to drive.
Saturday morning "ramble" switch turned off now :-)
Not to mention that Jaguar had a good design from the post ‘61 models, including the E Type, that could be carried over. Money and time saved, why reinvent the wheel? I don’t feel any task on theXJ-S is particularly difficult compared to similar vehicles, just different.
The Jaguar suspension was a marvel. I reckon competitors, if forced to admit the truth, were impressed by Jaguar's ability to offer a comfortable ride AND excellent control and road manners AND isolation from NVH. Besides good looks and style I really think this is what kept many Jaguar owners coming back year after year. Even today if a person jumps into a well-kept oldie Jag they'll be impressed, I think, by the overall combination of comfort and control.
I think we're missing a few of the realities here. We ask if maintenance was a concern... but we miss some of the other "issues".
Going back to the race cars (i.e. D Types), emphasis was on a gain to be made in lowering unsprung weight. This, plus the discs, was a major improvement over drums. considering the focus was on racing.
Then came the E Type. In addition to all else, pointing to the use of "racing" heritage was a marketing, not maintenance win. Besides, how many were doing their own maintenance on Jags then?
Now we get to the XJS (and others). Does anyone really believe British Leyland would have approved the redesign of a major component, when a perfectly useable one was on the shelf? Remember, the (possibly apocryphal) reason for the narrow XJS engine bay is if they made it wider, British Leyland would have tried to stick the Rover V-8 in there.
It wasn't until years in the future, after British Leyland was just a bad dream, and Margaret succeeded in de-nationalizing the British auto industry that there was funding available to look again at the supposed advantages of using that 1950s technology to reduce unsprung weight that the discs were moved outboard. Perhaps that change could have been made earlier, but what other things were going on at the time?
You always have limited resources. How you use (and balance) those resources are important. Was ease of maintenance a concern? Not originally, as other concerns were a much higher priority. But once chosen, you're on a path. That path then becomes limiting to other things.
Yes, the C3 dash is a PITA. I cursed those engineers out also, but at least i was able to sit in the seat while working on it, and not be under the car or bent over something.
Back to the XJS, Yes, the interior ride is superb, and quiet. I am amazed at how little road/tire noise there is in the drivers seat. My '16 Z06 is MUCH louder inside, I am sure tires have something to with it, but the C7 is loud inside, diff pavements have drastically different loudness. The Z06 is running 8 YO factory Mich PSS run flats, the XJS has new V rated Cooper CS 5 tires.
Occasionally the thought has crossed my mind that Brit engineers made things as complex as possible to provide employment security to factory workers and maintenance mechanics.
It takes 10 minutes to remove a Corvette caliper.
Doug
Doug.
You do realize that Jaguar was using disk brakes back in 1958 on production cars and 1954 on the D type race car? So yes Chevy learned how to make disk brakes from Jaguar. Since the Corvette never did handle that well, they didn’t care about things like unsprung weight.
Even today 63 years later race cars have inboard brakes.
While Chevy makes a pretty decent car ( I’ve bought 22 new ones in my lifetime). We Jaguar enthusiasts have a different priority. We seek not the ordinary, inexpensive, mundane. But rather something special.
A car that no less than Enzo Ferrari called the most beautiful car ever.
One that the less knowledgeable will stuff a Chevy in because they fail to understand what a Jaguar is really all about.
True, but the question is what do you want, the ability to easily change a caliper, or the priceerformer supercar of its time? (1975). Comparing apples with apples and eras with eras, a 1975 Corvette would be outcornered and outrun by a 1975 XJS and would have 5% of its refinement. The inboard brakes (as I am sure you know) are to reduce unsprung weight and thus enhance the suspension's optimum performance. So do you want a cart sprung rear or the best axle available at that time, is the question!
Now as one who has struggled with all this, I also acknowledge that an inboard braked axle that could have the calipers removed without dropping the axle would be ideal! But the design heralds from an era where ease of maintenance was not a consideration.
I don’t know if it’s true, ( Although oft repeated)
But wasn’t the rear end designed on a £100 bet over a weekend?
I don’t know if it’s true, ( Although oft repeated)
But wasn’t the rear end designed on a £100 bet over a weekend?
Bob Knight was the Jaguar NVH and handling/ride guru. He is said to have told William Lyons in the mid 1950s that the then standard live rear axle needed to be independently sprung if improvements in this area were to be gained.
Lyons allegedly bet him he could not come up with such a design that was manufacturable within a reasonable cost, and gave him a month to try. The story goes that Bob Knight sketched it out over the next weekend!
By the way, I think the D type had a live, not independently sprung rear? Is this true or am I mistaken?
Rear cage removal
erformer supercar of its time? (1975). Comparing apples with apples and eras with eras, a 1975 Corvette would be outcornered and outrun by a 1975 XJS and would have 5% of its refinement. The inboard brakes (as I am sure you know) are to reduce unsprung weight and thus enhance the suspension's optimum performance. So do you want a cart sprung rear or the best axle available at that time, is the question!
