Hello all, just a dumb enquiry, if you were to change the rear shocks on an XJ-S is it an automatic to change the rear springs too. They seem OK , n o signs of damage or anything. The only thing I would say is they’re 30 years old.
Not a dumb inquiry Diane. When I replaced the the rear shocks the rear springs where also replaced at the same time. Clearance had been too low and now the car is at correct height.
The forward clearance had also been low and replacing the front spring corrected that also.
Rear was easy. Front springs where a dangerous challenge.
My car is a 1987 XJ-S coupe.
Check the ride height at the rear. Jag rear springs can last a lifetime. My 1973 XJ6 still has the original rear springs. Shocks are new, but springs the same. The ride height is spot on.
The answer depends on your definition of “no signs of damage or anything”.
If mileage of XJS is above 100k miles, if the springs are rusty, you’re planning to do it in the workshop or simply you don’t want to carve in poop (making savings on something thst will consume your cash anyway) - the answer is yes, those shall be replaced.
If you’re doing it in the workshop, not by yourself, the answer is absolutely yes, those shall be replaced - you will pay the same money for the labour.
There have been dozens of posts where replacement springs were not the same rate as original, and people were not happy.
I have an XJ12 where the PO had changed springs and it’s obvious that the springs are far too hard.
Like John, I had a S1 XJ for 36 years, and reused the springs. I even took them to a race shop to best tested. If I recall…they were 200 pounds - same as new?
Good luck,
Rob
1 Like
Thank you all , not a job I’m comfortable doing myself so my Jaguar mechanic will do. He recommends changing them while under there. I was trying to stick to a budget with KYB shocks but have ordered the springs. I know the forum talks a lot about ride height which I really didn’t intend to mess up if it can be avoided.
So only because Im lazy and didn’t look, what is the proper height in the rear? Is it pretty much the same throughout the years? Mines a 93my convertible
Don’t know how much you trust your mechanic but a good habit to get into is always request that the used parts be saved, that way you can verify the parts were indeed replaced. That’s a good habit regardless of the vehicle being worked on.
If the shop when they furnish the parts give an excuse they need the parts for core returns tell them you don’t want them but you want to see them. That’s a good way to keep shops honest if they say no or give excuses for why that’s not possible that’s reason for concern as to whether they actually replaced them
2 Likes
Replacing the rear shocks on the XJS is surprisingly simple job that doesn’t require special tools. The picture below speaks for itself. Works better than any of the spring compressors:
If no rust, I’d reuse the old springs. It is unlikely you’ll be able to find OE springs anymore and the aftermarket parts are probably going to be inferior.
Good luck!
2 Likes
IIRC, convertibles are all the same year-wise. Coupes will be different, depending on whether they have the sport-suspension or not.
As far as the number - there is a fixed value required for the alignment (the mid-laden height, set with the tool), but the actual height in the rear is a function of too many variables - I don’t recall seeing one. I’d just make sure left and right are the same
PS Condition of the shocks in the rear is a factor as well. There are verbal wars in the archives on this subject. I am in the camps that believes a new shock absorber could raise the back of the car by ca. 1/2" or even more. With softer springs, such as those of the convertibles, this is very obvious.
If you’re using KYB shocks, you may consider telling your mechanic to use spacers as well. Not sure about aftermarket products, I’ve managed to get genuine ones with manufacture date of 94ish. Those will fit KYBs and does not require any additional locking bits. You also don’t need any scavenged brake discs to take those off/put those on (as per photo below)
Good thing to do - spray with underseal/cavity wax
The springs in a Jaguar XJ have been known to sag with age and ride low. It should be kept in mind, though, that the most common reason one of these cars rides about an inch low at either end is that the shocks are shot. This car came from the factory with gas shocks, and the gas charge lifts the car a little bit. The springs are designed accordingly. If the shock loses its gas charge, the car will ride low. If the ride is just a bit low, consider replacing the shocks and not the springs and see the results before deciding to $pend for new springs. As others have reported, new springs often opens a can of worms.
2 Likes
Doing this worked for me- in fact, two spacers were too much and I had to remove one. Perfect height now.
(At least for me!)
2 Likes
Oh, I forgot: There’s some official specs for ride height for the XJ-S, and they are all wrong. The specs reflected where the first cars off the line sat, but year after year more garbage was loaded onto the car without any change in spring rates. So unless your car is a mid-70’s model, it sits lower than spec and it did on the showroom floor.
2 Likes
So my 94 convertible is one of the heaviest of all. To get the correct ride height shims would have to be added? Now I am really confused about alignment.
Is it better to get the correct ride height the car was originally designed for or what was done for my MY?
Have a differential leak at passenger side driveshaft. With 100,000 miles and unknown service history am contemplating taking out IRS, inspecting components, and changing seals at a minimum.
Kirbert, why should we keep worms behing chrome liners, like most of XJS owners do…
With every change to the subframe, we will need to tune it in slightly, no reason to panic.
KYB shocks are entirely different, not that bulky, with locking plate on top. Springs these days are different, even the subframe mounts are different. That’s why Jaguar introduced “spring packer”…
Bill
Always better to make rear slightly higher. You can always compensate with a toolbox or full tank of petrol. This doesn’t work other way around.
Jaguar introduced it? If you look at the Mercedes models from the same vintage, there are 4 (four) different thickness of spring pads (“packers” if you insist on proper English)
Not true. :-))) My 1995 convertible has the brace AND a rear spoiler AND two fuel pumps. Probably a bit heavier than yours.
Alignment, again, is done at the mid-laden height, which is set with a tool.
How high or low your rear end will actually be sitting will be a determined by all the factors that were discussed already, including the amount of fuel in the tank and the toolbox XjsBanger recommended.
1 Like
From what I’ve read so far, it doesn’t appear that you actually know what the ride height is before changing the rear springs.
From my perspective adjusting and fine tuning the suspension is not a chore that a paid mechanic can readily carry out successfully. To get it right requires careful measurements before during and after. These jobs are time consuming to begin with and keep in mind, the rear ride height is not totally dependent on springs, but also the spacers that are used with the springs. It’s conceivable that the springs might need to be mounted and dismounted numerous times before getting it right.
1 Like