It just strikes me as funny, since I’m going through the suspension on my own car. A question came up whay back, when is the time to change the springs. I’m afraid to mess with them as they seem OK to me . Except the fact my car will be 33 years old this year. I don’t want to screw up ride height etc. But I don’t have some spring test sag tool.
I have a 1988 V-12 with original springs and yet you have a newer XJS with a 4.0L engine which I assume is quite a bit lighter on the front end. You have changed them with what appears to be inferior quality and just looking at the picture look rusty almost from the inside.
I would hate to say just a bad batch or road conditions, but maybe a rebranded set from a not very stringent quality standard manufacturer.
Not sure if they will take returns but they look like your basic toss over the hedge variety.
All coil springs are in essence torsion bars rolled into a cylindrical shape. When you design a coil spring, what you design for is torsional stress. Do you live near a university with an engineering school? They would have PhD level materials science and metallurgical resources. They should be able to look at the broken ends and give you a highly educated opinion as to what caused the failure.
In 1997 I bought one of the first Mercedes-Benz ML320 SUVs. I drove it for 17 years. After 15 years, both rear coil springs broke. The cause: To eliminate the possibility of squeeks, they had encapsulated the end coil with a urethane sleeve. The sleeve trapped water and the spring rusted to the point that it fractured.
I’ll issue an educated guess: brittle fracture due to improper heat treat. Second guess, the steel came from China. Further, either no one requested material certifications, or they were simply falsified, and no one verified that the steel met the spec.
Agreed , I would concur as your doctor would say!
You can see material failure by closer inspection at the cracked parts and looking for round to oval pitting.
The place shown on the photos is usual failure point as flexing the most on shortest length. I’ve had the same issue some time ago, these are 30+ years old:
I think that the answer to your topic was automatically answered in the first post by yourself:
I do. I graduated from there myself in '94 with, wait for it …
… a degree in engineering. It clearly didn’t help me choose good replacement parts for my car!!
Thanks to everyone who weighed in on this. I have new Eibach springs on the way. When I get them installed I might take some more pictures of the old ones and share here for anyone that wants to see them. But I think I agree with the general consensus that they were just badly made aftermarket parts.
on a tangent topic, I’m about to remove\refit my fine condition 1988 front coils so I can replace bushings. Tiny bit of surface rust only.
Is it worth painting them? I’m bringing in my subframe and control arms to be sandblasted/repainted. Should I do coils too? Or Por15 them myself? Or not bother? Or actually buy some Eibachs?
I would Buy some Elbachs . Why mess around at this point of the game? Only to find out that they only have two years left in them at the onset.
Not only that but there’s something to be said about installing nice new shiny parts for that feeling of accomplishment.
I do like that idea, since i do want to lower front end 1"+. I just have no idea what Eibachs to get, they dont list our V12s . Any references?
Captain Obvious here:
Rust kills springs. Coil springs are wound from high carbon spring steel. Surface rust causes a stress riser which creates a cracking point and it starts the spiral crack that you find on a coil spring.
Yah I just had a look at their pro lowering springs. They don’t appear to be very XJ-S friendly.
There’s a company in the UK that does XJ lowering springs. Harry’s garage mentioned them where he got them for his V~12 XJ coupe.
XJ Restorations in Eastbourne UK (no affiliation) uses the Eibachs, .
I’m sure they can point you in the right direction.
I forgot, SNG sells Eibach springs for our V12 XJSs
Special order.
Weren’t the Eibachs initially designated for the Aston Martin DB7? I believe the DB7 springs are your reference.
I have DB7 front springs in my XJR-S, they are stiffer and will lower the front end by about 10mm compared to the original JaguarSport items (one of which broke, hence the upgrade). Not sure if they are Eibachs. I got them a long time ago from a guy called Ray Ingham, but I can’t find any business details for him through a Google search. Maybe try some Aston Martin forums.
All that is true, but but these springs were virtually new. This is clearly a manufacturing defect. 100’s of millions of automotive steel coil springs go decade after decade after decade in harsh environments without failure. It is entirely possible to design a steel coil spring with an infinite fatigue life. Fatigue life design criteria is a fundamental part of machine design engineering. These springs failed from brittle fracture, millions of cycles before they should have. That means that either the steel did not meet the specifications, or that the heat treat process was deficient.
Every piece of steel plate or pipe is imprinted with a heat treat batch number. When you design critical structure, you require the vendor to submit the documents that certify that the supplied material conforms to the engineering specification. If you were designing for the military or aviation, you would probably also engage third-party testing to verify the truthfulness of the document. Those material certs give the actual, assayed composition of the alloying elements and the heat treatment. In this case, one of those steps was skipped or falsified.
Here’s a spring manufacturing video. Skip to around 2:30 for similar springs.
I think the trick will be to find the right ride height if you want the lowered look without having any rubbing issues.
I know when I replaced the front shocks and went to a 17” wheel with a lower proof file tire it appears to have more gap in the front fender .
I should have done a before and after picture for comparison. I think there might be room for a 1” lowering max. I’ve never had any rub issues by going with a larger wheel.
The trick is not knowing how much things will be lowered until all the hard work is done.
The treat is getting it right first time 
Some people dont believe me, but the Bilsteins raised the front end 1/2". So the front visibly rides higher. The Eibachs claim to lower 1". I also assume i have oem spring spacer? So need to remove that to get 1" lower than stock? And if i ever remove Bilsteins, it may need the spacer back in.
Greg I believe you.
Bilsteins run a gas charge of about 250 psi when they’re new. If the shock rod is half inch, then the area is 0.2 inches square. That makes a load of 50 pounds per shock. Maybe I rounded up so it’s only 40 lbs, but still significant. Sorry about the old fashioned units but that’s when my brain was programmed.