Jaguar xjr rear suspension - is it magic?

Just got to do some initial poking around on the xjr I picked up from lugnut. Good news is the trans mount looks fine and the motor mounts actually look serviceable, they do look like they might have leaked, but I'm not sure they are fluid filled at all, meaning it might be road grime. The engine does not flop around when revving in neutral (didn't try in drive since I was already up on jackstands at that point), it looks quite tight. Either way replacing them looks not too hard.

The bad news is both rear wheels have a bit of top to bottom slop, like a wheel bearing on the way out (no noise while driving, but I did get a teensy bit of a loose feel in the rear over expansion joints on the highway). I popped one up in the air, and I don't feel any side to side play on the wheel. Took the wheel off, and was suddenly boondoggled by the suspension.

There is a lower control arm that bolts to the car and to the lower spring perch, as well as the hub (it bolts in two spots on the bottom of the hub - looks like it controls the toe action of the hub as well as locates the hub). It obviously is functioning like a trailing arm or the lower a-arm. Then there is the axle, it is large, and has two u-joints rather than CV joints.

Then the boondoggle. Nothing else seems to connect to this hub. What the heck controls the camber movement? Could it really be that the axle serves as the upper a-arm?

If the axle is serving as the upper a-arm, then a bad axle u-joint could explain my top to bottom wheel movement while side to side is stable. And on the side I took the wheel off of looks like the inner u-joint might be on the way out.

How does this suspension work? Is it possible I need new u-joints and not new wheel bearings?

Note: I have not signed up for a Jag forum yet, any suggestions?

Trying to add Flickr photos from phone.

https://flic.kr/p/W8XP6T https://flic.kr/p/Xiv8jL

I give up.

Yep, axle is the upper control arm as it were, C2, 3 and 4 Corvettes are similar. New u-joints would be a good idea, at least you will be sure of them being good then.

Yes, it works exactly like you think, the axle acts as the upper control arm, and yes, there's a good chance one of the u-joints is bad causing the tire to lean out. Another potential issue is where the lower control arm attaches to the hub - there are bearings in the hub instead of bushings and they can go bad and cause some play. It could also just be the alignment is really bad.

What year is your XJR? I've got a pdf of the service manual for the X308 (97-2003) I can give you if it will help. It's too big to email but I can put it on dropbox or something.

I've had decent luck with jaguarforums.com (I have a 2001) but there can be a lot of useless crap and ridiculous speculation to dig through at times too. forums.jag-lovers.com and http://jagrepair.com are other sites I've used.

For factory parts I've ordered from www.jaguarmerriamparts.com, www.coventrywest.com, www.jaguarlandroverrenoparts.com, and www.motorcarsltd.com/jaguar or RockAuto when they it didn't have to be a factory part.

The halfshafts are the top links

The axle shafts are the upper "a-arm". That's why they have u-joints instead of CV joints. It was done for reduced unsprung weight.

Basically, the suspension on older Jags (through the X308 for full-size ones) is pretty much magic. It just does a lot of things really well.

Curious to see what you choose to do with the rear suspension as there is little aftermarket support for the air ride setups. I have to imagine there is a GRM solution but didn't get that far in my research.

Thanks Ross!

Also, thanks all for the explanation! After further searching online last night it seems that this type of suspension setup wears out wheels bearings, diff axle bearings, and u-joints faster than in most cars. I'm not hearing any groaning like is normally associated with a bearing, so here's hoping its the u-joints. I'll check for play at the bottom of the hub too, but I think the play was mainly at the top of the wheel.

Oooh, it's British Racing Green!
Pretty.

PS: leave the paint on it.

84FSP wrote: Curious to see what you choose to do with the rear suspension as there is little aftermarket support for the air ride setups. I have to imagine there is a GRM solution but didn't get that far in my research.

No air ride on this specimen. Some XJRs of this vintage had CATS which was a system to adjust the shock damping settings electronically, but this car doesn't have that either.

My plan is to leave this car stock or very close to it, but hardly anyone even makes a shock for these bad boys, much less a performance shock. KYB gas-a-just look like the only "performance" shock I can find so far, Koni and Bilstein do not make performance shocks for this car it would seem.

For flickr, view the photo and find the download button on the bottom right and click on the 'View all sizes' option on the fly-out menu. Then right click on that photo and copy the URL or image location. Use that address in the GRM photo popup thingy.

Oh, my gosh.

John Welsh wrote: PS: leave the paint on it.

Tried to post a gif of the trolls movie: "Solid burn, Branch", but was completely unsuccessful.

This is ridiculous. I am horrible at this.

RossD wrote: For flickr, view the photo and find the download button on the bottom right and click on the 'View all sizes' option on the fly-out menu. Then right click on that photo and copy the URL or image location. Use that address in the GRM photo popup thingy.

I can do it from my computer, but on the mobile you cant get to the same link. Er, I cant get to it, maybe someone can.

Yup definitely easier not on mobile. You can 'request desktop site' usually, but that can be a pain too.

I don't remember any of the XJs (at least not the XJ40 and newer) having air ride. Some XJ40s and maybe newer did have hydraulic self-leveling though.

rslifkin wrote: Some XJ40s and maybe newer did have hydraulic self-leveling though.

My reading has shown this (at least for 308s) to be a non-us only option. But basically it was just different rear shocks that would pump up if rear ride height was low. Another recent thread about Chrysler minivans brought up a similar type of shock (I forget the name).

Schmidlap wrote: What year is your XJR? I've got a pdf of the service manual for the X308 (97-2003) I can give you if it will help. It's too big to email but I can put it on dropbox or something.

I have a 1998. Thanks for the offer! I was able to download one too, its like 3500 pages or something of PDF. wow.

Also, thanks for the links!

Use Imgur ppl. It's loads easier from a phone.

Since it's a 1998, make sure the timing chain tensioners have been updated to the latest (metal) design?

In my opinion you don't need any performance shocks on these cars. My xjr handles really well to the point where I have no suspension desires at all. Maybe lower it a little? Maybe not but that's for looks. I do suggest a really good set of tires though. Wish they had lsd.

I was going to sell mine. But I'm keeping it!

yupididit wrote: In my opinion you don't need any performance shocks on these cars. My xjr handles really well to the point where I have no suspension desires at all. Maybe lower it a little? Maybe not but that's for looks. I do suggest a really good set of tires though. Wish they had lsd. I was going to sell mine. But I'm keeping it!

It's got Pilot Super Sports on it. This wasn't some rando's car. I knew what I was doing, I just couldn't do any work on it on my own anymore.

Oh this is the one from the GRM classifieds!

Nice!!! Semi envious.