New to the site so advance apologies if this has been covered before - I did search but nothing popped up.
I'm rebuilding a 1989 5.3 XJS and now onto the front suspension. Nothing too drastic so far, dropped the frame, dismantled and now rebuilding with mainly new parts. My question is...just how big are the springs supposed to be?! I've got new ones and they are quite a bit bigger than the old ones. Part number is OK, same number of coils and the metal diameter is the same, so do old ones just compress this much over time? Take a look at the picture....
Thoughts gratefully accepted.

 

I don't know the spring length/height measurement.

Was the ride height OK before disassembly?

Some sag is inevitable but the difference in the tow springs you have seems too dramatic.

There are any many cases where new springs yield incorrect ride height....to the extent where I went with good used springs rather than take chances with new ones.

Are the new springs from Jaguar or an aftermarket supplier? My opinion is that spring manufacturers are playing things fast and loose with specs and part numbers....trying to sell a single spring to fit too many different applications.

Cheers
DD

 

I think the old ones were just shot. The new one looks right to me. I have a new one here, so if you measure yours I can check if you like. Probably best to leave out the large circular packing pieces when you refit though.
Greg

 

Thanks for the replies. The new springs are 310mm and the old ones 250mm. I didn't measure the ride height before disassembly but after I replaced the IRS it was certainly low in the front end! Appreciate the measurement Greg. I was not sure about the packing washers. The original set up had one, and I did wonder if it was needed at all. I've done a couple of springs before and neither had washers. Thanks all.

 

The packing washers are to trim the ride height. They are .125" thick and yield about a .375" difference in height.

I didn't use them as I was hoping for (and got!) a slightly lower stance.

Cheers
DD

 

310mm is bang on. The springs will be fine.
Greg

 

Greg, just to be clear, you've confirmed that your new springs yield the correct (or acceptable) ride height?

Cheers
DD

 

Doug
Yes, they do, with no packing washers. I got them from Berkshire Jaguar Components in the UK.
Greg

 

Thanks again. I'll post an update when the front suspension is back on (thats after I've replaced the rad, steering rack, replaced hoses..and just about everything else while the front is accessible!)

 

Just dug out a picture I took of the droop after I popped the car back on its feet after rebuilding the IRS.

 

Looks to me like the rear is too high....rather the the front being too low

Cheers
DD

 

Here is my ride height with original springs.

 

+1 Doug,

Certainly on a facelift with 16" wheels and 225/55 tyres, set to factory spec, you can't put a finger horizontally across the rear tyre under the lip of the wheelarch. I bet that if the ride height is measured, it would be nearly 2" higher than spec.

Paul

 

My thoughts too provided the car as it sits has not been lifted clear at the rear and then lowered back to earth without rolling a distance to settle.

 

Yes! The IRS has new shocks/springs and as far as I'm aware there is no adjustment? The old shock/spring units the same size as the new ones. Other than its just been gently dropped back to ground level (all work done while sitting on a 2-poster ramp) the suspension has not moved. I suspect if I bounced the rear end it may move, but have I missed something? All shafts move freely....

 

Piccy of rebuilt IRS while up on the ramps

 

Once the car has rolled a bit the rear will settle. The reason is that as the car is raised, the wheels droop and move inward. When the car is set back on the ground the tires contact the ground and stay in position and then the wheels can't move outward.

When I am doing wheel alignments I have 2 pieces of plexiglass and I put grease in-between them. I put those under the tires as the car comes down and that lets the tire slide sideways as the car comes down. It lets the wheels move quite a bit sideways, often in the region of 2" per wheel and lets the suspension settle to normal ride height.

 

Nice work !


Cheers
DD

 

Phew - got me worried there for a moment guys....:-)
I think the only person that will notice the Jaguar Racing Green coloured UJ cups will be an exhaust fitter but I couldn't help myself....

 

Front done now......