Rear radius arm bushing

[a_romeo_75491]

Hi all,
Just got my 1995 4 litre back from the mechanic. New thermostat, water pump, belts, oil and filter, brake pads and handbrake adjustment. He advises me that the rear radius arm bushes are cracked and need replacing.
Some advice please, do I replace the arms too and which bushes do I get, oem or polybushes ? The arms were replaced a few years ago and seem fine but is it a good idea to get new ones as he's replacing the bushes anyway? I have been warned off polybushes as I can't abide creaking but other forums say its a question of how they are fitted that causes issues.

Thoughts/advice welcome. I have looked at other posts but none seem to have the answers.

Regards
David

[PaulGover]

The only real reason to replace a radius arm is rust damage. It's not like the aluminium wishbones on the later XJs which can be damaged by ham-fisted press operators.

The false reason to replace them is lacking a press capable of removing the large bush.

I remember replacing the large bushes myself without using a press, many years ago. I had to cut through the old bushes to get them out. I can't remember how I pressed the new ones in.

Replacing the large bushes ought to be within the capabilities of a good garage, but not all have big enough adapters - indeed my local Jaguar agent refused the work a few years ago for exactly that reason.

[Jaguar5993]

Hi David,
I can see where you are coming from.
As you said your arms were new a few years ago,its tempting just to get new bushes.
There is obviously a lot of stress on these arms and they can deteriorate quickly ,especially after 5 years plus.
Many will say stick to Jag Metalastic. I have found over the 24 years with mine, the Poly ones (small and large) worked well for my 6.0. I still set the Polybush holes at right angles and not in-line as per factory.
I have just bought some new bare arms from David Manners (£75 each, C41831*UB)) and going to strip the paint off and re-do and slosh some Galvi paint inside.
Getting your old bushes out and in is a pain. No problem with a press and the right push-through's etc.
So if you are not doing it yourself or to save garage labour, I would buy two new complete C41831's at £79-£96 each with standard bushes or pay a little more for Poly's.
Many of our usual Jag parts sellers have these, but just wax-oil the new ones inside.
I hope this helps.

[davidr]

Hi - for what my opinion is worth I would not replace the bushes with anything other than the standard metalastic. My fear is twofold. First the radius arm must have sufficient give in it. Its movement is compound and not a straightforward radius so it relies on some lateral movement. If the bush is too stiff you could over stress the mountings. Secondly, I would worry for the quality of the ride.
It’s not hard to change the bushes if you have a press. Easy job for a properly equipped workshop.

[PaulGover]

There's an interesting article on Roger Bywater's old AJ6 Engineering web site that points out the radius arm bushes need a fair bit of compliance and that the handling benefits as a result - which makes me doubt the common advice for racing enthusiasts to turn the large bushes so the small voids are not longitudinal:

In some respects the use of compliant rubber mountings was actually an essential part of the design. For example, for true geometry the forward mounting points of the rear radius arms should be on the same axes as the lower arm inner pivots, but, by being aligned fore and aft, as they are (to be technically correct they should therefore really be called trailing arms), the radius arms generate slight toe-in of the outer wheel under roll which tends to improve stability by opposing oversteer. They are also better able to control torsional loads on the complete axle assembly, even if compliance is necessary for it all to work. Those purists who want to scoff at such compromise should take a look at the rear suspension of the highly regarded Subaru Impreza where rubber mounted trailing arms can be found doing the same thing, 30 or more years after Jaguar first did it.

[Jaguar5993]

Thats great Paul...this is why I like this forum.
As I said I have never had a problem adopting the racing enthusiasts 90 degree hole position, but upon reading that article I am going to fit my large poly's as per factory this time. There is still a good bit of tension taken up with these bushes, and my rear end was always tight They definitely last longer than the rubber ones, as that was the main reason I have been using polybushes here.
Have a great Christmas all.

[a_romeo_75491]

Thank you gents,
Agreed, the forum is the best. As she sits currently, I have the oem bushes up front with Bilstein dampers and the oem Boge dampers at the rear. On refection I will go with oem bushes at the rear too.
I priced the poly bushes and was quite surprised at the price difference.

As an aside, as the headlining was beginning to sag I had it and the sun visors recovered in suede. Ive been stroking it each time I sit in her. Is this wrong?
Drive serenely.
David