When my oil was changed, I took the opportunity to give the underside of the car a good look while she was up on the lift. Seems to me that the radius arm bushes need changing. Or is this just the normal state of a used bush and not something I need to worry about? Is any cracking in a bush a Bad Sign?
Somehow I suspect it's not good, and they could do with replacement. The shiny new wires on the large bushes make me think they were replaced recently, but I'm pretty sure it wasn't under my ownership. Though the radius arms themselves were checked in her big inspection back in Dec. 2017 and found to be fine. Radius arms with bushes added can be bought as sets, but if the arms are fine, perhaps just the Bushes, Senior and Junior.


Right small bush

Left small bush

Left large bush

Right large bush

 

MY opinion:

They are showing wear, that would be normal.
Those cracks are not terminal, OK, no one likes to see cracks in bushes, but they are minimal.

I would NOT go the bush only route, UNLESS your shop has the equipment and mindset, to replace them without distorting the arms. The Big bush is the main culprit. Those arms will distort in less than a heartbeat if great care is not used, mainly at the "pushing in": stage.

I got the pre installed arms every time, and it just sat well with me.

AGAIN, they are not bad, some of mine went for years with more "cracks" than that.

It gets back to the "while I am getting stuff shipped" scenario again.
My shed is FULL of those items, oh dear.

 

Looks like the begining of the begining of a failure, I'd do it but thats just because I have nothing better to work on.

would be a good time to improve handling with poly bushings!

 

While definitely ageing, it doesn't look too bad yet. I'd keep it in the back of your mind as needing to be done but not urgently. Call it deferrable maintenance. Maybe before the next Shaken if that's a fail as it stands now? The wire is stainless, so that's why it's shiny.

Depending on what your shop charges, it may end up cheaper to buy new arms with the bushes already in place than replacing the old ones. It's not difficult to change them, you just need a hydraulic press and some properly shaped metal rings to press on the bush and not the arm. If it's a Jaguar specialist I'm sure they have the tools already. Although freight on new arms wouldn't be cheap...

This is one place where you should only use the original Metalistic bushes, nothing aftermarket. If you want a firmer mounted IRS that will make it a bit harder, you can go to solid poly bushes on the small end only. Also on the big end turn the bush 90 degrees, so the pair of holes are across the car, not along it. That makes them around 20% stiffer.

 

Thanks for all your comments and advice. This is exactly why I post on this forum - I'd have panicked, thinking they're about to rip asunder. The wisdom of the sages is much appreciated.

I've heard about the benefits of replacing the entire arm and how hard it is to get the bushes out (Hmm. Bill Clinton managed it...). The next shaken (MOT/WOF whatever you call it) is next month, but I don't think it'll be a problem, not if it's not that bad. I'll talk to the mechanic then about whether they can easily push in the new bushes or whether the whole arm would be preferable.
I don't have a shed, let along a shed with room for "eventually, when it fails" so I'll hold off on ordering I think. Freight on the arms couldn't be too much worse than on other heavy things like brake discs or four shock absorbers.
I definitely do not want a firmer ride. She's already rather firmer than I was expecting. I'll stick with the metalastic, no aftermarket if possible. JagBoi - I've read a few posts and that by people who've done the 90-degree route, which apparently is what Jaguar Sports did. One guy described his car as now "bunny-hopping" across the road. That would not be the ideal "Jaguar ride" I feel.

 

I will just add that I did do full Poly on both, and ended up tearing the mounting peg the large bush sits in, though PARTLY due to a prior shitty weld.

Third time's the charm I guess. Definately did not bunny hop more of a F-35 Fighter jet darting maneuverability, which of course strained the structural integrity. I'm back to OEM large bushings poly on the small end its a good balance if aiming to retain Jaguarness

 

Eesh. Nasty. And I don't want to strain Lady Mary's integrity - heaven forbid. She'd never forgive me.
So OEM aren't metalistic, then? Several vendors have different types, and it's not always clear to me which is OEM and and which is aftermarket.

 

SNG designates reproduction, original or performance, race etc however genuine OEM is all metalastik as in rubber bonded to steel like you see in your pics

 

Turning the bush 90 degrees should not affect the ride at all. In corners or under power the rear suspension wants to twist sideways and the arms resist that. As you can imagine though, with the holes orientated as they are in the photo there is less rubber there to take the forces, so you will get some small rear end steering effects as the rubber compresses. Turning the bush so there is more rubber in the force path makes the bush stiffer and it holds the IRS in place where it should be- perpendicular to the direction of travel.

Yes, Metalastik is the OEM supplier, I think a brand made by Dunlop, the bushes have the small D logo on them. In my experience, they are by far the best makers of rubber bonded steel products and outlast all others.

 

A further thought, the arms are often replaced because many cars are driven in wet/salted roads and the arms rust from the inside out. By the time the rubber bushes have deteriorated, so have the arms. Your arms appear in amazingly good shape, so that condition doesn't apply to you.

 

Yes for some reason they are hollow with holes in them, maybe for some purpose? But they get water in there. I have been meaning to fill mine with foam.

 

Yes, Japan doesn't use salt on the roads. They do use a snow-melting thing on certain roads which doesn't do wonders for steel, but I don't drive her in the snow. I do drive her in the wet, of course.
Huh. Didn't realise "Metalastik" was a brand name.
In terms of their orientation affecting the ride, I was going by this post in particular:
The discussion there is whether the increased stiffness simply transfers the stresses to the frame mounts.

Greg (in France, not any of the other fake Gregs in other countries) also comments that

 

Probably a weight-saving measure. Jaguar designed them to gradually get lighter and lighter as they rust away....

Wouldn't foam just hold water and get soggy and rust things even worse?

I actually try to drive my car soon after she's been rained on (which is often) in order to shake loose any pooled water and dry her off through a combination of heat and wind.

 

Well here we have 3 pound closed cell spray foam cans, I wont get into the technical nonsense but it is a waterproof heavy foam insulation used in construction etc. Good to permenantly fill any void.

 

Most interesting, I have done the bushing turn on several various Jaguars and never experienced any sort of hop or other irregularity, just a more "in control" feeling and the car felt better planted on the road through bends.

 

It's like old Land Rovers: they know they can't keep the water out, so they design them to drain well.

 

They are hollow because solid ones would weigh a ton. A coating of cavity wax inside and outside the new ones will preserve them.

 

I just did mine last weekend.
right side I did with the uro ones prob a year ago. and the left had metalastik prob the originals. now the uro have delaminated on the small bush, and my metalastik one has seen better days but is still together, 35 years +/- I grabbed the metalastik ones from sng, they did differentiate between the brands as of 2 months ago but today I looked and they do but don't say "metalastik".
Let me tell you I noticed a huge difference.