Working around the hubs I noticed that the small bushing on both radius arms has failed after 5 years of (ab)use. Yes, I did wait to tighten them until I had the full weight of the car on the ground.
Has anyone had experience with the genuine original Jaguar bushing for that end of the radius arm?
Do you think these are Metalastic (yeah I can ask the vendor when I call it in)?
Not a job I wanted to get good at but looks like I will at least get some more practice on it now.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
2
I dunno how the E-Type IRS compares to the XJ-S/6/12, but on the XJ’s the answers to your questions may depend on whether the car has a rear anti-roll bar fitted. On the XJ’s, the rear anti-roll bar is connected to a clevis on the radius arm just above this bushing. As a result, the action of the anti-roll bar is conducted through the small end bushing to the rear swingarm. Which means a soft bushing is absorbing part of your anti-roll bar’s influence.
On XJ’s, I recommend that this bushing always be replaced with a poly aftermarket. Besides being cheaper, it will provide slightly better control of suspension movement. It won’t really make the ride any more harsh because the great big soft rubber bushing at the other end of the radius arm is more than smooshy enough to soak up road noise. If you have a rear anti-roll bar, replacing those bushings with poly bushings will have a similar effect to installing a thicker anti-roll bar.
Like I said, the E-type may be totally different, notably in how the anti-roll bar attaches to the swingarms.
Geo
I have learned to not buy the cheap stuff. Years ago replaced small end bushings with original and they did not last and these were not the cheap ones. When car is jacked up it puts a lot of strain on those bushings. I now have the poly version from SNG, put in years ago and are holding up well.
Glenn
I’d use Metalastic if available. That’s not a fun job to repeat. I think that’s what I put in 20 years ago and still holding up. They have some cracking around the peripher,y visible in flexion but the collar hadn’t torn free from the rubber.
The poly ones do sound like a good idea too though. SNG has those.
George, similar issue of perished cheap bushings. The rubber tore loose from inner sleeve. Spooky handling. Replaced with Metalastiks I think from SNG. There were 3 choices (and a poly which I passed on).
This was years ago, so perhaps not still relevant. But I believe I asked the SNG guys if they were Metalastik and they said yes. And they were.
Didn’t we read here that you can buy small and big ones at Jag dealers?
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
10
Gee, I would expect stiffer radius arm bushings to decrease the stress in the four cage mounts.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
11
Interesting. I’m wondering how you would even notice. Presuming the rubber was still there, not missing altogether, it wouldn’t seem to make much difference whether it was bonded to the inner sleeve. I’m confident it’s not bonded to the inner sleeve in the poly versions.
As the wheels travel up and down, the radius arm swings and arc that pulls the lower control arm fore and aft. As the LCA is mounted on bearings to the cage, this will rock the cage about a center between the mounts. So the large bushings have voids and lots of rubber to reduce the pull on the LCA. The small one contributes less compliance, so its rate is less important (maybe harder is ok?)
My point is that unlike most suspension designs, this one is over constrained. (If you eliminate the compliance of the rubber, you are left with no motion or degrees of freedom.) It just makes the compliance of the rubber critical to the motion of the suspension.
Kirby, think of the tire being on the end of a lever arm. The perished bush allows the wheel to move fore and aft. These days rear wheel steering is engineered in. 1960 probably not so much. Large amounts of toe in & out changing under gas & brake.
I dunno, I didn’t like it much. Plus it clunked a bit.
In the end I ordered the high-priced spread - hoping that paying 6 times as much for a part makes it better (and not just a similar part in a box with a cat on it).
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
15
True. But if you hammer the throttle at standstill, the torque applied to the rear wheels twists the subframe in its mounts – and the soft bushings in both ends of the radius arms allow it to twist much too far, stressing the bejeezus out of the cage mounts. That’s what destroys the cage mounts, not the couple of degrees of rotation due to the suspension geometry.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
16
Yeah, that’s knackered. Can anyone post a photo of what a poly bushing looks like for this application?
Poly is not good for the radius arm bushings, for the reasons discussed. It will stress the mount points, and it will also limit suspension travel. Another common mistake is to rotate the front radius bushing 90 degrees to “stiffen them up”.
If you are troubled with rear wheel effects when you drop the pedal and you’re serious about fixing it, consider relocating the trailing arms as has been described here many times. The vintage GTJ mod was to delete the trailing arm altogether, and reinforce the LCA with triangulating supports. This also allows you to build some anti-squat into the geometry, which will fix the problem. The more modern approach is to relocate the forward mounting point inboard. If the mount point is in line with the inner LCA bearings, then the trailing arm can be made up with Heim joints. That done, you can and should hard mount the cage to maintain alignment with the inboard mounts. Either mod allows the rear to drop without twisting.
Bill Richert used to make an appliance that incorporated this mod. It replaced the cage tie plate with a t-shaped aluminum platform which mounted to the LCA forward mount points. This effectively hard mounted the cage. The gadget carried inboard mount points which allowed the use of a standard rose joint in line and about six inches in front of the LCA inboard bearings. A couple of light aluminum arms connected this with the hub, transforming the LCA into a huge triangular frame. Very rigid, yet with no effect on NVH, and a complete fix for axle location problems.
There are a couple of vendors that make the drop link bushings in poly, and they work pretty fine. Superpro SPF1274K works,but I don’t know if there are any US distributors left. Prothane and Energy Suspension have generic bushings that fit this application as well, I just don’t have the PN’s handy.
