TR4a Swing arm mounting with poly bushes

[grimboh]

Well I guess I must be stupid as I can't find any other comment or post on this, but I can't get the swing arm bolts into the brackets - presumably no one else has had the same problem. I can get the inner bolt thru both bracket holes and the outer one thru the first bracket hole and into the swing arm, but it's then miles out of alignment to get it thru the other bracket hole. And I've slackened the bracket to the chassis off completely to help give some movement.

 

So is my swing arm bent? It does not look like it as there is no strain evidence on the aluminium surface, but does look as though the casting was way off straight in the first place. Checked the other swing arm and it's the same.

So its not bent but is cast as though it is - so they must all be like that, for the 4a's as least.

And with the poly bushes that makes it impossible (for me) to get both bolts thru the brackets and swing arm.

 

OK, so fix the brackets to the bushes first then offer the whole assembly up to the chassis and feed the bracket bolts in - but again the outer side being out of alignment means the bolts won't go into the chassis holes - one bracket pair or the other, but not both.

But the 'bend' makes the distance between the 2 bushes effectively less than it would be if the casting was straight. And so the holes for the 2 brackets and the chassis won't line up. They will if the bushes are forced, and I can see on the old one (still on the car) that the rubber bushes are both biased to account for this, and worn accordingly.

 

I guess its not so difficult with the rubber bushes as the bolts can probably be moved and waggled around a bit but even so must be tricky as its so far out of line. And then with poly bushes it seems to me there's no chance - I can't even waggle the bolt 1mm and it must be 1cm out of line for the hole.

 

So has anyone successfully fitted poly bushes on a 4a? If so did you have the same problem, and how did you manage to get it assembled?

 

Any advice for a hapless mechanic would be much appreciated.

Thanks

Graham

[RogerH]

Hi Graham,

I had this problem two years ago or so. I fitted new brackets and had a devil of a job getting the hinge bolts in.

 

When I originally fitted the Polybushes i don;t think I had a problem, but that was quite a while ago.

 

I did much the same as you. Try to fit the hinge bolts with brackets attached to chassis and the try to fit the brackets with the hinge bolts in situ.

 

I think I ended up fitting the hinge bolts last but not sure.

 

Try fitting the hinge bolts last and somehow levering the TA over to align.

If that doesn't work Fit the hinge bolts and try to align brackets with the chassis.

 

I'm sure a great deal of levering and swearing was involved.

 

Roger

Edited February 13, 2017 by RogerH

[grimboh]

Thanks Roger,

 

So taking your advice in reverse order I first tried swearing at it, a lot, but that alone didn't seem to have any great impact.

I then resorted to some serious levering and modest use of a hammer and, despite my lack of optimism, that did the trick!

 

That aluminium casting is some strong alloy - barely a mark where I levered against it.

 

Thanks for giving me the confidence to use the necessary force.

 

All I have to do now is take it off and on a couple more times to swap in different brackets so that I can get the camber corrected to what I want it to be - deep joy!

 

Cheers

Graham

[RogerH]

Hi Graham,

good to see that the swearing worked. It may not have a great impact on the surface but deep down stuck things stand no chance.

 

In trial fitting the brackets how have you calculated what combination of brackets you require?

Have you seen the Buckeye website in the US - very good tables on every combination of what is needed.

 

Roger

[grimboh]

Yes, thanks Roger seen that and worked out in theory what I need, remains to be seen in practice how it will sit. Hoping to experiment knowing the wheel centre to wheel arch measurement when fully weighted, and use that to position the swing arm at the correct height as if fully weighted (no spring in place) and then measure the camber. Saves a lot re-assembly/disassembly. I've got the rear bearing without the rest of the half-shaft (new Uj's to go in once sorted) to bolt to trailing arm, mount the wheel and check the geometry.

I've used the last table in this article http://www.buckeyetriumphs.org/technical/Suspension/RSGeometry/RSGeometry.htm

So knowing my starting position I can then use the table relative to that.

Time will tell, got some painting of bits to do as well so likely to be an elapsed week or so before I'll have it sorted.

Cheers

Graham