Adjustable rear arms

[tonyabacus]

Previously posted elsewhere on the site, but still curious, so trying some of those that perhaps use these setups.

Curiosity gets the better of me but can anyone explain the rear geometry when using adjustable rear suspension arms/(frames).

As the adjuster is inserted in one of the tubes, how does this affect the angles and tensions being put on the inner chassis bushes and the outer mounting points on the suspension struts, as well as the welded joints on the suspension arms themselves. As the adjuster is moved in or out, this must put a strain on the other joints?
Tony

[Andy8421]

Tony,

Adjustable lower wishbone

Looking at the picture, the adjuster won't impact the inner chassis bushing geometry, but could effect the alignment of the outer mounting bushes where the strut base attaches. It must also bend the tube / weld at the point 'opposite' the side of the triangle that the adjuster is mounted in.

I guess the changes in geometry required are small, and any alignment / bending issues are negligible.

Andy.

[tonyabacus]

Andy
Thanks for the response.
You are probably correct in terms of the inner bushes although the outer as you say must take most of the strain. Given that in the main these are likely to be used under racing conditions, then the forces going through the standard set up would be okay. However I still wonder under such conditions what additional strain is put on the other welded joints, although again as you suggest given the small adjustments that are perhaps made.maybe as long as these welds are regularly checked, they may well be okay.

I was just curious as to others thoughts/experiences from practical use of such arms, so again thanks for the input.
Tony

[snowyelan]

I have this style, although they are stock arms I modified. I did this to allow for adjusting the rear tow to spec if required. After assembly it was less than 1 turn on the adjuster to bring the toe dimension to nominal so not really worth it in the end. Because of the fine adjustment required, the added stress to the welds was minimal with the thin wall tube taking up some it as well.
I do not consider these to be race items. There are/were arms available with heim/rose joints which are more suited to modified geometry.

[tonyabacus]

Hi Snowy
Thanks for the input, with such a small adjustment you refer to, I can understand the stress on the welded joints is likely to be very small.
Do you know who used to supply the rose jointed type?
Tony

[snowyelan]

Unfortunately I don't recall who it was. The mental snapshot I have of them has the joints at the inner pivots. The disadvantage of this is that it alters the wheelbase.

[Mike Ostrov]

I created two Elite/Elans. Type 14 Climax Elite bodies on S2 Elan frames (7 degrees of castor, same as our Climax Elites) , which were cut in two, extended 4.125 inches to match the wheel base of my Elites and re enforced. All have fully adjustable Elan suspension including rear wishbones with the outer rubber bushings replaced with heim (rose) joints for accurate toe adjustment. Go for it. Cheers. Mike in the San Francisco Bay Area if anyone cares to pop in for a drive.

[alan.barker]

I thought the joints were Brazed not Welded.
I think Brazing is more flexible
Alan

[elansprint71]

Those adjustable bones are not racing items and do not appear in my set of Homologation papers (127 2/ET); the adjustable ones which are Homologated have adjustable inner pivots/bushes which put no strain on the tubular components. Part numbers are: LH 26.D.013A and RH 26.D.014A

Do the Scrutineers bother with things like this these days?

[JonB]

I thought the joints were Brazed not Welded.
I think Brazing is more flexible
Alan

Correct.

[tonyabacus]

Hello Pete
You quoted some part numbers for the homologated rear arms, but do you have any pictures of them and who supplied them
Tony

[prezoom]

Merlin Motorsports in the UK is a good source for Rose/Heim joints and AN hose and fittings.

[bigvalvehead]

TTR makes them for the 26R
They have rose joints at both ends.