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Indy rear suspension geometry mods?
Mave - 11/9/08 at 08:11 AM

Before anyone starts shouting again; no, I don't think my Indy has a handling problem, and especially with my kind of use any suspension system would be good enough.

Right. Having said that, I can now proceed with my question.

I'm planning on an extensive rebuild this winter with my Indy. I will be doing modifications to the chassis, bodywork and engine. And as I'll be using my welder at the rear of the chassis anyway, I thought it might be a good idea to perform the "much talked about" modification of the rear suspension, to dial out the unwanted camber change. I read that the upper wishbone brackets need to be moved. But how/what/where exactly?

Again, I'm not saying that my car has handling problems, but as I'm working on it anyway, it wouldn't hurt to make it better (even if it's just theoretically better).

Marcel


nick205 - 11/9/08 at 08:59 AM

I can't advise, but you have put your question very well


mackei23b - 11/9/08 at 09:06 AM

Have a look here........

http://www.locostbuilders.co.uk/viewthread.php?tid=62442


mangogrooveworkshop - 11/9/08 at 05:15 PM

Andys dropped the top mounts down 2". If my memory is correct so the bones are not parallel. sending the wheel in an arc when its loaded up, this then ensures it stays vertical.

[Edited on 11-9-08 by mangogrooveworkshop]


mangogrooveworkshop - 11/9/08 at 05:18 PM

And just to sort the self centering problem this was done to patricks car REDEYE..
I have yet to get this mod done to my chassis

[Edited on 11-9-08 by mangogrooveworkshop] Rescued attachment Wisbone.jpg
Rescued attachment Wisbone.jpg


Mave - 11/9/08 at 06:01 PM

Thanks, my front wishbones are modified in a similar way to provide more self-centering. It succesfully passed SVA without weird toe-angles, tire pressures of springs in the steeringrack.

But regarding the rear; I've been doing some analysis myself today. The rear roll centre is -35 mm (140 mm riding height). That's LOW. And it's a lot lower than the front (+15 mm at 125 mm riding height).
Dropping the upper inner brackets by 1 inch brings the roll centre up to +37 mm. Camber change is a bit more. (about 0.35 deg/m)

All in all that seems like a sensible change, when you keep the front suspension as it is.


whitestu - 11/9/08 at 06:23 PM

Do you know if anyone sells wishbones with that modification?

Is it a mod to existing bones or a new set?

Thanks

Stu

[Edited on 11/9/08 by whitestu]


Mave - 11/9/08 at 06:51 PM

Mine were done to the existing bones. Not very pretty: they just cut the threaded tube together with a bit of front and rear tube. Turn it over (so bit from front tube becomes rear, and vice versa).
Hmm, doesn't sound very clear does it?


whitestu - 12/9/08 at 10:12 AM

I think I get what ypu mean. How well does the car self centre with the mod? Is it anything like a production car?

Have you got a pic of the modified bones?

Thanks

Stu

[Edited on 12/9/08 by whitestu]


mad-butcher - 12/9/08 at 07:28 PM

Just printed the pic off and overlaid my spare wishbone on top and notice the offset is almost double that of a standard one, Is this not going to change the angles of and put too much strain on the top and bottom balljoints
Tony