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Suspension Question
liam.mccaffrey - 21/1/09 at 01:32 AM

Can you guys have a look at this piccie please and give your opinion.

This is the cover feature car from Jan 09 PPC. Its a 4x4 volvo engined hot rod.

This pic is a section from the full page photo on pg 13.

It appears to have an anti roll linkage system which if I have understood it correctly would behave like a completely non compliant anti roll bar. Not just limiting roll but opposing it solidly. Or maybe not, is the linkage utilising the coilover themselves to limit roll

Thinking Aloud
In a right hander the car will roll to the left compressing the left suspension and unloading the right. Won't this linkage try to compress the right suspension on a right hand bend?

Regular arb's work, by using the unloaded wheel to produce a torsional resistance and preventing the loded wheel compressing and thus preventing body roll. What are the functional differences between this and a regular arb

Have I understood this right???? I think I may be missing something obvious

PPC feature 2
PPC feature 2





[Edited on 21/1/09 by liam.mccaffrey]


MikeRJ - 21/1/09 at 01:55 AM

You are assuming the pivot in the middle has a completely solid bush, if either the bush or the way it's mounted has some compliance you'd get the anti-roll action whilst still allowing some roll.


liam.mccaffrey - 21/1/09 at 02:00 AM

do you mean like a metalastic bush preventing rotation, wouldn't you then get the more resistance to 2 wheel bump and droop than you would to roll

I see what you mean, in roll the suspension will try and move the pivot laterally in the chassis (left on a left hander and vice versa). The level of compliance in its mounting will determine the opposition to body roll

[Edited on 21/1/09 by liam.mccaffrey]


A1 - 21/1/09 at 07:32 AM

youve got me thinking about sticking that on the indy now


gottabedone - 21/1/09 at 07:59 AM

If one wheel is in bump, the movement is transferred through the linkage/pivot and linkage on the other side to the opposite wheel. From this one pikkie it looks like it would also cause the opposing wheel to raise as well.

hard to tell from this one pic though.

Steve


Mr Whippy - 21/1/09 at 08:05 AM

quote:
Originally posted by gottabedone
If one wheel is in bump, the movement is transferred through the linkage/pivot and linkage on the other side to the opposite wheel. From this one pikkie it looks like it would also cause the opposing wheel to raise as well.

hard to tell from this one pic though.

Steve


Yeah that's what I see, don't like it at all tbh makes the front almost behave like it’s a solid axle and removes any benefit of independent suspension.


MikeRJ - 21/1/09 at 08:33 AM

quote:
Originally posted by Mr Whippy

Yeah that's what I see, don't like it at all tbh makes the front almost behave like it’s a solid axle and removes any benefit of independent suspension.


Read my post above regarding compliant bush or mounting.

Even if the mounting were solid, it would not act like a live axle, since a live axle doesn't offer infinite resistance to roll.


mr henderson - 21/1/09 at 09:19 AM

quote:
Originally posted by liam.mccaffrey

Have I understood this right???? I think I may be missing something obvious

PPC feature 2
PPC feature 2








If that's the only picture then I wouldn't be surprised if something was being missed.


hughpinder - 21/1/09 at 09:22 AM

I think the central bush allows free rotation, so no resistance if the wheels move up and down together, but is probably mounted on the end of a lenth of flexible bar to provide the roll resistance - just move the bush up and down the bar to tune the roll resistance.

Regards
Hugh


liam.mccaffrey - 21/1/09 at 09:41 AM

quote:
Originally posted by hughpinder
I think the central bush allows free rotation, so no resistance if the wheels move up and down together, but is probably mounted on the end of a lenth of flexible bar to provide the roll resistance - just move the bush up and down the bar to tune the roll resistance.

Regards
Hugh



After some thought I would probably agree, quite neat if it works

The only other picture in the mag (PPC Jan 09) doesn't show any more detail unfortunatley