stiffer suspension

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Sep 27, 2009 | 02:46 PM

yamaha731

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Heel & Toe

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stiffer suspension

I ran my first autocross to day and loved it but it feels like i get allot of body roll in my 88 convertible. Whats the best way and cheapest way to stiffen things up a bit?

Sep 27, 2009 | 06:11 PM

redrose

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From: backwoods upstate ny

Quote:

Originally Posted by yamaha731

I ran my first autocross to day and loved it but it feels like i get allot of body roll in my 88 convertible. Whats the best way and cheapest way to stiffen things up a bit?

your vette USES body roll to create 'camber change' to maintain full tire tread contact with the ground, by complex suspension design...reducing body roll will likely degrade your car's cornering ability, unless you make other mods (most contrary to normal street requirements for tire wear/ etc)

Sep 27, 2009 | 08:16 PM

Mojave

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From: College Station TX

Quote:

Originally Posted by redrose

This is totally and completely wrong. Like any suspension that is setup properly, C4's gain camber in compression, but you still lose more camber to body roll than you gain back. In an ideal world, your car would have zero body roll and your tires would always the optimum contact patch. Clearly, this isn't the case. Increasing the wheel rate (either by stiffer springs or larger sway bars) will improve grip by reducing body roll and the associated camber loss. Too stiff, however, and the car will skip and skate over bumps.

To the OP: quite honestly, the thing holding you back now is you, not the car. Auto-x is 60% driver, 30% tires, and 10% everything else (car setup, etc). You really should focus on improving your performance before you go changing the car. However, to answer your question, you can upgrade to Z51 springs and bars, get custom springs from someplace like VB&P, or change to coil overs. I strongly recommended leaving the springs alone, getting a good performance alignment, and go improve your driving by going to more AX events and getting lots and lots of seat time.

Sep 27, 2009 | 08:24 PM

BADDUCK

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From: One day you're a Comet...the next day you're dust... Arkansas

The first two changes I would make is Z51 type sway bars and coil overs. I agree with Mojave, leave the springs alone.

Sep 28, 2009 | 10:39 AM

BrianCunningham

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Check and see if the shocks and bushings are worn.

I have almost no body roll on my car

Sep 28, 2009 | 10:44 AM

Kubs

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Quote:

Originally Posted by BrianCunningham

Check and see if the shocks and bushings are worn.

I have almost no body roll on my car

That is with your "soft" base suspension too isnt it?

Sep 28, 2009 | 10:48 AM

yamaha731

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Heel & Toe

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its an 88 so i need to replace the shocks(they look original). any recommendations ?

Sep 28, 2009 | 11:01 AM

BrianCunningham

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Quote:

Originally Posted by yamaha731

its an 88 so i need to replace the shocks(they look original). any recommendations ?

Z51 Bilstiens for starting out.

or adjustables, but you want to autox for a while before you start adjusting stuff.

Quote:

Originally Posted by Kubs

That is with your "soft" base suspension too isnt it?

Soft base springs
Z51 swaybars
QA1 shocks cranked up all the way.

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Sep 28, 2009 | 09:10 PM

redrose

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From: backwoods upstate ny

Quote:

Originally Posted by Mojave

In an ideal world, your car would have zero body roll and your tires would always the optimum contact patch.

this is totally wrong ...your tires are made from rubber (synthetic, but still very flexible) and during lateral acceleration (cornering) the tires WILL ''roll under'', reducing tire/road contact to a sliver of rubber at the tire's edge if the tire is held near vertical...changing wheel camber by using body roll/ suspension member length interaction is how ''those who know what they're doing'' keep the tire working to it's max capability.

bbtw, in jounce (wheel travel is upward relative to chassis) a C4 will LOOSE camber (wheel moves ''in'' at the top, this is "negative'' camber)

Last edited by redrose; Sep 28, 2009 at 09:21 PM.

Sep 28, 2009 | 11:40 PM

#10

Mojave

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From: College Station TX

Quote:

Originally Posted by redrose

Are you seriously telling me body roll makes your car handle better? I understand you don't want the car to be overly stiff, but if you could set it up with no body roll and still be compliant enough to handle bumps, you would. Eliminating body roll means the car will transfer weight faster, be more responsive, and you could set your static camber for maximum grip and not have to worry about camber curves at all.

No crap it gains negative camber in jounce, THAT'S WHAT YOU WANT. You LOSE negative camber to body roll, and you gain back some of that negative camber with negative camber gain. You don't want the tire near vertical, you want negative camber all the time. If you end up at zero camber (or positive camber), you screwed up.

Last edited by Grumpy; Sep 29, 2009 at 12:00 PM.

Sep 29, 2009 | 08:24 AM

#11

darkstallion_69

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From: Hialeah Florida

oh boy...

Sep 29, 2009 | 09:31 AM

#12

BrianCunningham

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From: Boston, Dallas, Detroit, SoCal, back to Boston MA

FYI the rear on a C4 has camber loss when compressed.

Sep 29, 2009 | 10:19 AM

#13

Kubs

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Quote:

Originally Posted by redrose

tires are made from rubber (synthetic, but still very flexible) and during lateral acceleration (cornering) the tires WILL ''roll under'', reducing tire/road contact to a sliver of rubber at the tire's edge if the tire is held near vertical

This is part of the reason you add negative camber. With less body roll the car becomes more responsive but the tire still rolls under a bit like you mentioned. If you have negative camber the tire will flatten onto more of the contact patch instead of rolling onto the side. This is ideal. Body roll is never ideal.