Rear Camber?

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Oct 5, 2006 | 10:28 AM

JPhil

Thread Starter

Burning Brakes

Joined: Oct 2004

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From: Loveland Colo

Rear Camber?

If the design of front control arms is to change wheel camber in relation to the vehicle to keep maximum tire patch on the road during cornering loads (body roll), then why do we want to minimize rear camber change using VBP's "Smart Struts" or similar ideas? Would we not want a similar camber change for the rear?
I know smarter people than I have figured this all out, can someone help me understand?

Thanks, John

Oct 5, 2006 | 10:57 AM

TedH

Le Mans Master

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From: Tampa Bay FL

Quote:

Originally Posted by JPhil

From my shadetree mechanical knowledge... I think it has to do with the fact the front tires also turn left/right; greater camber changes in the front assist with steering/turning (a good thing). Too much camber change in the rear when the tire is travelling up and down can cause handling issues (read the rear can start to do its own steering/dancing when the strut bushings are too loose). I installed the poly adjustable struts in the rear of my '80 L48 when I replaced all bushings (used rubber for all of the other bushings) and had the t-arms and half-shafts rebuilt by Van-Steel. While I was at it, I had a new blue-printed Dana 44 with 3.54 Spicer gears installed that had its own new bushings and added the snub/snout bushing kit where the diff mounts to the frame in the center; below the driveshaft. Resolved alot of handling issues with those changes (more stable). New tires and shocks rounded out the package and now I can easily drive the car; very stable.

Last edited by TedH; Oct 5, 2006 at 10:59 AM.

Oct 5, 2006 | 11:01 AM

strokervette

Racer

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From: Charleston South Carolina

The idea is to stabilize the geometry of the rear suspension so that the camber dosen't change as the halfshafts move in and out as the rear of the car compresses under hard acceration, and we get max tire contact with the road. The geometry, as it is supposed to be designed, is to keep the camber even to the road throughout its movement. BUT, do to the poor stock design of the camber rod bracket location,that is mounted under the rear diff, the camber does change a little and creates unwanted stress on the driveline parts. Actually the driveline parts act as part of the suspension. With a 1 inch spacer mounted between the bracket and the rear (Lowering the bracket), you get a better geometry and there is less stress on the halfshafts.The camber rods and halfshafts are now parallel. You can also set up the ride height so that the halfshafts are parralel to the ground. That eliminates 1/2 of the unwanted in/out movement of the halfshafts under acceleration. Here is a link that shows some pics and has more info.
http://www.dragvette.com/products.html

Oct 5, 2006 | 11:38 AM

JPhil

Thread Starter

Burning Brakes

Joined: Oct 2004

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From: Loveland Colo

OK, that makes sense....
Per the "Vette Improvement Program", I did install a spacer under my OEM strut rod bracket when I replaced all my rear suspension with VBP heavy duty parts and dual mount spring. However I only used a 1/2" spacer block because of problems with exhaust pipe-to-road clearance. The VBP strut rods I have came with no cams, just a fixed center pivot mount. Now I'm thinking I should put my OEM cams back in and set them to the bottom to get as much spread between them and the axle pivot at the differential for a squarer geometry, similar to the "Smart Struts" bracket. Does that sound like a reasonable idea? Unfortunatly, until I rebuild the diff to fix the side slop, I won't be able to see any difference.

Thanks both for your help.

John

Oct 5, 2006 | 01:46 PM

69427

Tech Contributor

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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.

Quote:

Originally Posted by JPhil

The idea of a suspension is to keep your tires upright despite the car/frame bouncing up and down, or leaning over in a corner. You need the appropriate camber gain (front and rear) to compensate for the car not being a stable, level platform under all driving conditions. During cornerning, the car will lean toward the outside. If there were no camber gain the tires would exhibit the same lean angle as the car. Not the fastest way around a corner. Hence, you set the suspension geometry to allow sufficient camber gain to keep the tires upright. Zero camber gain is great on a straight line drag car, but not for a vehicle that is expected to also corner (with the resulting body lean).

Oct 5, 2006 | 03:18 PM

DaveL82

Drifting

Joined: Jul 1999

Posts: 1,542

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From: Plano TX

69427 is spot on. You need some camber gain in the rear however not as much as the front which is more heavily loaded in a turn.

For drag racing no camber is probably a good thing. And the majority or folks that just drive of the street probaly won't know the difference.

Heck the whole point of having an independent rear is so that it follows the road and can provide camber gain. If not you might as well through a straight axle under it.

Now if I could fix the front camber gain issue I'd be happy.

Oct 5, 2006 | 03:20 PM

simpson36

Instructor

Joined: Nov 2005

Posts: 129

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From: Plano Texas

Camber change is intentionally designed INTO the suspension for exactly the reason stated; the vehicle's body roll in corners requires a camber change to keep the wheel perpendicular to the road.

It is only useful to reduce camber change if you also reduce body roll with high rate springs or big bars.

Oct 5, 2006 | 03:24 PM

JPhil

Thread Starter

Burning Brakes

Joined: Oct 2004

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From: Loveland Colo

Right! So would a stock or near stock strut set up with several degrees of change be desirable for a cornering car? What would be a desirable amount of camber gain?
Am I overthinking an idea which is not that big a deal?
I'm not a racer, but I like to make my poop run well and efficiently...."the stuff that dreams are made of."

John

Edit: Woops, didn't get this posted in time, You guys answered my questions already! Thanks

Last edited by JPhil; Oct 5, 2006 at 03:26 PM.