Help Translating Alignment/Cross Balance Specs . . .

[rcl4668]

Can anyone help me translate the following alignment and cross balance specs for a 2008 (non-ACR) Viper? Thanks.

For example, what does "wedge" mean?

I take it that since the shop found the rear camber, caster, toe to be near ideal for a mild street/track alignment, the remaining figures are just for the front?

I assume the weight figures are for each corner of the car?

Again, thanks for helping an alignment/balance newbie.

/Rich

 

[Catwood]

Corner Weight Calculator

Read away

 

[j-rho]

"Wedge" is a circle-track term. Since circle-track cars only turn left, they can change the under/oversteer characteristics by changing the corner weights. You can't change total front or rear weight, or left or right weight, but you can change how much the LF + RR vs. RF + LR carries.

For a general-purpose track/autocross car, one generally aims for 50% cross weight, where LF + RR = RF + LR. IMO people tend to stress over this a little more than necessary - your car is close enough.

Total weight seems pretty high - were you in the car?

Looks like you finally got some negative camber in the front, that's good, it'll help with outside edge wear.

 

[rcl4668]

"Wedge" is a circle-track term. Since circle-track cars only turn left, they can change the under/oversteer characteristics by changing the corner weights. You can't change total front or rear weight, or left or right weight, but you can change how much the LF + RR vs. RF + LR carries.

For a general-purpose track/autocross car, one generally aims for 50% cross weight, where LF + RR = RF + LR. IMO people tend to stress over this a little more than necessary - your car is close enough.

Total weight seems pretty high - were you in the car?

Looks like you finally got some negative camber in the front, that's good, it'll help with outside edge wear.

They asked for my weight with safety gear on (helmet etc) so I think they factored that in when doing calculations. I think that's the 235# number in the upper left hand corner.

/Rich

 

[mjorgensen Woodhouse]

Why did they take all the castor out of your car? I like close to 6 on mine.

Plus staggering tire pressures is questionable to me for the corner weight factor.

 

[j-rho]

Why did they take all the castor out of your car? I like close to 6 on mine.

Plus staggering tire pressures is questionable to me for the corner weight factor.

Mark, that's about equal to the most caster I've been able to get in mine once negative camber is maxed out. Have you guys been able to get more caster than that at maxed out negataive camber and stock ride height?

 

[mjorgensen Woodhouse]

Mark, that's about equal to the most caster I've been able to get in mine once negative camber is maxed out. Have you guys been able to get more caster than that at maxed out negataive camber and stock ride height?

No not at the stock height, I have close to 6 on each side. with 2.3 neg.

 

[rcl4668]

FYI, my car has the stock, non-ACR, non-adjustable suspension so the ride height should be stock.

 

[Tom F&L GoR]

On an non-ABS car, that setting would produce the RF wheel lock up problem because it's "light". I adjusted mine to have same front weights (with me in it) and allowed the RR to become lighter. Theory says in right turns I move to more oversteer, left turns to more understeer, but I can't tell. But I can tell when one front wheel smokes....

With ABS, you can forget everything I said. But I do think it is odd to vary tire pressure, moreso when you think a tire is a spring and you made two of them stiffer than the other two.

 

[mjorgensen Woodhouse]

Agreed Tom, even with ABS though you loose some braking because the ABS comes on before you need it and IMO lessens your stopping power if you are a good braker.

 

[Viper X]

Yeah,

Mark is right on. Castor is too low. Could make this car "squirelly" at speed and under braking on a track. +5 would be the minimum IMHO. I try to run 5.7 or more with -2.5 or more negative camber.

Right front tire is not carrying enough weight. This will be an issue when braking.

You can only do so much with the OE non-adjustable suspension. If you are serious about making your car handle better, you need to get it lower. Adjustable shocks would be best way to go.

Dan