Dodge SRT Viper Forums : ViperAlley banner
1 - 12 of 12 Posts

·
Registered
Joined
·
161 Posts
Discussion Starter · #1 ·
On my last track session, it seemed as though the back end of my '97 wants to unexpected come around during moderate acceleration out of a corner. Maybe I'm driving more aggressively these days, but I didn't notice it quite so much at Motorsport ranch in Oct.

Since TMR, I've cut two coils off front spring, one off back to drop car 1.5". I've increased koni stiffness from 1/4 to 1 full turn, and I've gone from an unknown alignment to an aggressive street alignment. My tires are at least 2 years old (18" pilot sports 285 and 335s). I put down a 1.85 60' at V-10 nationals last Dec, so there's still a little stick left in them.

My thoughts are to drop the rear stiffness back down to 1/2 turn to see if that will give me more squat (and traction) on acceleration, kindof like going to a 17" rear tire. Another option is to ignore the suspension and put the pilot cup tires on the rear and keep the front pilots as is. \

Any ideas before I do anything.

thanks
 

·
Registered
Joined
·
10,727 Posts
I'd rip the front shocks to full dampening, and back the rears off to half, like you said...then I'd be off to the alignment shop...

Have you pulled the sport shims??? What are your current alignment specs???
 

·
Registered
Joined
·
932 Posts
I'm sure you've already been down this road but what tire pressures were you running front and rear?
 

·
Landscaping Professional
Joined
·
14,148 Posts
Cutting the coils is the most likely culprit. Softening the damping might help, but you're going to have to be much more judicious in throttle application out of the corners no matter what. When you're driving the Viper fast, the back end gets more twitchy. Dropping the air pressure a pound or two will soften up the back too, but it could get too lazy for comfort. I'd try the air first - it's easier than the shock adjustment.
 

·
STALKED
Joined
·
4,483 Posts
Maybe I am dense - but why would you cut a spring when they are made in different heights?
 

·
Hooray for me, & fuck you
Joined
·
7,863 Posts
JT said:
Maybe I am dense - but why would you cut a spring when they are made in different heights?
and tuned to different rates at those sizes..
 

·
The Burn Clinic
Joined
·
12,779 Posts
JT said:
Maybe I am dense - but why would you cut a spring when they are made in different heights?
It ain't you, Janni!

Cutting the spring will also increase the rate of the coil. Your shocks probably aren't ready for this and what you have now is a damping problem. Also, you can't change squat characteristics without moving pick-up points, but that's just me being semantic.

Having a power-on problem is worse than having no brakes. The biggest reason Vipers put down the lap times they do is because they put down more grip coming out of the corners...ie they are accelerating harder and longer.

Also, which corners at MSR. Half the corners there are off-freaking-camber and not fast enough to invoke any real aero (so a wing is a useless band-aid to your traction problems).

Get some real springs and real shocks, play with the tire pressures, and make sure you don't have any bent control arms (which would bumpsteer you into the problems you are describing, as well)
 

·
Hooray for me, & fuck you
Joined
·
7,863 Posts
Smackie said:
Cutting the spring will also increase the rate of the coil.
thats what i said.. err... meant

Smackie said:
that's just me being semantic.
you hate jews?
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #10 ·
Nobody mentioned the pilot cups, so I guess you guys don't think much of them. Getting 5-6K miles/set doesn't really bother me--that's a couple of years driving!

I was running 30/29 in front and 28/27 psi in rear at TMR, and 30/29 front and rear at TWS. Maybe I should've gone softer in back.

I really dig the stance of the car now, and don't want to go back to stock springs. The eibachs, I've heard, are stiffer than even my cut springs (yes, they were kept cool during cutting). So I think for spring stiffness I am somewhere in between. In retrospect, I maybe should've done the custom 1/2" spring perches 1st, then later cut the springs a little less (I'm still not convinced that the springs are my problem).

JT, where do you get your springs from. All the places I checked out need expensive kits to add adjustability and such. I'd love to keep my dropped look and still be able to launch at the drag strip. Divulge your sources!

I can't find the suspension settings, but it was set up by an experienced vipertech for aggressive street/occasional track use.

I'm still thinking the rear springs are overdamped. At the factory 1/4 turn, you could compress the shock and watch it extend to full in about 20-30 seconds. At 1 turn (out of 1 1/2 turns) you can compress the shock and come back 5 minutes later and not see full extension. There is a lot of difference!
 

·
Registered
Joined
·
2,657 Posts
JT said:
Maybe I am dense - but why would you cut a spring when they are made in different heights?
Most of those lowering springs have rates that are high as hell and don't allow a good launch at the drag strip. My springs on my WS6 are cut and dropped the car about 3/4 of an inch all around and it still launches like I have stock springs in the rear.

I was planning on doing the same to my viper but not nearly as much coil cut off as this guy did.
 

·
Sexist
Joined
·
44,358 Posts
opnwide said:
I was running 30/29 in front and 28/27 psi in rear at TMR, and 30/29 front and rear at TWS. Maybe I should've gone softer in back.
Assuming that's cold I think your PSI is already way too low. Drag racing logic doesn't apply to road racing. You are not going perfectly straight coming out of a turn and therefore at least need SOME sidewall stiffness. The low pressure may be rolling the tire onto the sidewall.

Up the rears to 32-33 and the fronts to 34-36 and give it another try. Drop pressures in 1/2 psi increments until you find what's right.
 
1 - 12 of 12 Posts
Top