Road racing suspension setup

[INSOMNIAC]

We altered the suspension setup on the 1200 RWHP TT Viper for a race last Sunday but it didn’t help at all. The car drives very scary with BFG Drag Radials now.
It has Moton Clubsports with 700 lb/in front and 900 lb/in rear Eibach springs.

I’ll go back to the Sport Cups. What suspension setup Caster, Camber and Toe should I use to get the Viper back to road racing specs and give the rear all the traction it can get in straight line?

Thanks.

 

[Chuck 98 RT/10]

I've heard drag radials were pretty frightening regardless of setup.

You can't have a road racing setup and still get all the rear traction in a straight line. Dragracers want zero or even some positive rear camber, road racers go with various degrees of negative at all four corners.

You're going to road race 1200 hp?

 

[INSOMNIAC]

I've heard drag radials were pretty frightening regardless of setup.

You can't have a road racing setup and still get all the rear traction in a straight line. Dragracers want zero or even some positive rear camber, road racers go with various degrees of negative at all four corners.

You're going to road race 1200 hp?

That’s what we did Chuck. We went zero rear camber and the BFG drag radials held up ok after dropping the pressure to 10 psi and warming them up good. This was for drag racing. I drove the car back from track after getting the pressure up to 28 psi but it was a scary ride.

I’m using the same car for everything. Just changing the tires back to Sport Cups and twisting the suspension setup to get it ready for the road race. It’s not a prepared course. Wavy and slippery pavement that gets dangerous very fast. I don’t have the stock 05 SRT-10 specs but I was thinking I could pick you road racing guys’ brains on caster, camber and toe settings.

And yes I do road race 1200 RWHP.

 

[mjorgensen Woodhouse]

Check the toe front and rear. If you are asking for stability then you will need a bit more toe in than the factory settings. When you go to the road course this may push a bit but will be stable to balance out all that power on oversteer! If you are looking for a drivable setup then the negative camber will be less likely to hunt around under power than having the tire flat on the road, which gives the tramolining (sp) problems.

Mark Jorgensen
Woodhouse Viper

 

[INSOMNIAC]

Check the toe front and rear. If you are asking for stability then you will need a bit more toe in than the factory settings. When you go to the road course this may push a bit but will be stable to balance out all that power on oversteer! If you are looking for a drivable setup then the negative camber will be less likely to hunt around under power than having the tire flat on the road, which gives the tramolining (sp) problems.

Mark Jorgensen
Woodhouse Viper

Exactly. 345/30 – 18 BFG Drag Radial with zero rear camber was like driving on a trampoline on the back. Very scary going at 185 mph. The rear tires would follow every wave on the pavement and it’s difficult to hold the car in one lane. For the first time ever, I locked the rear tires braking hard and I was lucky to hold the car from spinning.

I will give the BFG Drag radials one more chance after changing the suspension setup to road racing specs and if it doesn’t hold again, that’s it. Drag Radials will only be on the car at the drag strip.

Mark, giving more toe in and negative camber to make the car stable and even out the oversteer sound like a great idea. I’m ok with the car pushing a little bit.

Do you have caster, camber and toe specs for stock 05 SRT-10?
What spec caster, camber and toe do you guys run in the Comp Coupe?

Thanks a lot.

 

[Janni]

Most of the comp coupe guys run different settings at all four corners based on the direction of the track and the types of turns. Also - shocks, springs and sway bars are different.

We can usually get away with less than one degree negative camber in the rear and anywhere from 1.2 to 1.9 in the front - depending on which direction the track is biased.

Toe - about 1/16th to 3/32nds total toe out in the front and about 3/32nds to 1/8th total toe in in the rear.

Don't muck with caster much setting the car up at home.

 

[Racer Robbie]

Here Are The Stock Specs For A 2003 Srt-10 Viper

http://www.alldatadiy.com/alldata/A.../97272324/34853741/34864218/58801095/58801120

 

[mjorgensen Woodhouse]

I would start with .4 degree of toe in front and rear with .8 rear camber and 1.2 - 1.5 neg. in the front.

 

[INSOMNIAC]

I would start with .4 degree of toe in front and rear with .8 rear camber and 1.2 - 1.5 neg. in the front.

Thanks Mark. Will give it a try.

 

[INSOMNIAC]

Most of the comp coupe guys run different settings at all four corners based on the direction of the track and the types of turns. Also - shocks, springs and sway bars are different.

We can usually get away with less than one degree negative camber in the rear and anywhere from 1.2 to 1.9 in the front - depending on which direction the track is biased.

Toe - about 1/16th to 3/32nds total toe out in the front and about 3/32nds to 1/8th total toe in in the rear.

Don't muck with caster much setting the car up at home.

Thanks Janni.

 

[INSOMNIAC]

Here Are The Stock Specs For A 2003 Srt-10 Viper

http://www.alldatadiy.com/alldata/A.../97272324/34853741/34864218/58801095/58801120

Robbie, the site asks for a login username and password.

 

[Viper X]

Not sure from what I've read which tires you're using for which purpose. The BFG drag radials are OK on the drag strip, certainly, they're not OK on a road course.

I will tell you that I tried PS Cups on the back of my Paxton SRT-10 at several tracks with only 780 rwhp. If I accelerated hard out of the turns and in a straight line, in a couple of laps these tires got very hot, very goouy and slippery.

I've had better luck with the Kumho's on my track car and I'd guess that you would too. I now use my Paxton SRT, now at 925 rwhp on 91 octane, for the street only.

Susupension set up was done by Archer Racing is about what Janni said above; it depends on the track and which way you want the car to turn.

Good luck,

Dan

 

[INSOMNIAC]

Not sure from what I've read which tires you're using for which purpose. The BFG drag radials are OK on the drag strip, certainly, they're not OK on a road course.

I will tell you that I tried PS Cups on the back of my Paxton SRT-10 at several tracks with only 780 rwhp. If I accelerated hard out of the turns and in a straight line, in a couple of laps these tires got very hot, very goouy and slippery.

I've had better luck with the Kumho's on my track car and I'd guess that you would too. I now use my Paxton SRT, now at 925 rwhp on 91 octane, for the street only.

Susupension set up was done by Archer Racing is about what Janni said above; it depends on the track and which way you want the car to turn.

Good luck,

Dan

Hey Dan,

I used the BFG Drag radials for the drag race and to drive to and back from the track. The ride back from the track was scary with zero rear cambers and 28 psi BFG’s.

I’ve had the Sport Cups for a while now and I wouldn’t say they can handle the brutal acceleration of 1200 RWHP but they are not bad in cornering and for spirited highway use. You just need to heat them up little bit. The wear on the tire is very good for a competition tire and I would recommend it to any high performance car up to 700 rwhp.

Now, at 1200 Rwhp any tire is obsolete. I haven’t used the Kumho’s but I doubt they will grab in 3rd gear. And I personally don’t like the way 335/30 – 18 Kumho sits on a 18x13 wheel. I am trying to order Hoosier R6’s now and I hope they will help my traction problem.

Tires have been and still are the limiting factor on high HP cars.

 

[mjorgensen Woodhouse]

Competition tires work well but the thing you need to remember is that with any soft compound tire the amount of heat cycling the tire sees is the real factor when they seem slippery. Most of these tires heat cycle out long before they wear out so it may just be time for new ones anyway. I have seen a drop off in performance in as little as 12-18 cycles. This is nothing if the tires are street driven so you should use them only for track events really.

Mark Jorgensen
Woodhouse Viper

 

[pakisho]

Your bfg drs will not get any better no matter what you do suspension wise. That soft sidewall does not lend itself well to high speed driving and cornering. I had a set on my car (not a viper), and yanked them off very quickly after experiencing what I would describe as "unsettling" handling characteristics.

 

[Viper X]

Insomniac,

I'd bet you a nickel the Kumhos would give very good traction in 3rd gear when warm, likely even second on a warm day, smooth road.

As for rim size, they do look and work better on a 12. 5-inch rear rim. This is what I run them on. A 12-inch rim might look even better.

I've tried a few Hoosiers and they need to be much warmer than the Kumhos to get sticky. They do stick well when hot.

Good luck,

Dan