C Murda

iTrader: (24)

ok ive got 27" tall hoosier QTPs i am lowered on G2 springs with a rear spring rate of 180-225, i have koni adjustables, Tq arm, LCAs and LCA relo brackets set to the bottom hole, spohn 1" solid rear sway bar (not anti roll bar)....
last season i was running DRs and best 60 was 1.8 and ET 11.7 and the hook would throw me back in my seat NOW with the Hoosiers the hooks seem a lot softer and my best 60 was a 1.8 and ET 11.8????? i marked the wheels and noticed the tire was spinning 1/2 inch on both rims but that cant affect my launching that bad. im told by my buddies it looks like off the line that my car is bottoming out hard in the rear. the car did feel weird in between 1-2 shift and 2-3 shift and the launch was not as violent as on the DRs...?

is it possible that i could be bottoming out bad enough for my times to not improve at all over using DRs?

tektrans

iTrader: (23)

lowered springs and the rim spinning in the tire isn't exactly a recipe for good 60' times.
plus if you're bottoming out bad enough I wonder if it could be causing a false knock reading.
either way the springs suck.
I suggest 1-you go back to stock springs or
2-you get a set of air lift airbags and run the lines separetely and set the ride height at the track and that will also stiffen out the rear so you don't bottom out. set of bags is like $100, could be an easy fix for you.
I run dual airbags in my car.

tomcowle

iTrader: (5)

The radial tire reacts quicker than a bias ply tire does. The bottoming out is most likely the bias tire "coiling up" of the sidewalls upon launch.

Old Geezer

iTrader: (3)

Instead of relying on your buddie's observation[s], I'd suggest some good videos. Review, and make your conclusions...

C Murda

iTrader: (24)

i wish i had some video.... how do bags work? do i need to fill them with a special pump or is it like filling a tire? i also have a pair of V6 rear springs i could put in but i dont want the hassle of swapping rear springs everytime i go to the track....

5.3LJimmy

iTrader: (10)

It sounds like you swapped to a slightly taller tire, which will raise your effective gear ratio. Add to that the fact that the bias ply will grow as speed increases and the effect is even higher. The feeling at launch is different because the radials have a much quicker response with very little distortion, while the bias ply will wrinkle before moving the car. I would say your ET reduction is due more to the height and growth of the tire than the launch. The 60 foot time is the same right?

Bitemark46

+1. Best advice.

Also keep an eye on the distance between the fender and the top of the tire. If the distance gets noticeable smaller then the car is unloading on the tires and you need to stiffen up the rear to keep the downward pressure constant all the way through the 60ft.

Is this a stick or auto?

-Mark

C Murda

iTrader: (24)

I noticed rings on the outer edge of my rear tires about half way down the sidewall as if my tires are rubbing on my quarters and they are rolled so that would explain why it's not cutting into my tires...

Yes it's a stick car. And I was told stiffening up the rear shocks won't do anything when it comes to compression because the SA konis only do rebound and I need stiff compression