All,

Does lowering or raising the rear help traction or not ?

My car sits kinda high in the rear, I wanted to lower it about 1" so it will be the same height as the front.

Will this affect hooking up at the track at all ?

Vic

 

My car isn't too good of an example whether it is bad or good by the few runs I make. I had mine lowered all around. That is a good question. I'd think lowering might help it squat a little more....or maybe it'll hurt seeing there's less travel? The die hards I am sure will chime in.

How is the car Vic? back in one piece.

JD

 

Vic, that is a good question. I've studied this to a considerable extent, and i still don't know the answer. But i do know this: Even though our IRS looks like a 4 link....it's not and doesn't react the same. Rotational torque is absorbed by the torque arm (not the trailing arms). If you lower the car, the geometry of the trailing arms will tend to make the car wanna squat more as the wheels try to drive up under the car. If you raise it, it will squat less and if you raise it enough, it will actually push the wheels down to try to drive under the car (which i think is desirable). I have used JPs car as a model since he is able to pull the wheels with less power & torque than i have. pulling the wheels means he has 100% of the weight on the rear wheels, which is as good as it gets. The two things that were most noticably different between our cars was that his rear was almost 2in higher than mine and his front suspension is much looser than mine. If you've ever watched JPs car launch, you'll notice that his car doesn't squat and it's not because his rear suspension is tight (it's actually very loose). It's because of the height and the geometry that goes with it. My car used to squat hard, but i have raised it over 2in...mostly to fit the big DRs, but also to change the geometry. Now my car doesn't squat either. Next i tried to get the front looser, but there are only a few springs available for my car and none of them are near as loose as Johns. I installed the softest spring, but it made almost no difference. You have a lot more choices.

So to answer your question: It depends...I think raising the rear is good to get the wheels pushing down into the track, but you also have to get the front to come up enough to transfer the weight. Like everything else, it all has to work together.


[Modified by ralph, 7:59 AM 8/22/2002]

 

I lowered mine in the rear only and have not see any gain on traction but then I have not been running the same weather either. Such a small change is hard to guage it's benefit on different days.

Having said that, some of the guys running the best times have lowered cars.

 

Vic,
I've raised & lowered mine a couple of times depending on the tires I was using, 1" either way didn't seem to matter at all. The most dramatic change was thru the shock settings on the HALs that I run. I can go from street ride to as stiff or soft as I like, but softening them up can get you violent traction! Big front end rise and squat out back, if I can figure out how to send a picture I will of my '90 or '92 at Etown. Maybe JD has a still of the '90 launching from July he will forward to you.

JD,
Are you still planning on coming down to Capitol on 9-8? Phil & I are going in spite of our problems there, but I have to fix a busted rear in the '90, broke it Monday @ MIR. I loosened up the rear shocks that run and dead hooked it for about 3" before the boom, got a spare 9" & a 4-link?
See 'ya there, Dave :cheers:

 

Dave

I spoke to Bill C and relayed your short times to Him(1.4 zone) He said if it keeps up there'll be parts sitting on the track. Looks like He was right eh? Sorry to hear that. Regarding the event, I have a spot on October 4th at LVD. I too don't want to break...we'll see how it hooks there and I am hoping for a mid 11 and still be able to drive it home. How many PSI did you run in the e.t. streets? Bill used 19...I was going to start there..Sorry to hear it's not in one piece...I don't have access to a spare D44 or 9".

Jay

 

I installed used stock Half Shafts. The big fiberglass gash is not repaired yet. The rear seems ok. No other damage as far as I tell.

There will be a major upgrade as soon as I have some time. :crazy:

Vic

 

glad to hear it is back together. I have found my car gets better 60' with the rear higher up. I have air shocks in the back of my car and if i pump up and harden the shocks they seem to hook better for some reason.

 

Vic,

Glad you got fixed, BTW, are you running a D-44 or 36? I'll have a couple of D-44s available as soon as I can swing a 9".


JD,
Just returned from Carlisle tonight, great show, didn't find my 9" setup!

I had mounted up a set of 10.5X28 MT's the week before and the car became deadly consistent off the line. On that last day I had 4 runs between 1.502-1.508 and the last was 1.512, then it went boom-clunk when it hooked. That last launch I loosened up the rear shocks a couple of clicks hoping to stop the spinning that happens 3-5' out, it worked too good! I was still experimenting with the tire pressure so I can't tell you what really worked best. I'll pull it out tomorrow and see if I can get back together for the 8th.

See ya, Dave :cheers:


[Modified by new92racer, 9:12 AM 8/25/2002]


[Modified by new92racer, 9:15 AM 8/25/2002]

 

Dave

I spoke to phil a few days ago. Glad your car is back together also. Those 500+ foot pounds of torque are tough to get to the ground reliably! Nice 60's! Hope it lasts a little longer this time.

I'm praying for a low 1.6 on October 11 at Lebanon valley dragway. I have Bill C's old slicks,and Red96Coupes former skinnies. We'll see how She does.

keep us updated if you click the magic "10" :D

 

Not that this will help answer your questions, but the MOPAR guys will use the super stock springs(I believe 6 leafs on the left and 6.5 on the right). They will take the clamp off the rear part of the spring after the axle and put an extra clamp on the front before the axle. For some reason, this makes the rear of the car rise up under launch and firmly plants the tires and the car just takes off.

Now that is a completely different set up than what we have, but like ralph said, JP's rear is loose, and the way the MOPAR guys have their set up, it could be considered loose also.