IC location blown door car

As some of you have read & responded to my previous post concerning tire shake, I started thinking about four link locations & that this car was set up initially for a 1600-1700 hp blown bbc. We have since added a bunch more power & have been experiencing tire shake at the hit. The car is a 2550#, 104" wheelbase 63 vette, Blown KB/Olds/big chief, bruno/lenco, 3 spd. 2.08 1st,1.44 2nd, 3.90 rear, 33x16.5x15 M/T stiff sidewall.weight is 48 % front 52% rear. After reading some other posts about instant center locations, I dug up my old paperwork from the original setup.
The IC is currently setup at 46.24 out & 8.37 up. I am thinking that this is too short. I have the fourlink wizard printout for this car & am thinking about 54.610 out & 8.25 up. I am thinking that this will not hit the tire as hard & will plant the tires downtrack better. Can anyone help confirm what I am thinking?


Thanks, Jason.

 

Jason.....
give this guy a call....very, very smart on door car setups. maybe he can point you in the right direction. Jim Unger http://www.jimungerracing.com/home.asp
hope this helps
Darren

 

Jason I believe you are the right track to lenghten your iC , I would talk a little more with a known chassis builder specially if you know the manufacturer of your parts ( fourlink brackets ect).

The other thing I would recommend you is to look at your overall combination. If you had started at 1700 hp and now you are at 2000-2100 then Is my belief that you are too agresive. Keep in mind you have a torque converter that multiplys torque....

So maybe going to a 4.10 gear and a 34.5 tire will give you more footprint and more gear for more rpm at the end.

Also you can always lower your first gear ratio a little...

Hope this helps

 

Ok I just read completely your other thread , I have some questions


1. What RPM are your running at the top end?

I see you are Billys customer , we are also ..

I just sent you a PM

 

2.08 sounds like a ton of 1st gear for a converter car

 

x2 you're gonna need a whole lot more rear gear. bump those rears to 4.86 to 5.13 make that trans a 2 speed 1.44 first and let er eat (you are running 1/8th mile?)

 

Danny, We run a mix of 1/4 & 1/8. I know there is gonna have to be a compromise, but what ratio would work best for both?

 

Depends on rpm you want, if you're gonna run both you might be better off with the 3 speed, but definitely less 1st gear, i'd go to about a 4.30 gear(maybe 4.56 if that doesn't get you where you want) and a 1.28 in both gears. That will keep the rpm from dropping so much at the shift (keeping theboost up and the motor happy) and give you a 1.63 first gear and 7.0 overall first gear ratio. Right now your running a 2.08 x 3.90 = 8.11 first, pretty steep for a converter deal.
How tight do you plan on turning the motor?

 

I dont want to wring its neck on every pass, Oddy dyno'ed it to 7500 rpm & it made 2345. I would be happy to run in the 6.70- 6.80 range. so like 8000 rpm max. Keep in mind that I can only fit a 33x16.5x15 tire.

 

Shoch

What kind of shocks are you using?

 

they are older koni double adjustable shocks. I have been running with them set in the middle for adjustment & they have worked fine running our match races @ 7.50. I know that I need to start making some shock adjustments. or should I replace them alltogether & if so, which shock do I buy? Keeping in mind that this is a self sponsored team.

 

Shocks

First i would adjust the shocks to full rebound and bump then i would adjust the rebound to 4 to 6 sweeps out then go to the bump and adjust them 8 to 10 clicks out this should give you a baseline most base lines are established with 46 to 48 inches and 6 to 8 inches IC, Extra long short or low IC will react different and you may have to tighten them up more, use video to record run from left side of car to see reaction Hope this helps Mike