Launch Tuning

[dirt91]

Hi All, To cut to the chase my car seems to launch hard and go straight during the day (wheels up 6.80's) on a clean track. later on after the cool down and track rubbers up it pulls hard left on launch. Is there any way to get a happy medium on this? I needed ladder bar preload on RR to make it work early but now after dark it almost seems like it's too much. Ladder bars are non adjustable so I have to remedy this with shocks or pressures. Shocks are now at 90/10 and 50/50. Thanks for any suggestions!

[TheYellaBrick]

Lower pressure on right side to essentially make the tire diameter smaller, putting little 'wedge' in it to pull it to the right.

[dirt91]

right is border line too low at 9, had 9.5-10 in LR to try to correct but no effect. I'm afraid if I add to LR it will lose traction and make it worse. they are 29 12 15 D05 Hoosiers
Thanks!

[itsabird]

Have you checked, the roll out on your slicks?

[wmeabates]

If your shocks are adj. you can try more rebound at the left front maybe 70/30.Or if you have travel limiters take some out of the left front.Either will slow the transfer to the right rear.Bill.

[dirt91]

Thanks for the input guys, I'll check the roll out in the back again but it was pretty close before. Bill, if I install some screws in my upper A arm that will bottom out on rise how much should I limit it vs how it was to see some difference? couple of threads, 1/4" 1/2" ect. I think making that mod now will be better for the future adjustability anyway. Simple enough to try the shock adjust too. :)

[wmeabates]

Jack the front up with both wheels hanging.Measure from the fenders down to the tops of the tires,set your stop so the left side is 1 inch less at the tire.Try that.If you you have single adj.shocks you will be taking out compresion when adding rebound,try the the brakes before jumping on them at the strip.The left front might dive.Good luck gitting it strait.Bill.

[wrightway]

right is border line too low at 9, had 9.5-10 in LR to try to correct but no effect. I'm afraid if I add to LR it will lose traction and make it worse. they are 29 12 15 D05 Hoosiers
Thanks!
Ok correct me if in wrong but hoosier has not made the D05 in that size in 4 or 5 years so maybe the slicks are done

[wrightway]

Double posted dam phone

[zipper06]

I'm having a little problem understanding this problem, correct me if i'm wrong, but if the car hooks good and goes straight on the launch, why would you care if the left front tire is carried a little higher and long if the car is performing consistently. My car has always pulled the left front tire higher than the right side (4 link setup). We scaled it a couple yrs ago and did all the correct adjustments, the car runs straight as a bullit but still lifts the left front tire about 4" while the right is barely touching the track. It used to do 4 ft wheelies before scaling the car.

JMO

Zip.

[wmeabates]

Zip,it sounds like the car is going left when the track is good,by limiting or slowing the travel of the left front it will let the right front load the left better.Once the wheels are up that part is over.Still might be in the tires though.Bill.

[dirt91]

right about the age of the slicks but they were stored properly and have very few runs on them but it still could be. The problem is not carrying the LF the real issue is that on a clean hot slick track it goes straight.... later on when the track cools off and rubbers up it pulls hard to the left, too much to make it consistent. I have to steer it hard and lose about .08 to hold it off of the center line or wall. it seems to yank left and right up about equal amounts, except the better the track gets it jumps to left on launch.
Thanks for all the input!

[TheYellaBrick]

Are all of your rear suspension pivot points solid with zero play ? A slick track gives you more wheel spin so any looseness wouldn't be as prominent as a hooked up launch.

[itsabird]

Do you have adjustible springs in the rear, if so check right rear spring height, you may need to load the left rear spring a little more.

[dirt91]

all suspension points seem tight, I have found that I had about 5/8 more travel in the LF before it comes off the ground than the RF ( I have evened that out with a travel adjuster). I will either have to shim or spring rubber the LR spring, they are stock type coils.

[itsabird]

You might think about a set of air bags, they may help.

[wmeabates]

Do you think you might have put a little more preload in the r/r than you needed?Maybe you can take some of it out and still ok early in the day. Bill.

[mopar1968]

According to Jegs the smallest set of hoosiers-Do5 is 30x9x15, So i agree better check your slicks :!: :!:


Mark

[dirt91]

Bill, that is exactly what i'm thinking lol, but to change it will require cutting and re welding the frame mount bracket.... which I already have made the replacement pieces to do that but since it worked so good early I was hoping to tune around it. :) Mark, I'm in on new slicks. These just work really well early so I'm trying to get as much out of them as I can since they are like new.

[wmeabates]

Ok Dirt now I got you.When you said non adj.I thought you just did not have the link to adj.them on the car without disconecting them.I had a ladder bar car with stock coils&shocks that worked good with 1/2 inch right side preload,it that tells you anything.Bill.

[wmeabates]

Something else,You're not using a worn out posi or an open rearend right? Bill.

[dirt91]

no, it's a lincoln lock :lol:

[TheYellaBrick]

no, it's a Lincoln lock :lol:

We use those a lot in the Bomber class in Circle track. Some guys don't get all the slag out and end up 'locking' EVERYthing them up when you are right behind 'em !

I'd think it'd be a questionable method in high HP drag racing though.

[dirt91]

The results.... put in travel stop to even back out LF RF, Raised air to 10 on both rear, lowered launch from 4000 to 3000, bumped up shift rpm (I had this a little conservative since it was a new motor) No pull to left all night and actually ran a little quicker. No big wheel stands but ran within about a .05 window most of the night. I think it actually got off the line a tad quicker since I got the red a couple of times. I'll go with it for now. Thanks!

[fast75vega]

no, it's a Lincoln lock :lol:

We use those a lot in the Bomber class in Circle track. Some guys don't get all the slag out and end up 'locking' EVERYthing them up when you are right behind 'em !

I'd think it'd be a questionable method in high HP drag racing though.

your not kidding either :(

[dirt91]

totally agree, I'm planning on a 9 with adjustable ladders vs the welded ones in the off season. This was in it when I got it. After doing a motor and a new tci glide I wanted to get some racing in if possible this season since the cash was gone and re do rear later. :wink: