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Author Topic:   dry slick push after entry; I need help
widebody
Member
posted July 02, 2003 03:58 PM
This past weekend, our local track finally reached its normal, dry slick surface thats the norm for 80% of the season. Thats where the problem started.
CAR;
3000# no driver,
I dont have my exact scale numbers here at work, but the % are 49% rear, 53.5% left, wedge was 55%.. The LR was 130# heavier I remember that.
Springs;1300LF, 1200RF, 225LR, 200RR.
Shocks; 4 LF, 6-4 RF, 4 LR, 5 RR.
RR ahead 1/2", NO front swaybar
shock travel; LF 2" ext,1"comp RF 3.5" comp, LR 2.5" ext,1"comp and RR 3"comp
3 link rear.
28" rear mounted, left side of frame, rule mandates rear mounted bar!
panhard 4.5" below axle centerline level. LR20* up RR15* up, 3rd link 25* down, with a monty type spring bar/rod. spring are mounted on top of rear, shocks behind.
1/2 mile low banked track, egg shaped, regular 1-2, sweeping 3, tight 4.
1/2" rear stagger.
90x11" hard hoosiers,soft LF
The LR had more heat than the RR

Problem;
The car would make the inital turn in, but before the apex it would start pushing. I could throttle or use brakes to free it up early in the feature, but after a while nothing helped. I could not even ROLL through the corner at that point. I was as far up the track as possible, and even further a few times. The tire wasnt rolling off the rim, my camber curve is good. Rear tires showed little wear, RF and LF were worn badly. Again the LR had more heat than the RR. the car PUSHED is the diagnosis.

Heres my dilema, I dont want to take the lead out of the car, I would hate to loose the wedge and like the side bite generated from the low panhard bar.
Will simply adding stagger be enough? or sould I remove some wedge also?

sidenote"
The reverse front spring split has helped greatly this year,wish i went to it sooner. In another week or so Ill be dropping to an 1100RF, should I keep a large reverse spring split? or swap the 1200 in place of the 1300?

Thanks; widebody

c21
Member
posted July 02, 2003 05:17 PM
drop the right front down to a 1100

aslo what air pressure do u run it might be

possible to adjust with the air pressure

widebody
Member
posted July 03, 2003 12:06 PM
Im running 13# of air in the RF, depending on track contitions. I just watch it the first couple laps. I think Ill switch to the 1100 on the RF, and keep a spring rubber handy.

One other thing I should add to this equation is, I dont have a ton of HP so I need the car to rotate as I cant free it up with the go-pedal!!

QUESTIONS:
When I add the 1100 RF, Should I keep the 1300#LF or **t in the 1200# ??

What effect will a larger reverse split have on a car in general?? More rotation??

Why should I NOT add more stagger? please explain, I know it will loosen my exit, what else will it hurt?

Thanks, for the help guys!
Widebody


c21
Member
posted July 07, 2003 11:37 AM
First, 49.5% Rear is WAY too low. especially for a flat track. You need to get that up around 55 - 56%. Get the torch out and lighten the front of the car if you have to. Next why do you run the cross (wedge) so high? The more cross, the tighter the car is in the center.
By saying RR ahead 1/2", are you saying the rearend is twisted in the car? If so, doing that ALSO tightens up the car....1/2" of lead is a TON. Go back to square.....a square car is more forgiving, easier to drive and usually will be alot faster than a crooked one...

Those 3 things will make a night and day difference in how the car acts in the center.......a dump truck will turn in, but it wont make the apex.

widebody
Member
posted July 08, 2003 03:38 PM
Thanks for the replies, I was going to post ealier this AM. C21 You get the prize. I had some front end issues.
Ill explain. My bump stop was limiting my travel on the RF, once I hit 3.5" the bump stop was done, and that explained my real nasty push once in a while. I did not change my front springs(am glad I didnt), I have a creased oil pan with a split from the ruts and burm in turn 2..
for the feature;
We lessend the wedge, went up on the frame side of the panhard. I now have 3" height difference, frame(left side) higher than diff, diff is about 4" down from center line of axle. 1" of stagger.

The car was drivable this week but still tended to push, I did rotate better just not enough, but with the stagger I was able to throttle it loose at the apex when needed, but as such drove it loose out.. I still had slightly more heat in the LR, but not baked like before..

Ive also noticed a camber problem in the RF, I need to add more initial camber, curently @2.5*, somewhere along the lines Ive lost my camber, I usually run 3-3.5*, so this could expalin some of the problem.. The tire is wearing about 75% across from the outside inwards.My camber curve is about 1.25* per inch.. Ill be using a pyrometer this next week. So look for better data!!!

3x, this is a stock clip car, stock lowers, im heavy as it is, so 48-49% is the best I can do, without going real heavy. The top runner dont get over %50 and some light cars end up putting weight over the LF, Those are numbers closer to our sportsman car(they run over 5" of stagger to turn them). We run average laps of 75-80 mph.

my thinking is along the lines of c21, less wedge, less stagger(@ 1/2"), and fix the camber. And a new oil pan!!

Can some one explain panhard rake on a rear mounted long panhard bar... How much is to much?

Thanks; Widebody

stockcar5
Member
posted July 09, 2003 12:36 PM
i have a question related to reverse split front springs. in general do they work well on a high banked fast 1/2 mile type track? and does it work with a stockcar (metric) that must use stock control arms front and rear...we do have weight jacks.

luke

3xracing
Member
posted July 09, 2003 02:16 PM
darn double post

[This message has been edited by 3xracing (edited July 09, 2003).]

3xracing
Member
posted July 09, 2003 02:19 PM
I was assuming it was a stock clip car....the numbers I'm looking at are from my Pro-Am (street Stock) Camaro. Stock Clip and frame, just gut all the firewall, kick panels, A-pillars......I took a good 150 - 200 pounds out of my car from the year I built it to the second year. Got the floor boards and firewall down to a single sheet of metal, took all the kick panel metal out, stuff like that. From what you said, sounds like the cross is a good start. Still wondering about your rear end being cocked in the car....Also to lower cross and help the tightness at the same time, see what you can do about moving some of the weight over your LR to the RR. 130# of bite is alot, and moving some of it to the right will lower the cross at the same time.


c21
Member
posted July 09, 2003 04:18 PM
Thanks for your opinion c21.
Glad you found a different way to set-up a car than me.
Funny though, how I can get good left and rear numbers, yet still be able to adjust my car's handling by adjusting the LR bite & or cross.........

[This message has been edited by 3xracing (edited July 10, 2003).]

c21
Member
posted July 10, 2003 10:38 AM
If ANYONE has ever had 450# of LR bite, Id love to see the scale numbers that add up.
I don't come on this forum to claim to be a know it all, only to share what information I have about a class that I was very sucessful in. I also don't come on here blasting other peoples comments or opinions. To tell me that the way I set-up a car is overrated when it has won me many features and championships is crazy. I'm not sure what part of the country most of you are from, but I've been to all the seminars, have almost 2 decades of racing experience and worked with some of the biggest names in dirt racing. I'm not tooting my own horn, but maybe know who or what you're talking about before trying to discredit someone just trying to help someone else out....

Still waiting on the rest of the scale numbers when you had 450# of bite and even tire temps.

c21
Member
posted July 10, 2003 12:46 PM
What kind of car was that on? I could believe a rear engined dune buggy, but wow that a ton of rear and cross in a stock clipped car. Not saying I don't believe you or anything, but man alive. Did you have to run against the guard rail to turn it?
Remember what springs and stagger you were running? Just curious because I know my car and my driving style wouldn't have even gotten around the first turn with that. Again, not saying I don't believe you.


c21
Member
posted July 10, 2003 01:32 PM
Man. I had a 81 trans-am. Same car basically except for minor front-end differences. My car was kinda tight in, but I buried in about 3 cars further than anyone else so it loosened up when I wanted it to. I could mash the gas real early in the corner though which is where I won all my races.

880LF
680RF
975LR
900RR
3435# car (3400# rule)
54%L
54.58% R
48.1%Cross

1200# & 76 shock LF
1400# & 77 shock RF
225# rear leafs w/ 94 shocks
2" frnt and 1" rear stagger
VERY high banked 1/3 mile & high banked 1/2 mile. Same set-up, just changed gears.
Car was very drivable high or low, and very forgiving. I could never afford new tires so I bought "wore out" ones from other guys and took the track championship with them. So I may be off from other guys' numbers that get more grip with newer tires, but I learned this set-up from the guy who dominated the tracks around before I did and went from a middle of the pack guy to totally dominating. But, as we all know, more than one way to skin a cat.


c21
Member
posted July 10, 2003 02:10 PM
Not sure about the lateral acceleration, on yours but mine was fairly consistant heat to feature with being pretty neutral coming off under WOT. It would tighten up alittle if the track was really dry-slick. 9 nights out of 10 I wouldn't make any adjustments from heat to feature and could win them both. I had to run to totally different lines and drive the car in alittle deeper for the feature, but pretty much run it the same all night.


c21
Member
posted July 10, 2003 06:14 PM
The 2 tracks I run most often can change so much lap times can go up a second or more (and lateral G's dropping proportionatly).

Sounds like you have got the fast set-up, although your comment about the car tightening up on slick is more typical of a car with a lower (front) roll-couple.

It doesn't get any better than neutral coming out at WOT.

Im out of here (got to go, racing tomorrow)
c21


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