Visit The Dirt Forum for More Information

Author Topic:   Dry Slick Track set ups
Hobbystocker
Member
posted June 12, 2003 01:27 PM
I'm curious as to some other opinions as to tire pressures on a dry slick track. I run IMCA Stock Cars and we run the G-60 American Racer "hockey puck" tires. We are having some trouble getting as much bite as some of the other cars. We are friends with a few of our competitors and our car is setup nearly identical to theirs,yet they seem to get a little more bite that we do. We've heard of running low pressure,SUPER low pressure and high pressures. If anyone else runs these type of tires,maybe I can get an "unbiased" opinion. We run a 3/8 mile clay track and it gets "BLACK SLICK" every week. I've followed other guys lines as far as entering/exiting the corners yet I'm still lightin' the tires up something fierce coming off and sliding the car going in. I use the gas pedal as if there were an egg underneath it, we've changed the gear to as tall as we can go without bogging the car down (5.14) Give me an option as to what you all run for pressures.

Thanks!
Hobby


backwoodsracer
Member
posted June 12, 2003 05:08 PM
How much cross are you running? Generally, when the track goes slick you want to lower your air pressure to put as much tire to the track as possible.

justin

younggunms
Member
posted June 16, 2003 08:39 PM
I'm a fellow IMCA stocker and also have a problem with those McCrearys. These tires are really soft and loose a lot of rubber in each race. When you run lower pressures, I think that the tires seem to lose more rubber. I run 11#rr and 13#lr. Also try dropping your spring rate. I run 175#rr and 180#lr on a 3/8 mile and seems not to slip much in the exits. It's smooth as butter going in and only gives a little towards the end.


Hobbystocker
Member
posted June 17, 2003 03:45 PM
We usually try and have around 52%-54% cross,51%-53% left and 52%-55% rear. We run a 200# on the left rear and a 175# on the right rear. 1100# right front,900# left front. Our pressures are close to what you guys are telling me. We gain a bunch in the right rear after 15 laps...like 8psi last week. Right rear tire was so hot you couldn't touch it. Left was warm but nothing close to the right. We added weight on the right rear of the car for the feature,but don't we want it on the left side? Left rear tire is what drives you off the corner right? As you can tell...I am totally lost on dry slick...we win our heat races pretty often only to slide around for 15 laps in the Main. I've concentrated very hard on not "mashing" the gas coming off the corners and I think I'm alright there. Alot of trouble starts getting into the corners. As I roll off the gas the car just begins to slide all over the track. This is before even touching the brakes. I've tried to adjust by not driving in as deep but it doesn't matter...I'm all over the place.
I keep reminding myself that this is FUN but it's getting harder to keep my head in the car when this happens every week. LOL

Give me some more opinions....I'm open to anything. Critisism works as well...just don't slam me too hard huh fellas?

Thanks!
Hobby
We ran a taller gear this past week as well ....5.29 . We had a 5.43 in it..helped some but not enough. What about a 5.14? With the 5.29 I still was able to turn 6100rpm.

[This message has been edited by Hobbystocker (edited June 17, 2003).]

Eljojo
Member
posted June 17, 2003 08:48 PM
OK It sounds to me like you're having so much trouble getting in the corner that you haven't any idea how the car really is on exit. So let's go first things first and try and get you IN the turn and then maybe you can get OUT on your own.
First. Set the car up on jackstands and pull off the tires, shocks, and springs. Move the suspension thru its travel. Is it binding anywhere? Are there any "tight spots" in the suspension-front or rear? How do the shocks look? Have you ever had them tested? Could you replace them, even with "loaners?"
Before you re-install the shocks, fully extend them and write down the total length.
OK, replace the springs, now put jackstands under the a frames and rear axels. Set your ride heights. I like an inch of "tilt" and an inch of rake. Start with the lower A arms at +/- level. Replace the shocks and measure how much travel is left in them. If you don't have at LEAST 4 inches of extension left on the left side, stop now and build an extension for it. Your right side should have at least 4 inches of compression left. You may have to build extensions for these too.
I would suggest squaring the rear end now. Just take a framing square off the floor up against the back of the rear end and put yourself a mark on the floor. Do this at both ends of the rear. With a chalk line "pop" a line on the floor thru these marks and on out from the side of the car.
Take that framing square and slide it up against the framerail (the straight part) as far forward and as far rearward as you can go and put marks on the floor. Do your thing with the chalk line again. You should now have a big + on the floor. One line parallel with the rear axel and one parallel with the frame. From the intersection of the + measure (accutately) and put a mark on the chalk mark forward at 6 foot. Measure once again from the + out and put a mark at 8 feet. Measure from the mark on the "side to side" line to the mark on the "front to back" line and you'd better have 10 feet(diagonally)! If not, You'll have to do some work on the trailing arms or their mounts. Don't "lead" the right side...on a track that gets really slick you will want to be VERY square.
Set the car down and check your front caster and camber numbers. Set the toe out from 1/8th to 1/4 inch. Set your air pressures and fill the cell. Climb in!
Once on the scales you'll want to work all four corners and bring the car in with LEFT side weight and REAR weight. Unless I have a heavy weight rule, I NEVER put weight in front of rear end or on the right side. Get REAR static at better than 52% and live with the left percentages. (I think 54% rear weight is the outside limit...more than that and you're asking for a push.)
Most cars I've worked with go loose with less than 48.5 cross. Most will offer to push over 51%. So with the desired tire pressures set the car (using ***** jacks, shims, or spring heights) to 49% crossweight. Now add two pounds to the tires, one at a time and record the crossweight changes each makes. You'll KNOW what is happening with your chassis when you change air. i.e. The car is a little tight...hey two pounds out of the left rear takes a "X" percent out of it...the car is a tick loose add two to the left rear That will bring the cross up to "XX%." Follow me?
Allow yourself plenty of time to set the chassis up properly. Don't rush around on race day hoping to get close enough in an hour or so. The guys who are consistantly fast KNOW what is happening with the chassis. If you are a rookie and haven't got a good baseline to work from, you'll get discouraged and will probably quit before you ever luck up into a good set up.
I see a lots of posts where guys are talking about their set up and call out a spring rate. That's to me like saying "I've got domed pistons.this motor will be a rocket" There is waaaaaaaaaaay more to it than that!
Good luck and if I can help...just ask!
Congratulations to anyone who has read this far. I'll bet your eyes are as tired as my fingers! LOL


4d_POWER
Member
posted June 17, 2003 09:06 PM
Eljojo,

That has to be the most in depth, interesting, and easy to understand
answer to a post I've ever seen.

Well done and Thanks!!



towmandan
Member
posted June 17, 2003 10:48 PM
All though there is lots of contraversy about the gear ratio deal a good driver and the right chassis set up will tell you going with a lower final gear (numerically) is not the fastest way to go ,killing horsepower on a dryslick track is a crutch for a poor handling chassis its very hard to explain with a keyboard but ask around and see what your told....Towman


tim gaeber
Member
posted July 14, 2003 11:53 AM
We tighten the car up on dry slick


340duster
Member
posted July 17, 2003 01:45 PM
We have been experimenting with easy up shocks on the front.(especially the RF) This seems to tighten the car up a little and allowed me to get on the gas much sooner(and picked-up lap times). We left them in for the wet track and it made a push at mid turn. This weekend we will try "regular" shocks on the front for the wet track and put the easy ups on for the dry slick at the end of the day. We also run about 49% cross weight which made the car turn in nice.

One difficulty with the American racer g60's is trying to get more than 2" of stagger out of them. You end up having to work around that.

Racer0
Member
posted July 17, 2003 10:42 PM
First off, Eljojo has the right plan. That was very easy to read and understand. Great Job.
Second, if your left rear tire is cool, you need more weight to transfer there. Weather this be a bind in the suspension or what not. Your cross numbers are a little high so adding weight over the left tire can't hurt.
Finally, as for the gear if you are going slower, then a lower gear (higher number) is what you need. Yes it is easier to spin the tires but it will keep the motor up in the power band. I think that is what towmandan is wanting to say.


Back to the Archives