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Author Topic:   Weight transfer and rear coil spring location
Dirt Roller

Total posts: 7
posted July 02, 2002 01:37 AM
I am beginning to think that the rear springs on my new mod aren't mounted far enough out on the housing. It has a 60 inch floater with the coils on top of the housing. The coils are at 34 1/4 inches from center to center.

The car transfers weight quickly. I think that with the springs so far inboard that it may be causing the left rear to be loaded with 95lbs at 48% cross (note that this car also has high % on the left side - 55% due to engine and fuel cell location).

My old mod has a 58 inch housing and the coil centers are 40 1/2 inches apart. Both cars are 2-link with a pull bar on Hoosiers (UMP). Old car has j-bar, new has long pan-hard bar fixed to the rear end on the right.

As you might guess, the new car has to be driven through the turns. I have to coast in and allow the car to roll before feathering the throttle. The car is difficult to drive quickly in traffic.

We have tried many things this side of heavier springs. Shock travel looks good and isn't bottoming out. My buddy has basically the same car (same chassis builder) and they are experiencing the same thing. You drive into the turn, the car plants/stops and then you drive through the rest of the turn. The car pushes in the middle of the turn when the track is very wet or dry-slick.

My buddy is going to try heavier springs. His motor is located closer to the center of the car and lower than mine. I am thinking about moving the rear springs closer to the tires. After measuring, I think that I can safely mount the springs at 42 1/2 inch centers (after also moving the weight jacks).

Am I going in the right direction? Are the coils on most cars mounted as close to the wheel as possible?

Thanks for your ideas!

Dirt Full Roller

Total posts: 40
posted July 02, 2002 10:19 PM
I have had the same problem with the long panhard bar. It loads the right rear hard going into the corner and makes it hard to turn. I think the J-bar will help loosen up your car in the middle of the corner.

Dirt Roller

Total posts: 7
posted July 03, 2002 03:38 PM
Thanks tls88mod.

My friend runs the j-bar w/ bisquits. He thinks that it has helped the car alot. Unfortunately it hasn't cured the car planting in the turns.

I went down to look at and talk to the builders of the Smiley's chassis. They typically run the coil-over eliminators and said that the springs should be mounted as close to the tire as possible.

I am leaning toward first giving the spring relocation and long panhard bar setup a chance. If that still doesnt do it then I will try adding the j-bar.

I wonder if the original setup works better with the IMCA tire (less bite)?

Dirt Roller

Total posts: 21
posted July 10, 2002 10:46 PM
Your springs and shocks do need to be as close to the tires as possible. This is where they have the greatest effect as far as planting the tires for traction and handling. The long rear panhard bar does load the right rear getting in the turn. Going to a shorter j-bar isn't going to help your problem of being to tight in the middle of the turn. Actually, it could make it a little worse. Because the shorter the bar, the faster it will work. If you don't want to change the shock and spring location, try raising the panhard bar about 1" on the frame side. This will keep the car from rolling over so much, thus, it will loosen the car on entry and in the middle. I ran my Smileys car with the panhard bar level. What chassis do you run? You need to calculate your roll center and see where it is. If your roll center occurs outside the spring an shock location, then raising the panhard bar will make your problem worse. If your roll center is outside the shock and spring location, then lower your bar, this will loosen the car up getting in and in the middle of the turns. Hope this helps. Let me know if I can help you anymore. Where do you race? I am from north texas area, too.

Greg Moran

Dirt Roller

Total posts: 7
posted July 15, 2002 02:07 AM
Hey Greg,

Thanks for the feedback. From your handle it looks as if we both may run the same number on our cars (#7).

This winter I was in the market for a new chassis to replace my elderly D&M. After some shopping, I was able to pickup a Millenium Modified for a much lower than retail price when the original customer that the car was built for had backed out the purchase.

I have a four hole panhard bar bracket on the rear end and like you mentioned run it level - in the top hole which is similiar in height with the top of the axles (with driver and 32 gallons of fuel).

Since the time of my original post I have had to remove the housing from the car to be straightened. So while the rearend was bare it seemed like a good time to do the required welding. After much labor, the springs are now closer to the wheels.

Being from this area you are aware that there are only about 4 tracks around Dallas that run hoosiers. I started out at the Devils Bowl and stuggled for a few seasons learning modifieds. We had a lot of fun racing there but were completely under powered in comparison to the competition. After 4 motors half way through last season (claimer and stock stuff doesn't live there for very long), we pieced together what we had left and gave 85 Speedway a try. Our high point was winning a B-main in the old car.

This year we have run mainly at 85, but occasionally venture out to Outlaw or Cowtown. I am hoping the spring relocation will help move us closer to having a successful season

Glad to have your input!

Darby Shelby

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