Relocating frt. susp. mtng. points, how much?

[SPEEDSTAR]

To improve the geometry of the front suspension, how far would the top and bottom control arm mounting points need to be moved, I am supposing both need to be moved down , but by how much? I have read here and on other sites that the bottom arm should be close to parrallel to the ground. Any suspension experts ideas welcome. Thanks Jeff

 

[sailbrd]

If I was you and wanted to go this far I would find a good stock car race shop. This is something you do not want to mess up. Talk to people who do this kind of stuff a lott.

 

[bruce]

To improve the geometry of the front suspension, how far would the top and bottom control arm mounting points need to be moved, I am supposing both need to be moved down , but by how much? I have read here and on other sites that the bottom arm should be close to parrallel to the ground. Any suspension experts ideas welcome. Thanks Jeff

Changing the front springs (if you use lowering ones), will lower the car, and effect how close to parallel to the arm gets. I have the LE1 3rd Gen Front Springs with one loop cut of, and the arm is just about right. The *problem* with the stock parts is getting enough caster, and chamber. For those reasons I went to the double adjustable front Upper A-Arms (Poleposition).

For more info.:
http://www.t6p.com/forums/showthread.php?t=6570

There's a number of suspsension brake related threads there.

 

[GNVAIR]

your best bet to answer that question is to go to www.montecarloss.com as their rolling chassis forum has a ton of guys who have done things to redesign the G body front end for handling.

 

[SPEEDSTAR]

I have the dbl. adj Lite Pole-Position uppers with the tall ball joint , 2" drop spindles and the Spohn chromemoly lowers/ heim-link ends, QA1 dbl. adj coil overs. I can cut,fab, weld the mnts. to lower the upper up to 3/4" , and the lowers parrallel to the ground in order to get a neg. camber gain. I will also use a bump-steer correction kit . Jeff

 

[SPEEDSTAR]

I am also going to turn a disc to fit on the coil-overs to be able to use stock car springs of the correct height and rate, I am going to make it stiff in the frt. and soft in the rear like a road-racer ,ie steer by rear and throttle , Oh yea I forgot to say earlier that I am building the car as an auto-crosser. Jeff

 

[SPEEDSTAR]

How much does the lower control arm mnt. need to be moved down to get it parrallel to the ground, Bruce, how much did just the spring cut lower your car to get the arm parrallel, 1 inch , 1 1/2 ? Would someone with a stock susp. t-regal measure from the bottom of the ball joint to the centerline of the mounting bolt . Thanks Jeff

 

[bruce]

Bruce, how much did just the spring cut lower your car to get the arm parrallel, 1 inch , 1 1/2 ?

I wouldn't venture a guess, the cars have so many miles, and varied lives, trying to make a statement about that would only be proven wrong.

I R+R the springs several times, cutting them in 1/4 turn increments till I got what I wanted. Yep, that was really time consuming, and alot of work, but I now have the lower arm par to the ground. In my case it turned out to be 1 turn, but that like I said can vary.

You might try reading Herb Adam's Chassis Book, and Dave Morgan's book Doorslammers. They both have a wealth of info about handling, brakes, etc., etc..

You basically want to run enough front spring rate to keep the front from diving too much under serious braking, and then rather soft rear springs, again enough to keep the suspension from moving too much. The *soft* spring, heavy bar tuning approach has been the way of the fast sedans/ cars for decades. From what I've gathered from reading, even the fast NASCAR teams are taking that approach, that is softer springs then what they traditonally ran.

While you've talked about the front, doing the QA-1 coil over rear conversion has really made the ride and handling better, in my car.

 

[SPEEDSTAR]

I think I am going to have to go slow , on how much to lower the bottom mtng. there are a couple of varibles , spring length, 2inch drop from the spindles, height adj. of the coil-overs. If I keep a full length spring ,the susp. will still have full travel if the fender and well clearance allow it, theres alot to think about. Bruce, I have a set of QA1 rear coil-overs , I made some stronger brackets to mount them, didn"t like the ones from summit, to flemsy looking, Jeff

 

[bruce]

I think I am going to have to go slow , on how much to lower the bottom mtng. there are a couple of varibles , spring length, 2inch drop from the spindles, height adj. of the coil-overs. If I keep a full length spring ,the susp. will still have full travel if the fender and well clearance allow it, theres alot to think about. Bruce, I have a set of QA1 rear coil-overs , I made some stronger brackets to mount them, didn"t like the ones from summit, to flemsy looking, Jeff

The last thing you want to do is run a set of dropped spindles, IMO.
I'd really suggest you try getting a hold of the books I mentioned, and/or Fred Puhn's How to make your car handle.

I also used a different upper mount, the lower seemed OK.

 

[SPEEDSTAR]

I think thatif I lower the lower mnt. 1 1/4 to 1 1/2", and choose the correct length spring, the coil-over height adj. will come into play to keep the arm in the best position, do you see any problems doing it this way? The SCCA cars use springs between 650 lbs. and 850 lbs., that will definitly require smooth road driving only! Jeff

 

[bruce]

I think thatif I lower the lower mnt. 1 1/4 to 1 1/2", and choose the correct length spring, the coil-over height adj. will come into play to keep the arm in the best position, do you see any problems doing it this way? The SCCA cars use springs between 650 lbs. and 850 lbs., that will definitly require smooth road driving only! Jeff

Have you looked under the car?.
1 1/4 - 1 1/2 is going to probably have them as being the lowest part of the car.

The LE1 springs as I recall were 750s, and I have a loop cut off of them. So while as a matter of habit, I try to be nice to all my cars about RR Tracks, and pot holes, the GN isn't that much firmer, if at all, then my 3/4t Pickup.

 

[SPEEDSTAR]

I am going to do a mock-up assembly of all the parts sat., and see what I can make it do better than stock, I sure wish someone made some wider fenders , not flares , for our cars. Jeff