front suspension question

Lucas van Altena · 08-19-06, 07:50 AM

My GTD has a very stif front.
If you push down hard the left or right front it wont move.
Frontsprings 400 lbs, yellow Spaxs.
The front wheels of the road you cannot move the swaybar.
Slow cornering queezing front tires.
My question what is the position of the swaybar.
The car with on the front wheels the ground or up, if you losen the swaybar how many mm must be between the heimjoint of the swaybar and the pichup point on lower whishbone?
What is the course of the queezing of the front tires?

regards, Lucas

Malcolm · 08-19-06, 08:31 AM

Hi Lucas

Sway bar question first. I would suggest you aim to get the lever arms for the sway bar horizontal when the car has its wheels on the ground. Make sure that the lenght of the drop links are the same both sides so there is no pre load on the sway bar. From what you say, you do not have a standard setup so there is no fixed distance, it is what is correct for your car alone.

Queezing - I think you meaning tyre squeal as you turn a slow speed corner. There will be number of factors here. You would need to say what uprights you are running, which tyres and pressures and what suspension set up. All could have an impact to make a tyre squeal more than other cars. Perhaps if you posted some pictures it would help find you the answers you wish for?

To say if 400lbs spring is too hard, you need to say what you have at the rear plus what you use the car for. I used to run 450 lbs on the front for competition work. Now it is very different/softer for road use.

Hope this helps.

Lucas van Altena · 08-19-06, 02:06 PM

Malcolm,
Thanks for replying.
Tires frontYokohama A539,15 x 215 1,5 bar.
1,5 mm toe-in.
front -0,7° camber, -0,7 ° castor.

Tires rear Yokohama 15 x 352, 265 1,8 bar.
Yellow Spax 450 lbs in teh rear.
0 toe-in.
rear -1,4° camber.

I use the GTD on the road and for trackdays.
Traying to put in pic the reply.
regards,
Lucas

Lucas van Altena · 08-20-06, 04:53 AM

I think we have a picture

Kalun D · 08-21-06, 10:05 PM

""My question what is the position of the swaybar.
The car with on the front wheels the ground or up, if you losen the swaybar how many mm must be between the heimjoint of the swaybar and the pichup point on lower whishbone?""

Swaybars transmit turn lean force from one side of the car to the other but only when the car leans. When the car leans it compresses the outboard suspension and extends the inboard. The swaybar tries to keep the car level by resisting differences in outboard to inboard suspension travel. A level car keeps more rubber on the road thus better handling.

Only when the car leans... so at resting ride height swaybars should not be loaded. In other words 0 mm between the swaybar heim and the wishbone pickup at rest.

""Slow cornering queezing front tires.
What is the course of the queezing of the front tires?""

""Tires frontYokohama A539,15 x 215 1,5 bar.
1,5 mm toe-in.
front -0,7° camber, -0,7 ° castor.""

""Tires rear Yokohama 15 x 352, 265 1,8 bar.
Yellow Spax 450 lbs in teh rear.
0 toe-in.
rear -1,4° camber.""

My guess is from the large differences in tire sizes front to rear is that the fronts are scrubbing or pushing at low speeds only. Especially if you have a locker diff. With that large of a difference in sizes there are compromises that have to be made. The larger size rear tires will get more power to the ground with the typical overpowered GT40, but you may sacrifice some low speed handling.

These spring weights are leaning toward track use.

Howard Jones · 08-21-06, 11:03 PM

From your picture I can tell you that that is not a "standard" GTD front sway bar. It looks like it might be 3/4" diameter or larger. The "standard" GTD bar is 5/8". Now that is not to say that anything is wrong. In fact the front of the GTD could use a little more front bar effectiveness when run with the standard 200 lb springs and crappy shocks. Sorry yes those Spax's are the ones in the picture I refer to.

It looks to me like you have quite a bit of ride height set in or the springs you are using are shorter that what came with the Spax's.

The main thing about the roll bar is it should not have any effect on spring rate unless the car is loaded side to side as in turning. It should be free, within reason considering that the rubber must compress just a little to locate the bar, to move up and down in its rubber mounts if the links are not connected. Check to see if the original 5/8 diameter rubber bushes were retained for use with the new thicker bar. The inside diameter of the rubber bush should not smaller that the diameter of the bar.

The comment above about pre load is correct. Attach one side (links) and then adjust the length of the other link so that it can be attached without deflecting the bar at all. This is done on level ground with the car sitting fully on it tires.

The actual orientation of the bar doesnt make any difference other than any possible interference with other suspension components throughout the suspension movement up and down. There should be none. I should tell you that the "standard" GTD sway bar links are designed to limmit turning radius. Contact with the steering links at full lock is normal.

As far as the tire squealing goes, mine does also. I have very little caster in the car and I think this is part of the the problem. Replacement adjustable front A arms are in the works for my car this winter.

Lucas van Altena · 08-22-06, 01:13 PM

Kalun and Howard thanks for the reply.

As i understand the yellow shocks can better be replaced.
I did hear that also from a super seven dealer.
First i will check the swaybars rubbers.
Btw the swaybar = 20mm.
Howard look the picture and see how i put the under u-ball of the vertical rod of the swaybar in attacht with an u-shaped peache of metal inwards on under wishbone.
I have full turns of the stearingrack now.

Front groundclearance 4 inche's
Rear groundclearance 5 inche's
I still hit speedbumbs.

Another question how many friction ( stickslip) may the suspension have with removed springelements and swaybar?
You can hardly moved up and down the axles by hand.
Regards
Lucas

Kalun D · 08-22-06, 08:42 PM

Quote:

Originally Posted by altena

Front groundclearance 4 inche's
Rear groundclearance 5 inche's
I still hit speedbumbs.

that is high for racing. Racing would be 3" front , 4" rear.
You shouldn't be hitting speed bumps at that height, your going too fast or something is hanging down lower.

Quote:

Another question how many friction ( stickslip) may the suspension have with removed springelements and swaybar?
You can hardly moved up and down the axles by hand.
Regards
Lucas

should be very little friction. With the car in the air on jacks with the shocks/springs off the suspension should fully drop from it's own weight after being raised.