2.7RS SPRING RATES FOR TRACK USE
10-13-2004, 03:02 AM
#1
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2.7RS SPRING RATES FOR TRACK USE
My track car (2.7 RS Replica) is nearing completion and I am toiling about appropriate spring rates to use. The car weighs 878 kg (1930 lb) with 328 kg (721 lb) on the front wheels and 550 kg (1210 lb) on the rear wheels. The tracks that I will be running on are pretty smooth as far as tracks go. Currently the car has coil overs front and rear with the rear torsion bar intact. Car has a full cage and the rear shock mounts have been strenthened.
My questions are:
1) Do I retain the torsion bar in the rear and supplement with an additional coil over?
2) What spring rates, front and rear) would be appropriate for the the above setup? (that is coils in front and a combo of coil and t/bar (24mm) at the rear) or;
3) Do I go full coil overs all around?
4) What spring rates would be appropriate for the above setup running coil overs only?
I realise that fine tuning has to be done but I would like to have a ball-park figure to work with.
Thanks
My questions are:
1) Do I retain the torsion bar in the rear and supplement with an additional coil over?
2) What spring rates, front and rear) would be appropriate for the the above setup? (that is coils in front and a combo of coil and t/bar (24mm) at the rear) or;
3) Do I go full coil overs all around?
4) What spring rates would be appropriate for the above setup running coil overs only?
I realise that fine tuning has to be done but I would like to have a ball-park figure to work with.
Thanks
12-17-2004, 11:42 AM
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Flat Spot,
1) Don't mix two springs. Remove the t/bars and fit springs with helpers. I suggest 750 pounds/inch (rear).
2) Front rate 400 pounds/inch, better for braking and turn-in with light nose.
3) See above.
4) See above.
For more details call C9. Regards Thomas
NB. When can I se your car?
1) Don't mix two springs. Remove the t/bars and fit springs with helpers. I suggest 750 pounds/inch (rear).
2) Front rate 400 pounds/inch, better for braking and turn-in with light nose.
3) See above.
4) See above.
For more details call C9. Regards Thomas
NB. When can I se your car?
12-17-2004, 04:40 PM
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I am running a 1900 lb RSR replica with a full race 3.4l. I use 10& 12" slicks. We have pretty bumpy tracks here in ColoradoI satarted out with 275 & 450lb springs. Roll was not too bad but I was having a shock bottoming problem. Instead of raising the shock pickups mid season I tried 325 & 550 lb springs.
They were too stiff for our bumpy tracks. I went to 500 in the rear which seems pretty good. One of my customers is running a 2000lb cra with 23 & 31 mm torsion bars and 9"&11" wheels on DOT tires. With the light car and DOT tires roll is minimal. 31mm torsion bars are only about 350lbs.
If you have smooth tracks I would try 325 & 500lb springs. With narrow DOT tires and a light car that should be plenty. I have a set of RSR rear shocks valved for such a car that a customer changed his mind on. I can give you a good deal. email me. dave@dartauto.com.
The nice thing about coil overs is they are cheaper to change. I agree do just coilovers. Do get your shocks custom valved for your application. The RSR or 934 valving is not right for these cars.
They were too stiff for our bumpy tracks. I went to 500 in the rear which seems pretty good. One of my customers is running a 2000lb cra with 23 & 31 mm torsion bars and 9"&11" wheels on DOT tires. With the light car and DOT tires roll is minimal. 31mm torsion bars are only about 350lbs.
If you have smooth tracks I would try 325 & 500lb springs. With narrow DOT tires and a light car that should be plenty. I have a set of RSR rear shocks valved for such a car that a customer changed his mind on. I can give you a good deal. email me. dave@dartauto.com.
The nice thing about coil overs is they are cheaper to change. I agree do just coilovers. Do get your shocks custom valved for your application. The RSR or 934 valving is not right for these cars.
