Input for Torsion bar mm /Coil rates for 2240Lb Track car

[slow car]

Hi im installing 2 way MCS shocks and are wanting a start point for Torsion bar sizes and Coil rates . Car is used for Track sprints and Hill Climbs. 300 Rwhp
The Car is 2240 lb with driver and fuel running r speck tires.
Im undecided if i should go to Coilovers or stay with Bars.
Please let me know your thoughts ?

[Bill Verburg]

Originally Posted by slow car

Hi im installing 2 way MCS shocks and are wanting a start point for Torsion bar sizes and Coil rates . Car is used for Track sprints and Hill Climbs. 300 Rwhp
The Car is 2240 lb with driver and fuel running r speck tires.
Im undecided if i should go to Coilovers or stay with Bars.
Please let me know your thoughts ?

main reasons to go w/ coil overs is if the available t-bars are too small or you want to vary ride heights more easily

Did you get the MCS billet struts?

[slow car]

Hi Bill,
Thanks for replying i respect your feed back.

I am currently on Torsion Bars
23mmF and 33mm Rear with adjustable ride height rear Spring plates. I cant really see the need to go to coil overs and raise the center of gravity and body stress.

As the new MCS have compression and rebound im wanting to find a spring rate that i can tune the car better with.
Any ideas?

[Bill Verburg]

Originally Posted by slow car

Hi Bill,
Thanks for replying i respect your feed back.

I am currently on Torsion Bars
23mmF and 33mm Rear with adjustable ride height rear Spring plates. I cant really see the need to go to coil overs and raise the center of gravity and body stress.

As the new MCS have compression and rebound im wanting to find a spring rate that i can tune the car better with.
Any ideas?

Nice, I've been eying then myself

how much did you raise the spindles?

currently at that weight and w/ those t-bars you are pretty well sprung, adj sways at one end or the both could tune what ever you want from there

[Jonny042]

Originally Posted by slow car

Hi Bill,
Thanks for replying i respect your feed back.

I am currently on Torsion Bars
23mmF and 33mm Rear with adjustable ride height rear Spring plates. I cant really see the need to go to coil overs and raise the center of gravity and body stress.

As the new MCS have compression and rebound im wanting to find a spring rate that i can tune the car better with.
Any ideas?

Not sure those are going to fit inside those Cookie Cutters on the front!

I can't see needing more torsion bar than you already have, either.

[Evan Fullerton]

Braking is where I have found 24mm front torsions to be too soft with lots of brake dive…… and the need for a 28mm+ front swaybar. Some people have experimented with shortening the torsion bars in restrictive classes to make them stiffer but you end up with very little droop travel that way.

I did the math one time for a 24mm front torsions taking into account the flex in the control arm itself and the actual wheel rate is under 280lb/in.

Your results may vary.

[slow car]

Thanks for the input.
Bill ,The spindle is 124mm from center of strut retainer bolt.

[slow car]

The new MCS shocks have less shaft travel than the adjustable koni shocks ,what is the minimum DROOP for a track car?
J

[Bill Verburg]

Originally Posted by slow car

Thanks for the input.
Bill ,The spindle is 124mm from center of strut retainer bolt.

you wouldn't happen to know how that compares to a stock Bilstein b6 front would you?

[slow car]

Hi i believe it is 105mm ie 19 mm difference.

[Cory M]

If you are happy with the bars you have start with them. If you are lifting front wheels a lot or waiting for your car to settle down to apply throttle or steering inputs, go stiffer. It's also very tire dependent, tires with stiffer sidewalls can get away with a softer spring sometimes. We've installed a couple of sets of the MCS rally/safari 1 way shocks and they are great.

[slow car]

Originally Posted by Cory M

If you are happy with the bars you have start with them. If you are lifting front wheels a lot or waiting for your car to settle down to apply throttle or steering inputs, go stiffer. It's also very tire dependent, tires with stiffer sidewalls can get away with a softer spring sometimes. We've installed a couple of sets of the MCS rally/safari 1 way shocks and they are great.

looking forward to testing the MCS units in the new year

[r lane]

Originally Posted by slow car

Hi Bill,
Thanks for replying i respect your feed back.

I am currently on Torsion Bars
23mmF and 33mm Rear with adjustable ride height rear Spring plates. I cant really see the need to go to coil overs and raise the center of gravity and body stress.

As the new MCS have compression and rebound im wanting to find a spring rate that i can tune the car better with.
Any ideas?

How does the roll couple, or CG differ from torsion bars to coil overs. What is the physics. With torsion bars, your load and hinge point is primarly at the end of the torsion tube. With coil overs, the load is at the top of the shock. I have never considered the difference in leverage. Bob

[Bill Verburg]

Originally Posted by r lane

How does the roll couple, or CG differ from torsion bars to coil overs. What is the physics. With torsion bars, your load and hinge point is primarly at the end of the torsion tube. With coil overs, the load is at the top of the shock. I have never considered the difference in leverage. Bob

I wouldn't think that there would be much difference

a stock 911 has a f/r roll steer of 14% & 2% as measured on a MTS K&C machine

this works out to .7deg steer per deg of roll front and .001deg steer per deg of roll rear

altering the car of course changes that

the more steer in back the less understeer on a 993 you can adjust these easily by changing the rear caster by adjusting the KT arm length

on a 911 you change the T-bars, the roll bars, the wheels, the tires, the alignment settings etc.


cg(CoM) is adjusted by changing ride height, the front front roll couple is determined by the King pin angle and the A arm angle, KPI is tough to alter so the main tool here is A-arm angle change through ride height and spindle heiight change.