nzedjared

Going further --
Calculating what kind of coilover addition you'd need to the above Stock/Base S2 24mm torsion bar & 136 in/lb frt spring, the 0.6-0.7 target would indicate a 137 lb/in rear spring is required to get a 0.65 target ratio.

mikey_audiogeek

Not sure where you get this 0.65 target ratio from. 944's are well balanced cars and you can do a lot worse than setting them up for the same wheel rate all the way around. Just like factory.

I run 400lb/in front springs (=360lb/in wheel rate) and 850lbin rear springs (= 360lb/in wheel rate).

The 24mm torsion bars are equivalent to a 325lb/in coilover spring. With 400lb front/500lb rear springs, I would leave the torsion bars in.

Just my $0.02

Mike

TonyG

I run 450lbs front and 650lbs rear with Weltmeister sway bars with no torsion bars.

*Edit* My car is 2625lbs > if I was running a street car and wanted close to the same effective rate it would be a 500lbs/750lbs setup.

Works great on the track and not too bad on the street.

The one thing that people don't mention is that if you remove the torsion bars you really need to get rid of the rubber torsion tube to chassis mounts and the rubber spring plate mounts.



TonyG

ZW 944

You mean use the polybronze bushing and a solid torsion tube-chassis mount?

TonyG

I use delrin bushings for the spring plates and Racer's Edge solid aluminum busihngs for the lower and upper torsion tube mount points.


TonyG

nzedjared

Thanks Mikey & TonyG. The 0.6-0.7 target ratio was a question I asked prior based upon Broderick's info.

1:1 seems to make more sense to me as well given the current balance.

And you are right, first I heard of having to change out the plates & bushing when deleting the TB.

TonyG

The ratio quoted is because the effective wheel rate is different than the actual spring rate because the spring is located inboard from the axle, which means that there is a mechanical disadvantage in play. That's why it's not a 1:1 ratio.

And that's why 350lbs rear spring is around 197lbs at the wheel (from memory). I'll have to find the chart.

TonyG

Bri Bro

Look at post #16. Try a 1.1 setup and tell us how it works out. Last person I talked to with a 944 with a 1.1 ratio ( 500# front spring and 1200# rear springs, no TB) went home wrecked because the car was "hard to handle". I have driven in a S2 car with 1000# springs all around (no TB) and it was very fast in the hands of a pro driver. The spring rate you run is a personal preference determined by how you like the car to feel.

There are tons of posts on changing out the rubber when deleting the TB. This is a common practice when deleting the TB.

What is being referred to is the front to back wheel rate. If you want the rear wheel rate, look at post #21. It is 0.42 for the rear wheel rate. Where did 0.56 (197/350) wheel rate come from?

Skip Wolfe

Holy smokes this car would be a nightmare on the track. Brian is spot on in is write up - very nicely done. I run 550/700 on a track car that weights about 2350. Was going to go with 500/700 which would be similar to what TonyG is running but was convinced by Jason @ Paragon to go with 550's up front. Intend to experiment with some different spring rates this year.

As far as the original question - yes you will want to delete your torsion bars and no there is no synergistic effect. If this is a track car deleting the torsion bars is key in that it allows you to experiment with spring rates to suit your car/driving style, and eliminates a variable in your setup which is key. Also as Tony said, you need to upgrade your spring plate bushings with the Racers Edge delrin or Elephant Racing polybronze (what i would use if I had a stock torsion bar assembly)

Another thread where this was discussed in detail:
https://rennlist.com/forums/racing-a...8-chassis.html

mikey_audiogeek

Skip, you have a lot more track experience than me so I take your opinion seriously. Same with Brian.

It would be good to get your opinion of my car after driving it.
It helps that I run a "staggered" wheel/tire combo: Wheels are 8.5" front, 10" rear; tires are 235/40x18 front and 265/35x18 rear. Also I run slight negative rake on the car to get the front RC up relative to the rear, which increases the front roll stiffness relative to the rear.
Our nearest track is not super fast, about 160km/hr top speed for me and a bunch of tight turns. Hope to run a faster track soon.

Cheers,
Mike

TonyG

Skip

Your car is pretty light.

What I've found through testing is that my car is faster with the 450lbs/650lbs springs than it was with the 550lbs/750lbs springs with a 275/315 tire package and a rear wing with my car at 2625lbs wet w/o driver.

TonyG

gulf944T

Are rear shock mounts, particularly the tops, strong enough to take the full rear spring load if the torsion bars are eliminated? Given the low motion ratio of .42, you are talking about some very high rear spring rates if you are using a pure coil over set up. For example, in a racing set up where you may be using 750 pound springs, you are probably talking about 1200 pound springs in the rear to get a reasonable front to rear balance (keeping in mind that 1200 pounds springs equate to only about a 500 pound effective rate using the .42 motion ratio).