944 S2 coilovers

[kierantrees95]

Had my S2 for a few years, and now I am looking at a set of coilovers for it. I have read the SPAX catologue and it states that the rear coilovers are in aid of the torsoin bar. where can I then go to set it all up and make sure the car drives well.
any advice is appreciated

 

[Cater_Racer]

We re-indexed them but let them in when we put KW's on. It means the torsion bars are not doing much until the kw's are quite heavily depressed (suicidal) . Gerry

 

[kierantrees95]

Can you reindex them yourself or is it a job that should really go to a workshop to be done?

 

[blade7]

We re-indexed them but let them in when we put KW's on. It means the torsion bars are not doing much until the kw's are quite heavily depressed (suicidal) . Gerry

I left the bars in when I fitted KW's, didn't have to re-index and just took the weight of the car on the coil overs. Don't know what you mean by 'suicidal'?

 

[kierantrees95]

I have just received this from SPAX, and if you look at the top corner it states that I should use the eccentric bolts on the torsion bar to lower the car as much as possible when fitting the coilovers

 

[Waylander]

its mainly to bring the rear down a bit, max about 12mm, because the front struts and springs are 20mm lower than standard

if you dont bring it down a bit it will look like a red bull F1 with its ass in the air

 

[kierantrees95]

The manufacturer states that putting the coilover on will reduce ride height between 35-65mm on the front and rear ?

 

[blade7]

Run.

 

[robwright]

I ended up taking the springs off my rears as I know many others have. With running the torsion bar also it practically shattered my spine. Runs just great lowered on the trailing arm with just the rear dampers and no springs.

 

[Cater_Racer]

Heavily depressed, suicidal...gedit? ??

 

[Waylander]

there is no way that just by removing the rear dampers and fitting coil over dampers will you lower the car 65mm which is far too much anyway

lower the front by 65mm and the wishbones will go past horizontal this will put massive stress on the ball joints

 

[924Srr27l]

There's a few things here to note:

1. The Torsion bars are a spring and they act like a Coil spring and also set the static ride height
2. If a rear damper and spring is being used the two spring rates need adding together (EG 160Lb Coil + 130Lbs T-Bar =280lbs)
This is the total spring rate, but the actual wheel spring rate due to the (.55 Motion ratio) is in this example 154lbs
Hence why RobWright only fitted the Damper and left the coils out, making the rear rate and ride Quality far better.

When the desired front spring platform and ride height has been set, the rear torsion bars will need to be pulled out and
put back in to produce a lower ride height, they are located by a spline in the centre of the torsion beam and another spline in the spring plate which is bolted to the trailing arm,

So wherever they sit their spring rates and it's resistance will always act and be additional should you also be using Coil springs wrapped around the damper (So Gerry your rear spring rate will be your S2 T-Bars + the Coils , from the get go... there's no way of delaying them to come in as they are a permanently fixed spring.

(As Waylander suggests, setting the front ride height too low and the wishbones will not only put more stress on the vulnerable ball joints but also the car will roll more as the Roll centre has been changed adversely)

Re-indexing and setting the rear ride height is not an easy task, especially with bolts etc..being 30+ years old!

I'd recommend taking them out, rather than re-indexing them which will then enable you to adjust the ride height far easier with the coil over dampers, and should you want to go stiffer the rear coils are again far easier to change.

R

 

[Eldavo]

My two penneth:

1: Don’t remove the torsion bars completely unless you have done a very thorough overhaul of the mounting areas for the coilovers. These cars weren’t designed to run on coilovers alone at the rear so strengthening of that area would be a must.

2: The eccentric bits and bolts will be far far far tighter than you imagine if they’ve not been tinkered with recently.

You'll need a ramp, a good breaker bar and probably a length of scaffolding pipe over it to get the leverage to crack them free. I’d expect a 30mm drop on available on the rears this way, combine that with a similar drop on the front and you’ll be happy.

 

[924Srr27l]

My two penneth:

1: Don’t remove the torsion bars completely unless you have done a very thorough overhaul of the mounting areas for the coilovers. These cars weren’t designed to run on coilovers alone at the rear so strengthening of that area would be a must.
Strengthening with a stronger lower Bolt yes, like (Ground control USA do one) but the top area is fine for road and race use. Gerry and I have both raced without any changes to the top bracket as do hundreds of Racers including the 944Turbo Cup racers in the 80's

 

[edh]

My understanding is that when running a spring/TB combo, you should set it up so that the helper spring is just coil bound when the car is at rest, i.e. the car is effectively just sitting on the torsion bars. FWIW several people have had issues with noise from Spax rear coilovers.

Unless the spring plates have lots of travel left, without re-indexing you may end up with the rear sitting too high. This isn't always the case though - my KW's were fitted and adjusted fine without re-indexing.

 

[924Srr27l]

My understanding is that when running a spring/TB combo, you should set it up so that the helper spring is just coil bound when the car is at rest, i.e. the car is effectively just sitting on the torsion bars.

Yes, so that statically (at rest) the bodies weight is not compressing the Main coil springs, but as soon as you move off and begin driving the first 1mm of downward travel the car's weight will begin pushing down on the extra (Coil) springs as well as the T-bars hence why you add them both together to give a driven resistance / weight / poundage.

It's not possible at all for the T-bars to not be working when driving, only when the car has stopped at rest..

I've tried all 3 Combo's :
Road Use + trackdays
- T-bars only (170 Lbs Hollow elephant racing)
- T bars + 80lb Coils - total Spring rate (250Lbs)

Full Race
- T bars + 130lb Coils - total Spring rate (300Lbs)
- Rear coils only (650 lbs + 800lbs)

If the car ever goes back to a Roadie (which i doubt), I'd stick with the rear coils only T-bars are a pain to set the ride height


R

 

[924Srr27l]

Further to this there is a way you can have one spring operating before the other one, but it has to be the Torsion bars first.

So you set the ride height on the torsion bars, with the coil spring loose and fully open then set the lower spring platforms
so that the helper spring is open for say 12mm.

So the first amount of travel will only be pushing on the torsion bars, but when the helper spring is fully compressed only
then will the extra resistance (of the coil springs) be working with the T-bar rates together.

Don't forgot the rear trailing arms has a motion ratio almost .55 so to make it easier it's virtually half.
When the wheel moves up the arch 24mm, the spring will compress by 12mm.

I tested this very setup on the road and it worked quite well but then the Coil spring I used only added an additional 80lbs rate.
I'm sure when I did some research the KW kits have a rear coil around 275lbs, which if you added this to a stock S2 130lb t-bar the total of 405lbs would be harsh for road use, hence it's best you remove the tbars....

R

 

[blade7]

Heavily depressed, suicidal...gedit? ??

They're compressed though......[].

 

[blade7]

I think the likes of Spax and Gaz are less than half the price of KW's. You probably get what you pay for. The 944 KW's are designed to be used with torsion bars, and are sprung accordingly. If I was on a limited budget, I think Gaz may have a better reputation, and could be custom valved for a fee.

 

[Waylander]

we could be in for a 944 with balloon tyres on too small rims, with suspension so hard you can see the drivers fillings scattered around the dash