rear coilovers
 

will rear coilovers fit stock type 1 rear trailing arms? never seen them on a car always seen people with 944 trailing arms.

Obviously depends on what coil-overs as they come in different sizes, externally 944 and type 1 steel trailing arms are the same (I've actually got the type 1 arms on my bug with coil-overs)

anybody have information abaout the coilovers from red9design?
http://red9design.co.uk/Rear%20Coilo...0IRS%20Bug.jpg

http://red9design.co.uk/type1.htm
IRS

If you are going to fit uniballs with coilovers then you must fit IMO a full 5 bar Kafer Cup Brace as the standard damper top mount is not designed to accept the full suspension loads that a uniball/coilover installation will impart.

I won't open the debate on the red9 designs.......................

Clive

Hi,

i want to use only the coilovers without the uniball system.

Any helpfull information about the spax coilovers?

If you don't want the uniball suspension then I assume you will still retain the torsion bars? In which case you will need to decide what spring rate you are going to use on the coilovers. It would not surprise me that you will only need a very light sping, if any at all.
The cause of concern with rear coilovers is that the top mount has not been designed to accept a spring load it being just a 12mm cantilever long bolt on the end of a forged arm that is weak in the lateral direction, hence the suggestion to use a Cup brace. However, I would guess that light loads say 50-100lb/in would not stress the fixing too much.
Why do you want to fit a rear coilover?

Clive

I will use a special bearing from GWD (Gerd Weiser)
http://www.gwd-weiser.de/aktuell/ang...tabdeckel.html
http://www.gwd-weiser.de/images/drehstab1_300.jpg

http://www.gwd-weiser.de/images/drehstabdeckel1_300.jpg

so i can remove the torsion bars

Cupbrace (three point) is already installed

red9design uses a 275lb/in spring on their own car

Dont know how to calculate lb/in in newtonmeter

Kerscher uses 120-140 nm spring without torsion bars aand three point cup brace

Nice..

I have a set too, but plan on using the torsion bars for now... was impressed by the quality of GWD.

I have the later wide alum arms that don't have the bump stop, so I am running some koni's yellow from a 944 turbo (I believe) that have incorporated the bump stop on them.. Just need to get them revalved soon.

Plus a 5 bar that needs to get welded on.
VR
Alex

I went through the exercise of calculating the spring rates front and rear that you may find of interest:

"Right! I have used Humbles corner weight and calculated the theoretical spring rates for the following spec:

Super Beetle Macpherson strut front and IRS rear with a sprung weight of 401.5lb at each front corner and 564lb at each rear corner. The lever arm at the front is 1:1 and at the rear is 1:1.277
For a quick road car the spring frequency would normally be between 80 and 100 CPM and for an unaerodynamically assisted race car would be 100 - 120 CPM
This gives the following results:
Road car:
Front
80CPM = 72lb/in spring rate
100CPM = 113lb/in spring rate
Rear
80CPM = 131lb/in coilover spring rate (no torsion bar)
100CPM = 204lb/in coilover spring rate (no torsion bar)

Comp Car
100CPM rates as above
120CPM front = 163lb/in
120CPM rear = 294lb/in (no torsion bar)

The above rates should be amended so that there is a 10 - 15% difference between the front and the rear spring frequency to prevent uncomfortable pitching that will occur if the spring frequencies are too close together (sympathetic resonance) with the fronts being softer. Please note that these rates are the theoretical ones that will only be a starting point for selecting the final settings, much of which will be governed by the feel and handling as well as the grip.

For comparison a standard 1303 super has the following equivalents:
Front spring rate + 80lb/in (83CPM)
Rear notional spring rate of the TB at the damper position (coil over position) = 186lb/in (95CPM)

Intuitively, the rears on the calculation are less than I would have expected although the normal recognised torsion bar upgrade to 23.5mm dia gives an equivalent spring rate of 216lb/in and a CPM of 102.

Hope these figures are of interest."

1lb/inch = 175.1N/mm


Clive