Porsche Enthusiasts Club Forum

Hi,

I have been looking for some donor struts for my 89 non turbo, I have found a set from an apparent 86 model, the problem is they have screw on tops not crimped, would it take much adjustment/ hassle for me to just replace the cartridges on the donors and refit in place of what I have now??

Thanks

I have found a part number on my current struts which is
94434303217

The donor ones state

944 34303103212

I've been told there are several different struts from a few different manufacturers that were used in 1989. I don't actually know what is fitted to mine and it's now so rusty that I can't read any numbers off of it. I'm thinking I might swap the inserts for the Bilstein B6's but i'm at a very early stage in researching this so if anyone has any info that will help us both i'll be pleased to read it.

I've been offered inserts made by sachs which apparently fit my suspension legs but others say they're NLA and the ones I've seen are actually only for the square dash models but the rears are available. Of course you don't want to mix and match bilstein B6 fronts with sachs rears. Has anyone changed their suspension recently and can suggest what I should get please? Getting seriously confused atm.

First off download this
http://www.porsche.com/all/media/pdf/originalparts/en/E_944_91_KATALOG.pdf

Will help with this and any other parts enquirers you may have in the future.

Part no. 944 343 032 17 is the insert for the 1989 standard 944 made by Sachs
Part No. 951 343 031 12 is the up rated insert for the S2 and Turbo cars made by Sachs

There are also several inserts listed from Koni as uprated options, these most likely will be of the adjustable variety.

Thanks but I've heard the ones that the OPC's have are many years out of date so I need to get aftermarket replacements, I'm just not sure which are the best to keep it as standard as possible with a smooth ride, I have no intention of using it as a track car so I don't want the ride to be too hard.

http://www.design911.co.uk/fu/pt385_390 ... ers-Front/

take your pick on this page - all the options for your car are listed.

Putting it simply; if the Bilsteins on that page are a drop-in fit then you'd be mad to buy anything else. They are worth the effort of cutting and welding to make them fit the crimped-top tubes so dropping them into the screw-top ones is a no-brainer (although I hate that phrase!)

They are on offer as well. Even more reason to choose them!


Oli.

Bilsteins are a good option. have a look on amazon as they can be cheaper on there

The Bilstein B6 are their top sport (Stiff) Mono tube damper which will give you a harsher ride than a standard one
Brand new base model Sachs etc.. will be a far better choice if your unsure than the risk of a stiffer valved damper may ruin
the enjoyment of your car.

Koni do a Classic damper which is their base model and not the stiffer Sport. However I think they only list an insert
and not a complete leg, so you'd need to find someone to cut and fabricate your existing struts to suit.
But at least if you did this for the future replacements should be no problem to source.

If your near the North West I may be able to get this done for you,

R

Interesting comments about the B6's being stiff. I have them on my S2 with the standard springs and they are much more compliant than the Koni struts that came off (although, to be fair, the Koni's had a few miles on them so weren't new.) I certainly wouldn't call the BIlsteins stiff, although it's hard to describe what they are. The car body feels much better controlled and you are aware of the surface you are driving on (the steering feedback is as good as ever) but it's more comfortable and a more pleasant car to both drive and be a passenger in. The difference is immediately noticeable - within a yard or two of driving.

The car still has the original springs and is used for road driving only, mainly on the cart tracks that pass as roads in London.


Oli.

Yes I think your description of the Billy's being "more compliant" can also be seen as more resistant and tighter in control
which can be harsh and give less movement and ride comfort

Bilstein list 2 different valved versions on the front Inserts for the Porsche 924 / 944 / 968

- 34-000403 (120/95)

- 34-001042 (150/95)

Bilstein Valve Ratings
Damping forces of Bilstein valvings are measured in Newtons at a velocity of 0.52 meters/seconds (approximately 20 inches/second). The ratings shown correspond to those measurements; rebound force is the first number, followed by compression force (rebound / compression). Conventionally, the ratings are written as one tenth the damping force in Newtons.
EXAMPLE: Valve rating: 120/95
Rebound force is 1200 Newtons at 0.52 m/s
Compression force is 950 Newtons at 0.52 m/s
Higher numbers mean higher (firmer) damping forces. For example, 150/95 has more control in rebound
(is firmer) that 120/95.

A coil or Torsion spring rate controls the downward compression (Bump) and the damper resistance controls both
the (Bump) and Upward force (Rebound).

The harder 150/95 Bilsteins Inserts are the same size insert as the softer versions (120/95) and can be fitted to all 924S / 944's and the 968.

Bilstein also list a Green coloured rear telescopic damper 24-001618 which I can't find the valving for but I think these
are a softer classic replacement.

Back to this thread's subject a (single) Mono tube Damper like the Bilstein B6's offer less comfort than a Twin tube design..

Mono-Tube
In a mono-tube shock absorber, the shocks components are contained within one tube. A mono-tube system contains a shell case which works as a cylinder. Within that cylinder you would find a piston valve, oil, and gas. The construction of a mono-tube does also include some differences compared to the twin-tube design. A mono-tube design utilizes a free piston which separates the oil chamber from the gas chamber within the shell case.

Twin-Tube
In a twin-tube shock absorber there are 2 cylinders: 1 cylinder is set inside the shell case, and the second cylinder contains the piston valve which moves up and down within this second cylinder known as the “inner cylinder”. With a twin-tube design, there is no piston or barrier between the oil chamber and gas chamber.

Pros of Mono-Tube
As temperature increases, oil is able to release heat with less effort.
Zero restrictions on installation angles.
Less prone to cavitation
Larger oil capacity and greater heat dissipation allows for a stable damping force that is continuous.
Air is not able to penetrate the oil or gas since they are completely separated.
100% efficiency through all temps.
The piston valve is bigger and wider in a mono-tube design which allows for a wider area of pressure. In turn this means the shock can create even a subtle damping force precisely.

Cons of Mono-Tube
A stiffer ride is expected because an injection of high pressured gas is required in the structural design.
This high pressured gas can also lead to a higher amount of stress on seals which can cause more friction.
More expensive to manufacture
When there is external damage or force on the shell case, that directly affects the inner cylinder.
Since the oil and gas chambers are positioned next to each other, it is increasingly difficult to maintain sufficient stroke.
The inverted design has more friction caused from more moving parts.

Pros of Twin-Tube
Unlike the inverted design, friction can be stopped.
External damage to the shell case does not effect the shock absorber.
The twin-tube design provides a superior manufacturing process which keeps the cost of production low.
Gas pressure is kept low thanks to the base valve, this creates a more comfortable ride.
Low gas pressure reduces stress on seals and also keeps friction to a minimum.
Sufficient stroke is attained with far less effort. This is because each oil and gas chamber are separated.

Cons of Twin-Tube
The construction causes difficulties when installing.
Aeration is possible since the oil and gas chambers are not seperated.
Size of Piston is greatly decreased compared to the mono-tube design.
Oil capacity is reduced in comparison to the the mono-tube.
Low Pressure – Generally very Soft
Small Pistons, more prone to heat and limited on damping
CAVITATION- Fluid and gas mix, exponential performance loss up to 35%



R

Control? - yes.

Harsh? - not at all.

Lack of ride comfort? - No, the car is more comfortable with the B6's on it than it was with either the original struts or the Koni's, even with the Koni's on their softest setting.

What is surprising about the B6's is that they combine a very controlled feel on the road with good (very good) levels of comfort. The car is composed and handles very tightly, without feeling at all unpleasant.


Oli.

I've bought the B6's with the model number 34-000403 for front which appears to be the softer option, however I was never offered the other option. I have the model number 24-020527 for the rears. I have been informed by Bilstein that this is the correct pairing between front and rear and will be ever so slightly firmer but nowhere near harsh. I'll find out when they're fitted.

Thanks Mike, at least your using your old original springs (which may of lost some of their strength and be softer) and if your on stock 15" wheels with large sidewalls? you've a fair chance the stiffer Bilsteins will not be too dramatic an increase.

I've gone from stock sachs / boge then to Spax Gas adjustables which were stiffer (as I expected) , but then I changed all 4
to Bilstein B6's all round but they are much stiffer than the Spax which surprised me as I was hoping they may be less so.


R