ian c - u.k

my new shox arrived this morning .

just been on bilstein website to check them out .

they sent me shox for 90-91

my car is a 1993 !!!!

whats the difference ??
can i fit them ??

http://www.bilstein.com/cgi/cars.cgi

only the rears are different , the fronts have same numbers throughout model 964

Bill Gregory

The rears shocks are different. In late 1990, at the start of the 1991 model year, Porsche changed some components in the rear suspension, including the length of the rear shock. Bilstein number B46-1735 fits the earlier rear, and number B46-1547 fits the later rear. You want the 1547 part.

ian c - u.k

oh my ...............
its been an epic getting these as it is !!!!!!!!!!!!
now they have to go back ??

what would happen if i fitted them ??

Phil Raby

They won't fit - the studs are in different places.

Cheers

ian c - u.k

hey phil
what studs ??
all i got is the actual strut unit , as i got eibachs to go on

ian c - u.k

porsche only list 1 bilstein rear part number for carrera rs .

so whats the difference in the bilstein ones ? bill

Ruairidh

Ian - Porsche changed the rear strut upper mount from MY1991 on. Basically - without modification - a shock designed for a 1989 and 1990 MY 964 will not fit the rear of a 1991 and later car.

Now, IIRC (and I may not as I have a 1991 and so this hasn't been an issue for me) you can make changes to fit a pre-1991 shock on a post-1991 car. Try a searh under "koni" as folks who have wanted to follow Adrian's lead and use Konis and not Bilsteins on a post-1991 car have been forced to look into this (as Konis are not available with a post-91 fittting).

Regards

ian c - u.k

thanks
search came back with 21 results , but noithing of help .

will have to wait until the company that sold me them answer my email .

by the way , i will be fitting the standard rubber top mounts

ian c - u.k

this is what i got

joey bagadonuts

The primary change between early and late 964 suspension systems is the top strut mount design, parts #10 (early) and 10A (late). Perhaps someone with suspension installation experience can clarify why your part won't work with the late strut mount.

Ade - C4 91

I believe that its the overall length of the shock, this is to cater for a position change to the mounting plate which was moved to allow space for cabriolet equipment.

to quote Bill Gregoy and Tom Masino:
In MY1991, Porsche modified the upper mount by 22mm, changed the outer tube length of the shock, the rear spring, the protective gator and bump stop, and the strut mount bolt pattern.

So there ya go.

I believe that it's possible to fit 92- shocks to a pre-91,, but I would doubt the other way round. Check out Bill and Toms conversion on http://www.porsche964.co.uk/ in the technical/suspension section

Ade.

ian c - u.k

joey ,
is 10a not a carrera rs mono-mount ??

ade ,
i checked the link , thanks
they where going the other way , fitting later rs stuff to an earlier car
i am fitting earlier shocks to a 1993 convertible .
so will they make my car sit too low ?

Bill Gregory

Here's the difference between the two mounts:



"A" is the original version, "B" is the modified version, 1991-on.

While shocks may have some affect on how high or low your car sits, it's the springs that primarily control height. FWIW, I wouldn't use the earlier shock on the later mount, as you know the rod will be 22mm out of it's intended operating range.

ian c - u.k

so ,
if i change my topmounts to the earlier type they will fit ok ??

btw , i will be changing my rear topmounts anyway

joey bagadonuts

I think the consensus is that the part can be installed but since it's not designed for this application, you're better off returning it and getting the right one.

I can understand your reluctance, though. It sounds like it was a headache just getting the part and now you've got something that's very close but not quite right. Perhaps the perch threads produce a slightly different ride height range or the bump stops are fractionally smaller. It may not make a huge difference but what if it does? More hassles, more shop bills, more aggravation.
Only you can decide if it's worth the risk.