996 C4s shock absorber concerns
Discussion
Hi all, I have had a 2004 996c4s 30000 miles from new, Coupe in for suspension refresh.
I used genuine springs, with matching colour and load code paint colours.
I used Bilstein rears shocks, without issues. I also fitted Bilstein 22-113344 B4 direct replacements, this is where my issues started.
The shock/springs and top mounts were fitted together, and the coil spring was very loose, not enough preload.
I ordered a second pair of springs from dealer with same outcome.
I eventually measured the original shock length, from top of shock to top of threaded piston rod.
The Bilstein measured 32 cm but the genuine, also Bilstein measured 21 cm.
I replaced shocks with genuine and no movement or spring slap was apparent.
I have had a second C4S in with the same issue, customer was aware of constant rattles from front, with lots of repairs in customer file.
I have had a full refund on the shocks, but cannot understand why the genuine is shorter, Bilstein have said this is the first time they have had any complaints.
Has anyone else seen this before.
Chris
I used genuine springs, with matching colour and load code paint colours.
I used Bilstein rears shocks, without issues. I also fitted Bilstein 22-113344 B4 direct replacements, this is where my issues started.
The shock/springs and top mounts were fitted together, and the coil spring was very loose, not enough preload.
I ordered a second pair of springs from dealer with same outcome.
I eventually measured the original shock length, from top of shock to top of threaded piston rod.
The Bilstein measured 32 cm but the genuine, also Bilstein measured 21 cm.
I replaced shocks with genuine and no movement or spring slap was apparent.
I have had a second C4S in with the same issue, customer was aware of constant rattles from front, with lots of repairs in customer file.
I have had a full refund on the shocks, but cannot understand why the genuine is shorter, Bilstein have said this is the first time they have had any complaints.
Has anyone else seen this before.
Chris
Quick Google:-
https://www.boxa.net/topic/91689-bilstein-b4s-shor...
Ok it's not a 911, but a BMW owner finding the same issue with B4's vs OEM ones.
https://www.e90post.com/forums/showthread.php?t=20...
https://www.boxa.net/topic/91689-bilstein-b4s-shor...
Ok it's not a 911, but a BMW owner finding the same issue with B4's vs OEM ones.
https://www.e90post.com/forums/showthread.php?t=20...
Edited by Rich_ on Tuesday 7th November 22:20
Bilstein only do one shock for the 996 AWD cars, the 113344, it is the same for all cars, whether C4, C4S, Turbo, M030 or standard.
The C4S and Turbo cars sit lower as standard. The M030 offers a firmer damper.
So you end up with a damper that is slightly too long for the M030 cars, C4S and Turbo.
And a damper that is too short for the others, as seen in the links above.
The fact the bump stop and dust sheild is taking up the whole of the piston should have been a warning it was not right.
The springs on these cars should be pretty loose when not compressed under the cars weight, so you can undo them without spring compressors, but not enough to rattle around when jacked up.
I'm not sure of they have altered the piston length over the years to try and find a compromise, but it is not right.
I don't know what the answer is. I don't think there is one.
The C4S and Turbo cars sit lower as standard. The M030 offers a firmer damper.
So you end up with a damper that is slightly too long for the M030 cars, C4S and Turbo.
And a damper that is too short for the others, as seen in the links above.
The fact the bump stop and dust sheild is taking up the whole of the piston should have been a warning it was not right.
The springs on these cars should be pretty loose when not compressed under the cars weight, so you can undo them without spring compressors, but not enough to rattle around when jacked up.
I'm not sure of they have altered the piston length over the years to try and find a compromise, but it is not right.
I don't know what the answer is. I don't think there is one.
FriedMarsBar said:
Garages/specialists like Center Gravity must have across this? I wonder if it's worth a call to CG, they may have a solution.
Center Gravity have a relationship with Bilstein I believe. They have there own spec Bilstein damper for 993's with custom valving to their spec.They should be able to advise, I'm sure they will have come across this issue before
This is for Ed.Neuman reply.
I understand what you are saying, but Bilstein make the genuine ones for Porsche, which are shorter than the 113344 version, by 12mm.
I even took the car for its MOT safety check and they commented on why does the spring jump when going from lock to lock, with wheels on the ground.
The genuine shocks fit perfect with correct preload on the spring holding it securely.
Thanks for all feedback.
Chris
I understand what you are saying, but Bilstein make the genuine ones for Porsche, which are shorter than the 113344 version, by 12mm.
I even took the car for its MOT safety check and they commented on why does the spring jump when going from lock to lock, with wheels on the ground.
The genuine shocks fit perfect with correct preload on the spring holding it securely.
Thanks for all feedback.
Chris
Porschekiduk said:
This is for Ed.Neuman reply.
I understand what you are saying, but Bilstein make the genuine ones for Porsche, which are shorter than the 113344 version, by 12mm.
I even took the car for its MOT safety check and they commented on why does the spring jump when going from lock to lock, with wheels on the ground.
The genuine shocks fit perfect with correct preload on the spring holding it securely.
Thanks for all feedback.
Chris
Yeah I get that, this is why them calling the B4 an oem replacement is weird and just not correct. I understand what you are saying, but Bilstein make the genuine ones for Porsche, which are shorter than the 113344 version, by 12mm.
I even took the car for its MOT safety check and they commented on why does the spring jump when going from lock to lock, with wheels on the ground.
The genuine shocks fit perfect with correct preload on the spring holding it securely.
Thanks for all feedback.
Chris
Unless they are valved to work when already compressed 15cm or more? But I doubt that.
I had it myself on two 996s. Springs loose.
However, I bought B4 dampers last year, and it was fine even with shorter M030 springs too.
I will be honest, it has put my off Bilstein.
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