996 C4S rear suspension harsh and crashy ...

[Por911T]

... as it says . My 996 C4S suspension seems a bit wooden, overly harsh and crashy on potholes or rough surfaces (2003 / 61000 miles). This my 7th 911 so I know how they should feel and by comparison my 997 RS is more compliant and less harsh than the 4S.

Has anyone else had experience of this ? Possibly needing a suspension refresh (shocks and springs) or could it be engine mounts ?

Appreciate all feedback, input and thoughts.

Thanks , Barry (Glasgow)

[Rockster]

Por911T said:

... as it says . My 996 C4S suspension seems a bit wooden, overly harsh and crashy on potholes or rough surfaces (2003 / 61000 miles). This my 7th 911 so I know how they should feel and by comparison my 997 RS is more compliant and less harsh than the 4S.

Has anyone else had experience of this ? Possibly needing a suspension refresh (shocks and springs) or could it be engine mounts ?

Appreciate all feedback, input and thoughts.

Thanks , Barry (Glasgow)

Maybe tire pressures are a bit too high? Some models have the tire pressures listed on a decal on the inside of the gas cap lid and the pressures are for a fully loaded car. For a less than fully loaded car then the tire pressures are too high.

Springs and shocks and even engine mounts aren't the problem unless you tell me ride height is off or there is shock leak sign or the engine mounts are bad. (These can be inspected from underneath. One in my 2002 Boxster was found bad but I had no sign of any problem before and after it was replaced -- and it was bad I got the old one -- I didn't notice any improvement.)

If there is a problem it can be with suspension bushings. These can and will age and can collapse and the car can get to feeling like one is riding a covered wagon with wooden wheels clad in iron.

I have no direct experience replacing these -- both the ones in my 2002 (and 310K mile) Boxster and my 2003 (and 152K mile) Turbo are original and the cars both ride ok -- but I came upon an article about a UK Boxster (I think it was a Boxster) the owner who had his car gone through fitted with new aftermarket suspension hardware and had all new suspension bushings fitted and afterwards didn't notice any difference.

[Onetrackmind]

Rear suspension in my 2002 turbo is also quite crash. I have the tyre pressures set to spec and have just replaced the rear shocks as they were leaking. Engine mounts were done 13k ago and exhaust hangs at the correct height so not sure what it is. Assumed they were just overly firm over little bumps. I notice it on mine is harsh when going over the painted warning lines when approaching a set of lights or roundabout on a dual carriageway.

[Por911T]

Ah great feedback guys. The tyres pressures are spot on . Last season I replaced all suspension bushes , drop links , arms , strut mounts , along with a full geometry and alignment check etc . So in fairness the old girls runs very well - just the ride is crashy and very hard (but not rattly or clunky - seems tight) . Ill monitor things and see how I go. Car is a 2003 / 61000 miles.

[Chris Stott]

My 996 feels really harsh/crashy on factory tyre pressures. Completely different at 4pai lower.

[TheLordJohn]

Chris Stott said:

My 996 feels really harsh/crashy on factory tyre pressures. Completely different at 4pai lower.

What do you set your tyres to?

[EGTE]

That would be 32/40 if it's a 996.2 C2.

[Chris Stott]

Mines a .1, on 265 rears. I run 32 f, 38 r.

Would imagine the same princple would apply to a .2, just with different starting points. Steering feels nicer on the lower front pressured too.

[1 Pheasant Plucker]

Book cold pressures are 36Fr/44Rr on a 996-4S, however this is like concrete on the rear, I run 41/2 and although only 2/3psi under it makes for a much more comfortable ride and the wear is fine, give it a try..

[TheLordJohn]

EGTE said:

That would be 32/40 if it's a 996.2 C2.

Thanks

[johnint]

Are the tyres more than 5/6 years old? I recently replaced some on 997 ( which had plenty of tread life and good condition) . Ride , crashyness , grip improved very much.

[Por911T]

All great feed back . Ill drop the pressures a little - would be the wise move before shelling out on new shock and springs. Tyres are about 6 years old . Im determined to get this right as Ive shelled out a lot of money getting the car to run and look as new. Thanks again guys - keep you posted .Regards Barry

[Pope]

Good call on the tyre age - most manufacturers recommend 6yr change interval (summer tyres) and 4yr (winter).

[ATM]

Por911T said:

All great feed back . Ill drop the pressures a little - would be the wise move before shelling out on new shock and springs. Tyres are about 6 years old . Im determined to get this right as Ive shelled out a lot of money getting the car to run and look as new. Thanks again guys - keep you posted .Regards Barry

What tyres are they?

[Por911T]

The tyres are Pirelli P-Zeros ........ now don't shoot me here, but Ive dropped the pressures to 32 & 34 and the car is a LOT more civilised . I spoke with another C4S owner and he recommended I try it. Seems wrong but feels right !

[ATM]

Por911T said:

The tyres are Pirelli P-Zeros ........ now don't shoot me here, but Ive dropped the pressures to 32 & 34 and the car is a LOT more civilised . I spoke with another C4S owner and he recommended I try it. Seems wrong but feels right !

Early Boxster is the same car centre forward. It has recommended pressure for front 28. So you could try that.