Oracle

Hi,
Next week I'll get the H&R green springs in the car... and I'm not including the shocks in the final bill so this expense can get out of control quite easily.

I checked the car by pushing down the corners and watch the rebound (you know how Dad showed you how to check the shocks in the car) well as you can imagine that doesn't work on a 964 cause it's hard as hell..

I don't know if they're the originals or have been replaced in the past...

So the question is how can I tell if the shocks are shot?

Thanks
Jasper

hawk911

how many miles on the car, and how old is the car? If it's still a 964 we're talking about, I'd change them, even if you don't have lots of miles. Age is not your friend here.

elbeee964

Here, here.

I used to design aftermarket shocks. The 'bouncing bumper' method will only reveal hopelessly destroyed shocks. Short of encountering such rolling disasters, you'll need a cyclic velocity v. resistance machine used in the shock designing world... and compare those readings against a new OE shock. Obviously, that calls for waaay deeper pockets than it took to buy your car.

A shock's seals wear. Its internal hydraulic passages open up. Its hydraulic fluid 'burns' and, so, degrades -- 'thinning' its viscosity. All these things soften up your shock's resistance. This degradation takes place so gradually that your butt accommodates to ever sloppier handling. Half the time you may even think, "must be my tires or suspension is getting worn out"

So, [sigh] when in doubt, change 'em out.

Time, mileage, and abusive conditions all work against your shock's lifetime.

Trivia: By 'abusive conditions' -- I don't mean high speed track use. That isn't the worst environment in the shock world. (Lots of air flow helps cool shocks. And a cool shock is a happy shock...) The worst environment? Continuous, high displacement (ie, pot holes), low speed driving -- NYC cabs! Go figure.

Indycam

http://www.shockdyno.com/

http://hcidyno.com/index.html
* Shock Dyno Service:
* Price: $10.00/Shock

elbeee964
How far from new spec is still ok ?

elbeee964

Good question. We were happy if we replicated OE plot values within 5%, high or low.

Here's an interesting PCA article that touches on the subject.
(See Chart 9 & 10 for a representative view of the compression/rebound plots I was mentioning. Also note that different markets around the world are sent different shock valving to match local preferences.)

If you can find someone who'll take your shocks...
and have on hand your (local) Porsche OE's shock data...
and get back a superimposed graph like that Chart 9 plot...
for $10/corner
-- I'd say, boy -- RUN, don't walk, ta Git-R-Done! (Sorry, LarryTCG...)

BTW, don't worry about hooking your shocks into one of those machines. They won't be hurt in the least by the experience.

last toy

drive your car at 100kph on a highway. If the front end jumps around when you go over a moderate bump in the road and you need to keep you hands on the steering wheel, it's time to change the shocks out. You could also need a front end alignment but most cases the shocks are gone. Go with Heavy Duty Bilsteins with your springs. You may need corner balancing if you drive hard.

Bull

What shocks are they and how many miles are on them?

Oracle

I can't find any traces in the service history the shocks were ever replaced.
I asked the mechanic and he said the Boge (OEM) struts are really-really good and most likely they're still good (unlike the Munro in the 993), when the suspension is taken apart we'll see if they need to be replaced or not.

I like his approach rather than yeah let's spend more money blindly.

But on the other hand I believe that after 99,000 miles the shocks are tired to say the least... probably I'll just get them replaced..

By the way I found this in the H&R web site about trimming the bumpstops (check page 2/4), has anyone here done that?
H&R Bumpstop Information

Also I can't find the green springs, looks like H&R has just the sport and Coilovers...Does that mean green ones are NLA?:

Click here:
H&R WebSite

Christer

If yuo have more than 60K miles on them or they are more than 10 years old, just replace them.

Geoffrey

Regardless of the age of the shock, I think you'll likely have a different problem. The factory shocks are valved to accomodate the stock springs which means the compression and rebound dampening are specific for the stock springs. When you install stiffer springs, you'll need to change the compression and rebound dampening to match the stiffer spring rate. I have found that if you have M030 shocks, they will marginally work with the stiffer springs. They are a little soft for H&R Red springs. I drove my car awhile with that combination and if you weren't tuned in, you probably wouldn't notice it, but they were soft. When I upgraded to the Bilstein HDs, I found the valving to be nuch better suited to the stiffer springs.

So, if you have standard shocks, they certainly will not have valving that will work with the uprated springs. Ever see a Honda FNF that has been lowered bouncing down the road over bumps...well, you get the idea.

kgorman

Steve W at www.rennsportsystems.com can source you the bilstien/H&R setup. he did for me. no affil.

pat056

I have a '92 964 race car. The car is has 35,000 miles on it...all race miles. I think I have Bilstien coilovers.
My question? My mechanic says he can rebuild them (not very cheap, btw). I can feel no change in suspension and the car sticks like glue.
Should I do something as a maintance item?
rebuild or replace?

MisterRisky

No offense intended Pat, but why screw with them if they work great and the car handles well?

pat056

Point well taken!

pat056

As she waits for further instructions