AndyA

I have recently bought my first Porsche, a 95 C4 993 Varioram. The previous owner covered 10,000 miles in 4 years, and it still has the tyres that came with the car when he bought it (Pirelli P Zero's). The tread is around 5 mm on the front and 4 mm on the rear. The shocks are originals, and the car has done 29,000m.

The car has just had a major Porsche service, and a full pre sale check. The geometry has also been checked although not by Porsche.

The issue is that when cornering reasonably fast (50mph) to fast (110 mph), particularly over bumpy roads, a yawing type of movement can happen, which seems to come from the rear. The car feels a bit vague through the seat and does not encourage me to push any harder. It also tramlines on uneven roads. Compared to my previous VW Corrado VR6, it feels significantly less secure at the same speeds.

Any comments on this would be appreciated. Are these characteristics of the car? My suspicion is that the tyres and shocks need replacing, and the car should feel planted and controlled.

Jeff 993TT

I would probably have your alignment adjusted. The shop that you go to should know how to do the kinematic toe adjustment on the rears.

There is much more information in the archives.

Another easy thing to check is your tire pressures too.

Jeff

Viken

First, change your tires as they are too old and might have dried and hardened. Then, get yourself a new set of shocks and have the car aligned and corner balanced. The original shocks are not known to last too long.

The Pope

[quote]Originally posted by Silver Bullet:
<strong>Hey Viken - DING DING...Post "993"...</strong><hr></blockquote>

I guess this is could be it. Might he be officially retired now?

tom_993

Please refer to the following two threads:

<a href="http://forums.rennlist.com/scripts/rennforums/ultimatebb.cgi?ubb=get_topic&f=3&t=001762" target="_blank">1995 rear suspension anomaly</a>

<a href="http://forums.rennlist.com/scripts/rennforums/ultimatebb.cgi?ubb=get_topic&f=3&t=002147" target="_blank">question on my car's behavior</a>

bet

Andy,

I agree with everything Viken said.

I would add that I had a similar problem with my coupe when I first got it. I had the "yawing" or as I discribed it a "hopping with some swaying from side to side" when I went over uneven pavement and it even happened when going in a straight line (but not as bad). The car felt very nervous and unsettled and gave me no confidence to drive it even at highway speeds in any curves. The car had 44k miles and the original shocks as far as I could tell. I knew one was bad and decided to change out all four. WOW is all I can say. The new shocks cured the yawing feeling and after the corner balance and alignment the car is not nervous or unsettled. Much more confidence inspiring.

A word of caution, when getting your alignment done look at your driving application, because from what I have read a more agressive alignment will result in "better handling" but has the side effect of higher tire wear and a somewhat twitchy feel on the highway and the possiblity of some tramlining.

leslie

Andy,

All of Bet's and Viken's points are spot on. I got new tires (the old S-02s were 70% worn) and new front and rear shocks done in 3 progressive stages and all the changes improved handling dramatically.

However, I wouldn't suggest you change the front and rear shocks seperately as I did cos each time any of the shocks get replaced, you have to redo your 4 wheel alingment. Also, make very sure that the shop can to the kinematic alingment that the unique 993 rear suspension requires.

For the suspension, there is NO need to replace the springs (unless you want to upgrade the suspension of course )

Edward

Andy,

Original tires from 1995??? Yikes!!!
I'd replace those first. Though your shocks still may be worn, at only 10K miles, I'm much more inclined to blame any handling quirks on old, hard rubber, despite the amount of tread left. New tires and an alignment may be all that's needed

Edward

DJF1

Andy,

You are not the only one that feels this way!
When i bought my 95 it scared the living daylights out of me! It felt like the way you describe it and it was certainly not old rubber on mine as it has new S0-2's...
Tom's links will help you understand that this is a suspension related matter, last weekend I rode on a 993 with the H&R suspension which is similar to the PSS-9 I guess and wow what a difference!
I'm not suggesting spending all this money, maybe just replacing your shocks could do the trick. I just had my kinematics checked as well and they are ok so at least in my case with 40K on its the shocks...
Good luck!

Steve-95 C4 Cab

All,
This has been an exercise in futility up until now. I, too, had experienced the hops on curves and the unsettled feeling going over uneven road sections. So I took my car to a Porsche mechanic who drove it for about 30 minutes, but didn't see anything wrong with it. He was whipping it from side to side trying to push the suspension. Even though my p-car is new to me and I have no other basis for comparison, it still feels wierd when I go over those seams, not dangerous, but very vague nonetheless.

Sounds like I need to check out some shocks on my 20K miles car.

AndyA

Thanks to all you guys for the comments and advice. I had been wondering who would pay the price for a Porsche that handled that way. Looks like I have to find a good dealer and get the tyres/shocks replaced and alignment checked out.
Then have some fun!!

E. J. - 993 Alumni

Steve and Andy, Check the Kinematic Toe. If a dealer or alingment shop doesn't know what you are talking about or says it doesnt matter, then find another place. Ask for the printout that shows it, or stand there and watch them adjust it.

Andy, change your tires first then see if the problem persists.

E. J.

911-TOUR

Just as a data point...I have 70K on my orignal OEM (non 030) shocks, and the car feels stuck to the road like glue. No hoping, no tramlining. I do not have the suspension geometry changes, but I do have it aligned to 96+ specs.

The dealer I've been taking the car to claims the shocks should go 100K+ miles, even if used in Houston (really bad roads) & on the track. They have not replaced many on 993s or 964s. Shocks wearing out after 20K, 30K, 40K just seems ludicrous to this ear...

Just for the knowledge base...

sean

Steve-95 C4 Cab

E.J.
Know anyone in NoVa who can do the Kinematic toe check? (Preferably open Saturday.) I'm in Richmond.

I'm also a little surprised at the idea of changing out shocks at 20K. I'll do it if necessary. (Suggestions anyone? Change just shocks or go all the way with coilovers?)

bet

Steve,

When I was doing my research on the very question you asked regarding coilovers vs. new shock, I was very surprised to find that if durability is a concern then the general consensus is to change out the Porsche shocks for aftermarket. Sean points out that he has gotten good mileage on his factory shocks but my findings indicate he is the exception rather than the rule. There are many who claim if you compare shock performance after 10k the factory shocks are definitely showing signs of wear (maybe not worn out but showing their age), whereas, the aftermarket ones seem to last much longer.

The one problem with all this research is most of data come from people who switched from factory shocks to aftermarket coilovers. The difference in valving and spring rates may account for why everyone thought they factory shocks were “worn-out.” It would be interesting to hear from some owners who just replaced the shocks with factory shocks without changing the set up and to get their opinion of whether the shocks were “worn-out”. Just some food for thought.