Levent

I had Dunlop's on my 95 C2 (Eibach springs)and had enough of the temporary flat spots, I thought and told, and changed to Bridgestone S-03's. I used to have horrible vibration at 55 and 110 mph.
With the new tires there is still a little vibration but even worse is whenever I hit a little hump or pot hole on the road the tires hit the wheel wells and the shocks bottom out (this wasn't happening with the Dunlops, I have 17" rims).
The guys at AJUSA is telling me that the Eibachs are not suitable for this car and the car is way too low. They are recommending to change to Euro springs and they also think that the shocks/springs causing the vibration. They checked out all other suspension components but couldn't find anything wrong.
Should I go ahead and get Euro springs installed? This will raise the car probably half an inch and cost me $1150. I really lkie the car as is sans the minor vibration.
Any comments appreciated, thanks.

Viken

Your bottoming-out is caused by springs AND shocks that are too soft. You must upgrade both and have a proper alignment with corner balancing. You can find more info on 993 suspension here:
http://p-car.com/susfaq.html

Levent

Thanks for the reply, so the suggestion is not to change just the springs but also change the shocks. There goes another two grand plus.

I still don't understand that changing the tires have caused this bottoming out. Probably S-03's are much softer.

993Widebody

You can get the entire ROW M030 suspension, springs, struts, swaybars for about$1500. Installation and alignment will run you another $500-800.

Levent

Am I to assume that ROW M030 is only available from the Porsche dealer? Also, since I have the Eibachs can I get away with just changing the shocks?

Viken

The ROW M030 is not available through north American dealers. You can buy it from independent tuning shops or overseas. Try the following:
www.carnewal.com
www.schatzmotorsport.com

Viken

There is no way a different tire will cause bottoming-out unless it is severely under-inflated which will cause the wheels to bend anyway.

Levent

Hi all, thanks for the replies. I am scratching my head, I can't believe it either. The car once in a blue moon used to bottom out but today I went for for 100 mile ride to check out the S-03's and I bottom out about 5 time and even worse scraped the tires into the wheel wells about 30 times. I don't want to ruin these tires that I just payed thousand bucks. These tires are very very soft after Dunlops and perhaps the outside diameter is little larger, hard to tell. I checked the pressure they are OK. The vibration is still there too after warming up the tires. Since I don't track I think I will get the ROW M030 package rather than the H&R coilovers.

Chris in Detroit

As the wheel/tire is deflected up into the wheel well are you scraping past the wheel arch edge ?

How much of a lip / protruding sidewall / rim protector do the S-03s have compared with your old Dunlops ? I know the S-02s have quite a "lip" on them .......

Also, what is your distance ground to top of fender - there was a recent post - last entry 6-29-01 entitled "Recommendations for Drop" which included some photos of a tape measure alongside a wheel well - before drop 27" and after lowering 26"

What is your ride height ?

mani-1

Hi,
I had the same problem when I changed my tires to SO2 from Conti Sport. I have Tech Art Springs, which drop the car lower and I also have 18inch rims. To solve this problem, I rolled my rear fenders. Now, it no longer scrapes or give the feeling that my shocks bottom out.

You dont have to change your suspension. That would be a waste of money. You still have a lot of room under those fenders.

Ray Calvo

I would tend to agree with Chris; tires alons can make the difference. If the tread is wider or tread pattern is flatter, or diameter is a little larger than old ones, all this is in direction to make rubbing worse. I experienced that myself in rears when went to RE71's on my track wheels (255/40 on Mille Miglia 17X9"; these wheels definitely have more outside offset than OE wheels). BFG Comp T/A R1s I used before didn't have a problem.

I eliminated the rear interference by rolling the fender lips. Fronts are not a problem. This is on US M030 suspension with Euro M030 springs (did a trial fit of H&R springs and felt car would sit too low for comfortable street driving. Euros are low enuf for me).

Try to find out where they're rubbing (dealer should know or be able to find out). If it's the side shoulder, see if rolling the rear fender lips help. If you've got non-stock rims, might look at OE rims (maybe dealer has a set you can at least use as a trial fit).

Chris in Detroit

To see if the sidewall is scraping, two options (easy and technical)

1. EASY way would be to coat the sidewall in something slimy and noticeable - I would suggest white shoe polish, but you don't really want the Lincoln Town car look permanently so perhaps instead use LOTS of tire shine / protectorant. Do all 4 wheels. Go out and get the tire to rub / drive pretty aggresively, then stop and check whether the tirewall shine has been rubbed off - and where on the fender it rubbed (should be noticeable). careful to check all 4 wheels for comparison since the tirewall shine may fling off and LOOK like it rubbed

2. TECHNICAL way would be to disconnect rear sway bars then jack car up, place 4 of 5 pieces of 2by4 wood under just the ONE rear (suspected) offending wheel then SLOWLY drop car back to the ground. The wheel should rest on the wood and since the sways are disconnected, it will compress up into the wheel well. This should allow you to see whether it clears the fender lip or not.

Chris

Levent

Finally I managed to get onto the board.

I measured the height. It is 25.25 inches into top of the wheel well on all corners. With 17" OEM turbo style rims this is I believe too low after checking out some other 993s. Eibachs with stock shocks which are now 6 years old (probably totally shot) there isn't much play in the suspension.

I can see the rubbing mark on the tire and on the well (car is white so it not too hard to see the rubber mark). There is no rubbing in front tires only on the backs. It rubs at the edge of the thread pattern just before it becomes the side wall.

I agree that I can solve the rubbing problem by rolling the fenders but the primary reason why I changed the tires still remains. The vibration at 55 and 110 is still there. I think I will get the Euro sport package for $1595 and pay AJUSA $700 for the installation and alignment. Waiting for a quote froom Black Forest guys. My teory is that there is no dampening from the shocks so the springs are resonating at 55/110mph causing the vibration.

The person at AJUSA did not recommend the H&R coilovers, he says they seized on two cars they put them on and too hard for normal street use (will find out more on this seizing part tomorrow).

On a side note car is looser at the back with SO3's compared to Dunlop's.

Just for curiosity, can I do the rolling myself?

Levent

Here are two pics from two years back. Gives an idea how low the car is with Eibachs and stock shocks.

Terry Adams

I had the vibration at the same speeds after putting on 4 new tires, SO2 but the vibration issue could be the same. Two independents could not balance the wheels (18"). I found a third shop with a Hunter 9700, and it came back with no vibration at any speed. Also check that your lugs are torqued to the spec 94 ft lbs. Good luck.