f11

I bought my '97 993 Carrera Cab in Nov07, as the third owner with 44k km on the clock. One of the previous owners had lowered the car without doing the proper suspension mods - that is, they just pulled the front wheels forward and rear wheels backwards to drop the body. Looks great. I knew nothing of Porsche suspension mods at the time and didn't think anything of it. The car handled well for my driving habits and I was happy.

Until the rear tires wore down to the cords on the insides with lots of tread left on the outsides. The local Porsche shop explained to me that the lowering method threw the rear tire camber WAY out of spec, and that there was no room to adjust it back into spec without reversing the lowering mod and/or doing the lowering properly, perhaps via a Bilstein/M033 setup. It was a pricey option, and replacing rear tires every 3 summers seemed like a more practical solution. I thought I was being practical.

I provide that lengthy preamble (sorry) because after 8 years of (what I considered) normal handling, suddenly the car has become very unstable. I first noticed it on the highway in June where the car would "jump" a little side to side for no apparent reason - not a lot, just enough to make the hair on the back of my neck stand up. VERY unsettling at 110kph on a public road. I thought it was the rear tires telling me it was time for a change, and since they were getting a bit thin on the insides, I replaced them, and all seemed well after that. I was never comfortable with the worn-tire explanation though.

Then it got cold and the roads got slippery. Now it wasn't just that little jump that came back, but the front end seemed to float side to side a little, the sort of feeling you get just as you hit black ice and realize you are no longer steering the car, but still going more or less straight ... sort of a sideways wander back and forth as if hydroplaning. It was showing up at 50kph, felt dangerous past 60kph, and required both hands on the wheel and full attention to driving just to keep the car stable. The steering wheel feels solid (no slop), and the wheels don't seem to have any side-to-side or top-to-bottom play when the car's on jacks. But what do I know.

I've been reading here about control arm bushings and suspension and shocks and my first impression is that's where to start. Is this a reasonable assumption? Is there another plausible explanation for the sudden instability? I understand a bit more about suspension now than in 2007, but not enough to offer much input as to what might be going on.

The car goes into the shop tomorrow, and since I'm pretty sure the suspension, shocks and bushings are all as they were when I bought the car and except for the lowering mod (I haven't taken it in for work in these areas), they could all be original equipment. The car now has about 84k km's on it, so it seems likely that at least the bushings have finally had it.

Any suggestions or ideas on what to look for once they get it up on the hoist? I'm pretty sure its time to spend money on the suspension system, but at minimum I have to fix the instability or the car is un-driveable and unsafe.

Leander

Given your description of the way the car jumps around I would definitely check the front control arm bushings. If they have never been replaced they must be overdue by now.

Someone more qualified than I will speak to your suspension set up, but the same applies, if you're on the original Monroes they definitely need to be replaced.

chsu74

Not having an alignment in 8 years would do that to the handling of your car. I realign my car every 2-3 years and usually find toe numbers out of spec..

nile13

Given the complete and utter lack of understanding of suspension, painfully obvious from this sentence (not that there's anything wrong with it), please stop and take a deep breath.

Do not try to diagnose anything yourself, else the result will be even more random. Find a decent suspension shop and talk to them. Let them show you, not just tell you, what is wrong with the car. Like leaking shocks (likely). bad alignment (likely), etc. Alternately, or even better, before then, find a local 993 person to drive your car and give an opinion. I'm sure you're not the only 993 person in the area.

PS, If someone sold you the BS above, about moving the lowering by moving the wheels... don't ever go there again and out them here, so others don't have to suffer. Ouch.

f11

Fair enough. I may have had an alignment of the front wheels sometime in the past, presumably when they tried to align the rear wheels and discovered they couldn't dial in enough to bring in the camber to spec. Front tire wear has been low, fairly even and typical across the tread, leading me to suspect that they've been aligned at least once since I bought the car. I'd have to go through my old paperwork to be sure.

Is what I'm experiencing the way bushing and shocks fail with age? I'm more used to gradual deterioration as opposed to good today, bad tomorrow behaviour.

I know the shocks are the original green Munroe units, from the under-car inspection I did when the rear wheel camber problem cropped up. I believe the springs are also original.

If I want to keep the lowered stance, is the right approach to go with the Bilstein/M033 solution? If I want to go back to stock ride height, is the best approach simply to replace the old gear with the same model new OEM gear, or is there a better aftermarket solution? I like the lowered look (although perhaps not QUITE as low), but not if its at the expense of the car's handling.

Thanks for the help. I feel a bit better about taking the car in and talking with the shop guys now. And you've helped me get a feel for the approximate costs of this service visit.

f11

Nile13, my description of the lowering was my own words, not that of the experienced Porsche tech who sketched out what was done. What I was trying to get across is that the lowering wasn't done in the usual way with different springs and shocks.

I'm not trying to diagnose this myself, or tell the techs what they should do ... when I take it in, I'll describe what I'm experiencing, and let them draw conclusions regarding what and where to look. These guys have serviced my car since I bought it, and are the acknowledged Porsche experts in my city, so while I don't take everything at face value, I have reason to believe most of what I'm told.

I'm just trying to get a handle on what's going on: the car felt fine for so long, now it feels unsafe, and I don't know why the apparent sudden change. Its an old car and lots of stuff wears out as it ages, so grasping what may have happened is tricky (for me at least).

But as you point out, my knowledge of suspension isn't that great, so your input is appreciated.

nile13

What you've described is pretty much a physical impossibility. That is why I drew the conclusion that you do not understand how a car suspension works. Which, is fine, just don't try to spend money on the thing that you are not familiar with to that degree.

My suggestion would be not to tell them what's wrong with the car. At least not at first and not in detail. Let them drive it. You might or might not be describing the car's behavior properly, which can easily send them on a wild goose chase. For which you'll pay some serious $$. That, btw, is where the suggestion to let another experienced 993 driver simply drive your car and share conclusions.

I hesitate with input, honestly simply to try to save you money. But what I would do, step by step:

1. Understand how the car was lowered. I can bet that it has aftermarket springs. This was one of the common and more idiotic things in the 80s and 90s, randomly replace, or, better yet, cut springs while leaving stock shocks in place. That also leads to too much camber, btw.

2. Once above understood, inspect shocks and springs. OEM Monroes are dead at that point anyway, but the question, in the "Princess Bride" sense, are they completely dead? In other words, is one or more leaking and simply not working at all? Inspecting springs might very well reveal that one of them is cracked, especially if they were cut in the first place.

3. Check front toe. Instability is often associated with toe setting of the front wheels. Check rear toe as well, that could cause the rear of the car to wonder but it's a bit different from what you are describing. the issue is that checking toe would probably require a full alignment, unless it's a decent race shop or they decide to save you money with a quick check.

4. Check front tires for a broken cord if they are older. Not trivial, but is a possibility.

5. Check the front bushings, sway bar drop links, camber bolts and assorted bits and pieces that should not normally break, but do. But, again, I'd start with more common wear items as above.

So... I would again advise to forget everything I've polluted your head with and let someone local shake the car out and give an opinion. Too may variables and the description is a bit all over the place, so I don't want to cost you more $$.

PS. If you decide to replace your suspension, it's a process. You'll have to decide how you use the car, whether you need adjustable suspension and a number of other things. Under _no circumstances_ would I go with OEM Monroe as a replacement. You can go with Bilstein HD, for examples, or Koni yellows, or Koni FSD. whether or nto you replace springs, you can go with US M030 (higher and stiffer ), Row M030 (lower and stiffer), RoW M033 (lower and softer). And a number of others, but that's a decision after you honestly decide what the car is used for. I'm personally on HDs and M030s in my own 993 cab.

golfnutintib

op - if you love that car, want it at its best (for sporty street use), plan to keep it...

1) find excellent indy who knows 993's and has kinematic toe tool for proper 4 wheel alignment for inspection of suspension

2) get walrod bushings for front arms and bilstein pss9/10 kit (lifetime warranty) - set dampers at 4 clicks from full soft at front, 6 clicks at rear

3) get fresh tires as needed

4) corner balance off euro spec ride height and set alignment

5) thank me later

good luck!!

chsu74

I think it is important to note that PSS10s plus new tires will be USD$3K to $3.5 just for parts before install. $500 variable for the type of tires you buy. There are cheaper and better valued alternatives. No reason to spend this kind of money on a cab. It's like taking a gun to a knife fight.

First and foremost, take Mike's advice and find a good Indy to shake the car down. Since it is not driving season anymore in Canada, take your time and make good decisions if you want to approach this wisely.

pp000830

Get an alignment before considering any suspension purchases, something a simple as a rear toe adjustment slipping will make the car feel unsettled and wonder at higher speeds.

f11

Thanks, all. I don't know any other 993 drivers/owners in my area, except for the owner and tech at the service shop I use. Even if I did, I'm not sure I'd be comfortable him/her taking a risk driving the car in this state. But I understand what you're saying.

As for the springs, when I looked at the shocks, I also looked at the springs. I THINK they're original, but who knows. They looked ok at that time, but could have been damaged since then, as that was a couple years ago now. The tires looked physically ok when I put them on a month ago - no apparent physical damage and or strange wear. There are no puddles on the garage floor, and when I changed the summers for winters, I didn't see any obvious leaks in the shocks, although a leak could be on the inner facing exterior of the casing where I wouldn't see it.

[ Edit: found my old notes from when the techs discovered the rear camber problem: <the shocks appear to be the original green Munroe unit, but the springs read "Eibach Springs" on the coil, and "44/96" and "7208.002"> From that I conclude the shocks are OEM but the springs were replaced. This would have been done sometime prior to 44k km. ]

nine9six

+993!
New tires, Bilstein HD suspension, M033 springs, align and corner balance.
Enjoy your car come springtime.

Porsche alignments done correctly by a qualified alignment shop, cost money. Doing suspension changes after the fact, seems counter productive and not in proper logical sequence.

nile13

Well, d'oh. This is why the car is lowered. Somewhat randomly, as predicted above.

993-TJC

Although everyone here likes a Euro spec height, another solution is to get a used set of USA spec springs and change the shocks. Most of us have a set of springs in storage when we lowered ours. Adds about 1.25" from where your car is now.

chsu74

People have run Eibach springs here on a 993. I would install Bilstein HD or Koni FSD(softer ride) with an alignment and call it a day.