Am I reading that right......3,915 miles on the SO-4's? That's pretty extreme. As others have said, have your toe and camber adjusted to more conservative settings. I told me dealer to set both for regular street use and I get on average 10,000 to 11,000 miles on the rears and twice that on the fronts. And my car is lowered. No reason you shouldn't be able to get the same, or even better if you're not lowered.

As for hydroplaning, the rear starts to dance around on a rain soaked road once the inner 2"-3" start going bald. Doesn't matter how good the rest of the tire looks. And I think a lot of people don't realize that you really have to get on the ground to see what's going on with the rear tires. You can be down to the cord on those inside 2" to 3" while looking at it standing next to the car you'd think you have at least 15,000 miles left on that same tire.

 

That's right. Extreme tire wear. It's got to be the toe (rather than camber) because the wear across the tire from outer to inner is uniform. My alignment values are in an earlier post - I didn't think a misaligned toe could wreak such havoc.

Is it possible there's a suspension part that's broken/worn that could contribute to excessive tire but not necessarily show up on a static alignment?

 

You can try a little less toe in for the rear ala the latest gt3 specs

 

 

Hydroplaning is also a function of the tire pressures. When I ever get into a potentially squirrel situation when the back end, I deploy the tail.

 

When researching my car's issues, I came to learn that it's best to increase tire pressure judiciously to combat hydroplaning because the proper/extra pressure reduces/resists the amount of tire deflection due to the impinging water. I had always approached it the other way - reduce the tire pressure - no longer.

 

Thank you for this article. I'd read it before but the toe/hydroplane connection is near the bottom and I must have glossed over it. But the squirrel-y feeling they describe is one of my major symptoms when driving through intermittent standing water at speeds above 45-50 mph.

 

I'm making an appointment with Innovative Autosports to have them diagnose the problem. Will report back.

 

Well hell, tell them I said hey! (They did the PPI on my C4GTS. Great guys, amazingly knowledgeable, and tremendously patient with a Porsche newbie. Absolutely recommended.)

And I might not be a Porsche expert, but oh gods yes am I suspension and alignment. Oh yes. And it's your toe. It's absolutely your toe as the starting point. Thankfully you don't have a C4, where toe adjustment is not open season. I could go in depth on what I'd do (which is honestly going to be a LOT more than Innovative only because I am a perfectionist who won't accept anything but absolute dead-on,) but if I was going to have anyone else do it in Texas? I'd call Innovative.

 

Negative toe-in is the reason rear tires wear. The factory sets relatively high rear toe-in to induce understeer, and make the car safer for most drivers. Now, if you know how these cars should be driven you can cut on understeer and reduce tire wear. I routinely wore rear tires in the 10-12k mile range. Since i minimized rear toe-in (and changed to Michelin Pilot Super Sport) my rears have 22k miles and they are wearing evenly. Same rear negative camber and same driving style. In dry weather I figure the rears have another1-2k miles left. The extra wear is due both to minimal toe-in and the much longer wear Michelin tires (both Pilot Super Sport and Piot Sport 4S). All street/road driving.

 

Come on man, don't set off my Granny Alignment rant! I can't deliver it with less than a 50% cussing ratio. (Plus it really needs to be delivered over beers.)

Something people definitely, definitely do not understand about alignment is just how much it really affects tire wear and just how little adjustment is required to do it. Seriously. You try to put DOT tires up against the RH compound alignment on my toy, you will melt the tread right off 35k rated all-seasons in 500 miles. Literally melt. Switching from tread-melter to terrible-road-manners is two notches on the caster plates and 0.5deg camber. As little as 0.2deg of toe in the wrong direction on just one side can wipe thousands of miles off a tire's life.
And this is why I insist on checking (NOT performing, just checking) the alignment on anything high performance pretty much every oil change. Especially since a check now takes less than 30 seconds. Or worst case, . Sure, alignment isn't supposed to change. Which is the same as theory and practice. Roads are not perfect. Drivers are not perfect. Tires are not perfect. Mechanics are not perfect. Bolts are not perfect. 2000 miles with bad alignment courtesy a pothole or road construction can easily turn into 20,000 miles of tire life lost.

 

Charlie says it's the shocks - all around. The fronts have excessive bushing wear (at least) at the top of the strut. The rear struts offered not enough resistance to compression when fully extended. The rear LCAs had tears in the bushings so I'm going to replace them. No visible fluid leakage.

I'm thinking about going to Ohlin R&Ts (and coding-out PASM). I'm interested in opinions about the Ohlins. I'll probably dial-in some preload to reduce the ride height about 0.5 inch from where it is now.

After all that, an alignment to at least get rid of almost all rear toe-in...

Unfortunately, the damn AOS ruptured on the way home from work on Friday so the suspension will have to wait for a bit until I get that changed out, along with all the chain tensioners since I'll have the A/C compressor out.

 

Nothing wrong with ohlins but they do require rebuilds every 20k miles or so which can be a pita. When my pasm shocks go ill probably replace with bilstein b12 kit which matches awesome bilstein b8 damptronic performance plus dampers with matched eibach mild lower springs for under $1400

mike

 

... wow. Oh yeah. That would ABSOLUTELY thrash tires. That's... man. I'm glad Charlie was the one to look at Onyxia. REALLY glad. Because I honestly never would have thought to check the compression without more obvious symptoms or leakage. I would not have even GUESSED suspension until a lot of money and time in. A LOT. Now I just have to hope I don't have trouble finding non-pisswater gas driving her home.

Ohlins is who you call when you don't mind spending all the money. They are top in class for a reason. Which is also why they are so expensive. Also bear in mind that as bhvrdr mentioned, they DO require rebuilds. This is cheaper than new shocks obviously, but, the exact timing is going to vary based on your driving and setup. If you want to go all out though, I would strongly recommend an external reservoir model. These are MUCH easier to work on in general. If the price is the point of contention, I would check if Penske has something. They're just as good as Ohlins (better, in some regards) but often can be found cheaper.
Also, be cautious of used Ohlins. They are rebuildable, but not infinitely, and not all parts are replaceable. There is no part more expensive than a used racing part.

Man... what's the saying? If it wasn't for bad luck, I wouldn't have any?

 

A question about the rear wishbones (aka, LCAs?) - is it important that the bushing be oriented so that the "connected" portion of the rubber be aligned with the control arm (aka, trailing arm?)?

Should they come from the factory like this? How about if it's the Meyle brand?