suspension problems....

[Bart Geerts]

I have some serious problems here...

Ok, my tires are worn, a lot even. But the symptoms are to bad for just a tire problem.
In the rain, my car doesn't drive how it should. The rear goes in all directions, even at 30mph, with or without power one the wheels. Changing lanes is quite a task. And diving over a white line (paint on road, not the narcotic one) is dangerous, I don't know where the car will end.
I already had this problem on a dry road, but didn't care to much, it was just a little, it's like the rear of the car 'moves' when one tire hits a cover on the road.
I had the correct camber etcetera set after I put in the engine a couple months ago.
It's this scary that I canceled a meeting that I had just 15 miles down the road... And believe me, I don't care for rain normally.

I'll put in a pic of the tire, but at 30 mph, just letting the car 'roll' in neutral, shouldn't have the rear go left and right...

thx for any input.

 

[DONYMO]

Get 4 new tires mounted and balanced and have an alignment done to factory specs. That should take care of it.

 

[Bart Geerts]

Get 4 new tires mounted and balanced and have an alignment done to factory specs. That should take care of it.

the probs are to bad just for tires and allignment...
2 new tires are being installed on monday.
car has been alligned to specs 2 months ago.

I'm afraid I messed something up when reinstalling the engine.

 

[nsxtasy]

In the rain, my car doesn't drive how it should. The rear goes in all directions, even at 30mph, with or without power one the wheels.

That's not unusual for tires with only 2/32" of tread, like yours have. Some people replace their tires before that point, for exactly this reason.

Since you had your car aligned recently, and assuming you haven't had any reason to think that the alignment is off (like hitting a big pothole in the pavement), then I would just replace the tires with new ones. I bet the problem goes away.

I realize that you don't agree that it's just the tires, but I'm not sure why you don't want to believe that. I'm pretty certain that the tires are responsible for somewhere between 80 and 100 percent of your problem. It's easy enough to test. Get four new tires and see if the problem goes away. (Or two new tires on the rear that match the front tires, if the front tires still have a lot of tread.) If the problem goes away with new tires, then that was the problem. If the problem is still there, then you could try getting another alignment and/or look for other causes. (Alignments are not always done properly, and even when they are, they can change.)

Good luck, and let us know how the car behaves after you get the new tires and have a chance to drive on them in both wet and dry conditions.

 

[Bart Geerts]

some more info...

When I took the engine out, my tires were maybe down to 80% thread left after something like 6000miles... After that I've done maybe 1500 miles to wear the tires completely. Have the Potenza S02 a special compound that stays good for a long time and then goes very quickly or do I have a problem?

If tires are gone, I understand that driving fast in the rain, and cornering fast is dangerous, but letting it roll at 30 mph in a straight line shouldn't be a problem I think!!!

I'm having new tires on monday morning, and put the rear-allignment back to '0'. I had it put to toe in 2 because the books said it needs in 6, but I know that's bad for tires, and only used when tracking car. I didn't put it to 0 to have 'something in between' but the inside of the tires go to quickly.

I didn't drive in the rain for a long time, and I hope it stops raining quickly now, so I can check that the car handles in the dry like it did before it started raining. (to check something went wrong the last few miles)

 

[ATERPAK]

If you've worn 80% of the remaining tire in less than 1500 miles, then you have an alignment problem. The tire shown definitely shows a toe problem and possibly too much negative camber. If the tire shown in the picture is the right rear, it shows that you probably have a toe-out condition in the rear in which the tire is pointing out in the direction of travel. This is a no-no for this car and will cause you the problems you've encountered. The rear tires should be toed-in (again looking forward towards the front of the car). If the car is lowered you will be lucky to get less than -1.5 degrees negative camber. That's not too bad. I"ve run my car at close to -2 degrees negative camber but my rear toe is only slightly negative and I get very even wear across the whole tire. I also get good tire wear mileage.

I also doubt changing the engine will affect the suspension and handlling as you say unless you left something loose or off the car. Check your engine mounts to see if any are cracked. Finally you should have aligned the car after the installation and if so, it may have not been done right. If not then get it done correctly. Good luck.

 

[NSX-Racer]

Bart, I also claim that to the tires. The effect of worn tires on wet roads is worse with stiffer suspensions like your Koni shocks (do you also have aftermarket swaybars?). I remember one day at the track of Dijon when I tried to cruise with race slicks on damp straight (not really wet) in the year they had renewed the tarmac and starting grid signs. The tail went all over the place even at very low speed (appr. 60 km/h, but not because of aquaplaning). No problems on the rest of the track where the surface was "old". Problem was completely gone when I changed to street legal Bridgestones. Maximum speed was over 220 km/h with no danger.

Same experience with worn rear street tires on wet german autobahn. Even 60 km/h was too fast and made the tail twitching. If the surface is only a bit uneven or has different grip levels (white markers!) you get in trouble without tread.

 

[Bart Geerts]

Thx Wolfgang,

First of all, I know I shouldn't be driving around with these tires, but they went that quickly and there is a 3 week ordering time for the not so common size.

Indeed at 60km/hr in the wet I get scared, the car is driving with me, not me with the car. Good to know that you experienced the same with slicks. Makes me hope again I can go to the suisse meeting.
My tire provider told me that it's not unusual not to see that much wear on tires for a long time and then suddenly a lot in a short time. He says it's the mix of compound (close to being formula tires he claims) Can you confirm this?

Indeed I have koni, eibach sports and the koni are set up very stiff

 

[NSX-Racer]

He says it's the mix of compound (close to being formula tires he claims) Can you confirm this?

I wouldn't see a F1 relation but modern sports tires have indeed different compounds - the deeper, the smoother. That should compensate that the rubber gets harder with age and use to maintain about the same grip for the whole tire life. And, yes, this could lead to very quick wear for the last millimeters.

 

[lhpnsx]

THis is a bit off topic, but perhaps someone has a suggestion. I just got a set of HP Lightings, and ran into spacer wierdness on the rears, thought a 3mm would work, but ended up with 5mm. Then, I put the Eiback springs in over the stock shocks and the shop couldnt get below 2.1deg of neg camber on the rear..fronts are fine. Is there anthing I can do to remedy, any supension bits that would help? DOn't want to thrash the nice new 275's back there.

 

[drew]

I'm also voting for worn tires as your problem.

I've taken my tire depth down to a little more than yours and it is completely scary. I probably maxed out at 15-20 MPH during a trip on Highway 1 from San Francisco to Los Angeles one weekend....for those that don't know: two lane road with sheer cliffs on less than a couple of feet (~50cm) of shoulder.

The car would just over correct from any steering, torque slip from one side to the other under even the slightest throttle change and I would just pull over and let the minivans drive by.

New tires solved the problem the next day.

Your alignment looks ok as the tires are worn evenly.

Drew
/the wife kept telling me the whole ride down: "I'm scared! I don't like this. Today is NOT a good day to die! Okay?"

 

[Bart Geerts]

Suspension problems not that bad after all!

Car alligned and new tires mounted.
Problem GONE!!

allignment : They misalligned the rear completely. They had toe out at 3 degrees set instead of toe in 2 degrees like I asked. Camber was 1 degree of to the high side. (2.30 instead 1.30)
My allignment now : camber 1.50 couldn't go less, toe set at 0 degrees.
I'll check the wear when I get back from switserland, about a 1000 miles this weekend

The toe out caused the agreesive rear of the car. It rides very smooth now straight and level without the tail looking for its position. It really drives like a HONDA now :wink:

 

[Enzo]

Good news ! Can't wait to meet you again ! :smile:

 

[twizted]

Hmm, I was going to vote tires/alignment too Since I have aftermarket springs, shocks, wheels, tires, etc. and the car drives like it's on rails even at 100mph dry and 70mph wet :biggrin:

ADDED: Hell at that rate, I remember 80-100mph wet on the Turnpike riding perfectly too! :smile: