Rennteam 2.0 - EN - Forum - Re: Possible Wheel Design flaw?? - Page1

Jul 9, 2005 9:30:25 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005

Possible Wheel Design flaw??

I'm going to try my best to describe what my situation is:

My setup: lowered, on Techart's version of the PSS9 coilovers. Running on 19 inch iForged Seneka wheels, and PS2.

The problem: it seems that when it rains, I get a VERY strong vibration from the steering wheel. It only happens when the car is traveling about 77-79 miles per hour. It shakes so violently that my arms go numb, and my whole upper body is affected. This has happened on all road surfaces (I've checked it on different roads). Strangely enough, when the road is dry, I can't recreate the problem! I've had the car aligned and corner balanced twice. I've checked the numbers several times to ensure that everything is good. The car tracks straight when I let go of the steering wheel. I'm so baffled!

The only 2 things that I can think of is the wheel might be out of circle, or out of balance. But if this is the problem, why would it only affect the car when it's wet out, and not dry? The other thing is that maybe the IForged wheel design is flawed. Maybe somehow it's catching the rain water from the road and somehow the centrifugal force of the wheel is preventing it from coming out?

So confused and at a loss.....

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Jul 9, 2005 11:40:12 PM

Statman: Junior; Loc: Boulder, Santa Monica , United States; Posts: 100, Gallery; Registered on: Jul 6, 2005; Reply to: saveur

Re: Possible Wheel Design flaw??

First I don't know what your car is...Assuming a turbo, you will lose performance with the 19" wheels. However, I think the wheels are out-of-balance. I know it sounds strange, but it is basically a physics problem dealing with distribution of mass (remember f=ma). So what happens, to keep it simple, the "stars" align at certain moments and the force is dispersed as a vibration (amplitude increases enough for the vibration to be felt.). Anyway, Check the wheel balance 1st (then out-of-round).

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Jul 10, 2005 8:52:35 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: Statman

Re: Possible Wheel Design flaw??

Sorry, yes, it's a 996TT. I will be checking the wheel balance soon. But it still doesn't explain why it only happens when it's wet out?? The "loss of performance" is minimal; in fact, I think road feel is greatly improved under hard driving.

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Jul 10, 2005 10:02:48 PM

Dr. Phil: Rennteam Master; Loc: Denmark , Denmark; Posts: 5884, Gallery; Registered on: Nov 30, 2004; Reply to: saveur

Re: Possible Wheel Design flaw??

Sounds like it's your tires, not your rims that are at fault.
I had problems with a set of winter tires that seemed to "coldspot" after a night of standing still. Meaning, the tires simply gets a minutely flat area on the surface where the tire touched the ground. When you drive your car after a night of coldspotting, it feels like the tire is out of balance...which it actually is.. but the effect usually wears off with heat.
I even get that with my Dunlop SP9090 summer tires, but they seem to get better as the tire warms up.

Here's my theory:
My guess is you normally don't go 80 mph before the engine + tires are relatively warm. Correct? If coldspotting is the problem, the case might be that
a) you get overnight coldspots
b) on rainy days the rain cools down the tire
c) on dry days the tire warms up faster and the coldspotting disappears quicklier

I suggest you take you car out for a spin in the morning - A DRY MORNING- after a night of standing still (10 hours appr) and then immediately take it to 80 mph and see if you can recreate the shaking.

Solution to this: File a complaint with the tire manufacturer.
Make SURE you have "N"-marked tires that are porsche approved.
N-marked tires are heavier constructionwise.

My only other theory would involve warn ball bearings (sorry, my tech english isnt perfect...I mean those things holding the wheel + brakes.) and the rain somehow lubricating them..?

Hope this helps!

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Jul 10, 2005 10:45:01 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: Dr. Phil

Re: Possible Wheel Design flaw??

Dr. Phil,

Thanks for the suggestions. I think I'm out of luck on the "N" marked tires. I don't think the Michelin Pilot Sport 2 has it on the side (or I didn't see it).

I also thought about the wheel bearings, but I don't think it would cause the wheel to shake like that. More than likely, it's just an audilble thrumming if it was the bearings. i will try a early morning run and see what happens...

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Jul 11, 2005 12:13:38 AM

Statman: Junior; Loc: Boulder, Santa Monica , United States; Posts: 100, Gallery; Registered on: Jul 6, 2005; Reply to: saveur

Re: Possible Wheel Design flaw??

Michelin Pilot Sport PS2s are N3 rated!

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Jul 11, 2005 9:55:26 PM

Ferdie: Rennteam VIP; Loc: Europe , Germany; Posts: 8234, Gallery; Registered on: Jul 2, 2004; Reply to: Statman

Re: Possible Wheel Design flaw??

Quote:
Statman said:
Michelin Pilot Sport PS2s are N3 rated!

Regarding the "N"-rating I suppose you are thinking about Porsche's approval? I don't think that there have been tyres with that size wearing Porsche's approval since the 987/997 models are the first ones to wear 19" wheels.

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Jul 11, 2005 10:24:24 PM

Statman: Junior; Loc: Boulder, Santa Monica , United States; Posts: 100, Gallery; Registered on: Jul 6, 2005; Reply to: Ferdie

Re: Possible Wheel Design flaw??

According to Tire Rack:
235/35YR-19 N1
265/35YR-19 N0 or N1
295/30YR-19 N1

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Jul 12, 2005 6:00:54 AM

oak: Newbie; Loc:; Posts: 8, Gallery; Registered on: Apr 9, 2002; Reply to: Statman

Re: Possible Wheel Design flaw??

I think there have been issues with some installers not being able to balance the 19" PS2's. Ask Arling he knows. That maybe the problem.

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Jul 12, 2005 10:00:57 AM

Ferdie: Rennteam VIP; Loc: Europe , Germany; Posts: 8234, Gallery; Registered on: Jul 2, 2004; Reply to: Statman

Re: Possible Wheel Design flaw??

Quote:
Statman said:
According to Tire Rack:
235/35YR-19 N1
265/35YR-19 N0 or N1
295/30YR-19 N1

That are the tire sizes for the new model generation, aren't they? How long have they been on the market?

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Jul 12, 2005 12:44:44 PM

turbolite: Veteran; Loc: Switzerland , Switzerland; Posts: 1012, Gallery; Registered on: Jul 26, 2004; Reply to: saveur

Re: Possible Wheel Design flaw??

My 996 tt has a similar problem as the steering wheel vibrates between 100 and 120 kmh. imo it's not the wheels but the steering itself which i beleive has a defect insofar as that problem only initiated after the whole steering was taken apart to replace a default sensor (that for the steering angle, you need it for PSM). I told my garage, they dont wanna hear and are blaming it on the wheels, but also when balancing them nothing changed. I will take the car to another dealer now and otherwise get in touch with porsche directly, the car still has warranty.

cheers

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Jul 12, 2005 6:13:45 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: turbolite

Re: Possible Wheel Design flaw??

Hmm. Thanks for all the suggestions.

Turbolite, I donn't think your situation applies to me however, since the steering wheel was never removed for any work. I'm still looking at the possibiliity of cold spots as Dr. Phil suggested earlier, but I'm not keeping my hopes up.

Again, in the front, its 235/40/19, rear is 315/35/19. During the initial installation they didn't have a problem balancing the wheel at all, and this is from a major tuning shop (the owner is the head tech for some Porsche driver at Le mans Alex something). But that was over 6 months ago.

Again, this is not a "slight" vibration, rather, it's a whole arm-shaking event!

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Jul 13, 2005 10:39:57 AM

Ferdie: Rennteam VIP; Loc: Europe , Germany; Posts: 8234, Gallery; Registered on: Jul 2, 2004; Reply to: saveur

Re: Possible Wheel Design flaw??

Quote:
saveur said:
Hmm. Thanks for all the suggestions.

Turbolite, I donn't think your situation applies to me however, since the steering wheel was never removed for any work. I'm still looking at the possibiliity of cold spots as Dr. Phil suggested earlier, but I'm not keeping my hopes up.
...

I guess he was suspecting a defective steering angle sensor.

Are you talking about Alex Job racing? If the problem is that severe - and you still have warranty - I would imediately have it repaired! Vibrations don't do any good to your steering/suspension/wheels!

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Jul 14, 2005 5:23:30 PM

Stephen: Co-Pilot; Loc: Dallas, TX; Posts: 200, Gallery; Registered on: Jun 30, 2003; Reply to: Ferdie

Re: Possible Wheel Design flaw??

Whether or not the car still has warranty is a moot point until he goes back to spec wheels and tires.

It may sound odd, but I have seen guys with a particular two-piece wheel that has a trough where the pieces are joined. They have told me that sometimes rain water accumulates (even at speed) and has a negative effect.

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Jul 14, 2005 7:38:15 PM

fritz: Rennteam VIP; Loc: BaWü , Germany; Posts: 10248, Gallery; Registered on: Jul 23, 2003; Reply to: Stephen

Re: Possible Wheel Design flaw??

Quote:
Stephen said:
It may sound odd, but I have seen guys with a particular two-piece wheel that has a trough where the pieces are joined. They have told me that sometimes rain water accumulates (even at speed) and has a negative effect.

So Saveur's title for this thread could well have been right all along?

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Jul 14, 2005 8:58:53 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: fritz

Re: Possible Wheel Design flaw??

Ya, I had a funny feeling that it may be the actual design of the wheel. Honestly, I think this is the last time I will deal with iForged wheels as a company again. Their final product just doesn't have much quality to it, let alone sound engineering. I don't have any good pics to post of it, but there is a trough designed into the wheel. I suspect that it does catch water, and when the wheel is in motion, the water can't escape due to centrifugal force.

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Jul 18, 2005 12:51:04 AM

derder: Senior; Loc: Australia , Australia; Posts: 593, Gallery; Registered on: Dec 4, 2004; Reply to: saveur

Re: Possible Wheel Design flaw??

Hi,
It can happen if your alloys arent custom made for 996TT.
all manufacturers hv varying hub size. and wheel makers could not be bothered to produce 20 different hub-ring sizes for all models.

So what they do is during installation, they fit in CENTERING RINGS. they either come with the wheels or the tyre guys make them for u.

now. if the center-rings do not fit perfectly. i mean PERFECTLY. then u get vibrations at high speed.

I had this problem with my Mini Cooper S when I got aftermarket wheels. the damn idiots made the wrong size centre rings for me. and everytime I go on highways, 110km+. the s/wheel jiggles like crazy.

So, check that
1) if u actually have or need some centre-rings
2) make sure its high-grade aluminium or something strong. never use plastic ones.
3) if u do hv them, are they the rite size?? check when the wheels are warm (ie after driving) as they shrink/expand with heat.

Ta.

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Jul 18, 2005 6:18:04 AM

CarreraGtRacer: Veteran; Loc: Houston, TX; Posts: 1181, Gallery; Registered on: Jan 1, 2004; Reply to: derder

Re: Possible Wheel Design flaw??

going 77-79 mph in the rain isn't safe

Think of it as a safety measure.

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Jul 25, 2005 8:14:22 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: CarreraGtRacer

Re: Possible Wheel Design flaw??

UPDATE: I've had everything checked over, and so far we've narrowed it down to the wheel itself. The wheels look great and all, but I think I'm ready to go back to the stockers. It'll just look a little strange....

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Jul 26, 2005 11:46:07 AM

Crash: Rennteam VIP; Loc: Never been to , Antarctica; Posts: 8287, Gallery; Registered on: Oct 17, 2002; Reply to: saveur

Re: Possible Wheel Design flaw??

Quote:
saveur said:
UPDATE: I've had everything checked over, and so far we've narrowed it down to the wheel itself. The wheels look great and all, but I think I'm ready to go back to the stockers. It'll just look a little strange....

Do you have reverse lips? If so, it's definitely rain water. It's not company specific, also happens on HREs, etc.

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Jul 26, 2005 4:39:31 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: Crash

Re: Possible Wheel Design flaw??

Crash,

I'm not sure what kind of lip it's called, but I'm attaching a pic so you can see what I mean. The side that faces out, towards the road, actually clears the water just fine. It's the lip BEHIND the face that I'm very suspicious about....

iForged Seneka, 19"

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Jul 26, 2005 4:42:28 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: saveur

Re: Possible Wheel Design flaw??

That pic is of the rear wheel, the lip facing outside. Looks fine. here's another one:

hehe. this one is not too good of a pic. Anyway, they are staggered, 235 F and 315 rear. But I've already eliminated that as a possible culprit. I will be putting these wheels up for sale soon.

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Jul 27, 2005 1:55:56 PM

TT Surgeon: Senior; Loc: Long Island, NY , United States; Posts: 783, Gallery; Registered on: Dec 28, 2004; Reply to: Ferdie

Re: Possible Wheel Design flaw??

Check the alignment, another possibility is the motor mounts. When porsche sells the x73, it includes new stiffer motor mounts for use with the lowered/aggressive suspension, they won't even warranty the parts if you don't install them at the same time. You may have cracked your stock mounts. Most 'tuners' who install pss9s tend to ignore this part of the equation.

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Jul 30, 2005 2:34:49 PM

Ferdie: Rennteam VIP; Loc: Europe , Germany; Posts: 8234, Gallery; Registered on: Jul 2, 2004; Reply to: saveur

Re: Possible Wheel Design flaw??

If you SHOULD go back to stock wheels I would paint them black as well, this shouldn't look too weird then...

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Jul 30, 2005 3:09:19 PM

Crash: Rennteam VIP; Loc: Never been to , Antarctica; Posts: 8287, Gallery; Registered on: Oct 17, 2002; Reply to: Ferdie

Re: Possible Wheel Design flaw??

Yes, that's the reverse lip design. Sell the wheels and buy something else.

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Jul 30, 2005 9:49:18 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: Crash

Re: Possible Wheel Design flaw??

Thanks guys for all the input and guidance!! I'm afraid to look at those Techart wheels now......sigh.

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Aug 10, 2005 8:03:09 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: saveur

Re: Possible Wheel Design flaw??

UPDATE:

Over the weekend I went and saw a wheel shop, where they took off the tires, and did a "road force" balance and check. The end result:

It turns out that the permissible run-off allowed on the wheels were TOTALLY exceeded. All 4 wheels were slightly twisted, and the rears were out of round. The shop owner felt that it's damn near impossible to twist a wheel, unless it hit the curb or something (which I didn't), so it had to had left the factory out of spec. As for the rears, he explained that the stainless steel that the wheel manufacturer used was pretty soft, and felt that it shouldn't have been used at all for a wheel. And this is a company claiming that their wheels are "high-performance forged alloys"!! So now, I'm going back to the stockers.

I've sent a scathing letter to iforged, but it doesn't seem like they give a damn....

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Aug 10, 2005 8:29:14 PM

Statman: Junior; Loc: Boulder, Santa Monica , United States; Posts: 100, Gallery; Registered on: Jul 6, 2005; Reply to: saveur

Re: Possible Wheel Design flaw??

Quote:
saveur said: As for the rears, he explained that the stainless steel that the wheel manufacturer used was pretty soft, and felt that it shouldn't have been used at all for a wheel. And this is a company claiming that their wheels are "high-performance forged alloys"!!

That does suck.
Just a stupid question/observation...What is meant by they used "soft stainless steel"? Forged alloys are forged alluminum. Where is the stainless steel?

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Aug 10, 2005 10:47:38 PM

saveur: Newbie; Loc: Vancouver; Posts: 35, Gallery; Registered on: Feb 23, 2005; Reply to: Statman

Re: Possible Wheel Design flaw??

Statman,

I was referring to the lip portion of the wheel.

The rest of the wheel is forged aluminum. El-crapo is what i call it.

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