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TheArtfulDubber
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« on: August 09, 2005, 04:16:15 PM » |
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I drove the Tail of the Dragon this weekend and for the first time ever managed to get my tires to rub. Having 17x7s I didn't expect anything to rub.
Turns out it was my sidewalls flexing under the HEAVY load of the Dragon's turns. I've hit every curvy road around here without any issue, but the Dragon is a road unlike any other. Think: Auto-x on the side of a mountain.
I was running the tires at 39 psi, which I figured would be high enough to reduce the flex a bit, but obviously not enough. The rubbing was in the front right (which on a sidenote, any reason one side would rub and not the other if everything was the same on both in terms of suspension??)
Now, in the front I have a front upper stress bar and control arm bushings, but nothing else. Would a front sway help in this circumstance? I was avoiding buying one because I am concerned it would stiffen the front too much and reintroduce the understeer I got rid of with the rear sway. How about a lower stress bar?
I know buying new tires would eliminate the problem, but that isn't in the cards right now financially and won't be for a long time.
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ricerocket
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« Reply #1 on: August 09, 2005, 06:53:23 PM » |
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Are you rolling onto the sidewalls? I had to run ~42 psi on falken Azenis RT-215's (i.e. stiff-ass tire) when I had 'em my Passat to keep off the sidewalls when I autocrossed.
A front sway bar would help, but your ultimate level of grip will be reduced.
Can you dial in more negative camber? It'll help clearances, and it'll also help your contact patch under lateral load.
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- Jimmy
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TheArtfulDubber
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« Reply #2 on: August 09, 2005, 07:46:27 PM » |
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Yeah, I have Ventus HRII H405s on there, nice tires for the money, but by no means top performance tires. They stick very very well, just a little soft on the walls. And like I said, never had an issue before, but these turns were tight enough I finally had them rub.
I'll try bumping it up a few pounds next time. I am trying to avoid a rear sway, I know it would reduce dive, but I'm damn near neutral right now with a slight hint of controllable oversteer and I'd like to keep it that way. I have a feeling that a front sway would take me back into understeer.
I don't have any way of tweaking camber myself, but when I get it aligned next I might have them keep it one or two degrees negative.
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TheArtfulDubber
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« Reply #3 on: August 15, 2005, 10:33:24 PM » |
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Ok... brainstorm with me here.
Tire pressure was even. The course was driven both ways, so each turn was taken in both directions. The car ONLY rubbed on the front right corner.
Is the MkIV more prone to rub on the right hand side (engine weight more on right, etc?) or is something most likely wrong with my front right corner?
Relevant Mods:
Autotech Clubsport Stg 1 - 20k miles
Autotech 28mm RSB
Autotech 85 durometer Control Arm Bushings
Autotech Upper Front Strut Brace
Eurosport Upper rear Strut Brace
17x7 wheels w/ 225/45 rubber @ 39 psi
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ricerocket
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« Reply #4 on: August 15, 2005, 10:47:20 PM » |
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Probably alignment? The strut setup really doesn't do shit for dynamic camber, and if your wheels aren't tucking in at all under load, it could rub the fender. Any tell tale signs (scuff marks, scratches, etc) of what rubbed?
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- Jimmy
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TheArtfulDubber
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« Reply #5 on: August 15, 2005, 10:58:14 PM » |
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Yeah, very small ring of hot rubber around the edge of the tread, not quite on the sidewall, but only milimeters away.
It is probably perfectly normal and nothing to worry about, but it bugs me that only one side is rubbing.
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enginerd
Suspension & Transmission Masta
Global Moderator
Padawan
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Posts: 580
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« Reply #6 on: August 16, 2005, 06:36:30 PM » |
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There is no real adjustment of camber on these cars. The only thing that can be done is shifting the sub frame. If your sub frame was shifted to one side it would explain why you are rubbing on one side and not the other. Also drivers tend to corner better in one direction than another. Its easier to puss out when your taking a right hander and you see the other side of the road approaching quickly. Not to mention the cross weight of the car is messed up from the weight of the driver, and they turn left better than right.
I get a little rubbing from 234/45/17 on my car mostly at full lock on the inside of the fenders. 17x7 should not be a problem. what is your offsett? How low is your car?
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TheArtfulDubber
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« Reply #7 on: August 16, 2005, 06:46:12 PM » |
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OEM 35mm offset, mild 1" drop.
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enginerd
Suspension & Transmission Masta
Global Moderator
Padawan
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Posts: 580
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« Reply #8 on: August 17, 2005, 12:34:26 PM » |
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I would suggest an alignment and some camber plates. The camber will move the top of the tire inward, adn give you more negative camber. What is this dragon road you speak of? Where is it?
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ricerocket
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« Reply #9 on: August 17, 2005, 10:11:45 PM » |
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- Jimmy
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