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scary back and forth wobble at end of the 1/8th

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Old Mar 31, 2012 | 10:28 PM
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Default scary back and forth wobble at end of the 1/8th

Hey guys, i run 26x9x16" Hoosier QTP's on the rear and 17" ws6 wheels on the front of my 99 TA at the track. I'm a M6 and have to run them at 13lbs to get any kind of traction while launching at 4500-5000 rpm's. I run 1/8th mile and trap at 92mph. The car sways side to side terribly at that speed and scares the hell out of me but i stay in it till i cross the line. Other than putting more air in the tires, reducing my traction, what can i do to stop this? Do i need skinnies up front? Any info would help. Thanks.
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Old Mar 31, 2012 | 10:43 PM
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Just the nature of a bias ply tire. I run mine at 11 psi and doesnt really do that much swaying to me.
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Old Mar 31, 2012 | 10:49 PM
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what are you runing up front? would that affect the amount of sway?
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Old Mar 31, 2012 | 10:54 PM
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I run M/T sportsman 8 ply tire up front. I dont know if that affect it. But dont know other than going to a true stiff wall slick would probly help on the swaying
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Old Mar 31, 2012 | 11:04 PM
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Thats what im trying to figure out. Do i need skinnies or similiar upfront or just scrap the QTP's and try a full slick. They dont hook as well as i thought they would anyway. I thought i'd blow thru my ls7 clutch before those tires would spin.
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Old Mar 31, 2012 | 11:40 PM
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You can run a tube in the rear or switch to a bias ply tire in the front
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Old Apr 1, 2012 | 01:00 AM
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sounds like the bias ply sway from having radials on the front
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Old Apr 1, 2012 | 07:08 AM
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The mix of bias and radial tires is not really the issue, every drag radial car out there runs a radial rear and bias front with no issues, having a bias ply on the back period does this. Get used to it, only thing you can do is tubes, or a stiff sidewall slick, even then it will still do it some.
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Old Apr 1, 2012 | 09:29 AM
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Like JL said thats normal its going to feel like that.If you think its moving around alot in the 1/8th wait till you till you do a full pass.Thats were i really noticed the car moving around.I run drag radials now et streets there stable the whole run
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Old Apr 1, 2012 | 10:29 AM
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Thanks for the replies guys. The sway is so bad that I have to correct it with steering to stay straight. I never had this problem when I ran drag radials on the back. This is my first set of bias ply's. My best 60' was a 1.72 on Hoosier and bfg drag radials. I figured these QTP's would drop me into the 1.50's. I got a 1.68 best short time out of them but all the sway at the end. So... What's my best next move? Bias ply skinnies up front to see if it lessens the sway but also drops my times because of the weight reduction or try the tubes? My goal is to reduce my short time also.
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Old Apr 1, 2012 | 10:32 AM
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Correcting is not a good practice, that's usually where people lose it and wreck the car
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Old Apr 1, 2012 | 10:34 AM
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As for the short time improvement, slow motion video from the rear of the drivers side would be very helpful
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Old Apr 1, 2012 | 10:35 AM
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If you must stick with that tire try tubes first, I dont think changing the front will do much. Stiff side wall slick or drag radial is the easiest fix for this though.
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Old Apr 1, 2012 | 10:59 AM
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I'm not impressed with the qtp's traction so I think I'll try a different rear tire all together. Probably a full slick. I've got to stay with 26" because of my gearing. Thanks for the help guys. I do have a video but it's from the drivers side, side of the car. I soften up my rear shocks, and play with air pressure. Under 4500, I bog, over, I usually spin.
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Old Apr 1, 2012 | 12:12 PM
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Originally Posted by JL ws-6
The mix of bias and radial tires is not really the issue, every drag radial car out there runs a radial rear and bias front with no issues, having a bias ply on the back period does this. Get used to it, only thing you can do is tubes, or a stiff sidewall slick, even then it will still do it some.
I would agree to some point but I have found from my own personal experience that a radial skinny and a Bias ply rear tire is ok and sways very little. But running a Bias ply rear tires and a 17x9 wheel up front with a wide radial makes the car sway a lot more.

I think the OP will notice the car is much more stable switching to a skinny.
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Old Apr 1, 2012 | 02:02 PM
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Op, how wide is the rim that the rear tire is mounted on?
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Old Apr 1, 2012 | 05:52 PM
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I have gone 130 mph highway pulls with my qtp and i am just use to it. But its not as bad really as your stating. But as JL said corrcting is not a good practice. Just have to have the feel of tire sway from breaking the tires loose.
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Old Apr 1, 2012 | 06:38 PM
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Originally Posted by dschmittie1
I would agree to some point but I have found from my own personal experience that a radial skinny and a Bias ply rear tire is ok and sways very little. But running a Bias ply rear tires and a 17x9 wheel up front with a wide radial makes the car sway a lot more.

I think the OP will notice the car is much more stable switching to a skinny.
Agreed, I ran the last 2 years on QTP's with a radial skinny up front. They had a little sway at the 1/4 but not enough to need to compensate. I run tubes now, they still move but I don't even notice it anymore. I'd guess the wide front radial is very stable making the back feel worse!
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Old Apr 1, 2012 | 11:21 PM
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I've got ws6 wheels with 275/40's up front. The rear are 16x8 firebird aluminum wheels. The sway is terrible and unsafe. I'm not goin to run them again till I try a new combo. Maybe skinnies up front is the way to go? I was thinking the size of the fronts and the bias ply radial combo was bad originally but I wanted to check with everyone on the forum for insight. Should I run a bias ply or radial skinny up front? For the record, I've learned alot from this forum and I really appreciate all the time you guys are taking to help me sort this out. Thanks.
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Old Apr 2, 2012 | 05:54 AM
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Bias ply front skinny, you won't find a radial one that's the right size, and a radial would negate a large part of the weight savings. If you must stay on a 16 inch rim there's an et street that's 10 or 11 inches wide that would probably help with traction too fwiw
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