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Author Topic: Autocross Wheel Hop  (Read 756 times)

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Offline HoboSolstice

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  • Location: New England
Autocross Wheel Hop
« on: May 14, 2014, 06:45:45 PM »
Hi Everyone!

I'm kinda new around here but I figured this would be the place best to ask.

I've got an autocross this weekend and I'm looking for a remedy for wheelhop.

The car is a 2007 N/A and I am running around 28psi for tire pressure for starters.

I have been launching in the vicinity of 3-4k and I get severe wheelhop.

I've heard raising tire pressure to around 40 is good for autocross, but wouldn't this make wheel hop worse (or into just tire spin?)?

Just trying to find a way to not blow my diff this weekend!  :drive:

Offline GXP_Matt

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Re: Autocross Wheel Hop
« Reply #1 on: May 15, 2014, 11:03:10 AM »
Easy solution- launch at a lower RPM or let the clutch out more slowly!  I launch at 2500-3000 RPM and feed the clutch out instead of dropping it.  You can see from the accelerometer data when you have a good launch and it usually involves just a tiny bit of wheelspin.  Whenever I get the wheel hop I know I launched too hard.

What tires are you running?  I'd stay at 32-34 for most autocross street tires (Dunlop ZII, Rival).  If you are on soft all-seasons, then more like 38-40 since their sidewalls are so soft.
2007 zero option GXP, SCCA A-Street
Full LNF Z0k conversion, Koni Yellows, Solo Race, SSR wheels, BF Goodrich Rivals in 245/40-18

2013 North Carolina Street Tire class champion

Offline username

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Re: Autocross Wheel Hop
« Reply #2 on: May 15, 2014, 01:44:40 PM »
Poly nose bushing for the differential, plus the GXP z0K rear x-member eliminated most wheel hop for my car.

Offline HoboSolstice

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Re: Autocross Wheel Hop
« Reply #3 on: May 17, 2014, 11:00:50 PM »
I'm running the stock Goodyear R-SAs. 

I would like to invest in a set of dedicated autocross tires, but I still live in an apartment, and would need a trailer for those. In time!

I will try launching at lower RPM and feeding slower. I like easy solutions!

And I am going to look into the poly bushing, but I"m not sure it's legal as I'm going to be running B-Stock/Street for the time being.

Thanks!

Offline DrJones

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Re: Autocross Wheel Hop
« Reply #4 on: May 20, 2014, 12:08:09 PM »
I have the opposite problem with wheel hop.
If i launch at too low an RPM it causes wheel hop. I need to keep the RPMs up and do a quick but smooth clutch release.
Too slow and it roasts the clutch, to abrupt and the wheels spin too much.
To low of an RPM and the Avon slicks grab, release, grab release (wheel hop). Which is bad for gears and mounts.
2007 - GXP - White
F-Prepared - Crazy Monkey Racing
Westers Garage/Norms Fiberglass/AVON TYRES

Offline HoboSolstice

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  • Location: New England
Re: Autocross Wheel Hop
« Reply #5 on: May 20, 2014, 06:29:46 PM »
Agreed!

I have had the clutch roast problem a while ago (only once and decided that was too slow of a release).

And I have tried a little lower of a launch rpm, but it all goes out the window as far as planning goes once I get to the line haha.

I am planning on getting rather serious about autocross as money and time permits, and I hope to learn/share anything I can.

 

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