Finally caught up on Tivo. NASCAR Nextel Cup at the Glen. What's with wheel hop on braking?

Potomac-Greg · 08-24-2007, 06:01 AM

I'm just a fan, not a racer, and certainly not a NASCAR fan, but I watch the roadcourse races and root for "our" guys (Boris Said, Scott Pruett, etc.).

It seems like there was an epidemic of "wheel hop" in braking zones. Is it the solid axles and balloon-like tires? I can't say I've ever heard of this before (on braking, that is). The announcers frequently said, "There it is. You can see the hopping that led to the spin." I never saw any hopping.

Overall, I like the look of the "car-of-tomorrow." It's a more modern looking thing, and doesn't have that bizarre, distorted look that the previous stock cars had taken on. I couldn't tell how quick they ran because they almost never mentioned nor displayed lap times. It was all about average MPH. It's good racing, with plenty of passing. There were a LOT of pits and a variety of pit strategies, so it was pretty hard to tell during the race who was REALLY leading. A guy would go from 4th to 25th, and it was impossible to know when or why.

Mike/A.W.E. · 08-24-2007, 06:53 AM

but my guess is from the guys engine braking with the revs to high rather than heel/toe and using the brakes to slow the car.

I had heard an interview with Dale Jr. saying he feels he popped his motor in the race from too much "engine braking" in practice.

This is all speculative. I could be WAY off on my assesment.

pattycakes® iCode · 08-24-2007, 08:44 AM

or too much rear bias causing the backs to lock up. Since all the weight is on the front (espeically at Watkins T1), locking the backs just bounces the car and..voila, pirouette.

If you haven't deleted it, watch the Tony Stewart spin again, especially when they show the bumper cam, you can see the rear end start chattering before it swaps ends on him.

I watch the roadcourses as well, I just wish NASCAR would be more like Aussie V8s...*sigh*

mirth · 08-24-2007, 01:03 PM

I don't really know the physics of it, but threshold braking really exacerbates the effects of any imperfections in the track. Turn one in particular has a pretty bumpy braking zone, and you can definitely get wheel hop there. Same with the braking zone for turn one at lime rock...

jbchinoca · 08-24-2007, 05:27 PM

PWR · 08-28-2007, 07:45 AM

Mike you are spot one with this assessment. None of the road racers seem to experience wheel hop to any extent. Why, they use the brakes instead of motor.

Wheel hop can occur on a rear wheel drive street car, regardless of rear suspension type, just by using too much engine when braking. Solid rear axles just seem to make the problem more apparent.

08-24-2007, 06:53 AM	#2
Mike/A.W.E. AudiWorld Super User Garage is empty, add now Join Date: Oct 2000 Posts: 2,502	I am not 100% sure on this.... but my guess is from the guys engine braking with the revs to high rather than heel/toe and using the brakes to slow the car. I had heard an interview with Dale Jr. saying he feels he popped his motor in the race from too much "engine braking" in practice. This is all speculative. I could be WAY off on my assesment. __________________ Mike A.W.E Tuning www.awe-tuning.com techline- 215.658.1670 orderline- 1.888.565.2257

08-24-2007, 08:44 AM	#3
pattycakes® iCode Member Garage is empty, add now Join Date: Apr 2005 Posts: 6,823	It's either a heel toe gone wrong (not close enough on the rev matching) rattling the drive line or too much rear bias causing the backs to lock up. Since all the weight is on the front (espeically at Watkins T1), locking the backs just bounces the car and..voila, pirouette. If you haven't deleted it, watch the Tony Stewart spin again, especially when they show the bumper cam, you can see the rear end start chattering before it swaps ends on him. I watch the roadcourses as well, I just wish NASCAR would be more like Aussie V8s...sigh

08-24-2007, 01:03 PM	#4
mirth Junior Member Garage is empty, add now Join Date: Nov 2000 Posts: 771	where was it happening? turn one at the glen is pretty bumpy I don't really know the physics of it, but threshold braking really exacerbates the effects of any imperfections in the track. Turn one in particular has a pretty bumpy braking zone, and you can definitely get wheel hop there. Same with the braking zone for turn one at lime rock... __________________ 1988 BMW M3 #110 (NASA GTS2, BMWCCA JS) 2003 Expedition tow rig ex: Audi Coupe Quattro Porsche 911sc RoW Honda CRX Si (x2) 1988 BMW M3 1988 BMW 325is 1991 Mazda Miata 1994 BMW 318i 1964 Dodge Dart - check out the rally blog http://cars.g93.net

08-24-2007, 05:27 PM	#5
jbchinoca AudiWorld Super User Garage is empty, add now Join Date: May 2004 Posts: 21,755	It was occurring mostly in turn one. __________________ 2007 A4 2.0t, Quartz grey/blk, premium, titanium, Bose. Be kind to the noobies, and never say STFA no matter how many posts someone has. It's a club here, be helpful. "Never say Never" 2007 B7 A4 2.0 CVT, wifies ride, silver/black. Premium pkg. Audi's Before: 2003 A4 1.8TQ, blk/blk/Tip 2000 A6 4.2, bye bye 6-21, Happy Father's day/B-day 1999 A6 2.8, 1988 80 1981 4000E 2007&2008 MOTORSPORTS FORUM POSTSLUT. Others, Saab 9-3, Saab 900C,7 Opel 1900's, GT6, Lotus Cortina, and enough other cars to open my own lot.

08-28-2007, 07:45 AM	#6
PWR AudiWorld Member Garage is empty, add now Join Date: Jul 2000 Posts: 111	Re: I am not 100% sure on this.... Mike you are spot one with this assessment. None of the road racers seem to experience wheel hop to any extent. Why, they use the brakes instead of motor. Wheel hop can occur on a rear wheel drive street car, regardless of rear suspension type, just by using too much engine when braking. Solid rear axles just seem to make the problem more apparent.

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