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wheel hop with A8 ScatPack

spazzman72

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#1
hey guys, i had some issues with wheel hop this past week at the track on 2 of my passes, as soon as i felt the wheel hop chatter i got out of it fast., what causes wheel hop over a full out tire spin ? would rather have the tires totally spin then that nasty wheel hop, I'm running M/T 305 R's on 17" racestars at 23 PSI.. usually don't have a issue with the wheel hop so not sure if its something im doing wrong or the track prep was going away.. appreciate any pointers..
thanks..
 


MiHiHemi

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#2
Kind of the nature of the beast with our cars. My SRT does that depending on track surface on occasion. Not usually a problem on the street where the tires just spin. I've heard a rear diff. brace can help with that. Think I'm going to try one just to see.
 


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#3
You didn’t say if you are using a diff brace or not. If not.... get one fast. The new DIRS from Per4mance is the way to go for a car not using a bunch of other control arm and bushing mods.
 


PaVaSteeler

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#4
Kind of the nature of the beast with our cars. My SRT does that depending on track surface on occasion. Not usually a problem on the street where the tires just spin. I've heard a rear diff. brace can help with that. Think I'm going to try one just to see.
Any report of lessening of wheel hop through use of a differential brace is speculative, and any reduction an unintended benefit of the brace. Don't buy one on the presumption it will reduce wheel hop.
 


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#5
Any report of lessening of wheel hop through use of a differential brace is speculative, and any reduction an unintended benefit of the brace. Don't buy one on the presumption it will reduce wheel hop.
The main benefit of a differential brace is protecting the case from fracture and the resulting damage that happens when it does. It is just one of the number of components involved when it comes to wheel hop. It may help some but will not eliminate it altogether.
 


OP
spazzman72

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Thread Starter #6
i heard the diff. brace helps the demon , but my Scat isnt making nowhere near that power:cool:
 


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#7
Any report of lessening of wheel hop through use of a differential brace is speculative, and any reduction an unintended benefit of the brace. Don't buy one on the presumption it will reduce wheel hop.
I tend to agree with this. I don't see how a brace designed to help keep the aluminum diff case from distorting and causing failure could also prevent wheel hop. If it does, please explain how. I know several years ago someone was selling "Hop Not" kits, but whether they helped or not I don't know. I have not heard anything about them lately so...Also heard of some changing out the rubber rear cradle bushings with either solid, poly or other type of bushing to stiffen that up...
 


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#8
When my A8 Scat was stock I had occasional wheel hop with 20in MT ET Street SS. I did Whiteline poly rear cradle bushings and a Per4mance diff brace . even after a significant power increase I no longer have wheelhop.
 


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MiHiHemi

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#9
I heard the diff. brace helps keep the rear end from rotating thus reducing wheel hop...any truth to that?
 


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#10
I heard the diff. brace helps keep the rear end from rotating thus reducing wheel hop...any truth to that?
Although it's not marketed for it ..it seems to me keeping the diff stable with the brace has to contribute to it. the brace removes one pivot point in the IRS. I will say..even at stock power levels I had a little side to side sway/wiggle from the rear of the car under WOT . cradle bushings and brace cured that. both were done at the same time so not sure what gets credit .
 


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spazzman72

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Thread Starter #11
i Know wheel hop is a issue with the manual trans guys but didn’t think the A8 would have that issue.
 


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#12
I can bounce an A8 like a jumping jack, if you let me drive yours. Easy, get in it, just go WOT like you just dead hooked. It will be over in a few seconds when something breaks or bends.
 


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#13
The main benefit of a differential brace is protecting the case from fracture and the resulting damage that happens when it does. It is just one of the number of components involved when it comes to wheel hop. It may help some but will not eliminate it altogether.
This ^^^. Wheel hop contributes to the torquing of the differential that causes the case to break. The brace was designed to stabilize the case from the torque, not the hop.

I tend to agree with this. I don't see how a brace designed to help keep the aluminum diff case from distorting and causing failure could also prevent wheel hop. If it does, please explain how. I know several years ago someone was selling "Hop Not" kits, but whether they helped or not I don't know. I have not heard anything about them lately so...Also heard of some changing out the rubber rear cradle bushings with either solid, poly or other type of bushing to stiffen that up...
With my M6 I solved wheel hop simply by using drag radials at the strip. I never had it on the street.

Imagine a front strut brace where the horizontal portion is connected to the two risers by an independent coupling. As the car yaws such a brace would be ineffective...until you stiffened the coupling...in a very crude manner, this might describe how the brace helps.

I heard the diff. brace helps keep the rear end from rotating thus reducing wheel hop...any truth to that?
Don’t know...but the brace limits the stresses on the case.

Although it's not marketed for it ..it seems to me keeping the diff stable with the brace has to contribute to it. the brace removes one pivot point in the IRS. I will say..even at stock power levels I had a little side to side sway/wiggle from the rear of the car under WOT . cradle bushings and brace cured that. both were done at the same time so not sure what gets credit .
This^^^
 


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#14
Wheel hop can occur even with great track prep. I raced at the Legion of Demons event in Houston and I can assure you track prep was the best. People were walking out of their shoes on the track. Several broke rear diff from hop. You are a wise man for lifting immediately when it happens.

A word of warning about a diff brace. FCA has been denying Demon warranty diff claims if a brace was installed. Even if you take the brace off before taking it to the dealer they have been looking for marks on the diff.

On stock suspension the best way is to launch a little softer, letting the front end come up while the rear settles, and then roll into the throttle. That all happens in less than a second. It will take practice to find the sweet spot on how your car reacts to throttle input, and unfortunately track prep differences will have an impact.
 


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spazzman72

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Thread Starter #15
Wheel hop can occur even with great track prep. I raced at the Legion of Demons event in Houston and I can assure you track prep was the best. People were walking out of their shoes on the track. Several broke rear diff from hop. You are a wise man for lifting immediately when it happens.

A word of warning about a diff brace. FCA has been denying Demon warranty diff claims if a brace was installed. Even if you take the brace off before taking it to the dealer they have been looking for marks on the diff.

On stock suspension the best way is to launch a little softer, letting the front end come up while the rear settles, and then roll into the throttle. That all happens in less than a second. It will take practice to find the sweet spot on how your car reacts to throttle input, and unfortunately track prep differences will have an impact.
yea' this is the first time I've encountered the wheel hop... usually i dead hook with good track prep. never had to ease into the throttle just nail it at about 1300-1500 RPM's.. or if the track prep is crap i would just get tire spin...
 


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#16
yea' this is the first time I've encountered the wheel hop... usually i dead hook with good track prep. never had to ease into the throttle just nail it at about 1300-1500 RPM's.. or if the track prep is crap i would just get tire spin...
Did you try adjusting your tire pressure? If track prep is good you can up the pressure.
 


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yea' this is the first time I've encountered the wheel hop... usually i dead hook with good track prep. never had to ease into the throttle just nail it at about 1300-1500 RPM's.. or if the track prep is crap i would just get tire spin...
It is the bushings. Whiteline cradle bushings and changing the control arms or all their bushings will nearly make it all good for you my friend. In the meantime you (me too) have to ease into it like you have figured out. This Redeye is even more sensitive than a HC with the extra power. I have really learned to slow my right foot down. I am having all that done this winter season, and more, but I need it yanked down tighter so I can also go left and right.
 


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#18
I would have lowered the pressure. I’ve had to go as low as 16psi to get my 17” MTs to hook. I was never able to get them to hook over 20.
This is with a stock HC.
 


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spazzman72

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Thread Starter #19
I usually start at 24 PSI and adjust from there , I try to run as much pressure as the track can hold... I also don't do huge burnouts usually just 1st-2nd gear manual mode and roll out of burnout 3-4 seconds max.. I was told the M/T R's don't need john force style burnouts..lol
 


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I usually start at 24 PSI and adjust from there , I try to run as much pressure as the track can hold... I also don't do huge burnouts usually just 1st-2nd gear manual mode and roll out of burnout 3-4 seconds max.. I was told the M/T R's don't need john force style burnouts..lol
24 psi on MT Rs is high. I'd start more in the 18-19 range. You are correct about MT Rs not needing big burnouts if there is good track prep. In fact, a big burnout on those tires is counterproductive with good track prep. If the track prep is poor or marginal you will need more.
 




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