# rear end booty bounce



## badtmpdgoat (Nov 9, 2004)

Why does the rear end bounce up and down so dramatically under hard acceleration? Any way to reduce this or even eliminate it? Does this hurt help or anything at all to the performance? :rofl:


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## Braman'sGTO (Mar 14, 2005)

the best thing is to put on a rear sway bar and some polyurathane bushings. From what they say it will reduce avout 75-85% of the rearend hopping that you are getting. Common problem with IRS but fairly easely fixed, SLP and Hotchkis both make kits fot the GTO but it's realy up to the indevidual which one you go with. I dont know much about SLP but havnt heard anything bad. I had a 71 Cutlass and the Hotchkis suspension packages are the SH!& for old muscle cars so I would venture to guess they are quit good for the GTO.


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## Groucho (Sep 11, 2004)

I haven't gone the full swaybar route, but I did install polyurethane bushings. This helped _big _ time, stabilizing the arse end under hard rowing noticeably...


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## GTODEALER (Jan 7, 2005)

badtmpdgoat said:


> Why does the rear end bounce up and down so dramatically under hard acceleration? Any way to reduce this or even eliminate it? Does this hurt help or anything at all to the performance? :rofl:


SLP sway bar $139.00, poly end links $34.95, and Harrop rear subframe poly bushings for $149.00. This combination isn't expensive and will definetly reduce wheel hop (85-90%)!! Good thing is I stock everything but subframe bushings which I will get in about a week and a half. :cheers


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## ncgoat (Feb 22, 2005)

Is this post asking about "bounce" or "squat"?? I got the impression that the post was asking about the degree of squat the GTO experiences under hard acceleration.

Greg


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## badtmpdgoat (Nov 9, 2004)

squat,,,under hard accel. I see a driver behind me then bumper tjhen driver,,every hard shift,,, :lol:


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## GTO_Newbie (Dec 13, 2004)

On the street, the mods mentioned seem to reduce a majority of the wheelhop. With drag radials at the strip, the wheelhop was as bad as ever. If I had stock tires, it wouldn't have been so bad cause I would have been spinning more.

I put adjustable shocks in this weekend to stiffen the rear end to control the pogo effect. Hope to have some reports shortly.

Here is what it was like, even after all the mentioned mods, with drag radials on a nice sticky track, but before the rear shocks.

Bouncing down the track


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## GTODEALER (Jan 7, 2005)

GTO_Newbie said:


> On the street, the mods mentioned seem to reduce a majority of the wheelhop. With drag radials at the strip, the wheelhop was as bad as ever. If I had stock tires, it wouldn't have been so bad cause I would have been spinning more.
> 
> I put adjustable shocks in this weekend to stiffen the rear end to control the pogo effect. Hope to have some reports shortly.
> 
> ...


Interesting, you have ALL of the mentioned parts, including the subframe urethane bushings? :confused


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## GTO_Newbie (Dec 13, 2004)

GTODEALER said:


> Interesting, you have ALL of the mentioned parts, including the subframe urethane bushings? :confused


SLP rear swaybar
Harrop diff cover with urethane bushings
Cradle urethane bushings
BMR one piece driveshaft
3.91 gears
Nitto 245/45/17 555R drag radials


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## GTODEALER (Jan 7, 2005)

GTO_Newbie said:


> SLP rear swaybar
> Harrop diff cover with urethane bushings
> Cradle urethane bushings
> BMR one piece driveshaft
> ...


I know this may sound crazy, but, try going to a 275/40/17 drag radial (I used the new Mickey Thompson), for some reason I had a ton of wheel hop with the Nitto's in a 245/45/17 and when I switched to the different tire and size it stopped (with above mentioned mods). :cheers


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## GTO_Newbie (Dec 13, 2004)

GTODEALER said:


> I know this may sound crazy, but, try going to a 275/40/17 drag radial (I used the new Mickey Thompson), for some reason I had a ton of wheel hop with the Nitto's in a 245/45/17 and when I switched to the different tire and size it stopped (with above mentioned mods). :cheers


Did you notice a change in traction? My plan is to try out a firmer shock and launching at a higher rpm, if the weather clears I'll try it tomorrow night.


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## rushhour (Aug 3, 2004)

Have the sway bar & cross member bushings in and still a ton of hop at ETown last weekend - even with street tires & A4. Shocks are the next thing I am trying.


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## GTODEALER (Jan 7, 2005)

GTO_Newbie said:


> Did you notice a change in traction? My plan is to try out a firmer shock and launching at a higher rpm, if the weather clears I'll try it tomorrow night.


HUGE improvment in traction!!!! I sell the QA1 adjustable shock kit for the GTO's along with the entire BMR line call me and I'll go over pricing!! :cheers


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## GTO_Newbie (Dec 13, 2004)

GTODEALER said:


> HUGE improvment in traction!!!! I sell the QA1 adjustable shock kit for the GTO's along with the entire BMR line call me and I'll go over pricing!! :cheers


Already setup on the BMR and shocks - just awaiting a track to test them, works great for the street with the Nittos :cheers


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## sandlakeont (Jan 18, 2005)

*wheel hop*

this problem is beginning to bother me as a soon to be purchaser........you mean to say that every time you nail it from a standstill you get this wheel hop?  please reply with your firsthand information so that i may make an informed decision.....thanks i am thinking of getting the 05...


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## vmax (Mar 19, 2005)

badtmpdgoat said:


> squat,,,under hard accel. I see a driver behind me then bumper tjhen driver,,every hard shift,,, :lol:


I still don't think anyone addressed SQUAT (pun intended!) under acceleration. I won't be drag racing my GTO but that squat is really annoying when I blast away from a light. What can remedy this? Also has anyone replaced their gauge covers with color matched ones from Arrowhead or anyone else? And finally-shifter and cold air induction-where can I get them?


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## GTODEALER (Jan 7, 2005)

We just finished the install on DFWGTO's red '04, we did the Harrop rear mount, subframe bushings, swaybar, and poly end links and there was NO wheel hop at all (on stock tires)!!! One of my techs that owns a GTO drove it and he's ordering the same parts for his today!!! I'm not sure why some of you with the same mods are still having this problem, I'm aware that most tracks are stickier than the street, but, I don't understand. :cheers


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## GM Kid (Mar 21, 2005)

sandlakeont said:


> you mean to say that every time you nail it from a standstill you get this wheel hop?


Okay, I'm starting to feel inadequate here: I've never experienced wheel hop, so I take that to mean that I must not be accelerating hard enough. I don't drag race the car, though. I've never been on a drag strip in my life. I just like to make the most of every opportunity I have when I'm first in line at a stoplight.

My launches are modest, though: I raise the RPMs _just_ enough so that when I dump the clutch it elicits a little chirp from the tires, and then I ease into the power and I'm off. No smokey burnouts or tail-wagging, no hopping, no drama--just rapid forward motion.

So in answer to your question, Sandlakeont, it's entirely possible to drive this car--and drive it aggressively--day-in and day-out without it turning into a bucking bronco.

But now I'm curious: What depths of performance have I left untapped?


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## DFWGTO (May 4, 2005)

Wheel Hop is nothing more than the resonate frequency of the car directly reacting to power and friction. AKA reduce the resonate frequency with shocks, stiffeners, swaybars... and / or change the power more or less and or change the friction, different tires even same tire different size... Its sorta like a wine glass and a wet finger running around the rim... I would guess you could even find certain spots of street that seem to do it more or less depending on the slickness of the surface. GTO NEWBIE Do you have adjustable shocks? 495.00 a set *Lots of money*. We might even find that the rear height weight shift helps or hurts us (spring spacers) dunno just a thought


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## DavidT (Feb 18, 2005)

GTODEALER said:


> SLP sway bar $139.00, poly end links $34.95, and Harrop rear subframe poly bushings for $149.00. This combination isn't expensive and will definetly reduce wheel hop (85-90%)!! Good thing is I stock everything but subframe bushings which I will get in about a week and a half. :cheers


I must be blind because I can't find where to order from you


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## GTODEALER (Jan 7, 2005)

DavidT said:


> I must be blind because I can't find where to order from you


All orders are done through email ([email protected]), we currently do not have a web site you can order from but that will change soon. For now, just email me with questions and what you want and I'll take care of you. :cheers


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