[jasonblair]

Well, I've finally got my '65 GTO back with the new engine in it. It's now a 461 stroker with ported 6X heads, hydraulic roller cam, and the stock tripower port-matched. I knew I'd have problems hooking up with the new setup, but I was surprised at how serious the problem is!

When I engage the secondary carbs on the tripower, the car will immediately start wheel hopping BADLY in first gear. What I didn't expect was that I'd also get wheel hop in 2nd gear at 35mph! In third gear, the tires break loose at 40mph when I floor it, but hop is non-existent or minimal.

I have new springs and shocks on the car, but everything else on the suspension is stock, and probably pretty worn, making the hop a problem. I know I won't be able to eliminate the problem entirely, but I'd like to reduce it as much as possible. Which brings me to my question -

I've been looking at a complete set of rear end components from UMI. UMI offers both a lift bar that "GREATLY reduces wheel hop," and they also offer a lower control arm with spherical delrin bushings that "helps reduce wheel hop." (UMI's lift bar replaces the lower control arm, so both cannot be used simultaneously.)

Obviously "GREATLY reduces" sounds better than "helps reduce." But this car is not a strip car, so I'm not looking to sacrifice everything else for better 60' times. The car is a pro-tourer that I want to handle, corner, and ride well. What are the real-world pros and cons to the lift bar vs the control arm?

Thanks!

Jason

(PS - I can provide links to the products if need be, but I wasn't sure what linking was allowed under the forum rules.)

[67drake]

First see what condition your rubber bushings are in. The rubber on these dry rots and the rubber can actually get kind of wallowed out over the years. The bushings were about $15 a piece,and my local NAPA still carried them. Also,is your car at stock ride height. Raising or lowering the front or back end can make wheel hop worse. A few pics here-
http://forums.maxperformanceinc.com/...ight=wheel+hop

I had BAD wheel hop on my 71' when I first got it. I replaced all my bushings and it still hopped,but not as bad. I then went to lower control arm relocation brackets. These took care of all my wheel hop issues,but I HATED the way they looked!
I had plans on removing my original rear end and putting an 8.5 in. So when I did that swap I pulled the lower arm brackets off and went with "No Hop" bars for the upper control arms. These work as good as the lower brackets,but not nearly as ugly!
Another thread of mine- http://forums.maxperformanceinc.com/...ight=wheel+hop

[TCSGTO]

Lots of good info in the post & link above. I had severe wheel hop that was cured by replacing all the bushings in the rear suspension. Getting the rear end down as far as possible will allow the GM 4 link to work as it was designed to and help both straight line and cornering traction.

If your building a pro touring type car the no-hops can cause unbalanced braking on hard stops.

[jasonblair]

The car is slightly higher than stock. I have the A/C springs in front (even though I have no A/C), and I have the wagon springs in the back... I love the stance, although I know that being slightly higher = more hop.

Like I said, I don't want to mess up the ride height and all that just to improve traction and reduce hop at all costs... I'm sure that replacing the bushings will go A LONG way to helping, and that no matter what UMI setup I go with, I'll be much better off than I am now... But I just wanted some feedback on how the UMI lower control arms compared to the UMI lift bars.

Things like the unbalanced braking and having the car's rear end dump to the ground on every takeoff are NOT where I want to be... But I want to improve the traction as much as possible without ruining the ride height or streetability of the car.

My gut feeling is that the lift bars are great for a drag car, and that the spherical bushing control arms are great for a street car, but getting some more expert feedback is appreciated.

In the meantime, I'll check out the thread you linked to above.

Thanks!

[67drake]

Sorry,I know I didn't answer your questions directly,but figured it was relevant. I forgot I also played with adjustable upper arms too. I have other threads besides the ones I listed,as well as some other good threads from others too, if you do a search.
Wheel hop is very hard on the suspension and rear end,so don't leave it as is.

[jasonblair]

It's even harder on my head! Haha... I let right off the throttle when it starts to hop.

I just read through your thread. Definitely good to know the upper adjustable control arms and lower UMI control arms solved your problem... What about them is so ugly? Did they alter the ride height of your car? Or was it just that you could see them from behind the car? (I was planning on buying the black powercoated ones, not the red.) Let me know!

[Hammertime Mike]

I used the QA1 anti hop bars on my 65. They attach to the upper control arms and rearend. So they are not visible nor cause ground clearance issues. And they stopped the wheel hop.

[67drake]

This is what one of my worn bushings looked like. It's hard to see how bad they are worn when they are installed.


Original rear with UMI lower brackets installed. No wheel hop,but I could have drove across my lawn and cut my grass with this! I hate the way the anti sway bar looked so low. Without the rear anti sway bar it would not have looked so bad.


Another shot of the brackets installed.


My current set up. Removed the lower brackets,installed an 8.5 that I built,and put the no hop bars on,which you can't see.


Hope this helped.

[jasonblair]

Yow! That is low! I know that Global West and a few other high-end suspension shops insist that a rear sway bar is not necessary if the proper control arms are installed... But then again, I've had people try to steal my gas tank this summer (you can search for the thread discussing it), and I did come to the conclusion that a sway bar would serve as a theft deterrent!

So did using the prior setup affect ride height at all?

[67drake]

Ride height was not affected with the lower brackets installed.
I did just remember something though. Right after I put the lower brackets on I test drove it and everything seemed OK (except for the looks). I don't think I ever checked my pinion angle after this as my wheel hop was gone. When I pulled them off the car I sold them to another member here. He used them for awhile then put them up for sale here on PY. In his ad he mentioned he had to drill new holes in the brackets because he couldn't get them to work right with the factory holes.
A few months later another member PM's me asking about the bars (He now owned them). Turns out he put them on his car and noticed his pinion angle was way off. He asked if it was the same way while on my car. I told him honestly I never noticed. Last I heard he was going to get a hold of UMI and ask them if this was a common problem. That's the last I heard from him about it. Just a heads up.
Maybe I'll PM him and ask what UMI said.

[rexs73gto]

I know you say you like the car up a bit but when the car was designed they put them down for a reason, It needs to be close to correct ride height with whatever parts you use or you'll just be wasting your money. It may help but it won't stop it. If you put the new bushings on the car & get some correct NEW springs & go with a good shock a lot of your wheel hop will be gone. Shocks suspend the hop , springs control the ride & height of the car. The bushings keep the car going straight under load & pressure. Weather your going straight or around a corner the bushings hold the moving parts in place so it doesn't BOUNCE around. If you just get the correct springs & a good set of shocks (QA1) with the new bushings it will be close to the way it was designed & those cars had some wheel hop under very heavy accl. but It can be controlled with a few upgrades. So before you spend all the money on the UMI stuff get the small stuff done first. remember one step at a time is the best bet.

[AG]

I put polyurethane graphite bushings in boxed lower control arms, stop hop bars and adjustable upper control arms on and adjusted the pinion angle to 3° down on my '65. I had bad wheel hop before and broke my rear on the drag strip. After, never any wheel hop and hooks great on the strip with the car running low 12s. The car is a street car I race once in a while.

[jasonblair]

Originally Posted by rexs73gto

If you just get the correct springs & a good set of shocks (QA1) with the new bushings it will be close to the way it was designed.

I had QA1 shocks on my 2004 Mercury Marauder... Those shocks had to be rebuilt every single year! I think they are a great shock for racing and autocross, but needing a rebuild every 20k miles got to be expensive! (And every time I rebuilt them, the rebuilder would tell me how bad they looked, because they were supposed to be rebuilt every 10k miles!) QA1 = Great for the track, not great for a driver.

I've got new Bilsteins on it now. The wagon springs raise the rear end about 3/4"... I think. When I bought the car, it had a worn-out saggy rear end, so "stock" height is a little tough to determine.

Everywhere I go, I get compliments on the stance, so I'm not going to change it, even if it means my traction is not 100% perfect. But 90% perfect is better than about the 20% perfect I have right now.

[jasonblair]

Here's the current stance... I know the slight downward slope of the driveway might make the rear end look taller than it really is... It's pretty conservative.

[67drake]

Nice,my favorite year and color (besides black!)

[indymanjoe]

That does look Good!

[Nicks67GTO]

I had wheel hop problems in my 67' GTO. It was bad. Now I dont have them.

I did some research and discussion with Ramey@ UMI and Marc@ SC&C. I was informed that wheel hop is many times, a result of your rear 4 link binding. Many of them do this, even with new bushings because the factory frame boxes where the RCA's attach to the frame are off a bit in angle for one reason or another. I decided on Currie's Currectrac rear control arms and UMI RCA links. The Currectrac RCA's are adjustable and have Johnny joints which are like the delrin lined spherical bushings in the UMI pieces. They basically allow for the rear end to articulate and keep them from binding. I chose these parts because im going to run the entire SC&C stage II setup and they are a part of it as are the UMI pieces. I installed these pieces adjusted to stock length. I then set the pinion angle and found that was way off as well. After the install and pinion angle adjustment I have virtually no wheel hop now and I didnt use the relocation brackets, although I am running a moser 9" so they might have lowered the mounting point?? Im not sure if thats standard or not on those rears?

[jasonblair]

Thanks Nick! From what you are saying, I think I'm going to go with the control arms with the spherical delrin bushings rather than the lift bars! (Although we're expecting the first big snow of the year tonight, so I might not have an update on driving characteristics until spring!)

[Mike Smith]

That 65 is beautiful. The stance is perfect. I had wheel hop also. The lift bars above the rearend stopped all of it. Just saying.i could do perfect burnouts...Still run them after 25 years. No problems at all. Handling the same . And this thing hooks on the street very well.

[Nicks67GTO]

Originally Posted by jasonblair

Thanks Nick! From what you are saying, I think I'm going to go with the control arms with the spherical delrin bushings rather than the lift bars! (Although we're expecting the first big snow of the year tonight, so I might not have an update on driving characteristics until spring!)

I am no expert by any means and im only regurgatating info from conversations and my little first hand expierence. In other words dont take my advice and expect killer results. Ill give you one piece of advice that I give everyone when they are trying to decide on chassis parts. You cant go wrong here.... Call Marc @ SC&C {Savitske classic and custom} Tell him what you drive, what your goals are, what your budget looks like, get ready for a knowledge bomb,and get your credit card out.

I will tell you that currently I have bilstiens, the 12.7 JGC steering box swap, Hellwig front and rear swaybars and Currectrac RCA's and the car handles exceptionally well and is silky smooth even with big wall 60 series tires.