[leeklm]

Been brushing up on suspension articles to calm down my wheel hop. Chevy 12-bolt in my 66 and had bad wheel hop with the old control arms, so upgraded to shiny red ones with poly bushings all the way around and adjustable uppers. Stock rear springs and ride height.

Wheel hop did not change, so I played with pinion angle (now about -3* and trans/yoke at -3*) and changed air pressure in my air bags, tire pressure, etc. Also confirmed plenty of shock travel (standard gas shocks) and rear end moves up & down freely when springs are out.

End result is less wheel hop on my 265/60 street tires, but I have a feeling it will be much worse when I bolt a set of slicks on in a couple of weeks on a sticky track. If not for a little racing, I would call it good enough.

From what I have read, it looks like there are a few "next step" options. However, instead of just throwing money at it, I would like to hear some opinions from those that have been there & done that with the order of importance I should attack these things. Here is what I am thinking....

1. Spherical joint on uppers and/or lower control arms
2. No-Hop bars mounted on rear diff, or...
3. Brackets that lower rear of lower control arms

Should I try option #2 first, and then #1 if needed, or the other way around?

BTW, who sells the spherical joint kits that could be installed on existing control arms?

Thanks!

[242177P]

What's the ride height like? Stock configuration has the lower control arm almost parallel to the frame/ground. If the geometry is altered, moving back towards the stock height (coil springs) helps more than some might imagine. No hops can help correct geometry issues, but...

[leeklm]

Ride height is stock. I do get less hop at the lower ride height as compared to having the air bags pumped up some. The more I read, it feels like I should put something like the roto joints in that umi sells...

[67ramair4]

1.How much air in the bags?
Ultimate setting is 12 psi in the right one, and 4 psi in the left. (The 4 psi keeps the chaffing down on the bag)

2.Is this a four speed?
If car is a four speed, put the no hop bars on! Excellent fix.

3. Is the rear end a posi trac? If an open axle rear end the bags when inflated as mentioned above will keep hop to zero.

[leeklm]

For my recent street testing & cruising, I only have about 5psi in each air bag, and have not experimented much on offset pressures. I did offset pressures at the track last year and had really bad wheel hop on my street tires on the VHT soaked pad. I think it would be better as-is today just based on the changes I have made so far.

The car is a 4spd with 3:31/posi.

I have read a few posts where "binding" occurs under acceleration when running all poly bushings that limit any available movement to the rear diff. Is this a common issue?

It does look like people are seeing good results with the no-hop bars. I wanted to be sure I was not just masking a bigger problem by bolting them on. Kind of like taking aspirin for a headache, when I should first stop beating my head against the wall

[leeklm]

Originally Posted by 242177P

What's the ride height like? Stock configuration has the lower control arm almost parallel to the frame/ground. If the geometry is altered, moving back towards the stock height (coil springs) helps more than some might imagine. No hops can help correct geometry issues, but...

Was doing a little more checking tonight, and the lower arms have a 5* angle from front to rear. As seen in the attached snapshot, I really would not want to go any lower in the rear.

[Nicks67GTO]

The cheapest way might be to start with some Johnny Joints to replace the bushings on the rear axle housing as a starting point. Currie sells them and they fit stock housings. For $120 bucks that would take care of some binding issues right there.

I'm assuming your pinion angle is adjustable on the upper A arms?

If you want to go a step further and get some good quality control arms to replace the poly stuff on a budget, UMI makes nice parts in the USA and while I havent personally ran their RCA's, ive heard very good things. I do have their RCA braces and they are very good quality.

If you want some really nice beefy stuff look at the Currie RCA's.

Wheel hop is a condition of binding and poly bushings dont really help if it dosent eliminate the bind. Especially in corners. In corners I believe they can make the bind worse by themselves. The factory never welded the upper and lower perches on these frames correctly and even if they did, the frame is 45 years old and probably been beat on its whole life. My point is that the Johnny Joint bushings allow for full articulation on a frame that is proabably out of spec a little ways. I have the Currie uppers and lowers on my 67 GTO and I have absolutely 0 wheel hop. None. I can drop the clutch and do a 100' burnout anytime I want around corners or in a straight line and there will be no hop.

For the full disclouser....

A while back I had stock boxed rear control arms with new rubber bushings, bilstien shocks, stock springs, UMI RCA braces and no swaybar and I would wheel hop all over the place. Even on a flat road in a straight line it would hop and I had enough....

I then moved onto some QA1 adjustable upper control arms with spherical bushings Bilstien shocks, stock boxed lower RCA's, stock rear springs and no swaybar. Wheel hop was dramatically reduced and handling improved but I had a weird popping noise that I think came from the QA1's??

I then moved onto Currectrac upper and lower RCA's, bilstien shocks, stock springs and a hellwig rear adjustable swaybar. Parts from SC&C. 0 wheelhop and smooth as butter.

I've now replaced the coil springs with SPC's and the shocks with Ridetech HQ's and its just fantastic. Still 0 wheelhop and handles awesome.

Any questions let me know....

[archerytony]

Originally Posted by leeklm

Was doing a little more checking tonight, and the lower arms have a 5* angle from front to rear. As seen in the attached snapshot, I really would not want to go any lower in the rear.

Sounds like Im in the same boat as you on my 66 but I have mine a bit higher than stock with stiffer springs. I lowered the back of the lower control arms and it did help a bunch but it still wants to hop from a dead stop. Once Im rolling 20 mph or so it squats and smoothes out. Its frustrating I dont like braking stuff I know it hasnt been good to my tranny broke it a few times. I also have a chev 12 bolt with 331's poly bushings adjustable uppers and boxed lowers with sway bar and cheap shocks I did notice it is worse with taller tires. Heres what mine looked like before I put it on the frame. Since then I have been fighting it I changed the ends on the upper arms so they are higher in the back and centered more didnt make any diff. Going to try pinion angle again

[archerytony]

Originally Posted by Nicks67GTO

The cheapest way might be to start with some Johnny Joints to replace the bushings on the rear axle housing as a starting point. Currie sells them and they fit stock housings. For $120 bucks that would take care of some binding issues right there.

I'm assuming your pinion angle is adjustable on the upper A arms?

If you want to go a step further and get some good quality control arms to replace the poly stuff on a budget, UMI makes nice parts in the USA and while I havent personally ran their RCA's, ive heard very good things. I do have their RCA braces and they are very good quality.

If you want some really nice beefy stuff look at the Currie RCA's.

Wheel hop is a condition of binding and poly bushings dont really help if it dosent eliminate the bind. Especially in corners. In corners I believe they can make the bind worse by themselves. The factory never welded the upper and lower perches on these frames correctly and even if they did, the frame is 45 years old and probably been beat on its whole life. My point is that the Johnny Joint bushings allow for full articulation on a frame that is proabably out of spec a little ways. I have the Currie uppers and lowers on my 67 GTO and I have absolutely 0 wheel hop. None. I can drop the clutch and do a 100' burnout anytime I want around corners or in a straight line and there will be no hop.

For the full disclouser....

A while back I had stock boxed rear control arms with new rubber bushings, bilstien shocks, stock springs, UMI RCA braces and no swaybar and I would wheel hop all over the place. Even on a flat road in a straight line it would hop and I had enough....

I then moved onto some QA1 adjustable upper control arms with spherical bushings Bilstien shocks, stock boxed lower RCA's, stock rear springs and no swaybar. Wheel hop was dramatically reduced and handling improved but I had a weird popping noise that I think came from the QA1's??

I then moved onto Currectrac upper and lower RCA's, bilstien shocks, stock springs and a hellwig rear adjustable swaybar. Parts from SC&C. 0 wheelhop and smooth as butter.

I've now replaced the coil springs with SPC's and the shocks with Ridetech HQ's and its just fantastic. Still 0 wheelhop and handles awesome.

Any questions let me know....

Thanks fo the info Nick Im about at my wits end too. hate to keep throwing money at things that dont work. Were did you find this stuff?

[428GTO70]

Not sure if I missed it but did you also install new bushings in the axle housing? I had some serious wheel hop in my 70 and switching to UMI tubular control arms with adjustable uppers and all poly bushings (including uppers in the housing) completely cured it for me. I went from having a violent, whole car pounding wheel hop from the instant I started doing any kind of burnout, to a completely smooth as glass and even burnout. This was back when I had the rear end raised way up in 70's mode still too.

In my experience I believed it was just the new bushings that cured the problem, a little slop in any one bushing would allow the axle to twist/shift a little bit, then hit the end of the slop and grab which would cause a hop, then it would unspring and do it all over again until I let off the gas.

Anyways I guess what Im getting at is if you did not change the upper bushings (they can be a pain) I would start there. If you did change them....I dunno. Have you tried different tires in the rear, just temporary as a test?

[Nicks67GTO]

Originally Posted by archerytony

Thanks fo the info Nick Im about at my wits end too. hate to keep throwing money at things that dont work. Were did you find this stuff?

Summit has all the UMI stuff if you want it for the best price. Get the UMI RCA's with the "roto joints" as UMI likes to call them. If you want Currie stuff, I got all my chassis parts through Marc Savitske @ SC&C. Google Savitske Classic and custom. Call Marc. Listen to what he says......the conversation might get lengthy just to warn you. Get out your wallet and enjoy. The guy is a wealth of knowledge and has the best customer service I have ever expierenced.

[AG]

Get stop hop bars and you will fix it. Upper adjustable control arms are good so you can adjust pinion angle but you won't fix the problem with them.

[archerytony]

Originally Posted by 428GTO70

Not sure if I missed it but did you also install new bushings in the axle housing? I had some serious wheel hop in my 70 and switching to UMI tubular control arms with adjustable uppers and all poly bushings (including uppers in the housing) completely cured it for me. I went from having a violent, whole car pounding wheel hop from the instant I started doing any kind of burnout, to a completely smooth as glass and even burnout. This was back when I had the rear end raised way up in 70's mode still too.

In my experience I believed it was just the new bushings that cured the problem, a little slop in any one bushing would allow the axle to twist/shift a little bit, then hit the end of the slop and grab which would cause a hop, then it would unspring and do it all over again until I let off the gas.

Anyways I guess what Im getting at is if you did not change the upper bushings (they can be a pain) I would start there. If you did change them....I dunno. Have you tried different tires in the rear, just temporary as a test?

I replaced all my bushings with poly and yes I went to taller tires and it was worse

[archerytony]

Originally Posted by Nicks67GTO

Summit has all the UMI stuff if you want it for the best price. Get the UMI RCA's with the "roto joints" as UMI likes to call them. If you want Currie stuff, I got all my chassis parts through Marc Savitske @ SC&C. Google Savitske Classic and custom. Call Marc. Listen to what he says......the conversation might get lengthy just to warn you. Get out your wallet and enjoy. The guy is a wealth of knowledge and has the best customer service I have ever expierenced.

Thanks Nick I will checkem out. I hope you dont mind Leeklm me elbowing in here but maybe between the two of us we can get it fixed on both our cars

[archerytony]

Originally Posted by AG

Get stop hop bars and you will fix it. Upper adjustable control arms are good so you can adjust pinion angle but you won't fix the problem with them.

I will check those out too. Who carries them?

[grandville455]

I would not get the the roto style joints, I would get the heim style ones, I heard the roto ones can bind up etc. I ran the heim style Umi UPPERS on the grandville with relocation brackets on umi boxed lowers along with a sway bar with some preload in it using washers. Also make sure nothing is binding now in your bushings.

[archerytony]

Originally Posted by AG

Get stop hop bars and you will fix it. Upper adjustable control arms are good so you can adjust pinion angle but you won't fix the problem with them.

I called lakewood and talked to a guy who didnt seem to care but anyway he said all their products are designed to work with stock suspensions and height. I also asked about the lift bars same answer. Was your car high in the rear?

[archerytony]

Originally Posted by grandville455

I would not get the the roto style joints, I would get the heim style ones, I heard the roto ones can bind up etc. I ran the heim style Umi UPPERS on the grandville with relocation brackets on umi boxed lowers along with a sway bar with some preload in it using washers. Also make sure nothing is binding now in your bushings.

Darb
What are heim styles?

[archerytony]

OK I see they are like 3 point hookups on tractors I could add those to my upper arms wouldnt take much

[AG]

Originally Posted by archerytony

I called lakewood and talked to a guy who didnt seem to care but anyway he said all their products are designed to work with stock suspensions and height. I also asked about the lift bars same answer. Was your car high in the rear?

Your springs will determine your ride height, it will not change after installation of the stop hop bars. There are a number of manufacturers who make them, will be night and day afterwards. I installed them after hopping bad enough with my 4 spd car that the center section blew apart on the track.