# Rear Control Arm and Bushing recomendations please



## bowtie30 (Aug 10, 2014)

66 GTO, stock 389 tri-power, 12 bolt Chevy rear. Pretty much a daily driver with an occasional thrashing  I am replacing the rear control arms and bushings and would like to hear some recommendations. I have read that poly bushings can work harden over time and possibly transmit road noise and vibration. I am going with boxed or tubular lower control arms and adding a sway bar. My pinion angle is good between the transmission and rear end. I did have some serious wheel hop with the original control arms. So my questions are:
1. Rubber or Poly Bushings?
2. Boxed or Tubular lower control arms?
3. Tubular or Adjustable upper control arms?
4. Are the UMI arms with roto-joints OK?
5. Any brand I should stay away from?
6. Should I install no-hop bars while I have the rear end out?

Any and all input would be greatly appreciated. Thanks


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## Rukee (Feb 8, 2007)

I installed some drag bags in the rear spring and it cured the wheel hop. For normal driving I would do the rubber bushings.


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## bowtie30 (Aug 10, 2014)

Thanks Rukee. I put drag bags in last fall but still had the wheel hop. Not surprised as the original control arm bushings are whipped.


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## FMFC motorsports (Mar 21, 2015)

Poly for sure, shouldn't have any issues, tubular for sure...CPP had some good stuff at good prices if ur not a racer. Haven't had problems in 15 years. Don't need adjustable, ur not going for best times at the track.


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## FMFC motorsports (Mar 21, 2015)

While it's all apart, replace everything that could use it. Doesn't mean you have to spend a lot of $. UMI is great, just stay away from the "way too cheap no brands on eBay" if they put there brand in it, it's usually good!


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## bowtie30 (Aug 10, 2014)

Thanks FMFC. Right now I'm leaning toward the UMI upper and lower tubular control arms with the Roto-joints on one end. Also going with OPG's 1" rear sway bar kit. Right now the rear end is out of the car, all cleaned up and ready for paint. Ordering the new ring and pinion next week and hope to have everything back together and ready to go into the car in a few weeks.


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## BearGFR (Aug 25, 2008)

I'm running Spohn Uppers and lowers on my car, both fully adjustable in chome-moly with sphereical joints. If you can visualize what has to happen in the joints to allow the rear axle to "tilt" (one wheel "lower" than the other) with respect to the frame, you'll realize that the only way the axle can move in this manner with the factory arms and rubber bushings is for the bushings to compress/deform and/or for the arms themselves to twist. Running poly bushings only makes everything stiffer which puts even more twisting force into the arms. For this reason I don't like poly bushings on factory style arms. Using arms with sphereical type bushings allows the axle to freely rotate in this direction without putting tension on anything. THEN you control the body roll with a sway bar - like it should be. Use the adjustable lower arms to adjust "pinion angle" (actually drive line angle), and the adjustable upper arms to locate the axle front to rear and also "square" it with the drive line. 

Bear


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## bowtie30 (Aug 10, 2014)

Thanks for the input Bear. The car has always gone down the road straight and the tires wear evenly so I'm not sure if I need the extra expense of fully adjustable arms? For a few dollars more I can get the Roto-joints on both ends of the lower tubular arms which would eliminate any twist in those arms. On the uppers I'm thinking rubber bushings in the axle with the Roto-joints where the arms mount to the frame? What's your opinion of this set-up and what do you think about the Roto-joints used in the UMI arms? Again, thanks to you and everyone for their input.


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## Bensjammin66 (May 12, 2009)

I run UMI boxed lowers with greasable polys and Roto joints on my '66 Le Mans. Adjustable UMI uppers ( required for my longer drivetrain ) with Energy Suspension poly on the axle side and also their frame braces. A Hotchkis 1" rear sway bar ties it all together. Car handles like its on rails and I cant recommend UMI enough. $750 for everything. If you do a rear sway bar make sure your front is a hair thicker to prevent under steer and start carving those corners!


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## geeteeohguy (Feb 2, 2008)

What do you use the car for? I've run rubber bushings and stock stamped steel arms in both of mine for over 30 years and 100's of thousands of miles with no issues. I replaced the rubber bushings with Moog parts. If you want to upgrade, for higher performance, what Bear did is the way to go. But he's running 500HP, and I'm not even close to that. With your 389 tripower, the stock stuff, if good quality, will be fine. If you autocross the car, not so much. Time to upgrade.


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## Bensjammin66 (May 12, 2009)

So wait a minute.. Geeteeohguy, you mean you drive your cars like a human being? I thought every one went through curvy industrial parks at 3am pushing their cars to the G force limit that the tires and suspension can handle? I cant be the only one, its a hoot! Just watch for the boys in blue they kinda frown on it... 

Though they are kinda big and the suspension is poorly designed honestly, a few aftermarket parts make our cars cut corners pretty nicely. Even if just for changing lanes at 75mph on the turnpike. A little rigidness never hurt.


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## geeteeohguy (Feb 2, 2008)

Ben, I _was_ that guy, 25-30 years ago. I blew up engines. I blew up transmissions. I blew up rear ends. I spent hundreds of dollars on moving violations. I spent every weekend rebuilding my car so I could drive it to work. I am no longer that guy. I'm the OLD GUY driving the really cool car that young guys see and think: "what a _waste_ of a neat car". I'm having a LOT of fun with that one. Sometimes I strike though, like a snake, and the unsuspecting 20 year old in the 5.0 is left wondering what in the world just happened to him. Life goes on!


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## Bensjammin66 (May 12, 2009)

Haha I totally understand. Even if you are not thrashing them todays technology is 10 fold what they had in the 60s. The purests will argue im sure but everything modern ive done to my car has made it a better driver than what it was. From 4 wheel power discs and electric fans to HID headlights and a bluetooth radio. I have a Le Mans tho, and I never fault 242 owners for staying original.


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## BearGFR (Aug 25, 2008)

I love the sphereical (roto) joints top and bottom. My car runs mostly Spohn pieces but I've got the UMI control arm mount braces -- and they are quality parts as well. 
Like GeeTee said, for a more or less stock car the factory setup is fine. If you've got the budget headroom I think you'll really like the way the car feels with the upgrades you're talking about.

Bear


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## geeteeohguy (Feb 2, 2008)

Yes, I agree. These cars were built with a budget in mind. To change out cheap stamped parts for precision engineered, adjustable and higher quality pieces can do no harm. I agree on the tech aspect, too: new technology helps a bunch. I'm a semi-purist, but run radials on my cars. I drove them for years with bias plys back in the day, and I'm tellin' you, it's a world of difference with just that one change. Today, we treat our cars with more care and quality parts than back then, when they were merely cheap used transportation with a big hairy engine. Nothing wrong with that!


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