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#1060000 - 11/25/18 05:09 AM Rear control arms  
Joined: Dec 2003
Posts: 1,545
spacemanspif Offline
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spacemanspif  Offline
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Joined: Dec 2003
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Swedesboro, NJ
Hi guys,

Looking for advice on rear control arms and more specifically end styles with real world experience. The end choices are most commonly poly, heim, and heim with a bushing (used under many different trade names).

As I understand it, poly is the area between solid and sloppy stock rubber which sounds kinda good but has binding issues from what I’ve read.

Heim is solid but looks like it would wear out fast due to metal on metal connection. Cheap and light I can see why track-only cars would run these ends but worry about longevity on the street.

Solid with a bushing I’ve seen called “roto-joint” and “Johnny joint” offer solid feel and articulation with (I assume) better durability and option to replace plastic bushings if they wear out.

Now I think it’s obvious that the solid with bushing type is the best, but do they warrant the added costs?

Adjustable uppers allow pinion angle and side-to-side adjustment, so I want those, but do I need adjustable lowers? What more can I adjust with adjustable lowers that I can’t achieve by adjusting the uppers? I assume front-back in case the rear is not in the car perfectly straight and sitting on an angle?

Looking to upgrade arms as part of winter upgrades but am looking to see what options are. I know plenty of places sell arms but before I shop I’m looking to see what ends I should get and what ones need to be adjustable for a street car that sees some drag strip time and might get thrown around cones once in a while too. ~400hp 6.0ls engine going in as part of upgrades and I don’t think hard launches on stock arms/bushings is a good idea.


-Mike

F-body bucket seats, camaro console, carb'd 5.3/4L80E swap

Fastest time to date: 13.671 @ 103.79
Best r/t: 0.007 I got lucky smile

Killed a few cones too

#1060003 - 11/25/18 10:23 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Jan 2008
Posts: 1,124
FinallySS Offline
10+ Year
FinallySS  Offline
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Joined: Jan 2008
Posts: 1,124
Nice Sunny Hawaii
I have no experience with the rear arm or bushing, but word on poly bushing.

Squeaking and binding will be eliminated when you lube them really good. My current SS have real bad squeaking and binding due to not lubing the bushing good before installation. I have Energy Suspension stuff on and did not lube them good because I was afraid that it will run out of lube. At the end, I had plenty of them left but decided to install them anyway. Bad decision.

My second SS which is gone now, had same bushing installed but this time around, I lube them good and installed them. Before I trashed the car, I remove both front upper and lower arms and replaced them with rubber bushing ones ( I had spare because I was going to replace the ball-joint. run the rubber ones while I have the poly bushing ones service). Didn't have any squeaking while I had them on, and bushing didn't show any binding (no burnt mark or any wear mark on them). I plan to run them on my current SS as soon as I have time to remove the arms ( I'm currently working on, my SS, DD Lincoln LS, trying to restore 82' KZ750 and '89 ZX-7 and many other fixing project which my wife are yelling at me).

BTW, I have Hotchkis non-adjustable lower arm with stock upper at the rear, planning to upgrade the upper soon with adjustable ones. Lower arm has grease fitting and haven't give me any problem or squeaking.


1986 Silver MCSS - Poly bushing and Hotchkis spring w/Bilstein, Posi w/3.73, MSD 6-AL, E-Brock 600cfm, Aluminum 2-row radiator.
1986 Black MCSS - R.I.P............Finally.
#1060004 - 11/25/18 01:00 PM Re: Rear control arms [Re: spacemanspif]  
Joined: Dec 2007
Posts: 5,761
SSLance Offline
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SSLance  Offline
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Joined: Dec 2007
Posts: 5,761
Peoria, AZ
I have run both UMI Roti-Joint ends and Ridetech R joint ends on my car and yes...they are worth the added cost. They let the rear suspension work without any bind which is what you want. I only just recently replaced the rubber bushings in axle with R Joints and I can even tell the upgrade with just those.

The adjustable lowers let you dial in thrust angle. If you have ever had the car aligned, look at rear thrust angle #s on sheet to see how far yours is off if any at all. Double adjustable on uppers is nice when doing initial setup but you can get away with single adjustable with a little bit of extra work.


Lance
1985 Monte Carlo SS Street Car
#1060015 - 11/26/18 12:32 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Dec 2003
Posts: 1,545
spacemanspif Offline
15+ Year
spacemanspif  Offline
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Joined: Dec 2003
Posts: 1,545
Swedesboro, NJ
Thanks for the advice, Finally and Lance. Both have confirmed my suspicion that it’s better to do it right the first time. I’ll have to look at my old receipts to see if thrust angle is on the alignment sheets, but might get them just in case my rear is out of whack. Forgot ridetech makes arms, have to look into their offerings as well.


-Mike

F-body bucket seats, camaro console, carb'd 5.3/4L80E swap

Fastest time to date: 13.671 @ 103.79
Best r/t: 0.007 I got lucky smile

Killed a few cones too

#1060022 - 11/26/18 04:10 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Jan 2000
Posts: 4,158
mmc427ss Offline
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mmc427ss  Offline
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Joined: Jan 2000
Posts: 4,158
Pottstown, Pa
I've been running this Spohn LCA for 8 years now. The Del-Sphere (Roto Joint) hasn't needed any attention, it just works well. As Lance mention thrust angle adjustment is what you can dial in. Recently when I did the front end mods i also moved the rear back 1/8" via the arms. Thrust angle reset again.
https://www.spohn.net/shop/1978-198...-Adjustable-with-Spherical-Rod-Ends.html

Couple notes here:
The LCAs offered either have or don't have sway bar mount points. It's't best to get the bar off the LCA, bind is one problem but the LCA mounted bar is very ineffective.
I've found the length of most aftermarket LCAs are shorter than the stock arm. The Spohn arm came set at 18 5/8", the Global West arm it replaced was a fixed 18 13/16", a stock G arm is 19 1/4" if i remember correctly. Just be aware of this. As the LCA length changes it moves the wheel fore or aft in the wheel well, also this can effectively move the driveshaft in or out of the trans changing the endplay. Don't forget this also effect pinion angle with a shorter LCA. So after swapping in a new LCA these things are necessary to check.
LCA to adjust the thrust, fore/aft position in well, UCA for pinion angle and a little tweaking of rear position side to side.
Bob

#1060023 - 11/26/18 04:15 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Nov 2003
Posts: 493
Chevyman540 Offline
15+ Year
Chevyman540  Offline
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Joined: Nov 2003
Posts: 493
LaPorte, Indiana
SSLance, do you have the Roto-Joints on both ends of the control arms or just one end? I've been considering putting Roto-joints on the car but not sure if both ends of the arms are needed.


87 MCSS 540 BBC 736hp@6300 677tq@4800 t400w/transbrake 9"rear 4.30 gear
#1060024 - 11/26/18 04:27 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Dec 2007
Posts: 5,761
SSLance Offline
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SSLance  Offline
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Joined: Dec 2007
Posts: 5,761
Peoria, AZ
On Both ends is best...


Lance
1985 Monte Carlo SS Street Car
#1060026 - 11/26/18 04:45 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Jan 2000
Posts: 4,158
mmc427ss Offline
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mmc427ss  Offline
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Joined: Jan 2000
Posts: 4,158
Pottstown, Pa
Yep both ends, UCA and LCA is best.
Bob

#1060027 - 11/26/18 04:45 AM Re: Rear control arms [Re: spacemanspif]  
Joined: Nov 2003
Posts: 493
Chevyman540 Offline
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Chevyman540  Offline
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Joined: Nov 2003
Posts: 493
LaPorte, Indiana
Ok, when I get down to PRI next week I'll talk to the guys at UMI.


87 MCSS 540 BBC 736hp@6300 677tq@4800 t400w/transbrake 9"rear 4.30 gear
#1060041 - 11/26/18 11:39 PM Re: Rear control arms [Re: spacemanspif]  
Joined: May 2007
Posts: 4,634
Buick Runner Offline
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Buick Runner  Offline
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Posts: 4,634
Dharma station 1 the Hydra
The 4 link rear suspension that most G bodies use requires the bushings to deflect and the arms to twist to prevent binding. Basically, the stock rubber bushings act like a crude ball joint, allowing multi-axis rotation. The shaft doesn't rotate in rubber bushings, instead, the rubber bushing twists to allow for movement so there is little friction. Poly bushings act more like a metal bushing, only one axis of rotations, and the shaft rotates inside the bushing as poly doesn't twist which causes stiction which results in squeaking. Also, poly cold flows so it will deform and egg out sooner than rubber.

When the 4 link binds, it causes understeer which can trick the driver into thinking the car is handling better. However, if the suspension snaps out of the bind, the car will suddenly without any warning go from understeer to oversteer, what is called snap oversteer. When snap oversteer happens, you most likely will not be able to regain control and will crash. Even professional stunt drivers have a very difficult time recovering from snap oversteer.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1060161 - 12/05/18 09:33 PM Re: Rear control arms [Re: spacemanspif]  
Joined: Jun 2012
Posts: 150
axld Offline
Member
axld  Offline
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Joined: Jun 2012
Posts: 150
lakeland,fl
spacemanspif, I have used different styles over the years . I currently have the UMI UCA and LCA , roto joints all ends, and the uppers are the on car adjustable ( which are very handy to set pinion angle) and the rears are fixed square tubing. my rear wheels are close to being center ( Quick 9'' ) . no complaints . And I give it hell .


86 SS . Custom Paint. Built 6.0 with LS3 Top End .TSP Custom grind cam.TKO 600 5 spd. Quick 9'' / 3.70 Gearing. ZQ8 Spindles. KORE3 12.8'' frt Brake Kit. UMI Rear Adjustable UCA. Rear LCA. UMI Front Chassis Bar. BMR Coil Springs. BMR Rear Sway Bar. N90 17'' Wheels . 255/45-17 Nitto 555 G2's. SO FAR..............lol.

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