Latest mod...stock UCAs!!! - Chevy Impala SS Forum
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post #1 of 18 (permalink) Old 04-05-2004, 10:11 PM
Imalabil
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In the live and learn category, I had my stock length BMR uppers pulled off and my old upper CAs bolted back in place. 80-90% of my wheel hop on turning while accelerating from a stop is now GONE!! It's SO nice not to have that constant shuddering when launching. As I expected, it's quieter, too.

The BMR bushings at the diff had their edges torn, no doubt from the twisting action of the steel yoke when one side of the car jounced and the other didn't. One of the arms had the sleeve in the black plastic bushing at the frame end shifted to one side, permanently deformed. I'm a definite believer in the Global West assertion that the uppers MUST be able to twist when one side of the axle compresses and the other doesn't. It only cost me $380 (arms + two installs) to learn this lesson. [img]graemlins/1.gif[/img]

I don't doubt rigid upper arms are fine for drag racing applications, but given the geometry of the 4 link design of our rears they are unsuited for track work or street driving unless a different, more compliant bushing can be designed. But at that point, what's the advantage over stock uppers? The alternative would be an upper split in cross section half way along its length with a real stout joint that permits rotation of the two sections but no axial movement. Probably too rich for my blood.

My old uppers, BTW, were in great shape after being on the car over 100k miles. No cracks in the metal or rubber, and no oblong holes, just a little surface rust.

I guess to have only one truely bad experience in over 9 years of modding is still a pretty good record.

If anyone wants two slightly used stock length BMR uppers, make me an offer. [img]tongue.gif[/img]
Bill
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post #2 of 18 (permalink) Old 04-05-2004, 11:18 PM
spaughman
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I don't think their is an "advantage" over stock uppers, unless you're trying to center the rear wheels.

Global West is supposedly making headway on their new uppers...
post #3 of 18 (permalink) Old 04-06-2004, 02:07 PM
coprice
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I need a set of adjustable uppers; hope they build them soon...
George
 
post #4 of 18 (permalink) Old 04-06-2004, 06:02 PM
JRP09
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Hi:

Spoke to Global West yesterday. He said give him a month. So, probably by the end of June they'll be ready.

John
post #5 of 18 (permalink) Old 04-06-2004, 07:15 PM
Imalabil
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I think Wayne summed it up, sometimes you do more research on the mod AFTER you've gone & done it.
Bill
post #6 of 18 (permalink) Old 04-06-2004, 08:30 PM
threeimpalas
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This is why you leave the factory style rubber bushings at one end of the upper arms when you switch to poly. I left the stockers in the axle when I went to extended arms and haven't had a problem with the bushings in them.
post #7 of 18 (permalink) Old 04-08-2004, 08:01 PM
Imalabil
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I have to wonder how long the stock bushings will last. The stock design has compliance in both bushings and the arm itself. The hard plastic bushing/BMR arm is not very compliant, so most of the twist will have to be taken by the stock bushing.

Bill
post #8 of 18 (permalink) Old 04-09-2004, 11:53 AM
Chrisbequick
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Quote:
Originally posted by Imalabil:
I don't doubt rigid upper arms are fine for drag racing applications, but given the geometry of the 4 link design of our rears they are unsuited for track work or street driving unless a different, more compliant bushing can be designed. But at that point, what's the advantage over stock uppers? The alternative would be an upper split in cross section half way along its length with a real stout joint that permits rotation of the two sections but no axial movement. Probably too rich for my blood.
Two words: Heim joint. BMR and Spohn use them for their control arms and panhard rods for F-bodies and they work great.

-Chris
post #9 of 18 (permalink) Old 04-09-2004, 12:43 PM
AutocroSSer
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Actually, the even better solution is a lined spherical bushing.

There's a reason that Global West uses those on the front of their lower arms
post #10 of 18 (permalink) Old 05-06-2004, 01:47 PM
coprice
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Nice pieces them Global West products... I am impressed that the GW sphericals do not use any grease fittings like they do for the Del-Alum ends...
[img]graemlins/5.gif[/img]
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