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Discussion Starter #1
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.


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. :rolleyes:

If anyone wants two slightly used stock length BMR uppers, make me an offer.

Bill
 
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Discussion Starter #2
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...
 
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Discussion Starter #3
I need a set of adjustable uppers; hope they build them soon...
George
 
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Discussion Starter #4
Hi:

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

John
 
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Discussion Starter #5
I think Wayne summed it up, sometimes you do more research on the mod AFTER you've gone & done it.
Bill
 
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Discussion Starter #6
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.
 
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Discussion Starter #7
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
 
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Discussion Starter #8
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
 
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Discussion Starter #9
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 ;)
 
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Discussion Starter #10
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...
 
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Discussion Starter #11
I am impressed that the GW sphericals do not use any grease fittings like they do for the Del-Alum ends...
I think that's because they are "lined" with a teflon impregnation... but i'm not positive on that.

I'm in the process of working with a couple of companies to come up with a spherical for our upper arms... one that you could use in whatever arms you happen to have. Really just a repalcement for the factory bushing on the Diff end. This way you can run a poly bushing at the frame end and not worry about bind.
 
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Discussion Starter #12
Rustic,
Maybe I will have a set of shperical & adjustable rear upper arms on my car for the Vegas trip and a spare set for people to gawk at...
I'll retain the stock rear upper bushings on the pumpkin to account for axle "wrap-up" no other rubber bushings though; lower arms Global West....<---Need some movement allowance as the axle winds up & spins on the ring gear & tries to twist in an opposite direction of the wheels.<---Same principle as racing slicks have thin sidewalls to allow the tire to twist & wrap-up instead of applying all the power to the ground in one big instantly sharp blast. Interesting toys are available to install on a car to control rear axle wrap-up; internet search "Wrap up".
George
 
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Discussion Starter #13
I love my new spherical upper control arms & the handling improvements. No more wandering in road wear troughs :D




George
 
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Discussion Starter #15
GODSPEED,
Thanks-A-Lot...

I gotta get a move on and do a chassis bind test on them to ensure they don't hit or touch anywhere when the axle is tilted to the maximum possible, i.e. bumpstop firm against chassis on one side & shock fully extended on other side. Should be fine the way it drives out my steep driveway & the driving I did over speed bumps today!

Also, I gotta move quick to finish up my 2nd Gen model which will use 7/8"-14 turnbuckle versus 3/4"-16 [for the descriminating customers with supercharged engines]. Furthermore the 2nd Gens will have a darn wrench flat on the turnbuckle.

George
 
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Discussion Starter #16
Looks like you could use rod ends from March, although you might want larger diameter. Check out www.mcmaster.com for all kinds of specialized hardware like that.

c.
 
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Discussion Starter #17
CC,
Rod ends would be nice but they would have to be aircraft quality type [Mc Master Carr is not the place to go for high quality & low prices]. Using them would increase the cost to build & price to buy the control arms. How much are you willing to pay for a pair of rear upper control arms; way more than $300.00..? Please re-read Imalabil's original post which started this thread; he was only into it for $380.00..!

Rod ends would be no better than the sphericals which are already on the foward end of my arm design. The sphericals I am using are for heavy duty 4 x 4 off road use; they have a 1/8" thick Chrome Moly case and are high articulation. If I used sperical rod ends or beefy Delrin bushings on the axle end then I would need four to support the two yokes but still use the stock rubber axle bushing. Having the one spherical & using a yoke to attach to the stock rubber axle bushing works well. The stock rubber bushing has some compliance which helps reduce wheel spin under heavy throttle. I don't plan on ditching the axle's rubber bushings even if I used rod ends to attach to them: Does Your Suspension Bite?

An extreemly expensive & fancier arm could be of great benefit in a more capable automobile but these work fine. The spherical arms are on my car now and they work great; a big improvement over the stock arms.

FWIW, check-out my web page for the "Bind" testing I just completed...

Most respectfully--George
 
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