GW solution for rear uppers is coming (soon???) - Chevy Impala SS Forum
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post #1 of 14 (permalink) Old 02-29-2004, 07:31 PM
Navy Lifer
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This is a follow-on to an old post that seemed to best provide the background to add in these comments but put a new Subject title in play.

https://impalassforum.com/noncgi/ulti...;f=16;t=001769

(new comments)
I was at Global West's shop on Friday, and I have seen their new "no-bind" adjustable rear upper control arms--well, actually photos of the prototype parts. The design is trick enough that they are applying for a patent--that's all I will tell you about them, other than they should work very well, and will accomodate extended rear axle situations. Doug did tell me they will offer the TBC-12 rear lower control arms in an extended version once this new upper arm is available.

The adjustable upper and extended lower arms are NOT available yet--I'll keep everyone posted on this, so please don't "BUG" the guys at GW about them. Bottom line is that once the patent application is filed and their design is "protected" they'll start making them.
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post #2 of 14 (permalink) Old 02-29-2004, 08:32 PM
BAD ROD
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Cool! great news Bill.

Mike [img]smile.gif[/img]
post #3 of 14 (permalink) Old 03-01-2004, 02:33 AM
coprice
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Thanks Bill,
Maybe there is some good in the Global West 3/4 inch extended lower arms in my garage...

I hope they just install a trunion affair and have bushings on either end. I think going with a spherical joint anywhere on an upper arm would allow the axle to move left & right. I also hope their design will allow use of the stock 9C1 bushing in the axle ears to get good launches without wheel hop...
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Thanks Again for the Good News
George
 
post #4 of 14 (permalink) Old 03-01-2004, 06:39 AM
Navy Lifer
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George,

Can you explain what you mean about a "trunnion affair"?

I can only say that in the design of the typical 4-link rear suspension system, it is the opposing angle of each control arm pair that keeps the side to side movement from occuring, while still allowing up and down movement. I share your concern, but I'm confident the new GW system works. There are other upper control arm systems in use (Dick Miller Racing, for example) that have spherical bearings on both ends of the uppers--and I've not heard of any issues with lateral location using them. I don't know what part the presence of spherical bearings on the lower arm (front of the GW arm) plays in how much lateral motion can occur, if any. This would assume all of the components are working as designed, as I can see that worn components (bushings, bearings, etc) might change the behavior.

Since I'm not running a conventional rear sway bar, I do wonder what part the rear sway bar plays in affecting the lateral motion of the rear suspension, regardless of the design of the rear control arms.
post #5 of 14 (permalink) Old 03-01-2004, 07:02 AM
Lynden
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Quote:
Originally posted by XBOXROX:
Thanks Bill,
Maybe there is some good in the Global West 3/4 inch extended lower arms in my garage...
Thanks Again for the Good News
George
How did you get the GW LCA's in extended? I called them up and they said that the only did stock length arms. I had to take mine to a guy and have them lengthened.
post #6 of 14 (permalink) Old 03-01-2004, 06:16 PM
Brick B-Body
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Is it too soon to sign up for a GP on these arms?
post #7 of 14 (permalink) Old 03-01-2004, 10:45 PM
coprice
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Grimpala,
Maybe I was just lucky but I spoke with Doug the Global West manager last November and he said no problem ordering extended arms. There was a good wait though because Global West relocated and Steve said the special order [same price] extended arms are seldom done and get put on the back burner while their regular wares are being produced. So, I think "Doug" is the person to speak with just as Ed Runnion instructed. Don't feel bad, I am going broke in other ways too.

Bill,
I am still a dummy with respect to the rear of these cars but eventually, I will get my butt under there and begin learning; gotta finish the front first: Global West Install [PICS]

The shperical joints [bolt sleeves] on these GW lower arms allow movement in every direction. The sleeve ends even move closer and further from the centerline of the control arm due to the arc they can achieve [20 degree angle?] although this end movement is a very minor amount. In other words; if only the front [shperical joint end] of the rear lower arm was fastened onto the car, the other end could move in any direction [a great deal of movement] as well as being able to twist the arm a good amount.

IMHO [remember I am still dumb about the rear] Global West already uses shperical joints on their rear lower control arms. If there were four shperical joints [all four rear control arms shperical jointed at their front] then I am wondering if they would prevent the rear from shifting left & right? Maybe? Maybe not? Help?

Maybe the other three control arms would prevent the one from allowing the rear end to shift left or right any appreciable amount [I dunno?]. I am not a rocket scientist but even I figured out by looking at the BMR adjustable upper rear arms that the twisting action placed upon them as a result of any bump to one rear wheel could cause the threaded adjustment to move. Worse, there is no provision to allow twist as the BMR arms have no flex like the stamped stock arms.

I meant trunnion in that it would be like having one GW Delalum bushing somewhere in the "length" of the arm to accept the twisting motion. It could even be threaded to allow length adjustments] and then use regular configuration bushings [no shpericals] on either end. So, if not using shperical joints, there [should] needs to be three bushings in any rear adjustable control arm to account for all the motions it will deal with [except] it will not allow [help prevent] left or right motion such as a shperical joint can do..?

Trunnion is an old fashioned suspension joint; think of it as a driveshaft universal joint without the fourth branch...

Sorry for the P Poor English --- Help us out here will ya Bill...
Thanks--George
post #8 of 14 (permalink) Old 03-01-2004, 11:18 PM
coprice
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Bill,
I think there might be another issue that hopefully Global West rear upper adjustable control arms will address. In that, by moving the rear end aft [say 3/4"] it causes the foward end of the upper control arm to be off an equal amount [in this case 3/4"] from its original bolt up point. The new center of this bolt up point would be 3/4" towards the center of the car. Probably the easiest way to get the 3/4" would be to jog the center of each end off by 3/8". So, the aft end of the arm would be shifted 3/8" "out" [to the side of the car] and the front of the arm shifted "in" towards the center of the car. I doubt these BMR arms are designed this way but maybe; I will need to get educated under the car...

Hope you understand my meaning?
George
post #9 of 14 (permalink) Old 03-02-2004, 12:38 AM
Navy Lifer
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A little early, Joel....but I'll do what I can when the time comes!

George,

Saw your front end pix and parts photos. Fun times ahead...

The GW (rear) lowers--assume we are talking the primo version with spherical bearing at the frame end and DelALum at the axle end--take all of the motion that resulted from deflection within the rubber bushings and flexing of the stamped arm and replaces that with the spherical bearing's ability to articulate "x-degrees" in each direction, sufficient for free axle movement in its normal limited range (by length of shocks--extended--and by bump stops--fully compressed) in a situation where one side is completely up and the other down. The Del-A-Lum bushing(s) in the axle-end of each arm has zero deflection, essentially. Properly installed, the lower arms alone will provide 90%of the work/force to locate the axle side to side, but when combined with the upper arms operating at opposing angles, the rear axle should be quite resistant to side motion, regardless of the type of bushings/bearings used in the upper arms. Look at it as a form of triangulation--thats about the best I can do to describe it.

Because of the way the GW lower arms rotate as the suspension moves, it is especially important to have good fasteners securing the rear sway bar to the arms.

This is not to cast doubt on the way the BMR upper arms you are speaking of work. If the link is adjustable, is a solid tube that cannot flex like the stock stamped part, and the bushings have limited flexibility (poly?) then I do see a problem with them. Based on a number of comments about the bushings coming out of them, I would be inclined to not use them unless I was doing "straight-line" work only--but very few of us limit our cars to that sort of driving.

Without spilling too many beans here, you are thinking in the right direction in your comments about having a DelALum in the "length" of the upper arm(s). Not exactly what it will be, but in the end it will seem to be a fairly simple (now why didn't I think of that!), even elegant design.

As for your last post, the concern you are expressing is what has been bothering me from the beginning with moving the axle back. The fixed "target" of the 2 frame mounting positions with 3/4" of additional control arm--or whatever the added length calculates out to for the angle that they run--would be to 2 new mounting points further out on each side of existing points on the frame bulkhead. So, when it comes time to put the bolt through the hole for the bushing at one end or the other of the upper arm, the only way to get the link and bushing to line up is by force, so you are starting out with the bushing side-loaded statically--NOT good, and part of the reason, I suspect, that the BMR uppers' bushings have been problematic. I have assumed that one solution would be to offset the link between the axle bushing and bulkhead bushing more or less as you describe, but no manufacturer has seen fit to do that yet, since the Impala SS and Caprice are the only cars this "axle relocation" is being performed on, to my knowledge, and they probably don't want to complicate their manufacturing by having a special part "just for this configuraton" even though it is fairly common in our community/vehicle population. Recognizing the problem is only half of the answer--getting someone to provide the fix is the other. Some of us with fabricating skills could cut and re-weld the link at one end or the other to correct this alignment problem--you too, George!

The new GW rear upper system will take care of this problem by its design, so no issue there. The system will work very well with stock rubber bushings (on the axle ears) for standard location axles. There will be an added bearing in place of the bushing(s) for the rear axle if the axle has been relocated, but the added bearing can also be used on standard location setups, too.

The only thing that has me a little "bugged" in the whole axle location business is just how important the actual angle of the upper control arms is to the overall side-to-side control and positioning of the axle in relation to the frame/body. From looking at it, I think the total angle spread between the 2 upper control arms is at or greater than 90 degrees. I have not done any measuring, nor have I determined what the change in angle is (it becomes less--a narrower angle--that I am certain) when the axle is moved back. If the stock arms are at exactly 90 degrees, then extended arms will result in a total angle of opposition of the 2 upper arms of less than 90 degrees. I'd have to go back and study my 7th grade geometry, but I am fairly certain that in a triangle, or in a triangulation situation, any angle other than "exactly" 90 degrees becomes unstable, so the whole question of how well the upper arms will maintain proper side-to-side location becomes a concern and occasion for further investigation. Maybe someone with a M.E. degree or with a CAD background can do a better job of evaluating how it works and why.

Are you still with me...George?
post #10 of 14 (permalink) Old 03-02-2004, 02:07 AM
BLAZN
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Quote:
Originally posted by Navy Lifer:
I was at Global West's shop on Friday, and I have seen their new "no-bind" adjustable rear upper control arms--well, actually photos of the prototype parts. The design is trick enough that they are applying for a patent--that's all I will tell you about them, other than they should work very well, and will accomodate extended rear axle situations. Doug did tell me they will offer the TBC-12 rear lower control arms in an extended version once this new upper arm is available.
Looks like I'll be going back into my suspension after I upgrade everything later this month. [img]smile.gif[/img]
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