Project Regress: Urban myths and legends about re-inforcing Z-Bars

CopperNick

CopperNick

Master Mechanic
Feb 20, 2018
270
43
Canada
For those who have been following my progress in the "Z" bar zone, it took a second trip to the welding bench before I was satisfied with the integrity of the welds that hold the upper arm for the upper clutch rod to the Z-Bar. I had been dressing the first passes using my trusty Dremel tool to knock down the high spots because lit is adjustable for speed and can get into tight areas where a 4.5 might reach but cause issues in doing so when I discovered that a second portion of the original welds had suffered pin holing as well. Rather than over-welding it, I decided to grind out all the suspicious material right down to the tube and replace it as well. Did that today but, before it goes to be cleaned and painted, I have an urban myth/legend about GM Z-bars that I want to run past the forum for comments.

It concerns an often repeated, bench racing anecdote, that GM Z-bars have a tendency to blow up or self-destruct under prolonged or repeated heavy use or load. IN support of that assertion, I do have one salvage orphan bar that has an upper arm with major welding done to the seam where the arm meets and attaches to the cross tube. The work either got done in the field or the welder was practicing because bubble gum does not begin to describe the quality of the work.

So what I am thinking here is that, while the Bar is out and before it gets cleaned and painted, I could go ahead and fabricate a pair of ribs or angle braces for the arms, upper and lower, using some orphan 1/2 inch wide by 1/8 thick angle that I have sitting in the surplus bin. Neither brace needs to be to big or long, thinking maybe 4 inches or less for the longer and whatever fits for the shorter.

Comments or thoughts on this??

Nick
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
7,077
113
Queens, NY
I took my advice from Tom Monroe's Clutch And Flywheel Handbook. My upper arm began to break away from the Z-bar as the factory weld was not very good. I stripped the Z-bar down, cleaned all the grease out from the inside, and welded the re-inforcments to it. What I did first was to re-weld the arms to the shaft. Then I found some big washers that fit the shaft, ran them up against the upper and lower arms, and welded them to the arms as well as all around the inner circumference of the washer. That way the arms were solid to the bar and washers, and the washers were solid to the bar. I used my acetylene torch to get the welds as thorough as I could. I have had zero issues ever since. Here you can see the upper arm while I was re-drilling a hole for better leverage and the spherical rod end pushrods. The weld is 27 years old.
IMG_1040.JPG
 

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xylorex

xylorex

Greasemonkey
Aug 2, 2018
183
43
New Orleans, LA
after reading your post, I put down my cocktail down and ran out to the garage to dig mine out -- sorry its not cleaned up better.

my dad and i had this made at a machine shop about 25 years ago because the original one broke, this one is pretty stout.
 

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bracketchev1221

G-Body Guru
Jan 18, 2018
640
93
I gusseted mine and then I even welded a pipe over the lower adjuster so I didn't have 2-3" of unsupported threaded rod.
 
TURNA

TURNA

Rocket Powered Basset Hound
Jul 24, 2009
11,007
113
Socialist NY
When I ran mechanical linkage I gusseted mine as well just like xylorex did.
Never had a issue with it.
 
CopperNick

CopperNick

Master Mechanic
Feb 20, 2018
270
43
Canada
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Yeah, I know, the pictures are blurry, but you do get the general idea. After reading what Bonnewagon and all of you who responded to my thread, I actually considered winding up the rubber bands on the lathe and whittling a couple of pairs of collars that I could split and insert on either side of the two arms; similar to what Bonnewagon came up with for his fix. But I had already gone through the exercise of cutting away all the rotten factory welding and rewelding the affected seams so a plan B had to be chosen. if you can get past the blurriness, what I did was to score some 1/8th x 3/4 angle, the stuff made by pressing flat plate, not the extruded product. Took some rough measurements and a guess or two and came up with the angle braces you see above. For the upper arm, all I did was to "extend" it by attaching the brace to the open face and bring it down to meet the tube but in a straight line, creating something of a triangle. For the bottom it was simpler, and again what I ended up with was a triangle. Using the angle for the braces should give me additional strength against twist or torque on the arms or fingers; at least that is the SWAG/Theory.

The welds are still waiting on a little more finishing and polishing before I throw some paint at them. My Dremel tools are being persnickety and demanding new brushes or they won't work. Despite getting great penetration on the passes due to having a lot of open edges to work with, I don't want to take too much away; just enough to make the seams look finished. Yeah, yeah, I know, I know, located where it is, you can't really see much of it but in my world there will always be someone who will get down on their belly like an inch worm and slither underneath the car to see if it is genuine and not bogus or a sham. (Idiots)

Nick
 
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TURNA

TURNA

Rocket Powered Basset Hound
Jul 24, 2009
11,007
113
Socialist NY
Nice, but do u have the clearance for such a large gusset?
 

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