The reproduction z-bar on my 70 GS 455 failed after about 500 miles. It bent to the point where it would no longer release the clutch. When I first installed the reproduction z-bar, I did have to slightly bend it to get the Zbar-to-clutch-fork push rod to align. Note that the original factory piece has this bend, where as the reproduction does not. Here is the thread that I posted to describe this process: http://www.v8buick.com/showthread.php?t=166724 The original z-bar that was in my car had been gusseted, so I have put that piece back in. So far so good. Prior to this failure the transmission shifted great with little pedal pressure and smooth shifts. Do you think that I have something set up wrong on my clutch linkage or transmission? The car is an original manual transmission GS 455, M-21, Hurst shifter, original linkage. The only reproduction parts are the z-bar, clutch fork, clutch push rod. The car runs in 13's at Bowling Green.
I'm running a LUK 04-020 clutch kit, which I understand to be an off-the-shelf stock equilivant. Pedal pressure is nominal.
Hi Mike! I took a look the linkage in the Aquamist car and there is no twist in the lower arm that attaches to the adjuster rod. Although, the Z bar itself isnt exactly purpendicular to the engine. Its at a bit of an angle. Notice the angle as compared to the frame bracket.
Hi Jason, The twist that I'm referring to is on the arm that attaches (via a threaded rod) to the clutch fork. Please see the link in my initial post and you'll see what I mean. -mike
Yes, I understood you. The lower arm on my Z bar has no twist. But the Z bar itself looks crooked when installed (see pic).
Yes, mine is like yours -also Greg Davis put a 4-speed into his '68 and his is also angled like yours- frame side slightly ahead of the block side. His works like butter- all Kleiner repo parts too.
GS Enterprises believes that the zbar failure was due to not using the original style zbar-to-clutch-fork threaded rod that they supply.
...begging the question, What were you using? The stock type with a crappy rubber bushing lends itself to misalignment, twisting, a quick degradation of the rubber, metal to metal contact, etc. I use a female spherical rod end with a stud and lock nut that truly is smooth like butter. My last clutch was a borg & beck style that ruined the clutch pedal, probably the thrust bearing, but never the Z-bar.
Hi Brad, I was using a female spherical rod end with a stud and lock nut. Yes, it was smooth like butter, right up until the zbar bent. I was also using a small piece of radiator hose to mimic the factory rubber boot covering the zbar-to-block-stud. Apparently this keeps debris out of this area. Perhaps the hose was too long and placed the zbar too far away from the block? A Buick 4 speed owner and engineer from Loveland Colorado blueprinted these 4 speed pieces some decades ago. I had thought that he was your uncle, Brad? It would be curious to see how an original zbar compares to the NOS copies. Again, both of my originals have a slight twist to the lower arm to better align with the push rod. That is why I modified the GS Enterprises arm to begin with. -mike
BTW, the clutch that I'm running (LUK 04-020) has a release load 450#, finger height 2.096". This is nearly the identical specs recommended by GS Enterprises.
Bill and Mark Macoubrie are the Buick GS guys that I was thinking of, i.e. they are relatives of the Buick 4 speed owner and engineer from Loveland Colorado who blueprinted these 4 speed pieces many years ago.
