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5/9/14 1:18pm - Original Message: 'Clutch linkage is 'wonky' '
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
I had previously inquired about adjusting the shifter linkage on an M21 in my 72. This was due to difficult shifting as in the lever does not want to push into the gate. One member had suggested that the clutch was not disengaging completely and that is where we are at. With slack at near 0 and the clutch mashed to the carpet the thing would shift "ok". The actual clutch engagement is about 1/3 to half way up off the floor. Odd. Kind of a long press to shift and then you foot comes up pretty far to engage. Yesterday I installed my ACC custom floor mats (blue with silver Stingray embroidery....Cool )and the darn thing wouldn't go into gear. That little extra bit of carpet is holding the clutch pedal up a smidge. Ok, something is wrong here. Either the clutch linkage is the wrong ratio (z-bar, clutch fork....I dunno) or there is an issue with the clutch itself. It engages and works smoothly and properly. It is new. I do not have receipts from the PO so I have no idea what clutch is inside the bell housing. Thoughts?

I found specs on the clutch fork: 64-81 Corvette Part # 3887177 Fork is approximately 10 3/8"
from tip of bearing retainer end to center of push rod pin hole.
Anyone have any z-bar measurements?
I've also noticed I do not not have a clutch return spring from z-bar to body.

Dave


____________________________________
My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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5/9/14 2:04pm - Reply: 'Re: Clutch linkage is 'wonky' '
F4Gary Gold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.

Joined: 8/26/2006
Posts: 904
I was under my car last weekend and I found that clutch return spring broken and hanging down limp at the firewall.  Don't know how long I've been driving it that way, but it seems to work fine.

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5/9/14 10:39pm - Reply: 'Re: Clutch linkage is 'wonky' '
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19507
Unless the z-bar is bent, it's not your problem. I'm assuming you have adjusted the clutch linkage as far as it will go, and still have the problem?
There are two different throw-out bearings....if you have the shorter one, and it takes the longer one, that could be the problem. The pivot ball for the fork on the bellhousing may have been changed to a shorter one, also. Either one of these can cause what you are describing.
These problems start when replacing the original Borg-Beck/Long type clutches with a diaphragm type clutch. They are not the same, geometrically, and if the parts are not matched, you run into this issue....no disengagement. The diaphragm type pressure plates are a lot easier on your legs/knees, but getting all of the correct parts in a kit can be tough.
Since you dint replace the clutch yourself, there's no telling what the heck it's got in it...Ouch

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Joel Adams
C3VR Lifetime Member #56    
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5/11/14 1:05am - Reply: 'Re: Clutch linkage is 'wonky' '
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
Z bar looks correct and not bent. I'm leaning towards the clutch having mus-matched parts. Everything else looks proper from the outside. I didn't run out of threads on the clutch pedal rod. I was able to adjust it to 0 slack. Not pre-loaded but no slack either. I contacted the PO and he doesn't recall what type of clutch or brand he installed but he's not a real knowledgeable guy so I would not be surprised if he just picked up a basic diaphragm type clutch. Now if this is the case, is there a method to updating the pivot ball and or throwout to appropriately matched parts?

Thanks again,
Dave


____________________________________
My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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5/12/14 3:08pm - Reply: 'Re: Clutch linkage is 'wonky' '
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
Joel, I think I have my research in order as far as which bearing for which type clutch, correct fork PN and ratio but do you know which of the two pivot studs should be paired with which type of clutch? That info seems to elude me.
It would appear there is no way to get around pulling the trans...Ouch . Major black eye for me. Boooo....Hey at least I'm well versed on how to pull the drive shaft now.

Thanks,
Dave

____________________________________
My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

 Reply Reply  Quote Reply w/Quote
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