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4sp manual trans shifter shaft pin. My views
Posted by: philgmx ()
Date: June 18, 2017 11:23AM

I meant to open a discussion of the problematic shifter/transmission pin premature wear and I found that a pretty good one already took place.
The problem discussed was that the GM pin holding the transmission shifter shaft and the coupling tends to have a short life. I have looked at the pictures provided and noticed that the wear occurs at both ends of the pin which suggest that the pin is chewing itself on the transmission shifter shaft at the coupling level. This is understandable: the 9/16" hardened steel shaft and the 7/32" pin hole are a straight fitting, no spline, no keyway. In other words nothing whatsoever to prevent the coupling from vibrating and repeated sliding/rotating motion to shorten the pin's life. My project by the way is a Corvair powered kit car, not a Corvair, therefore what I have done may be of interest to builders in my situation.

My answer is to fabricate a split coupling (see picture). Quite simple to make really. Two 5/8" mild steel flats. I drilled first the 1/2" shifter shaft end hole , then the 9/16" transmission shaft hole. Then I drilled all the smaller hole including the 7/32" pin's that you can see on the picture. I shaved about half a mm from each flat (under a vertical miller) and bolted the whole thing together as a split coupling. The pressure from all the 1/4" bolts holds both shafts pretty tight the pin does not move at all. I expect this arrangement to keep the pin from wearing.smileys with beer

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: MattNall ()
Date: June 18, 2017 11:40AM

That may work for your build.... but in our factory vehicles the powerpack is mounted in rubber and there needs to be a flex Joint.

[american-pi.com] makes a Billet coupling that we've heard no complaints.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: philgmx ()
Date: June 18, 2017 01:01PM

Yes I am aware of that. My system may be of use to non GM corvair powered vehicles tinkerers. Thanks for your point. I suppose the rubber dampener was designed by GM to cut down on transmission vibrations being transmitted to the shifter.....Hummm, I may have to look at that later.

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: steve c goodman ()
Date: June 18, 2017 01:45PM

philgmx can I ask what you think is 'premature' wear of the coupler/pin? I don't change them constantly at the shop. Sure they wear but I count it in years instead of months that a customer needs a replacement.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: jjohnsonjo ()
Date: June 18, 2017 02:33PM

I changed mine at 130K miles. That was several clutch jobs worth.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: philgmx ()
Date: June 18, 2017 06:20PM

I am just going by gut feeling and...what I have read here and there (including what some vendors are saying). I am building my second car from scratch and I try to do the best with what I have. To me the stock pin looks vulnerable even if it is not.
By the way I chose the Corvair power train among many. I like this mill and my post is not meant as a negative comment

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: MattNall ()
Date: June 18, 2017 06:22PM

Never sounded negative.... many "custom" pieces are made to cure problems..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: jjohnsonjo ()
Date: June 18, 2017 06:35PM

Not trying to bust your bolts, that was a Vairy nice piece of work. The orignal GM ones last a long time, sometimes longer than the car. I have a repo in now, see how long that one goes.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: steve c goodman ()
Date: June 18, 2017 08:01PM

philgmx: I wasn't trying to be negative either. I was only curious why you seemed to be having longevity issues but it wasn't a quick wear item in my experience. I am trying to learn from your concerns.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: Seth Emerson ()
Date: June 18, 2017 11:24PM

At least the pin is easily replaced. The stock coupler will eventually wear in the two slots on the side. Before I changed to the American Pi coupler, I modified the stock coupler by opening the two slots up to round holes and inserting little bronze bushings on each side. That, plus a new pin gave a solid feel to the shifter. You can also "solidize" the other pin in the rubber by welding the tip to the outer shell on both sides - be prepared for a lot of smoke. One final note, if you have a spare clamp for the shift tube, slide it on when you assemble your shifter and "double clamp" the tube to the shift coupler.

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: jjohnsonjo ()
Date: June 19, 2017 04:52AM

A lot of folks blame the pin and yoke when the real problem is the plastic bushings in the shifter tube. Those do go bad, the vendors have bronze inserts to correct that and once replaced go nearly forever.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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Re: 4sp manual trans shifter shaft pin. My views
Posted by: thumper477 ()
Date: June 19, 2017 04:53AM

On early fc's with the "mystery shifter",a worn set of holes on the trans end of the shift shaft will make shifting very difficult.I have found that if I weld up the holes on the end of the shaft and redrill them to the right size,shifting improves 50% or better.

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