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Transmission, One is Not Like the Other!
Posted by: vairmech ()
Date: February 20, 2018 06:01AM

I was doing trans work, actually still am! and as I was disassembling I notice something different. The first picture is what we normally see inside a 61-5 4 speed trans for the reverse detent.



I then start taking apart this other trans because I need parts from it, broken shift shaft in the first one, and I see this!



I suspect this case to be a very early 61 trans. I will know a little more when I get the diff apart and look at the date code on the differential gear set. I have not pushed on the detent yet to see if it is just a spring or a real detent.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Transmission, One is Not Like the Other!
Posted by: BobV66Vair ()
Date: February 20, 2018 10:06AM

Yeah, the reverse pin is different. Usually that means a change my the Mfg. to fix an early problem, or save money. The lower one looks kind of flimsy for sure. Maybe it was failing and the solid piece is the fix?

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: Transmission, One is Not Like the Other!
Posted by: vairchet ()
Date: February 20, 2018 10:49AM

Change occurred during early production of 4-speed as Vairmech pondered. It's actually a spring loaded, bolt-in reverse inhibitor. Design wasn't that great. Reverse inhibitor would also hang-up when pin wore into washer and retainer, altering angle when compressed.

Here's some interesting information:

Chet in Ramona

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Re: Transmission, One is Not Like the Other!
Posted by: RexJohnson ()
Date: February 20, 2018 08:47PM

I have an early 4sp with a May 12th '61 casting date on it and it still has that early reverse detent in it. If you look at the bottom of the case there is a wide casting where the detent bolts in that on the later style with the pressed in detent there is just a narrow rib with the soft plug in it. So it seems that Chet's TSB doesn't match what actually happened. There are several other differences in the '61 4sp such as the clutch gear and the front of the mainshaft. The rear bearing retainer only has a place for one of the small snap rings to hold in the mainshaft. They must have figured out that one was not enough when sometimes two will pop loose if you miss handle the trans by itself. In the 4sp section of the '65 shop manual one of the pictures that was used shows that early bolt in detent. The detent is not mentioned it was just a picture that showed what they were talking about and the detent happens to be in the background.

RJ tools
Salem,Oregon

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Re: Transmission, One is Not Like the Other!
Posted by: vairmech ()
Date: February 21, 2018 04:34AM

The TSB does address the reverse inhibitor but is a TSB that concerns the shift coupler more than the inhibitor. If you read the TSB they want you to weld the cross pin to make a solid coupler! I have not found any welded couplers but I have many that have short locating rings placed in the large hole and around the pin.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Transmission, One is Not Like the Other!
Posted by: v8vair ()
Date: February 21, 2018 05:44AM

Wow,back in the 70s my good friend who work at the chevy dealer welded the pins on my 65 Corsa.

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Re: Transmission, One is Not Like the Other!
Posted by: caroseiii ()
Date: February 21, 2018 07:31AM

Rex, you're right, they never updated the Corvair four speed diagram through 65 despite the multiple design changes. I exploded the attached picture from 1962 Pontiac Tempest literature. This diagram shows the spring and seat for the 62-65 detent.

Crawford

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