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1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 02:17PM

Hey All,

It's been a VERY long time since I've posted, hope everyone is well. I need some advise, last year at the Corvair Track Classic in Hastings NE I had a breakdown. I lost 2-1 downshift and has terrible grinding and when cornering it felt like it was disengaged. Today I finally got around to removing the drive train to find out what broke. Diff and clutch looked good so I popped the side cover off and found the 1-2 shift fork laying in the case intact. So, my question is what happened and what could have cause that? All the gears spin freely and none have any visible damage. Should I just reinstall the fork and run it or??

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: junkman ()
Date: May 16, 2020 02:32PM

Parts don't just fall out. Something inside has to have failed to cause this. Only total disassembly and very close inspection of each part, until you find the culprit. Once you find what failed, you can then fix it properly. Putting the part back in place without knowing why it fell out, is inviting disaster. The next time it falls out, it might jam up the gears, and bread a lot of parts in the process.

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Woodstock CT... Located on the Connecticut / Massachusetts border, approximately 6 miles from the center of Southbridge MA. About 45 minutes from Hartford CT. 1 1/2 hours West of Boston MA. Woodstock CT to Los Angeles CA 2,937.1 miles. 1 Mile as the crow flies to Big Bird's nest.

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 02:41PM

junkman Wrote:
-------------------------------------------------------
> Parts don't just fall out. Something inside has to have failed to cause this. Only total disassembly and very close inspection of each part, until you find the culprit. Once you find what failed, you can then fix it properly. Putting the part back in place without knowing why it fell out, is inviting disaster. The next time it falls out, it might jam up the gears, and bread a lot of parts in the process.


My thoughts exactly!

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 02:41PM

Anyone have a video or instruction on rebuilding a Saginaw?

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: steve c goodman ()
Date: May 16, 2020 02:47PM

How about a pic of the fork and one of side cover inside view Cory?

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/V8 Registry

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 03:07PM






-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 03:12PM

1
2
3

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: steve c goodman ()
Date: May 16, 2020 03:38PM

How is the fit of the fork into the hole in the shifter head?

Also curious only, from your pic of inside cover it appears the shifter is in neutral BUT your pic of gearset you are in reverse. What is blue tint on gears?

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/V8 Registry

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 03:53PM

It fits snug in the hole. It's in reverse because I was I was manually moving the gears. The blue tint is the fluid I run, Redline Lightweight Shockproof gear oil.

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: steve c goodman ()
Date: May 16, 2020 04:05PM

Teeth on rev idler gear and on countergear plus the synchro all good?

How is detents in cover when moving the heads back and forth?

I was wondering if grinding you describe was trying to mesh reverse idler.

When the shift noise happened I presume you never had first/sec or reverse again?

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/V8 Registry

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 04:32PM

All the gears and synchros look great
All the detents are solid
The grinding was when moving
I did loose loose the ability to shift unless I rev match or shut the car off and put into gear.

The strangest part of it all is when I was on the throttle in turns on the track it felt as if the clutch was slipping or the trans wasn't engaging until I was straight again.

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: joelsplace ()
Date: May 16, 2020 04:40PM

You'll find something terribly wrong when you take it apart.
Are you sure the shift fork didn't fall off as you were taking the cover off?

Joel
Northlake, TX
5 Ultravans, 114 Corvairs and counting...

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 16, 2020 04:41PM

joelsplace Wrote:
-------------------------------------------------------
> You'll find something terribly wrong when you take it apart.
> Are you sure the shift fork didn't fall off as you were taking the cover off?

Pretty sure

-Cory
'66 Corsa
Nebraska

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Re: 1-2 Shift Fork issue
Posted by: steve c goodman ()
Date: May 16, 2020 05:02PM

I didn't say correctly about trying for reverse but my thought was fork somehow trying to move reverse pawl.

Joel has good point the forks move easily.

Either put side cover back in place and take a chance or keep looking.

Good luck Cory

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/V8 Registry

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Re: 1-2 Shift Fork issue
Posted by: American Mel ()
Date: May 16, 2020 08:42PM

diegocorsa Wrote:
-------------------------------------------------------
> All the gears and synchros look great
> All the detents are solid
> The grinding was when moving
> I did loose loose the ability to shift unless I rev match or shut the car off and put into gear.
>
> The strangest part of it all is when I was on the throttle in turns on the track it felt as if the clutch was slipping or the trans wasn't engaging until I was straight again.

This statement makes me think that Joel is correct, and the fork fell off when the cover was removed.
You could still shift if you rev-matched, or the car was shut off?
If the fork had fallen out, how could you shift AT ALL?
I am thinking that this sounds more like a CLUTCH or DIFFERENTIAL problem!

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry



Edited 1 time(s). Last edit at 05/16/2020 08:44PM by American Mel.

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Re: 1-2 Shift Fork issue
Posted by: Wagon Master ()
Date: May 17, 2020 06:10AM


Cory wrote: The strangest part of it all is when I was on the throttle in turns on the track it felt as if the clutch was slipping or the trans wasn't engaging until I was straight again.

Posi with a chewed up side gear on the non clutch pack side?

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Re: 1-2 Shift Fork issue
Posted by: steve c goodman ()
Date: May 17, 2020 06:21AM

I really don't understand how the fork would come out while in use but strange things happen. Very good chance of something else is the cause of track issues. WM has good thought about the posi failure.

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/V8 Registry

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Re: 1-2 Shift Fork issue
Posted by: alphasud ()
Date: May 17, 2020 06:44AM

I looked at your pictures. your 1-2 shift slider is gone! That’s why your fork popped out. Time to take it apart and pull the chunks out.

David North Idaho
1965 Corsa Turbo converted to 140
1971 Super Beetle with 2.5L Subaru engine
1965 Corsa mid engine project
1973 Mercedes 280 project

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Re: 1-2 Shift Fork issue
Posted by: Wagon Master ()
Date: May 17, 2020 07:48AM

See the part in picture 3 that has the straight cut gear teeth on the outside, used for reverse? That's the 1-2 slider.

'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

Been aircooled since 1973
Northwest Ohio

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Re: 1-2 Shift Fork issue
Posted by: diegocorsa ()
Date: May 17, 2020 09:23AM

Hey All,

First off, thanks for all your responses! Some of you know that I am running Ken Hand's Dual Disc Clutch, I decided to pull it this morning just to check and what I found was a bit confusing. Looks like I found the source of my grinding, one of the flywheel bolts backed out and was grinding on the rivets on the disc. So, that issue is solved but still the issue of the "slipping/non-engagement" in turns??? Check out the picture n the gallery....

Dual Disc Clutch

-Cory
'66 Corsa
Nebraska

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