Downshift issues....Linkage or synchros...?
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
Downshift issues....Linkage or synchros...?
1972 M20....Previous owner said it was rebuilt and I can tell it has recently been opened up but I have not pulled the cover. He also said it was a M22 but the case # indicates a M20. Yes it did this when I bought it.....Long story.
The shifter seems loose to me but I'm used to Toyota 4X4 5 speeds and I know they are completely different.
I have no issues going up thru the gears or downshifting from 4th to 3rd....I have to double clutch it to go from 3rd to 2nd and from 2nd to 1st. If the car is at a dead stand still it will go in first but it's easier if I double clutch then as well...No grinding but I don't force it.
My gut tells me it's synchros or something inside the transmission out of adjustment.
Anybody got any insight on the best way to distinguish between the two and which may be causing my problem....?
Brian
The shifter seems loose to me but I'm used to Toyota 4X4 5 speeds and I know they are completely different.
I have no issues going up thru the gears or downshifting from 4th to 3rd....I have to double clutch it to go from 3rd to 2nd and from 2nd to 1st. If the car is at a dead stand still it will go in first but it's easier if I double clutch then as well...No grinding but I don't force it.
My gut tells me it's synchros or something inside the transmission out of adjustment.
Anybody got any insight on the best way to distinguish between the two and which may be causing my problem....?
Brian
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
No trans expert here, but being easier to check the shifter adjustment than to crack the tranny open, I'd definitely start there and cross your fingers and toes that it's not worn synchros and/or forks. The Muncie is a great old-school gearbox, but years do take a toll. FWIW, mine just had its 49th birthday this past month, and due another good going thru having started jumping out of 4th upon lifting, so I feel your pain.
Le Mans Master
Joined: Mar 2001
Posts: 5,738
Likes: 644
From: Lincoln, CA
Agree, verify the linkage 1st.
I bought a brand new Autogear M22 and it's still breaking in. Getting into 1st is stiff.
Easier when I'm still rolling.
They said it will take a few miles to wear the synchros in. Double clutching is a good sign that they are warn out.
I bought a brand new Autogear M22 and it's still breaking in. Getting into 1st is stiff.
Easier when I'm still rolling.
They said it will take a few miles to wear the synchros in. Double clutching is a good sign that they are warn out.
Pro
Joined: Nov 2012
Posts: 585
Likes: 39
From: FL
Just FYI - on mine, it would pop out of 2nd once I got in in 2nd. Inspection revealed the linkage arms were chafing, I discovered that after recent tranny work one of the lever arms on the tranny was installed incorrectly with the off-set facing the wrong way causing it to bind and not fully engage 2nd.
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
Stock shifter....When I was cleaning the underside I noticed some cotter pins on some of the linkage....I hope I just have a linkage issue but I don't really think so....It doesn't pop out of gear and It doesn't seem like the linkage is hitting. I'll get under it this weekend and see what I can figure out.
Brian
Brian
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Burning Brakes
Joined: Dec 2003
Posts: 1,150
Likes: 154
Look in the G.M. service manual for the tool you'll need adjust the linkage properly,if I remember correctly it't a flat piece of steel 13/16 wide x3/16 thick put a hook on the end,easier to hold and line up.Also dump the carter pins and use the clips.
Heel & Toe
Joined: Nov 2014
Posts: 15
Likes: 0
My stock shifter caused up and downshift problems between 3rd and 4th. One shop of course tried to get me to pay for a new trans but i always thought it was connected to the sloppy shifter. I ended up buying a Hurst shifter (mine is a super T10) and cured the problem once and for all. A guy who races convinced me its far better having the shifter bolted to the gearbox than the way GM originally did it on the C3.