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Old 08-26-2023, 10:32 AM   #1
New Member
Join Date: Aug 2023
Posts: 1
Year: 1969
Coachwork: GMC
Exclamation Transit, transmission and trouble

Hey, Iím new to the site and in need of some help.
Iíve got a 1969 GMC transit bus. Itís got a Detroit Deisel and an automatic transmission.
When I first got the unit it would grind slightly while putting it into Forward (shifter on the floor that shows Forward, Neutral and Reverse)
Last year I went to move it it made a long grinding noise while trying to put it into drive and once it quit It would not go into gear or engage. I could shift it into reverse and still move it but forward has nothing. (No grinding but doesnít feel like anything is there)
I have since tried to tow it home (it was parked on a friends property) but we struggled to get it to move. After banging on the brakes a bunch and, tugging on it and in both neutral and forward we were finally able to move it. It made a crazy grinding noise while tugging on it and changing from Forward to Neutral.
Right after that when I put into Forward it now drives in reverse. When put in reverse it works as it should.

Iíve had a lot of input and ideas from people but nobody who really knows anything about these units.

Does this sound like a transmission issue?
Maybe a clutch?
Or something to do with the linkage or shifting cable?
I was told I need to pull the engine to examine the transmission and or clutch.
Any info would be greatly appreciated
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Claytonshrubs is offline   Reply With Quote
Old 08-26-2023, 11:26 AM   #2
Bus Geek
Jolly Roger bus 223's Avatar
Join Date: Sep 2017
Location: Swansboro,NC
Posts: 2,989
Year: 86
Coachwork: Thomas
Chassis: Ford B700
Engine: 8.2
Rated Cap: 60 bodies
i dont know your bus but that sounds like a clutch issue.
could be the plate the throwout bearing or the cable wore out.
does the clutch pedal feel slack and then hit a hard area in the push down?
Jolly Roger bus 223 is offline   Reply With Quote
Old 08-26-2023, 12:58 PM   #3
Bus Crazy
Join Date: Oct 2020
Location: Near Flagstaff AZ
Posts: 1,951
Year: 1974
Coachwork: Crown
Chassis: "Atomic"
Engine: DD 8V71
Hi Mr. Shrubs and welcome to the forum.

That angled-drive hydraulic transmission is either a 2 or 3 speed Allison V drive...probably a VS based on the year. The shifting happens with a solenoid and, most likely, that solenoid linkage is either not adjusted right or the solenoid isn't working. Those solenoids are large and do stick, so if it's not working you can probably disassemble it and clean the plunger and sleeve so it slides freely.

Here's a bit of info on them:

In one of my GM books, I have some more info on these. I have 2 GM buses with these transmissions. I'll see if I can find anything helpful. But in the mean time, knowing what transmission it is might help in your search for documentation.
rossvtaylor is offline   Reply With Quote

1969 gmc, transit, transmission

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