Muncie M21 linkage install alignment - Chevelle Tech
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Transmission & Driveline Transmissions and Differentials

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  #1  
Old May 28th, 08, 7:27 PM
craigs67ss craigs67ss is offline
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Craig
 
Join Date: May 2008
Location: Tigard, Oregon
Posts: 61
Default Muncie M21 linkage install alignment

Hi guys, as I am new to all this forgive me for sounding incompetent. I am building my first car from the ground up literally, there was nothing but a shell when I started. I have a Muncie 4 speed M21, I bought all linkage as a kit from a local chevy parts resto place here in Oregon. I do not know how to set up the linkage correctly. I can move the shifter from 1-4th ok but having trouble getting it to go into rev. Also my classic manuals don't explain the linkage adjustment very well. I don't have it mounted to my 396 yet.
Sorry to be long winded, I think if I just keep at it and get it all lined up it will be ok but, you know, my first time..?
Thanks in advance

Craig
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  #2  
Old May 28th, 08, 8:14 PM
oman oman is offline
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Join Date: May 1999
Location: Atlanta
Posts: 4,358
Default Re: Muncie M21 linkage install alignment

Are you using a Chevy shifter or a Hurst? The instructions are more or less the same but it would be good to know what you are working on.

First of all ALL Muncie linkage installs are the same. ALL M20 / M21 and M22 are the same. With all the Hubbub about the M22 and all the talk about differences between the 20 21 and 22 versions it seems odd but they are externally the same when installing the linkage. Install the shifter and mounting plate onto the tail housing. If it is a Muncie shifter there is no plate between the tailshaft and the shifter. Hurst uses a plate, first attach the plate to the trans then attach the "shifter" to the adapter.

You need a picture of the final install to determine what parts are what. Describing what is what and which is which would tak forever in a text message format. Look up Hurst shifters on the web. Likely there are pictures there. If you have a Muncie shifter get a Service manual.

Set the transmission in neutral. Click the side cover levers to the center position (Center of three possible locations) and set the reverse linkage to the neutral position. Reverse has only two positions engaged or disengages. I can't recall which is forward and which is reward. Verify that you have neutral by turning the trans output shaft while the input shaft is not moving. The trans should spin freely in eather direction. If it is a Hurst be sure to back out the stop bolts on the front and rear of the shifter. There is a 1/3 stop and a 2/4 stop. Muncie shifters dont have stops.

Get the shifter into neutral. Hurst uses a pin thru the "guts " of the shifter body. I think a 1/4 perhaps it is 5/16 inch drill can be used. Muncie linkage uses a special GM tool for this. It really is nothin special and it can be fabricated with some metal stock and a bench grinder. This step is important: you MUST have the shifter in neutral ..real neutral ...and the only way to be sure is thru the use of the "tool" . If you are experienced with the process you can get away w/o the tool when working on a Hurst. The Muncie is a little tougher even with experience you need the tool. The Muncie tool is described in detail in the Chevy service manuals get one t will help a lot. Since you are new to this get that tool which ever shifter you have.

Install the arms onto the transmission at the reverse and the 1/2 and 3/4 positions. You are going to need a picture of the installation to do this. Install the rods onto the arms and onto the shifter: adjust arm lengths as required. Remember you MUST keep the shifter and the transmission in the neutral position while adjusting the length of the rods. You might have to take the shifter out of neutral to get the rod end into the shifter arm but the shifter and the lever on the side cover MUST be in neutral when you adjust the rod length. Too many people try adjusting the rod length while the trans is in a given gear. This is a fruitless effort. Leave the trans arms levers and the shifter arms in neutral and adjust the rod length to accomodate the neutral position of the shifter.

Adjust the stops (if you have a Hurst) by shifting the trans into 1st gear and tightning the stop bolt until it just touches the 1st gear arm inside the Hurst. To do this engage 1st or 3rd in the trans and then tighten the 1 / 3 stop until it just kisses the 1st or 3rd gear arm inside the Hurst. Repeat the process for the 2nd and 4th stop. The stops ARE NOT NOT NOT A TOOL / METHOD TO SHORTEN THE THROW OF THE LEVER IN THE CAR. Thinking they are is a critical mistake. The stops are there ONLY to assure that the shifter does NOT push the arms too far forward or pull them too far rearward. Going too far forward or rearward can break parts inside the trans. On the other hand if the stops are set with the intent of trying to shorten the throw all you accomplish is limit the ability of the trans to fully engage a given gear. This can be bad news for the syncros. None of this stop adjustment stuff applies to the GM made Muncie shifters. On the Hurst one stop is used to set 1st and 3rd gear and another is used to set 2nd and 4th. There is no reverse stop pn the Hurst.

Last edited by oman; May 28th, 08 at 9:41 PM.
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  #3  
Old May 28th, 08, 11:15 PM
craigs67ss craigs67ss is offline
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Craig
 
Join Date: May 2008
Location: Tigard, Oregon
Posts: 61
Default Re: Muncie M21 linkage install alignment

Thank you soooo much, man you guys aren't kidding, this kind of information is over $100/hr in shops. I have a GM shifter and I fiddled with it to get all of the gears to engage, it's still rough though. I didn't have the alignment tool the instructions and you mentioned. My shop manual also describes it. I do have something that should work. I will start again from where I'm at since it is close. Thank you again, I do appreciate your thoughtful time and knowledge.

Craig
Quote:
Originally Posted by oman View Post
Are you using a Chevy shifter or a Hurst? The instructions are more or less the same but it would be good to know what you are working on.

First of all ALL Muncie linkage installs are the same. ALL M20 / M21 and M22 are the same. With all the Hubbub about the M22 and all the talk about differences between the 20 21 and 22 versions it seems odd but they are externally the same when installing the linkage. Install the shifter and mounting plate onto the tail housing. If it is a Muncie shifter there is no plate between the tailshaft and the shifter. Hurst uses a plate, first attach the plate to the trans then attach the "shifter" to the adapter.

You need a picture of the final install to determine what parts are what. Describing what is what and which is which would tak forever in a text message format. Look up Hurst shifters on the web. Likely there are pictures there. If you have a Muncie shifter get a Service manual.

Set the transmission in neutral. Click the side cover levers to the center position (Center of three possible locations) and set the reverse linkage to the neutral position. Reverse has only two positions engaged or disengages. I can't recall which is forward and which is reward. Verify that you have neutral by turning the trans output shaft while the input shaft is not moving. The trans should spin freely in eather direction. If it is a Hurst be sure to back out the stop bolts on the front and rear of the shifter. There is a 1/3 stop and a 2/4 stop. Muncie shifters dont have stops.

Get the shifter into neutral. Hurst uses a pin thru the "guts " of the shifter body. I think a 1/4 perhaps it is 5/16 inch drill can be used. Muncie linkage uses a special GM tool for this. It really is nothin special and it can be fabricated with some metal stock and a bench grinder. This step is important: you MUST have the shifter in neutral ..real neutral ...and the only way to be sure is thru the use of the "tool" . If you are experienced with the process you can get away w/o the tool when working on a Hurst. The Muncie is a little tougher even with experience you need the tool. The Muncie tool is described in detail in the Chevy service manuals get one t will help a lot. Since you are new to this get that tool which ever shifter you have.

Install the arms onto the transmission at the reverse and the 1/2 and 3/4 positions. You are going to need a picture of the installation to do this. Install the rods onto the arms and onto the shifter: adjust arm lengths as required. Remember you MUST keep the shifter and the transmission in the neutral position while adjusting the length of the rods. You might have to take the shifter out of neutral to get the rod end into the shifter arm but the shifter and the lever on the side cover MUST be in neutral when you adjust the rod length. Too many people try adjusting the rod length while the trans is in a given gear. This is a fruitless effort. Leave the trans arms levers and the shifter arms in neutral and adjust the rod length to accomodate the neutral position of the shifter.

Adjust the stops (if you have a Hurst) by shifting the trans into 1st gear and tightning the stop bolt until it just touches the 1st gear arm inside the Hurst. To do this engage 1st or 3rd in the trans and then tighten the 1 / 3 stop until it just kisses the 1st or 3rd gear arm inside the Hurst. Repeat the process for the 2nd and 4th stop. The stops ARE NOT NOT NOT A TOOL / METHOD TO SHORTEN THE THROW OF THE LEVER IN THE CAR. Thinking they are is a critical mistake. The stops are there ONLY to assure that the shifter does NOT push the arms too far forward or pull them too far rearward. Going too far forward or rearward can break parts inside the trans. On the other hand if the stops are set with the intent of trying to shorten the throw all you accomplish is limit the ability of the trans to fully engage a given gear. This can be bad news for the syncros. None of this stop adjustment stuff applies to the GM made Muncie shifters. On the Hurst one stop is used to set 1st and 3rd gear and another is used to set 2nd and 4th. There is no reverse stop pn the Hurst.
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