Question: side-plate leak, M21 tranny

[SRReality]

I have a leak from the side plate on the M21 tranny in my '62 Corvette (it's from a '64). I don't want to take the tranny out just to replace the gasket that's supposed to be there. It appears to me there is no gasket, just a bunch of "sealant". It appears to me that I should be able to take the shifter off, remove the side plate bolts, pull the side plate out about an inch, clean the surfaces, maneuver a gasket back (with sealant) on, put it all back together, etc. without taking the tranny out. Not much room to work, but I can reach all the bolts. I've tightened the nuts before, but it still leaks.

Do ya think this'll work? Welllll, do ya?

 

[JohnZ]

You'll have to drain some lube first, as the bottom of the side cover opening (and the bolt holes below it) is below the fill level at the plug on the other side. You'll need a suction gun and a piece of vinyl tubing, through the fill hole, to suck out the lube (and to put it back in when you're done).

Before you pull the cover off, put the transmission in second gear; otherwise the 1-2 shift fork will hang up on the edge of the opening.

 

[SRReality]

You'll have to drain some lube first, as the bottom of the side cover opening (and the bolt holes below it) is below the fill level at the plug on the other side. You'll need a suction gun and a piece of vinyl tubing, through the fill hole, to suck out the lube (and to put it back in when you're done).

Before you pull the cover off, put the transmission in second gear; otherwise the 1-2 shift fork will hang up on the edge of the opening.

Thanks, John. I had planned to drain the lube, but did not know about the second gear part. Very helpful!

 

[GTR1999]

Replace the shaft seals as well and look at the combs they sometimes crack. I think it can be done but pulling the trans may be easier in the long run.

 

[SRReality]

Replace the shaft seals as well and look at the combs they sometimes crack. I think it can be done but pulling the trans may be easier in the long run.

After getting it apart, I was thinking the same thing about the shaft seals.......they appear to fit tight, I don't know their history. Where do I find shifter shaft seals? NAPA?

 

[GTR1999]

You might cross them at NAPA or a bearing house otherwise try a trans shop.
Online you can try Ed Harnett in PA and Dave Reed in CT. I know both and they would have them. I only use the master kits with them in it.

 

[SRReality]

M21 Tranny Leak

Found the shaft seals at a transmission rebuilder's shop in Denver, put them in, put the side plate back with a good gasket and the right amount of "blue goop", tightened everything up to spec, re-filled it with oil, took a test drive and "voila"..........no leaks. Finally!

Thanks for the help and advise from several members here. Always helps to talk to folks who know what they are doing and aren't figuring it out as they go along.........like me!