Muncie Heavy Duty "Cover Spring"

[Richard D.]

I read somewhere that there is available for Muncie trannies a heavier duty spring (the one on the inside of the cover plate).

I cannot for the life of me find the source for that article, and I would like to replace my original in my M-20 with it when I pull it out of the car this winter.

The reason is that I heard it gives the trans a more secure seating in the gear you're in. Don't know if that's true or not, but I have an occasional problem with 3rd gear staying in for some reason.

I will also be looking at the original factory shifter for any problems when I go through the disassembly to see if that's the cause, but figured I might try the spring too to see if that corrects the problem.

Any advise would be much appreciated.

Regards,

Rich

[Terry M.]

Re: Muncie Heavy Duty "Cover Spring"

Sorry Rich, I have nothing to offer on the spring -- but I do have a suggestion.
The FSM shows how to make a tool to align the shifter plates (at least all the FSMs from 1967 to 1972 show it, and I presume others do as well). Making and using that tool will give you a big assist in aligning the linkage when you are assembling it. The tool can be easily made from a hardware store putty knife.

[Wayne M.]

eBay to the rescue

click on link




Muncie 20 lb Detent Spring

[Richard D.]

Re: Muncie Heavy Duty "Cover Spring"

Thanks Terry, I have the Chassis and Service Manual for 1968 Chevrolet (includes Corvette).

That the one?

Rich

[Richard D.]

Re: eBay to the rescue

Thanks Wayne!

I will try to get it.

Would anyone know the part number for this if it's gone

Rich

[Terry M.]

Re: Muncie Heavy Duty "Cover Spring"

Yes. I can't at the moment recall if it is in the overhaul or service manual, but that is the one. Basically all the tool does is hold the shifter plates in the neutral position, and then with the transmission levers in the neutral position, the shifter rods can be adjusted for length. BTW: Lots easier to do when the transmission and linkage is out of the car.

[Jon #40768]

Re: Muncie Heavy Duty "Cover Spring"

If the trany jumps out of gear when you decelerate, it is vey possible that hte main shaft bearings are worn out. Although, this happens alot in fourth gear. I have not done this in about 20 years, but as I recall, the tool used to align the shifter levers is an 1/8" rod. A rod just small enough to fit through the slots in the shifter housing and the levers works well. The rod can be cut to the length of the shifter thichkess so it can easily be used if the shifter is in the car. I just used a piece of aluminum the width of the slot. Good luck
Jon

[Joe L.]

Re: eBay to the rescue

Rich-----

The 20 pound detent spring is GM #3831718. It's still available from GM for about 2 bucks, list. This spring was actually used in PRODUCTION on most Muncie transmissions. That "light duty" one in the picture is what I'd call the "rare" one.

[Jon #40768]

Re: shifter alignment tool

I just looked at a shifter on sale at ebay and relized that I gave you a bogus comment. I now remember that I made an aluminum alighment tool out of flat stock( I just rembered that this tool should still be in my tool box). If you look at the bottom of the shifter in the photo on ebay, you will see the grove that the flatstock enters. Sorry for the confussion.
Jon

[James F.]

Re: eBay to the rescue - Joe

Joe,
For the T-10 transmission was there ever a stronger detent spring offered? (I realize the detent assembly was a completely different design.) Thanks & Regards,

[Richard D.]

Re: eBay to the rescue

Thanks Joe.

I do not recall which spring is in my trans (post 70 M-20), but I figured I'd put a new one in it when it's pulled since it's very inexpensive.

We'll see if that helps cure the "3rd gear" problem on mine.

Regards,

Rich

[Terry M.]

Re: shifter alignment tool

Boy, am I glad to hear that Jon. Now I know the putty knife that I cut up, per the 1970 Chassis Service Manual will work for the shift linkage alignment.

[Joe L.]

Re: eBay to the rescue - Joe

Jim-----

There was never one offerred by GM. The same spring under the original 1957 part number, GM #3909310, was used for all T-10 and Super T-10 applications right through 1981. No other spring was offerred by GM for SERVICE, high performance use, either. Such a spring may have been offerred in the aftermarket, but I'm not aware of it.

[Joe L.]

Correction

That should have been 3709310 and NOT 3909310