C1 3 to 4-speed tranny upgrade

[Michael Jones]

I plan to soon upgrade my original transmission (of course I'll hang onto it) from the 3-speed to a 4-speed. I've also settled on the wide ratio (2.54 1st).

What are the considerations on whether to go to a T10 or a Muncie? The fact that the T10 "looks" original doesn't carry much weight because my car's build date precedes the introduction of the T10 4-speed in April, '57. So it's not gonna pass for original anyway.

Are there any "gotchas" with either tranny? Someone mentioned that you have to modify the transmission compartment to use the Muncie.

Thanks for your help.

Michael

[Mike E.]

Re: C1 3 to 4-speed tranny upgrade

Both bolt right in.
Muncie is a better tranny than the old T-10
Shifter levers on the tranny itself need to be modified to fit the Muncie
Muncie has fine spline output shaft, T-10 (and three speed) have course shaft
You'll need a 62-style adapter plate to mount Muncie to crossmember
That's all you need to know.

[Tom P.]

Re: C1 3 to 4-speed tranny upgrade

As mentioned, that's basically all you need to know. The 62 ONLY used the adapter plate (it mounts between the stock 56-62 rubber mount and the tail housing mount on the Muncie) mentioned which is available from the aftermarket sources for less than $20. Buy a Hurst shifter for a Muncie, buy one of the aftermarket 56-58 replica handles made specifically for the Hurst shifter, change the yoke on your driveshaft to the fine 26spline version, and you're done. This is what I have had in my 56 for over 30yrs. You would think it was installed by Chev. By the way, 63-4 Muncies have the speedo on the left side just like your 3 sp. The 65-later Muncies have the speedo on the right side pointing down at about a 45deg angle. Your speedo cable may or may not reach. If not, any speedo shop can make you a longer cable/housing. No big deal.

[Dennis C.]

Re: C1 3 to 4-speed tranny upgrade

Just leave the 3 speed shift pattern plate in place and start recording how many judges overlook the new improved conversion ...

[Tom P.]

Re: C1 3 to 4-speed tranny upgrade

Dennis should know. When he judged my 56 several years ago at a Regional in Joplin, I had installed a 3sp plate and he made a comment about the 3sp plate but the car had a Muncie in it!

[Dennis C.]

Re: C1 3 to 4-speed tranny upgrade

Told ya it might work... DC

[Verle R.]

Re: C1 3 to 4-speed tranny upgrade

Michael,

No modifications, that is cutting, of fiberglass or metal are required.

If you choose a Muncie, with the right shifter (ref Tom Parsons post), a new driveshaft yoke and the 62 adapter plate it is a bolt in.

Good driving.

Verle

[Theodore K.]

Re: C1 3 to 4-speed tranny upgrade

Tom,
My 57 also has a Muncie in it. Actually it is a 67 case with a 69 wide ratio gearset in it. I have the Hurst shifter and would like the shifter conversion you mentioned. Please tell me what aftermarket company sells this. I have never liked the Hurst because it rides against my leg and after a few hours is a source of aggravation. Love the Muncie though.
Thanks,
Ted von Kampen

[Wayne C.]

Check parts vendors...

Corvette Central lists the shifter lever in their catalog (56-58 and 59-63 style levers for Hurst shifter)

[Tom P.]

Re: C1 3 to 4-speed tranny upgrade

I got mine at Corvette Central, part number 531101, $63.15.

[Dick W.]

Re: C1 3 to 4-speed tranny upgrade

That was "back when" Dipstick could see