TH350 to Muncie swap

D

Double_take

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Joined
Apr 21, 2008
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58
Location
Chicago IL
This winter I want to switch my turbo 350 to a M20 (I have 355 gears and dont want a close ratio unless I find a killer deal). Ive done some research, but have never touched a manual transmission (except for driving). I have confidence that with some time and a lot of help from you guys I can get this done. Be prepared for some really really basic questions.

Since im starting with a TH350, I want a 10 spline input and a 27 spline output. Im assuming this for simplicity reasons. If its easy to switch to the 26 spline I would consider it. Also my transmission mount should be in the proper place and the drive shaft should be the proper length for the swap.

I want to us a hydraulic clutch. I have read that I should get one from a early 90's s-10. Any other good junk yard candidates? I found thisgreat thread on hydraulic clutches. What are the pros/cons to using a master/slave cylinders and a regular throwout bearing vs using only a master cylinder and a hydraulic throwout bearing?

I think it would be fun to rebuild a tired muncie. The rebuild kits are only $150. I assume this is only shims and bearings, not gears. What should I look for in an old unit? Or should I save myself a future headache and buy a rebuilt unit?

I will also need a bellhousing (will a standard one work with my 350 engine?), clutch, interior panel, and misc bolts etc.

Am I missing anything major? Can someone post links to good part sources and part numbers?

Thanks a lot.
 
I have an extra pedal assembly and a bellhousing if your interested....you don`t have a flywheel you have a flexplate...
 
Ok add flywheel to the list of things I need. I told you there would be stupid questions :footmouth:

As for the course spline. It seems like it wouldnt be a hard swap, to go with the course. Do the 10 spline shafts have strength issues? Should I be making my decision based solely on the gear ratios? You have PM.
 
Double_take said:
Ok add flywheel to the list of things I need. I told you there would be stupid questions :footmouth:

As for the course spline. It seems like it wouldnt be a hard swap, to go with the course. Do the 10 spline shafts have strength issues? Should I be making my decision based solely on the gear ratios? You have PM.
Click to expand...

I've been ruuning a 10 spline M20 since 1972. I have beat on them in ways most people would not think possible. Never broke an input shaft.:noworry:

I have 3.55s in mine and the M20 is the BEST for this ratio.
 
I'm getting ready to rebuild a M20 for my '73. I also had a TH350 installed.(I know they came with a TH400) I'll be sure and post some pics when I crack it open. I got a great video and book from 5speeds.com that you might want to check out if your going to rebuild a muncie.
 
BRUTAL64 said:
I've been ruuning a 10 spline M20 since 1972. I have beat on them in ways most people would not think possible. Never broke an input shaft.:noworry:

I have 3.55s in mine and the M20 is the BEST for this ratio.
Click to expand...

Thanks, thats what I wanted to hear.

'73inabasket said:
I'm getting ready to rebuild a M20 for my '73. I also had a TH350 installed.(I know they came with a TH400) I'll be sure and post some pics when I crack it open. I got a great video and book from 5speeds.com that you might want to check out if your going to rebuild a muncie.
Click to expand...

Please post pics of the internals and any installation pictures.
 
If you want just a track car, I can easily see the Muncie, but if you at all going to drive it on the street, I would strongly recommend a tranny with a .70 some overdrive, for the MPG, and engine wear....

Screaming along the freeway at ~4000 rpm gets old, but cutting 30% off that, makes it closer to ~2600 rpm....

:smash:

Had a buddy with a older S10 and he was always adding clutch fluid to it, and I think a bellcrank is far superior for the sheer simplicity of it....nothing there to fail, ever.....

I mean to think, with all the damn oil leaks, from steering, and brakes, anything hydraulic being introduced is another damn leak....some gasket or other, or seal or whatever....:tomato::eek:
 
mrvette said:
If you want just a track car, I can easily see the Muncie, but if you at all going to drive it on the street, I would strongly recommend a tranny with a .70 some overdrive, for the MPG, and engine wear....

Screaming along the freeway at ~4000 rpm gets old, but cutting 30% off that, makes it closer to ~2600 rpm....

:smash:

Had a buddy with a older S10 and he was always adding clutch fluid to it, and I think a bellcrank is far superior for the sheer simplicity of it....nothing there to fail, ever.....

I mean to think, with all the damn oil leaks, from steering, and brakes, anything hydraulic being introduced is another damn leak....some gasket or other, or seal or whatever....:tomato::eek:
Click to expand...


Well, with 3.55s 3,500 rpm is what I "cruise" at to keep up with traffic. I use 4,000 rpm to pass traffic.:wink:
 
mrvette said:
If you want just a track car, I can easily see the Muncie, but if you at all going to drive it on the street, I would strongly recommend a tranny with a .70 some overdrive, for the MPG, and engine wear....

Screaming along the freeway at ~4000 rpm gets old, but cutting 30% off that, makes it closer to ~2600 rpm....

:smash:

Had a buddy with a older S10 and he was always adding clutch fluid to it, and I think a bellcrank is far superior for the sheer simplicity of it....nothing there to fail, ever.....

I mean to think, with all the damn oil leaks, from steering, and brakes, anything hydraulic being introduced is another damn leak....some gasket or other, or seal or whatever....:tomato::eek:
Click to expand...

Sounds like this guy is on a budget. I have been checking on 5 speed swaps and they are much more expensive to do. The only one that that I have found that can be done for around the same price as a Muncie is the T5 and everyone knows that isn't the strongest trans.
 
Fuelie74 said:
Sounds like this guy is on a budget. I have been checking on 5 speed swaps and they are much more expensive to do. The only one that that I have found that can be done for around the same price as a Muncie is the T5 and everyone knows that isn't the strongest trans.
Click to expand...


Bingo. The jump in price from a muncie to a 5-6 speed equals a lot of gas. Plus the muncie will hold its value better for when its frame off time and I need to sell it to make room for a T-56.

I respect your opinion mrvette, but the hydraulic setup requires less fabrication (ie welding) and im not worried about new parts leaking.
 
HUH, though all frames had the bracket for the bellcrank on them....

otherwise it's just a stud on the block, and the pedals....

I would think it easier to do that than fab up brackets for the master and slave cylinders....much less the plumbing line....

been 15 years since I pulled the bellcrank on mine....it's nothing but a spring loaded later insertion as I recall....

:fishing:
 
The manual frames had nonremovable trans crossmember and the bracket for the Z bar. The Auto frames had a removable trans crossmember and no braket for the Z bar. It shouldn't be very hard to add the bracket if you have a welder.

My car has a manual frame that someone put a TH400 in. When I switch it back over to a manual I will go with a hydraulic clutch for a couple reasons.
1. Smoother operation.
2. Cheaper. I can buy all of the parts new to switch over to a hydraulic clutch using 85 Chevy truck parts for less than buying a new Z bar and linkage.
 
mrvette said:
HUH, though all frames had the bracket for the bellcrank on them....

otherwise it's just a stud on the block, and the pedals....

I would think it easier to do that than fab up brackets for the master and slave cylinders....much less the plumbing line....

been 15 years since I pulled the bellcrank on mine....it's nothing but a spring loaded later insertion as I recall....

:fishing:
Click to expand...

I have to agree with you here. It is much easier to put the factory bell crank with linkage in it. :wink:
 
Double_take said:
Fuelie74 said:
Sounds like this guy is on a budget. I have been checking on 5 speed swaps and they are much more expensive to do. The only one that that I have found that can be done for around the same price as a Muncie is the T5 and everyone knows that isn't the strongest trans.
Click to expand...


Bingo. The jump in price from a muncie to a 5-6 speed equals a lot of gas. Plus the muncie will hold its value better for when its frame off time and I need to sell it to make room for a T-56.

I respect your opinion mrvette, but the hydraulic setup requires less fabrication (ie welding) and im not worried about new parts leaking.
Click to expand...

If you have an auto frame, which you should have with the th350, you can use the bolt onto frame z-bar bracket from an '80? I believe and there should be no welding involved. This is the plan I am going by as I can't weld.
 
Suddenly its looking easier and cheaper to go with the z-bar. I have heard they are difficult to adjust properly. Is this true? What should I be concerned with? Im going to use a hurst shifter if that makes any difference.
 
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