Technical Muncie Tear Down, What’s Junk, What Can Be Reused?

End of the night. The green stuff now has a variety of earth and metallic colors in it and a unique smell. I pulled, rinsed and brushed the parts. They’re pretty pitted. I’m pretty sure it was the rust and not the green. Since they’re already rough, I’m going to leave them overnight to see if the green goo attacks machined surfaces. If my luck is good I’ll feed it some better parts.

 

Just what kind of wizardry is this green stuff you speak of? Looks like it is doing a great job though. I’d run those gears and slider.

 

I've always felt a Super T-10 was an upgrade in place of a std Muncie. No? Yeah?

 

GM Must have thought so too.

 

You may be surprised at how well it works. I do the same with citric acid, I use empty cat litter pails and safety wire to dangle the parts. Take care not to dip any aluminum parts in the bath.

 

Honestly, I’m not entirely sure what the green stuff is. Label data is limited.



I believe green contains citric acid plus “other”. It makes smells similar to Ospho.

Overnight left a textured finish on machined surfaces. I’ll keep parts down to maybe 4 hours in the future. I might grease good surfaces to protect them from the green.





I think I can put a fork in that reverse gear.

 

Make it a real short bath just to loosen, then maybe a nice soda blast? Soda cleans without removing metal. I mainly do soft stuff like diecast and aluminum (works awesome) but I have cleaned some steel stuff with reasonable success too. A 50lb bag is cheap at Harbor Fright...

 

I never had citric acid attack other non-rusty surfaces. At worst it may take some surface rust off. It seems to like where it can creep in and do what it does. I mix 1 large red drink cup (about a pound) to 5 or 6 quarts of water. I leave it outside with a cover on, loosely. I usually let parts sit for 2 days and then take a look. At that point I can elect to scrape off what might be loose.

 

I’m finding larger pits than I’d like in most of the Super T10 gears. By the time I look at replacing what I need to replace, getting a 26 spline clutch disc, new yoke, and a new Hurst mounting kit to make the Super T10 work, I might as well buy some Muncie guts. 5speeds.com seems sold out of about everything. Italian gears seem hard to find, especially for M20. I’m looking at a Korean M20 gear set, new counter shaft, rebuild kit, and a slider hub synchro set. I need to decide on torque lock or standard sliders. Some forums seem to think that Korean gears are machined for torque lock sliders but there’s a ton of contradictory info out there. I’m waiting to hear back from thegearbox.org customer service before I spend some of my hard earned loot.

 

How long is the wait from 5speeds? I never heard of Korean gear sets.

 

I have used the Gearbox numerous time with great success.

Use the slider that goes with the gear style.

I have been building transmissions for 40 years as my living, don't believe everything you read on the internet.

Why run a backcut tooth on a straight cut tooth, that will end up only have small contact patch.

I think I have a new Korean 2nd gear on the shelf and new Torque Loc synchro assemblies from Riverside Gear, I will look Monday when back in the shop.
If I do, I will post a close up photo of the engaging teeth, and then you decide what's right.

Too bad on the amount of rust in the ST10, looked like it was a nice trans before rotting away.

Bill

 

I’m not sure on how long the wait is. Most of the big parts on his website are listed as “out of stock”. I’m assuming he’s dealing with the same supply chain challenges that the rest of us are with everything. I’ve been all over muscle car and corvette forums reading everything I can and I found a thread where both Paul and Autogear both chimed in. The gist of it was that Italian M20 gears weren’t currently available, and Korean was the next best thing, but stay away for Taiwan. I wish I could find the thread to quote, but I’ve read so many and can’t find it this morning.

A pic would be great! I’m not clear if the Korean gears are back cut or not. I’ve got an email out to thegearbox trying to figure out what they sell, but I got them kinda late on a Friday and I’m Mountain time and they’re Eastern, so I imagine they won’t get back to me for a while.

 

Gear/slider photos:
1st photo: 2nd gear stamping, makes it Taiwan. Thought I had a Korean gear also but do not.
2nd photo: Back cut engaging teeth on Taiwan gear
3rd photo: OE main drive gear for comparison of the tooth shape.
4th photo: Torque Lock slider teeth.

Not sure if the Korean gear is back cut or not. Need to ask. Use the slider style that matches the gear.

Bill

 

Not for high Hp applications. They strip input gears

GM spec'd the Super T-10 so there was a greater distance between the mainshaft and counter shaft.
This provided room for lower ratio 1-2-3 gear [wide ratios] without compromising torque ratings with the input gear being too small.
The problem with Super T-10's is the Input / countershaft drive gears are too narrow [width] and they are prone to stripping. [The aftermarket race gearboxes addressed this issue]
GM spec'd the Super T-10 so they could use Wider ratio's with a high rear-end ratios [T5's made this obsolete]


Wide ratio M20 Muncie's suffer from too small diameter input shaft gear.
M21's are better but the M22 with the 22° helix is best [OEM]

 

As far as engines go, the GM hp/torque ship sailed a couple years before they replaced the Muncie 4 speed with the Super T-10, some pretty dismal years mid 70's moving forward!

 

Stay away from the North Korean made gears. When they blow up you get this little fat bastard behind you laughing!

 

I would trust used gears over those. The trick is to ferret out your local Muncie guru who is sitting on a literal ton of parts, he is probably 65 to 80 years old.

 

I have what looks like a very nice Super T-10 from a Fire ("cough-cough") bird, T/A ready for my 65 GTO. This topic makes me wanna open it up just because. The usual suspects around here would use these to keep their 4spd cars in good order vs a Muncie. I too always thought they were a better choice if you wanted to beat em just a bit. Not a race trans by any means but they always seemed to hold up well. I used to like the beefier looking cases. Am I just hopeful or...?

 

I have just about everything you need including a new 3 ring 2.64 input, and possibly even a new cluster gear (I'd have to check closer) sliders, main shaft, & good gears except for one. (Can't remember which) If you're interested, message me. Or, I'd be interested in you're case and tail housing if you decide to go Muncie.

 

Just run all those gears. Keep the hood shut and everybody will think you are running dual 6-71 blowers.

 

The best aftermarket gears I've used were made by AM Gears [Antonio Masiero] in Italy.
They are an OEM gear supplier for European cars and trucks.

 

Thank you. This is awesome and super helpful!

 

You’ve got me ready to bust out the Team America “Lonely” song. My bride has no tolerance for that shit…

 

PM sent

 

I’ve been traveling and just noticed that this thread has been doing its thing. I’ve never gotten a clear answer if the Super T10 or the Muncie is stronger, but clearly this crowd feels the Muncie is where it’s at. A fine gentleman from San Diego has put some gears in the mail. They should turn up around the time I get home. I think a lot of my problems have probably been solved. I’m pretty excited to move forward on the Muncie. I’ll put the Super T10 back in storage.

 

I wish I’d checked all my junk out earlier so I could have been parts hunting.

 

A little TMI buddy...

 

Just not a shifter fork…

 

Went to the dealership for specific lug nuts. Counter man asked “what do your nut’s look like?” Him Me