Muncie M21

[64Fugly]

Hey guys,

I am going to install a 292 engine in my 65' fleetside. Now would a Muncie M21 transmission be good enough for this engine. The transmission that is on there is a 4 spd. The purpose of me using a muncie is to at least get up to normal speed on the interstate. I could use all the info I can get.
Thanks guys.

[joe231]

is your current transmission a granny 4 speed?
are you going to convert the m21 to overdrive?
if not it will have the same 1:1 final ratio that your current transmission has......
and
GOT PICS?

[64Fugly]

yeah the current transmission is a granny 4. What would I need to do to convert to overdrive?

[TwoFiftyShifter]

Originally Posted by 64Fugly

Hey guys,

I am going to install a 292 engine in my 65' fleetside. Now would a Muncie M21 transmission be good enough for this engine. The transmission that is on there is a 4 spd. The purpose of me using a muncie is to at least get up to normal speed on the interstate. I could use all the info I can get.
Thanks guys.

Good enough, I don't know about that.... If you have some future plans for a small block V8 or something like that, the M21 will be perfect, if you're staying with the 292, you might want to cosider other options, for highway driving a 4 speed creeper might not be any good. Turbo 350/400 for auto, you might not get the best mileage because it's a 3 speed, but there are plentiful, cheap and strong. You might be able to get a 5 speed NV3500 for cheaper than a Muncie, around here you'd need $1K to get a decent Muncie.... But if you can get a deal on one, it would work well....

[joe231]

Originally Posted by 64Fugly

yeah the current transmission is a granny 4. What would I need to do to convert to overdrive?

$450......
http://www.riversidegear.com/categor...oduct-166.html

do you already have the m21?

[64Fugly]

$450......
http://www.riversidegear.com/categor...oduct-166.html

do you already have the m21?
__________________
Yes I do have the M21.

[64Fugly]

Thanks for the link Joe.

[joe231]

no problem
ought to be a nice set-up with OD

[bird7263]

I have a m21 behind a nice little 300hp small block and 355 posi rear. Truck is killer to drive and head turner at lights and around town. How ever, I would love to have the 5th gear or overdrive on the freeway. Even with 355's I am turning 3000rpm at 65-70mph. I agree that the NV3500 would be great.. I had one in my old Cummins. Loved that tranny.. Bullet proof. Munice's here in Portland go from $700-1000 even for a junk one. I have turned into a big fan of the T5's out 80's Camaro's and even better a truck version out of a s-10. I have seen several guys do this to there hot rods and trucks. If they can handle the abuse of the mullet craze in the 80's then they can handle one of our trucks. I know a guy that runs 500hp to his T5 and he has never had a porblem. Runs hard.

[19GMC63]

if your keeping the 292 or planning on a fairly mild SBC, I would look into a T5 from either a 4 banger S10 or a pre-92 F-body one. As far as strength, there were no differences between S10 and F-body non-World Class trannys.
I opted for one out of a camaro for the closer gear ratio, S10's will have lower first gears (which I didin't need), but I think they all used the same overdrive gears... .68 or .73 I can't rememember. They were behind 305's and are rated somewhere in the lower 300s ft. lbs. of torque but can handle more as long as you don't dump clutch it or anything.
They are really cheap too and easy to find, unless your looking for a F-body World Class T5 since they are fairly uncommon.... I paid $250 for mine locally through craigslist.

[Green77c10]

just out of curiousity, because i was thinking about the possibility of doing something like the OD kit for the same trans, how would it shift without having a synchronized first gear? with the granny it sure doesnt want to go into gear unless your at a dead stop and sitting just right. would the higher gear ratio counter that? not meaning to steal the thread, just curious...

[joe231]

the od kit is for a muncie m21, not the granny 4 speed.......

[Green77c10]

yea, just realized that, my mistake

[joe231]

ain't no thang!!
wouldn't it be sweet if someone made a conversion for those.....
bet they would sell like hot cakes....maybe

[ChiefRocka]

Hmmm...will that T5 slide right into your standard bell housing ?? What about the TO bearing and release fork ??

Man there are chit-loads of Camaros in the local wrecking yard here....What years should I be looking for ? -92 ??

[ChiefRocka]

Actually, I have this Stovebolt link to a T5 how-to:
-
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http://www.stovebolt.com/techtips/t5tranny.htm

[19GMC63]

Don't know if the OP is even interested in this swap, but the only thing you would have to watch for is bearing retainer size. Don't know how the early SM420's are, but my 4spd (SM465) bellhousing had a larger bearing retainer size than the T5. I just got another bellhousing, but I guess one could machine their existing bell.
Also, the SM465's lower two bolts threaded into the tranny, top two threaded into the bellhousing. All 4 on the T5 thread into the bellhousing, so you have to check that out. You also have to watch the bolt head size too... the T5's casting fins don't provide a lot of space to get a socket on. I've heard of some using round allen head bolts.

[ChiefRocka]

I had to use allen bolts on the Vette TremTec. So only the bell-housing opening will have to opened up ??

The TO bearing, and original clutch linkage should work then ??

This might be another option instead of running the 700R4 or Munice...

Wonder if the tranny will hold up to 6,000 RPM clutch dumping ??

[TimE]

Originally Posted by ChiefRocka

Wonder if the tranny will hold up to 6,000 RPM clutch dumping ??

Try it and then post lotsa pics!

[64Fugly]

What modifications would have to be done if I choose to go with a T5 into my 65' with the 292,(I can always use the Muncie for my 64).

[19GMC63]

Originally Posted by ChiefRocka

I had to use allen bolts on the Vette TremTec. So only the bell-housing opening will have to opened up ??

The TO bearing, and original clutch linkage should work then ??

This might be another option instead of running the 700R4 or Munice...

Wonder if the tranny will hold up to 6,000 RPM clutch dumping ??

Chief, I'm pretty sure the SM420s used the same bearing size that the T5 and most other car trannys use. So you could find a bellhousing out of an older 4spd. truck and it should be just bolt-in. Then you could use your existing pressure plate and just get a different disc. You could use a later truck 4spd bellhousing but you would have to machine a ring to be inserted to take up the space, not take metal out. And if all else fails, you could use a car bellhousing, but then you would have to use a smaller diameter clutch kit... and therefore flywheel... so that's a lot more work, and there's no guarantee the OG clutch linkage/fork/TO would work on a car bell.

You have a bench seat too right? Camaro tail-housings put the shifter as far back as it can go. S10 tails-housings put them a lot closer to factory location. Also, S10s use 1" 14 spline inputs, and Camaros user finer 1-1/8" 26 spline. Here you can kinda see the shifter placement...



A lot of guys swap tailhousings so they can have the nice gear ratio of the camaro case, and good shifter placement of the S10 tailhousing.

The HAMB has A LOT of info on this... check out Flat Ernie's "Ultimate T5 Tech Thread"
http://www.jalopyjournal.com/forum/s...d.php?t=169265

[19GMC63]

Originally Posted by 64Fugly

What modifications would have to be done if I choose to go with a T5 into my 65' with the 292,(I can always use the Muncie for my 64).

If your bellhousing will work, then it's just a matter of buying a new clutch disc to match the splines of the input shaft and the diameter of your pressure plate. Also, I'm not positive, but I think you have to take a bit off the end of the input shaft and collar for the T5 to fit in an I6.

Those 4spds. are pretty short... a lot shorter than the T5, so a shorter driveshaft would be needed.

And lastly, the T5 uses a rear tailhousing mount, unlike the 4spds, which just use bellhousing mounts.

[TimE]

If I'm not mistaken, the OG 3 speed bellhousings work perfect for the T5 swap. I was planning on this swap at one point, actually bought a T5 but then it needed synchronizers and I ended up just sticking it back for future purposes and picked up a NP833 instead. Still haven't installed it either though.

[19GMC63]

the only thing about the OG bellhousing are the lower two bolts. The holes in the tranny are too large to tap. I'm sure there is a solution though, but I took the easy route and used another bellhousing with all 4 holes tapped.

[TimE]

Gotcha!! Thanks for the clarification.