Quick Muncie Question - Team Camaro Tech
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post #1 of 7 (permalink) Old Jul 24th, 01, 04:15 PM Thread Starter
Join Date: Nov 2000
Posts: 28

I didn't want to post this question. But after doing a search everywhere I could think of I still need some advice.

I currently have:
68 Camaro
355(supposedly 400 HP/400TQ) need to verify
350TH decent
12-bolt posi 3.73

Now I've never been much on autos. So I've recently considered swapping to a manual. My dilemma is what to go with. I'm hung between the M21 and M22.

The M21 is a much better price but I question how it will stand up to any future power upgrades I might do. The car is more for a weekend warrior. Not a drag car not a cruiser. I know I don't have the green to go with a 5 speed or an overdrive. I really don't mind the 1 to 1 combo.

So I'm trying to get a grasp of just how much a M21 will stand up to. And is the M22 that much stronger. Or is it kind of like people preferring the 12 bolts to the 10 bolts? I've read the 12 bolts is stronger but in must cases the 10 would handle anything most people would throw at it?

I know I have the 12 bolts but I fell in to a great deal that I would have been stupid to turn down.

All help advise and criticism is welcome and appreciated.
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post #2 of 7 (permalink) Old Jul 24th, 01, 04:55 PM
Join Date: Aug 1998
Location: Waldorf Md. USA
Posts: 3,288

Save your money and go with the M-21 The only difference in the two is the straight cut gears in the M22. Contrary to what most people think, the only reason the M-22 was made with the straight cut gears was to reduce thrust loading of the gears when used in road racing, with all of its constant shifting. I have even heard that the M-22 is NOT as strong as the M-20 or 21 in certain applications. .
I ran a M-20 for years in my 71 Chevelle with no problems, and beleive me it saw some abuse getting that 3700 lb car down the 1/4 mile. It had a pretty stout 355 in it and went 12.50's with slicks. I never broke the trans.
The M-22's are in my opinion, completely over-rated and over priced unless you are restoring a car that had one in it from the factory.
By the way, if you need a nice M-20 or 21 send an e-mail to Wally at [email protected] he usually has a couple done and ready to go.
Hope this helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner
1973 Z-28 ..one family car...Brother bought it new in 73
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post #3 of 7 (permalink) Old Jul 25th, 01, 09:52 AM
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Join Date: May 2001
Location: Michigan
Posts: 2,920

BillK is right. Go with the M21. Let the primo resto guys fork out the bucks for the M22 that they don't really need, but want for braggin rights. The 21 will work great for your application. Don't even consider the Borg warner trans. I know some guys that tried to run these in high powered street cars and tore them up in their first Summer. The M20 by the way is identical to the M21 but has a lower first gear. You can get off the line a little quicker without as much rear, I suspect BillK was aware of that when he choose to run his. I know lots of guys that have preferred to run the M20 over the M21 for that reason.
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post #4 of 7 (permalink) Old Jul 27th, 01, 06:56 AM
Senior Tech
Join Date: May 2001
Location: Austin TX USA
Posts: 501

I concur...I had a M-22 rock-crusher (not from the factory) on a 69 Bowtie car with a 327 and it's only advantage that I could tell, is that it does have a drain plug. Not enough of a reason to spend $1000 more...plus they whine...alomost squeel...pretty loud! Get the M-21 or M-20, a pump to remove the 80 wt oil (with a tube which is sent thru the fill opening), and a nice clutch...I like the Centerforce II...and you'll love it! I'd go with M-21 if you're rear is 4.10 or more...go with M-20 if you're 3.73 or less...then blast off! My opinion.
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post #5 of 7 (permalink) Old Jul 27th, 01, 07:58 AM
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Join Date: Feb 2001
Location: Concord Cal. USA
Posts: 2,664

The only thing you must watch on a Muncie is {aside from obvious broken parts} is the fact that they stretch the case if they are hammered real hard. Once the case is stretched they are much more prone to breakage. I personally don't like used Muncies for the reason stated above although there is someone making new main cases which should cure all the problems. The gears and design is fine the main case should have been cast iron. I have a first design ST10 that I have abused since it was new with out hurting anything.{it's just a glorified Muncie with a small input and output but has an iron maincase}. I personally would recommend a ST10 the ratios are better you can get parts without morgaging your house and they are stronger especially if you get the iron main case.

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post #6 of 7 (permalink) Old Jul 28th, 01, 02:53 AM
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Join Date: May 2001
Location: Columbia, SC
Posts: 278

oger, is there a way to check for a streched case?

Turbo_Jet is offline  
post #7 of 7 (permalink) Old Jul 28th, 01, 06:11 AM
Senior Tech
Join Date: Feb 2001
Location: Concord Cal. USA
Posts: 2,664

You want to check the centerline of the cluster to centerline of mainshaft distance. The only way to do it is completely disassemble the case. We used to take the early 7/8 cases and bore them for the later 1in cluster but moved the centerline .003to.005 closer to the mainshaft to increase the gear engagement. It seemed to help the life expectancy. If you aren't going to really shock the trans real hard {slicks etc } it will probabily live. I had so much trouble with them when I was racing that I went to autos for reliablity.

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