midyearvette

maybe he has a really late 65 and they ran out of trannys so he got a 66 unit....

rayvaflav

Speaking 'o fun with Muncies....Whilst in the middle of my original wide-ratio M20 I could not get the loaded cluster gear to fit into the case. That prompted my repeated disassembly/assembly of the 128 uncaged needle bearings and the 6 spacer rings that were supplied with the kit from D&L Transmissions (recommended by Tom Parsons, thanks Tom). I called Larry and told him of my dilemma and informed him that only 4 spacer rings were found from the assortment of original parts. His response was "You must have a '66. That was the only year that used the spacer tube as a bearing surface and only four rings.". It fits better now....

Ray

1snake

No problem. The site you linked to is wrong.
When Tom posted - "In the beginning (63) when the Muncie replaced the Borg-Warner T-10, the 4sp transmission option was M20. Period. Depending on engine/rear gear ratio, the car was delivered with either a wide ratio or close ratio Muncie. The option was still M20 for the 4sp.", it wasn't a "claim", it's a fact supported by a countless number of GM documents and actual examples.

Jim

JohnZ

OK, try this - from my "Tech Bench" column in the August '08 issue of "Corvette Enthusiast" magazine.


Reader’s Question: I have a ’62 327/340hp Corvette I bought eight years ago with what I believe to be its original T-10 4-speed based on casting dates, and it has a 2.20:1 first gear based on comparing input to output shaft revolutions when it was rebuilt last year, which makes it a close-ratio transmission. A fellow Corvette club member says that’s not possible – he says the M-21 close-ratio 4-speed wasn’t available until 1966, after the T-10 was replaced by the Muncie. Isn’t it true that close-ratio 4-speeds were available before 1966?

Response: Yes, that’s correct – the very first Corvette 4-speed in 1957 was a close-ratio transmission with a 2.20:1 first gear, and ALL Corvette 4-speeds were close-ratio through 1961; the wide-ratio 4-speed didn’t appear until 1962.

Semantics are involved here as well; although both close- and wide-ratio transmissions were available beginning in 1962, the M-21 OPTION (RPO M21) for the close-ratio version didn’t appear on the order blank as a customer choice until 1966. That was the first year the customer could make the choice between wide and close-ratio transmissions (on some engines); prior to that, the 4-speed option was always M-20, and the engine selection made the ratio choice, not the customer – here’s the story on 4-speed transmission availability.

1957-1961: All 4-speeds were the Borg-Warner T-10, and all were close-ratio with a 2.20:1 first gear. 1957-1960 transmissions had a cast iron main case and an aluminum tailhousing, and the main case changed to aluminum in 1961.

1962-mid-1963: 250hp and 300hp engines got the new wide-ratio T-10, and the 340hp and 360hp engines got the close-ratio version.

Mid-1963 to end of 1963: The T-10 was replaced by the new Muncie 4-speed as a running change during the year, with the small front bearing retainer; both the main case and the tailhousing were aluminum. 250hp and 300hp engines got the wide-ratio version, and the 340hp and 360hp engines got the close-ratio version.

1964: The Muncie bearing retainer diameter was increased, and 250hp and 300hp engines got the wide-ratio version, and the 365hp and 375hp engines got the close-ratio version.

1965: 250hp and 300hp engines got the wide-ratio version, and the 350hp, 365hp, 375hp, and 396/425hp engines got the close-ratio version.

1966: 300hp only available with the wide-ratio, customer could choose wide or close-ratio with the 350hp and 390hp engines, and the 427/425hp engine got the close-ratio version.

1967: 300hp only available with the wide-ratio, customer could choose wide or close-ratio with the 350/390/400hp engines, 435hp got the close-ratio version.

Summary: Although the “M-21” OPTION didn’t appear on the order blank until 1966, Corvette 4-speeds were available with the close-ratio gearset right from the beginning in 1957.

blubu

If 66 was the first year for the one inch pin cluster
Does that mean the 396 cars available in 65 were 7/8 ?

1snake

Thanks for posting that John. Hopefully, that will clear up any questions created by wrong info. being posted on other web sites.

Jim

DZAUTO

OK, here is how a 1965 Muncie got a 26 spline input shaft in it with 2 grooves around the splines (26 spline inputs were ONLY in 71-74 trannys).
'Cause I built it that way for him!
Gene's 65 FI car originally had a close ratio Muncie, and he wanted to have a wide ratio (for the better response from a stop). Changing ANY Muncie from wide to close ratio or vice versa, requires changing BOTH the input and cluster gears. At the time, a 71-74 input cluster was available for an excellent price. BUT, the 63-65 cases use a 7/8in cluster shaft and the 66-74 cases use a 1in cluster shaft. So, I sent the 65 case to Larry Fischer and had him bore it out for a 1in shaft. Upon return of the case, I built Gene's matching number Muncie with the wide ratio, 26 spline input and matching cluster gears.
And that's how it was done.

Now, what is the whole point to all of this???????????
You CANNOT judge a book by it's cover, nor can you judge the guts of a Muncie by its casting number/stamped code. Some of us who have been building Muncies, since Moses brought down the Ten Commandants, have seen and done MANY things to them. You don't hear it mentioned much anymore, but in years past, it was common to upgrade a 63-65 Muncie with a 66-74 cluster, gear gear/shaft/input.
Now that the Auto Gear Muncies, Super cases and gears are available, there is not much point in spending a lot of money on an old worn out Muncie-----------------------UNLESS IT'S AN ORIGINAL NUMBERS MATCHING TRANNY. If that is the case, then it is worth almost any expense to restore the tranny back to new or excellent serviceable condition. Even if the case has severely enlarged holes for the cluster gear shaft or cracked or broken/missing mounting ears. I have several junk Muncie cases which I keep specifically for cutting off an ear and having it welded to a matching number Muncie case with a missing ear so that it can be saved.

Tom Parsons

thread baron

Sounds like some good info being passed around, this thread was not a horse beater after all!

You guys love answering these questions as much as we enjoy learning something new

DZAUTO

YEP!
Welllllllllllllllllllll, except for the tiny handfull of 65 M22s.
I personally have never had a 65 M22 on the workbench. But, all the authorative information about them indicates they had a "modified" casting number and a 1in cluster shaft/gear.
Also, there seems to be debate on their actual designation. The majority of knowledgeable people have indicated that the 65 M22s were NOT designated as an M22, but simply as a HEAVY DUTY Muncie.
John Z may be able to expand on this a little more.

Tom Parsons

midyearvette

sooo......you modified the tranny, and the bold ORIGINAL was meant to throw us off.....trick questions do not count....and the tranny is no longer ORIGINAL......bwtfdik??.....

midstyle

Tom -- In Colvin's Chevrolet-by-the-Numbers 1965-69, he has that excellent appendix on the 1965 M22. Reproduces the ECR (Engineering Change Recommendation) initiating the M22, dated 12-16-64. The RPO designation M22 is used several times, and was intended to replace M20 for RPO L76 L84 and L78 (for 1965) and RPO L36 and L72, (for 1966), with the H.D. [M22] transmission [as required or specified] for ratios 3.08 thru 4.56. So even at that early date, they knew what the engine line-up was for the 1966 MY.

Also, same appendix features that black/black L78 tanker that was ordered and delivered to Gorries Chevrolet in Toronto, Ontario, in mid-June '65. The Canadian paperwork shows M20 on the dealer order form and M22 on the delivery form. This car took 86 days from order to delivery.

Formula Outlaw

Well, now at least I don't have to buy a new lawn mower, but do need some landfill....

And after rereading this entire thread at least three times, I'm pretty sure I learned something.....Thanks......

MikeM

Prior to all this order form, alpha/numerical identification nonsense, we used to call them four speeds, then close ratio/ wide ratio when there became two different gearset ratios. When the "rock crusher" came along, that's what we called it. Rock crusher! There was NO confusion then about what was what!

Then came the NCRS and things changed! Then came the internet and many are confused!

DZAUTO

OK, I'll re-word it: ORIGINAL, numbers matching Muncie MAIN CASE. How's that?

Tom Parsons

DZAUTO

Mike,
You catch on REAL quick!

And yes, I too grew up knowing that the M22, Heavy Duty Muncie, whatever you wish to designate it, was most commonly referred to by ALLLLLLLLLLLLL the car guys as the Rock crusher. But today I seldom use that term because, as you say, people are now confused.
For example, who the heck knows what a babbit beater is today??? Or a stove bolt? Or a Flatty? Or a Columbia butt? Common terms when I was becoming car knowledgeable back in the 50s.

Tom Parsons

midyearvette

that's fine tom but i think i should get e beer for a consi prize since i don't get the venerated gold star....

VetteRed1965

MikeM

Did you ever have a babbit beater start knocking out in the middle of nowhere, take the pan off, scrape a little babbit out with a pocket knife, then cut a piece off your leather belt and put it in there and then drive on?



PS. I know what all those terms mean and I know what a Columbia axle is but I never heard it referred to as "butt".

DZAUTO

There is one or two or three or ten waiting for you in the fridge in the garage---------------------------I keep them so cold that when you pop the tab, they have little icy crystals inside!

Tom Parsons

DZAUTO

Nope! When they started rattling, I pulled it in my uncle's garage and rebuilt a 261 truck engine that he had against the wall and installed the Vette 3 side drafts and dual exhaust manifold. The 3 carbs are long gone, but I still have the 6cyl dual ex manifold under the workbench. Unfortunately, no pictures of the 51 with the 261/3 carbs.
Oh ya, but I'm still driving the 51 EVERY DAY-----------------5 engines later!

When and where I grew up, Columbia butt was the term----------------sounded swell, Columbia rear was nowhereville, man! C'mon daddyo, get with it!

Tom Parsons

Tom Parsons