Is the 3 speed as durable as the M-20?
 

A friend may have one of those dearborn (?) 3 speed trans that he says was pulled from an old 400 lemans.
I have not seen it but he wants $100.

I have a 71 GTO, with a fresh 464, 6x-4, (9.5:1) Melling 041 clone (spc-8), Rhoads lifters, 1.5 rockers, RA manifolds with X pipe, Muncie M-20, and a 3.73 12 bolt with a yukon posi.

I know folks have blown muncies with much smaller engines, so i'm guessing that this is the weak link in my setup?
I dont race the car but I am tempted to try a few passes.
There is nothing wrong with my muncie; I'm very happy with it. I never stray far from home with my car and so an overdrive trans doesnt interest me.
I was just wondering what the scoop is with the 3 speed and if it's worth buying and rebuilding for a quick fix backup?

Muncie also made a 3 speed, which was the base transmission in 1970.

No experience with either 3 speed...seem to recall reading that the earlier 3 speeds were Dearborn's because Muncie could not make enough, then by 70 they were able to produce sufficient quantity. Memory fuzzy on this so happy to be corrected...

One of my street racing buddies in the 70s liked 3 speeds for their ratios over a 3 speed. He had a 455 in a 65 Chevelle! Hammered on them hard.

The Dearborn 3 speed is a heavy duty beast. Stronger than a Muncie. Need a different yoke for it.

The Ford 3 speed is very strong and was used in Ford commercial vans for many years.
In the 1964-1968 timeframe you could get a Ford 3 speed trans instead of the GM trans in the A-Body vehicles. Some GM (Pontiac Bellhousings have both bolt patterns.
The bellhousings are more common than you would think.

If you just wanted a durable (strong) trans with 3 speeds - much like a Turbo 350 auto trans then the Ford piece is the way to go if you like rowing gears.
I have blown up Muncie Trans which is why I run a Doug Nash 5 speed trans today.

Tom V.

Never heard of one blowing up. It is a cast iron trans, top loader, just like it's bigger brother the Ford 4-speed top loader. It is a HD tranny, fully synchronized, and smooth.

I have had a couple of these and like them. The only downside is that they are 3-speeds. Taking off from a stop and rowing through the gears works great when racing from a stop. But, get challenged on the street where you are at a speed where you can't drop a gear to put a kick into the engine, and the other car may pull away even if you have the bigger engine - that's my only negative comment about them.

For $100.00, I would not pass on it. With a good torquey engine, probably a good choice. Try it, or keep it as a back-up.

Does it include the yoke and shifter?

My '68 GTO came new with the M-13 . IN '68 that meant a Dearborn Beast. Vs a whimsy saginsaw..this 3 speed Is the heavy duty 3 speed. And it's heavy.. That trans sat behind a Factory stock 2bbl 400.. basically the most basic GTO, but it had hideaways..

If it were mine, and you just want to have a little fun at the strip and make a few passes like you mentioned, I'd just run the M-20 and forget about it.

Since you're just wanting to "try" a few passes I sense you aren't serious about sticky tires, 4000 rpm clutch dumps and 60 foot times. With street tires I wouldn't worry about it.

There have been dozens of Muncies, I have personally seen, leave their parts on the street, or limped off to the side of the road with street tires on GTOs. I've never seen/heard of one of the ford three speeds ever break, but in shear numbers the Muncies outnumbered the ford by probably 50 to 1.

All you have to do is lift one of the ford transmissions up and compare how much heavier they are compared to a Muncie, even missing the parts for an extra gear, they out weigh a Muncie by a noticeable margin. If that doesn't convince you take the inspection cover off and compare the difference in size of the innards piece to piece. They also have the tougher case, being made out of iron, rather than aluminum, that the Muncies are made with.

When Pontiac came out with their 455 they also came out the following year (1971) with an M21 HD, which was touted to be nearly as strong as the fabled M22. The M21 HD was used until 1974, then GM used Borg Warner 4 speeds. I had one of the M21 HD transmissions in my 1973 Grand Am, and I was never able to break it, I just changed the car over to a T400, because I prefer the strength, over an OEM 4 speed. When the first clutch went south, out the 4 speed came. Since the car was a D/D the X wife wasn't that good at driving a stick anyway, it just simplified everything at the time.

Had I not seen the added strength in the T400 transmissions over the Muncies, and went with the T400, my next logical step would have been to outfit my GTOs with a ford top loader 4 speed. Since most Pontiac bellhousings were also drilled for the ford bolt pattern, it would have been a fairly easy swap. They are head and shoulders tougher than any Muncie made. They also take 2 people to lift one up laying on your back while changing clutches, so there is a weight penalty that is probably equal to a T400.

:focus:

John Sawruk was a drivetrain engineer at GM during the muscular years and one of his jobs was durability testing. That consisted of nonstop full throttle power shift passes until a failure occurred. When the 455 came out in 1970 he said the Dearborn 3 speed was the only trans they couldn’t break. The Muncie 4 speeds couldn’t handle the big torque engines which led to the Super T10 taking over as the 4 speed of choice for GM.
I’ve heard they had a tendency for the Dearborn to hang up between gears but that may have been more of a shifter issue.

Our 70 GTO had the Dearborn 3-speed; great ratios, and more fun than a 4-speed.

It would certainly get caught in 2- gear and lock-up.
usually while hitting the brakes while approaching a TollBooth. The Shifter needed Cal'd and tightened to prevent the lockups.

In talking to Arnie Beswick many times about racing in the "old days" he mentioned that the 3 speed manuals were stronger and more reliable than the 4 speeds of the day. So I assume he was talking about the Dearborn HD 3-speed VS the BW 1st generation T10 4-speed. Also fewer gear changes with the correct rear gearing could be quicker as well. Aluminum case Muncies, while light and super easy to repair, are not up to the kind of power we can easily make today and the sticky street tires we have either. They were borderline in the 60's with around 400 HP 450 lbs. of torque and the rock hard street tires of the time.

X4 or 5 that the Dearborn HD 3 speed is a stronger gearbox than the Muncie. By a bunch, I suspect.

The Saginaw had no synchro on 1st gear. Ypu had to "double clutch" or shift to second before you put it in first when stopped. When you're moving, there was no putting the trans in first. I had the Saginaw in my 1965 Lemans. It did not hold up to power shifting even with my 326 2 Bbl motor. I had mine rebuilt once in the 2 years I owned it. 2nd and 3rd gear synchros went bad and the trans would "snick" on the upshifts and downshifts.

I had a '64 Ford Galaxie w. the Dearborn trans, which had a synchro first gear, but I can't speak for durability other than having no issues behind a wimpy 2 Bbl 390.

RIP JOHN and MACK. You could always take his (and Mack McKellar's) info to the bank.

IF you installed a Proper Hurst 3 Speed Shifter on that 3 speed "Top Loader"
trans You rarely ever had shifting issues.

Tom V.

The Ford 3 speeds were tough, but they were put behind 240, 300 six cylinders and 289s, 292s and 352s, none of which were powerhouses.

There were 133 different versions of the TopLoader 3 & 4 speeds for different applications. GM received the 'RAT' 3 speed version which was primarily used for the higher horsepower cars, trucks, and Broncos.

This 3 speed transmission was updated to a four speed O'Drive in the late 70s (RUG Version) used behind small Ford V-8s and sixes. Not suitable for high horsepower
Chevrolet used the Dearborn in their 1/2 ton trucks during the mid 70s.
Rights to the design were sold to Tremac who used it in Jeeps.
The T5 is probably a direct descendent.

Yes, I know. My uncle built many Ford based circle track cars with the top loader, and he managed to destroy a few behind 427 FEs.
The overdrive one in pickups was more for70s economy concerns.

Many years ago I used one in my 1961 Chevy PU behind a mildly built 455 Pontiac engine. Used it as a TRUCK plus drag raced it once in awhile. Never had a problem. You have the fun of shifting with only 3/4's the work. Seriously use a good shifter and you should enjoy it.

Ford Transmission in Livonia Michigan was ALWAYS doing "Running Changes" on the parts trying to make them better and better. I worked with a few M/T Trans engineers who were very sharp. Buddy Ingersal's Turbo Pinto trans was designed by 3 of them and later became a first gen Doug Nash 5 speed. Doug Nash was a Skilled Traded guy for Ford at one time in his life.
Bob McNall was one of the engineers on that racing project.

Tom V.

this thread just makes me want to build an oddball car with cheap factory parts and see how fast i can go. something like an esprit, base firebird, or ventura with a 350 stroker, factory intake, and the 3 speed manual.

Were the HD muncie 3spds similar ratio? I had a 68 Chevelle SS396 with the factory hd 3spd. Even had the console with the shift pattern. If you could beat someone by 2nd you were good, but there was too big of a gap between 2nd and 3d. Basically seemed like a 4spd missing 3d gear. It also had the habit of getting locked in first and 2nd at the same time if you shifted too fast.

It has been mentioned a couple times here (including that prior post be "chevymad");

Unfortunately for this discussion, simply calling a "Muncie", doesn't benefit the matter;
Granted when people say "Muncie" 99.8% of the time the 1963-1974 Muncie four speed is being implied. What seems to often be forgotten these days is that the "Muncie" name is an implication of the manufacturing facility, moreover the city that they were manufactured in.
The Muncie plant made many transmissions, and the M-20/M21/M-22 are what most people think of these days.

There were at least two in-house GM three speeds manufactured at the Muncie plant.
The first in house Muncie three speed was manufactured from 1955 through 1965 - I understand these were the base "M12" RPO transmission in 1964, and replaced with the Dearborne unit in 1965. I do not know much about these three speeds.
The second was a Muncie three speed manufactured for 1969 through to either 1975 or 1976 - the last year or two it was exclusive to trucks.
This transmission came in two gear sets:
A = 3.03 / 1.75 / 1.00 / 3.02R
B = 2.42 / 1.58 / 1.00 / 2.41R
I found the GM name for the Muncie three speed was SM-330, for reasons of clarity, I will use SM330 from this point forward.
The SM330 was used mostly under RPO's MC1 & M13 - but the RPO doesn't mean it will be a Muncie three speed.
The SM330 was intended as an in house replacement for having to source the Dearborne three speed, and by all accounts it is indestructible.
I have never come across any first hand accounts of people having any issues with the SM330, it seems most were simply swapped for a four speed - not because anything was wrong with it, but a four speed had cool factor in spades over any three speed.


As far as I'm aware, the SM330 had Chevrolet division exclusivity for the 1969 model year, and was used as the base transmission in all 1969 Chevrolet SS396 vehicles.
For 1970, Chevrolet appears to have required a four speed for any Super Sport, but for 1970 & 1971 non-SS Chevelles with big blocks did received them as base equipment.

It is my understanding that Buick and Pontiac used the SM330 first in 1970, I am pretty sure I know what years Pontiac used it, but I do not know what other years Buick used it.
I am unaware of Oldsmobile ever using it.

For Pontiac, starting in 1970, the SM330 was either the base, or base-required option for anything more than a 350-2bbl depending on the model in question.

It was the base transmission for 1970 through 1973 GTO's.
For the Lemans line, the SM330 continued to be available through to 1974.

It was the base transmission for 1970 Formula 400's, and 1971 Firebird Formulas with either the 400 or 455HO engine.
It was optional on 1970 & 1971 Firebirds as the "heavy duty 3 speed" option for 350-2bbl cars.
After 1971, the SM 330 was no longer offered on Firebirds, and while the 350-2bbl cars still had a Saginaw three speed as base equipment, anything with a 400 or bigger, required a four speed or TH400.

The real trouble with SM330 is that they are nearly identical to the Saginaw three speeds, the quickest, and most sure way to identify a Saginaw from a Muncie is the side cover;

The Saginaw three speed has a single centred "ear" bolt boss:
https://forums.maxperformanceinc.com...1&d=1566404056

The Muncie three speed has two "ears" on either side of the top of the cover:
https://forums.maxperformanceinc.com...1&d=1566404056

In nearly every other way, the Muncie three speed looks like a Saginaw - except the castings are all unique, and other than maybe the output seal, nothing can be interchanged.

To answer the original question (title):

It depends on which three speed you're speaking about;

• As far as I am aware the Saginaw three speed has a torque rating somewhere around 300ft-lbs, which was why it was never behind anything high powered, or with high torque ratings.
• As far as I am aware, the Dearborne three speed is stronger than the Muncie four speed.
• As far as I am aware the Muncie "330" three speed was stronger than the Muncie four speed.

Thank You UnruhJohnny, for that info.

That is interesting information on the early Muncie 3-speeds. It seems in my very early years working on vehicles, I may have had an early Muncie 3-speed apart. As I recall, it didn't have a synchronized 1st gear. It had a spiral drum on the main shaft that first gear tracked-on to engage the gear, only when the vehicle was stationary. Similar to reverse gear in some manuals.

I quoted this, because it is relevant, and it affirms that referring to a transmission by the source, (aka Dearborne; which I may not have spelled correct), although common practice, can create confusion.
It has taken me a good while to garner the information that I have, and along the way, more than once, I nearly bought parts for the earlier Muncie three speed.

SM-330
 

I have several of each gear ratio transmissions. My '72 GTO came with the 2.5 first gear; much 'beating on' never bothered it.

The 3.0 (truck) transmissions have wider gears, and they are more straight cut. I never had a chance to try it out, but it should very stout.

There are also some differences in tail housings, depending if it was for Chev or Pontiac (speedo location) and whether it was floor shift or column shift

Maybe you know more than me, but as far as I could tell the tail housings were for floor or column shift, and the speedo cable was in it's location depending on the tail housing.

I have a truck transmission with the car (floor shift) tail housing and car (smaller OD) input bearing cover;
I had hoped to change it over fully to the "B" gear set, but the second gear, and main/input elude me.

SM-330
 

Not sure this answers your question, but you do have to change all the internals when changing from one ratio to the other. I also recall something about the front bearing cover; I unknowingly used bolts that were too short and pulled them out of the case on launch!

Went to a 400; wish I had stayed with the 3 speed.

If this is not useful, please explain further and I'll try to help.

Me too! But I'm thinking I'll replace the three speed with a TH400 :D

Interesting stuff for sure. The three speed gear boxes were always hard to sell... Mostly dirt track racers wanted them.

THIS ^^^^

No missed gears, shifter jambs, and worn out clutches, repeatable consistency, It's not the form of racing that appeals to me anyway (drag racing), I like corners incorporated into my racing, but have equally successful with T400 in dirt track cars, as well as autocross, and road racing.

99.9% of dirt cars, as Paul K lamented, have 1,2,3, or 4 speed manual shifted transmissions, but I never felt I gave anything away using a T400. For awhile, gutted Power Glides without convertors were in a good many late model stock cars. The early dirt cars I built back in the early 70s, (61 Catalina, Ventura's, bubbletop cars) we used the Dearborn 3 speeds, and ran them in 2nd gear to get the correct final drive. Never even a hint of problems with the Dearborns, but they also aren't shifting gears during the race.

Since I drove semi for 7 years, I have zero hankering to shift gears on a street car. I have one IH wrecker with a stick in it, and if I had an Allison sitting around, the wrecker would also have an automatic in it too. Typically the automatic transmission is easier on drivelines too.

The next street car I build will have a 4L80E in it. My late model 2005 GTO has a 4L60E in it. I bought it new, so I could have had a 6 speed in it, but was driving truck at the time, so the last thing I wanted to do in my D/D was to row gears.

When I first got into street cars, and racing, everything I had was a manual transmission in it. After lying under them fixing all the driveline failures from clutches to rear axles, and everything in between, I bought my first T400 equipped GTO, and my time underneath the cars was reduced dramatically, as well as monetary expenditures for broken driveline parts, :idea: lesson learned.

I think you may be off 1 year on the chevy's at least. My 68 had the muncie. As a kid I took the trans apart, and only had a book for the saginaw. The parts nearly matched, except all the shafts had a double row of bearings instead of single. My car also had the original floorshift/console with the Muncie stick and H pattern molded in the console plate. Car was a 325hp bare bones SS. No ps, no powerbrakes, 4wheel drum, no gauges, and a 3spd. It did have buckets and console and a vinyl top. Odd color combo, red with the obligatory black below the body molding for SS, but with white vinyl top and interior.

I am running a 3 sp. Dearborn in my 1967 Resto-Mod Convertible LeMans . I really like it. It does not shift fast from 1st to 2nd only because you're crossing the neutral zone, It is very positive and with the taller gears in the transmission along with the 3:23 the car was born with as was the transmission it is a great combo for me. In town driving from light to light in a lot of cases I don't even have to shift to 2nd gear. I am putting down 295 HP at the rear wheels with my little 389 with massaged #16 heads and a 2802 Summit cam. I am also running 235/60-14 Rally II's all the way around. Drove the car on a 1200 mile round trip it's first year of completion from a nut and bolt, frame off, rotisserie restoration to a Tribute GTO. Not even a hiccup on that trip or since and that was 2014!

64 Lemans I had came with the three speed Dearborn. No synchro between first and second, so I had to come to a complete stop whenever downshifting back into first. It was a pretty tough unit, however when I swapped it out for a four speed muncie the driving enjoyment factor went up considerably. No more crunching on the downshift, plus off the line the lower first gear ratio made it jump considerably faster than on the three speed. If my Muncie blew up, I would not go back to the Dearborn unless there was not an available Municie left on the planet.

Non synchronized gears being the norm seems like a foreign thing to me, only because I can't wrap my head around why non-synchronized transmissions were even a thing past the 1950's...
I wonder if that 1964 with a Dearborn was swapped in some time early in it's life.

As to Chevy mad, I don't know what to say.
My information all suggests the first year it was used was 1969, and that being dubbed a Chevrolet part, Chevrolet got a full year of divisional exclusivity in using it for the 1969 model year.
I wonder if your transmission was changed early in it's life?
I would think that swapping a three speed from a 1969 Chevelle into a 1968 Chevelle would have been a cinch.
If you can find any information that I haven't come across i am all ears - if anything, any new to me information might make finding parts easier.

If everyone is worried about to much power
for a 4 speed or 3 speed why not put a truck four speed or just be done with it and put in a Tremec

Dearborn heavy Duty 3-speed
 

One thing about the 3-speed transmission: Unless you have very deep gears you most likely will never see a '4th gear' before the finish line at the dragstrip. So the 3-speed was a very good choice for me as my cars never had deep (un-streetable) gear ratios out back. Yes they are heavy, but you probably aren't going to break it working it hard.
I have the answer to shifting it quickly: what I would call a 'pretty rare' NOS Hurst Inline Ram Rod shifter for this transmission. And it is for sale too !! Here you see it installed on a Saginaw 3-speed, and I'm quite sure it will work on a Muncie as well. I'm not finding any photos real quick of it installed on the Toploader, but I assure you it works there also since I still have my heavy Duty 3-Speed Dearborn that I would like to sell also. [email protected]

My Pal in college, Robert Schneeberger (RIP Bob) had a Hurst Inline Ram Rod shifter for a 4 speed in his 1964 GTO Hard Top.
It worked very well in his Drag Car. It shifted a Muncie 4 speed.

I was not aware that they even made a 3 speed version. Thanks for the new info on that Hurst Shifter.

Tom V.

In 1980 we found and picked up (for my buddy) a Barrier Blue/black '66 GTO with a built 389, dual 4 bbl's on a tunnel ram (through the hood) and a 4.11 12 bolt rear with ladder bars. It had the Hurst Ram Rod/straight line shifter. Car was $700. My buddy wanted to show it off to me, so he had me go through the gears as fast as I could.....I had it wound out in second (in town, on public streets, of course) and the throttle stuck wide open. I immediately shut the ignition key off and saved the day. I only wish I'd thought of turning off the ignition of my own '66 GTO a year earlier when the same thing happened, causing a head on wreck and a lot of grief. That Barrier Blue '66 with the Ram Rod shifter left an impression to this day. Wonder where it is now?

Happy to share the info (and photo) with you. Must also mention Pete Serio had a hand in helping me get it all together. Thanks Mr. Serio !!

Ok guys, edumaction time (for me, that is).

It's my understanding that before the advent of the Muncie, GM used Borg-Warner tranny's (along with Ford).
The 3-speed from those days was the T89.
Is that the "Dearborn" tranny we're referring to here, or is that something else I'm unaware of?

Borg-Warner 3-speed
 

I learned a while back from a member here that the 3-speed manual trannys used back in the very early '60's were, in fact, Borg Warner. Not the same as the Ford/Dearborn Heavy Duty 3-speeds that were in later GM vehicles.

The Dearborn 3 speed was used in performance '66-69 Pontiac A-bodys & '67-69 F-body's.

The late 50's - early 60's BorgWarner HD 3 speed was the T-85.

Thanks guys.
Appreciate the help.

T-85 very tough, heavy too.

Not that it's actually proof of anything, but here's a tech article from chevelles.net https://www.chevelles.net/yesterdays...cles/3munc.htm

Says that in 68 you could get the m13 3speed muncie on both the 325hp and 350hp 396ss cars.

Another point, I have no idea what the actual build date of my car was. It could have been a very late 68.

I have a 1968 Fbird with a 350 2 bbl, it has a 3 speed Dearborn floor shift which was an option over the base 3 speed manual transmission. The code is DB.

that's an RPO code.
Although there are some situations where the RPO code can mean the same transmission, it more often than not doesn't.
RPO codes are model year+division+platform specific.
As an example, in 1969 any Pontiac (AFAIK) which had the RPO M13 received the Dearborn three speed.

Although there are exceptions, typically with GM available equipment changed at the beginning with the model year - there were not rolling changes like Ford ect where depending on the time of year, different equipment could have been installed.

That is a good link, I am going to quote a couple points:
Then there is this quote, which almost seems to contradict the prior quote:
And more...
As a matter of fact, if you take your time to read that link, thematically, it appears as though when the SM330 came out, Chevrolet used the RPO code MC1, not M13 for it;
It appears as though the M13 RPO was quite probably applied to a Saginaw transmission - I had understood that as a matter of pride(?), Chevrolet would not use "Dearborn" parts, and would prefer to use Saginaw, or Borg-Warner.

I believe it was also used in 65s, and we shouldn't forget the B-bodies.