Who runs a 4 speed?

[HarrisonTX]

I have a 4 speed (super t-10) laying around the shop, and the t5 route looks like it will be $1000+. So, who runs a 4speed, and what can you tell me about it. Im sure rpms are crazy on the freeway with these little tires, and no o.d. but thats okay with me cause my power wont come online till mid-3000rpm anyways!

JTR book dosnt say anything about a 4speed, only mentions the 4+1 tranny. What about shifter hole? Im thinking this will be a pretty easy tranny to run seeing as how it is so small.

Harrison

[zeeboost]

My '75 widebody project has a 4 spd Muncie. I've talked to another guy at work that had a Bronco with a BB and a 4 spd rock crusher, he said first gear was a stump puller (granny gear), 2nd gear would bog down, 3rd gear wasn't bad, and 4th gear was heavily overdriven. He said the rpms were pretty decent at 85 mph. I don't know if mine is the rock crusher or not, I'm about to do some more research to find out exactly what I have, but I know that we both have a long throw to shift gears - I mean mine literally moves the center console when I shift. Other than that, I plan on keeping the 4spd as long as it holds up to the abuse I'll be dishing out.

[HarrisonTX]

huh, well, here is what i know about 4 speeds, that bronco guy...I wouldnt take his advice too much.

Theres 3 kind of muncie 4 speeds, m-20 m-21, and m-22.

none of them were Granny 4speeds. the lowest (numerically highest) gear any muncie had in it was a 2.52. All "rock crushers" had i think 2.20, which isnt even close to a Granny gear.

My super t-10 has a 3.42 which is pretty low and thats not even close to granny, altho i go have to shift at about 13mph.

Maybe 2nd gear bogged on the guy because he shifted at 2k or something, or maybe he had huge tires.

What is he talkin about 4th is "heavily overdriven" No muncie, borgworner, or saginaw 4 speed was over driven. I am pretty sure all 4 speed manuals have a 1:1 4th.

 

All m-22's where "rock crushers" they were just really really tough, and had straight cut gears that will whine like crazy, some people dig it.

 

If you tell me how many spline input shaft, and how man groves are on it, i might be able to tell you what you have.

Im no expert in 4 speeds, but i do know a little.

What size tires was this bronco running? if he had real tall tires, his rpms at 85 will be ALOT different then what yours are at 85 witch short ass z tires.

 

harrison

[dsommer]

I've got a 4 speed in the Scarab with a 3.36 geared rear end.

In my JTR car I have a WC T-5 and 3.70 LSD rear end.

 

A lot of it depends on the rear gears. With that being said, the JTR car (approx 400 hp est) is very quick, first gear goes by in the blink of an eye and you'd better be grabbing second or you're going to red line the engine every time (at full throttle). Even with a 5th gear the engine still spins around 2K+ at reasonable freeway speeds. I do not know what the top end of the car is.

 

The Scarab with the 4 speed, 3.36 gears makes it a bit of a dog stop light to stop light and at freeway speeds the engine turns 2.5K+. But it is in its power band at those RPMs however top end is limited to max RPMs in 4th gear.

 

So as the old addage goes around here, what are you trying to do with the car?

 

Personally I prefer the 5 speed over the 4. Going down the freeway spinng close to 3K RPM just doesn't sit too well with me. If you choose the 4 speed be sure to build your engine to withstand the higher RPM's it will experience on a regular basis.

 

Why the high price on the T-5? I picked mine up for $250, added a hurst shifter $125 clutch,PP, throw out bearing $150ish(?) custom clutch line $50.<$600.

[Alf]

I run an M20 Muncie in my 69 Camaro. It's a good tranny, but I can only go about 65 comfortably with 3.73 gears and 28" tires. I run a Saginaw three speed in my 300ZX which is also 1:1 final drive ratio. That car has 3.70 gears and 26" tires, I screamed that engine from KS to NJ at about 4,000 RPMs, I was doing 71 mph.

 

The good thing about the Muncie is that it is small and light, somewhere in the range of 85lbs, and pretty darn tough. I've dumpped the clutch in my Camaro at five grand with slicks, it just lifts the left front and books. In a small car like a Z I think it would be really hard to break.

 

The way to tell them apart is the stamping where the two halfs join, there will be a few numbers and either an A, M20, B, M21, or C, M22.

 

M20 - wide ratio - 2.201.641.281.00

 

M21 - close ratio - 2.521.881.461.00

 

M22 - "rock crusher" - 2.521.881.461.00

 

As can be seen the M22 and M21 have the same "close" ratios. A commom misconception is that "close ratio" reffers to the shifter throw and that it is shorter, it's not, all transmissions have the same shifter throw with the same shifter. Close ratio just means the ratios are more tightly spread. The M22 is called the rock crusher because the gears are straighter cut, they are NOT straight cut, just straighter than the M20 and 21.

 

From what I've heard from old muscle car guys is that when a Muncie breaks it blows up the cluster gear and usually takes out the main case.

[Pete84]

So the Muncie's are very tough? How much can they take in a muscle car?

[zeeboost]

I talked to him some more, and he said he had some 40" swampers on the Bronco, so that could help explain the lower rpms

 

He said he didn't know too many details about the tranny, except that it was pulled from a '72/'73 farm truck.

 

Thanks Alf for that reference post - I'll check as soon as I can to see what type of tranny is in my widebody.

[zeeboost]

All I could find were:

 

3851325 on the main case, which means "1964 –1965 7/8" Bore Patent Number"

 

and

 

3831707 on the side cover, meaning "1963-1965 Early side cover stud type shift shafts"

 

The stamping where the main and tail cases meet looks like it's been hit with a punch or shot-peened, so I can't see what letter it is supposed to be there. Anywho, from what I've gathered so far, it appears to be an M20. I also noticed it has a Hurst shifter. I don't know if this was standard on these or not.

[Guest zfan]

I ran a Super T-10 in my Z for 2 years and hated it. No freeway driving and for drag racing it wouldn't hook for poop. I put a 700r4 auto in her and have been happy ever since.

 

If you road race mainly then stick with the T-10, It will not let you down there.

[Trevor]

I fitted (but never ran) a Saginaw 4spd in my '77 280Z. Behind a SBC V8, in the "JTR set back, and slightly to the passenger's side position". I had to move the shifter back 6-to-8" from the stock position (was originally in a '79 Olds 442 with a bench seat) using a 1/4" steel plate and extended the 3 shifter rods with lengths off threaded rod. This put the shifter right in the stock hole.

[HarrisonTX]

I ran a Super T-10 in my Z for 2 years and hated it. No freeway driving and for drag racing it wouldn't hook for poop. I put a 700r4 auto in her and have been happy ever since.

 

If you road race mainly then stick with the T-10, It will not let you down there.

zfan, what about your shifter placement?