I went last night over to one of our local car shows, La Mesa. And ran into a guy I have spoke with several times who has the exact same car, 68 triple black convertible, with one exception, 427. Anyway he is going to talk to someone this weekend at Pomona swap meet who does Muncie conversions. Supposedly he sells the 4th gear in several ratios. My friend was excited as he can get his highway RPMs down while still mainitianing a matching #'s car and no outside noticible mods. Okay I see good and bad issues with this.

Positives
Maintain stock look
No need to change driveshafts etc.
Cheap, he quoted $400! Plus labor if you have a shop do it.

Negatives
Long gap between 3rd and 4th, can you imagine the RPM drop if 4th gear was .064 like the TKO-600
TKO internal rail shifter is silky smooth versus stock unit.

Tell me what you think.

 

That would be a cheap way to get OD. Just have to decide what you want, a highway cruiser or a weekend 1/4 miler.

 

That's what I thought to. However with 3.70's on mine I would have the low gears for good take-off's but a big gap to 4th. I'll see what this guy offers.
WHAT IS THE 4TH GEAR RATIO ON A M-21 CLOSE RATIO?

I think if he can't make a 4th gear .064-.80 then it's not worth it.

 

I don't quite know how he is doing this. The 4th gear on a muncie is just striaght through the trans. There is no 4th gear the power just goes straight through. You would have to make it an overdrive somehow. There is some talk about making a 5 speed mincie but it is expensive as a Tremec from what I hear. 400 dollars sounds real cheap for what he is planning on doing. I would do some real investigation on this before diving in.

The 4th gear on any muncie is 1:1

 

Okay I thought it was 1:1. Now you say there is no 4th gear. How the heck does that work? I know as much about the inside of a transmission as Kerry knows how to be President. Please explain.

 

I like your analogy. If you have ever seen the inside of a transmission the counter gear provides the lower gears. Think of 4th gear as a rod straight through the transmission. The counter gear is not used when you are in 4th gear. You will notice on the counter gear on a Muncie has 4 gears. The first is large and therefore 1st gear. The next is 2nd then 3rd gear and the 4th is used for reverse. I used to have an excellent diagram for this but I can't locate it right now. Kind of tough to explain without a picture.

 

Okay I thought it was 1:1. Now you say there is no 4th gear. How the heck does that work? I know as much about the inside of a transmission as Kerry knows how to be President. Please explain.

that has to be the best quote I have ever read

 

See:
http://auto.howstuffworks.com/transmission.htm

There's no good diagram of direct (1:1) drive, but just imagine the input shaft being directly coupled to the output shaft with a splined sleeve (...kinda).

//Pancho

 

Here is a pic of the main shaft gear set, notice there is only 3 gears:

 

What about trying to find a cheap T-5 speed? You could probably pick one up at a junkyrad fairly cheap?

 

TKO is probably where I'm headed. But I am keeping a close eye on my friend's plans. I'll test drive his car after the change and report back to you all on it.

 

Even if such a thing were true, I dunno. More gears is better, man. Row it!

 

Be very wary of someone offering "overdrive" 4th gear for a Muncie Or BW T-10. As pointed out earlier, 4th gear is the coupling of the input shaft and the output shaft by sliding the two shift collars to engage the input shaft to the intermediate shaft and the intermediate shaft to the output shaft.

Sounds like a scam.

 

Yes from the links provided I can see what your talking about. i'm crious now how the heck he plans to do this.

 

Guys, check out Autogear.net as he is the one that developed the overdrive Muncie 4th gear, it is on the website. They are also the ones developing the 5 speed Muncie. They are a very reputable operation. I don't think the 5 speed info is on the website yet, but the last I heard they are getting pretty close to testing it. There is a guy on the Chevelle site named Muncieman that is on the "inside" on this new transmission. It is based on the new Italian M22 gears you may have seen in the magazines a year or so ago. It also somehow uses the same case. I am waiting until this comes out until I decide on a tranny. IMHO, nothing shifts sweeter than a Muncie.

 

From what it shows on that website, I think they have modified the tranny so that 3rd gear is now the direct drive and they have new gears that are in the 3rd gear spot setup to run an overdrive. I would think this would require a modified shifter to operate properly.

The cost for this one would be way over $400 because you need a new countergear for it as well as a new driven gear for the new 4th gear.

Remember these are M22 style gears--- meaning they are going to be noisy.

 

The interenal rail shifter alone is a reason to upgrade.. It's a huge difference.. I love my TKO.. even though it'll be gone soon

 

Whats wrong with the super T10? Summit sells'm for $1,400 with a choice of 2.43, 2.65 wr, 2.65 nr, 2.88 first gear ratio (all 1:1 final/fourth) and I've read 3.42 first gear is availible (somewhere?). Okay lets look at my T10 with a 2.52 first gear (since I don't know yours) and 3.70 rear set. This give me 9.324 multiplier in first (2.52x3.70). And final drive is 1:1 through that 3.70 set. But a 3.42 first would allow a 2.73 rear set (if there is one) for the same first gear multiplier (9.324/3.42) but in forth gear the engine would be turning much slower with 1:1 final (fourth) through a 2.73 rear set. This is what I would call a wide ratio. And who really wants more gears to shift anyways. Four is enough for me.
Yes you would have to change the rear gear to a ratio you can live with - $500 to $1000 more for the rear work. But then maybe you can source a good used rear gear set and drop that pumkin yourself to save a few bucks. Ugly job but I did it. Hey maybe time to do the rear spring, trailing arms, bushings and brakes anyways right?
And do you really need a stronger trans for a mild street-able sb?
Just reading the other posts of the 5 sp and 6 sp swaps is a major effort to get it right. Alignment angles and shifter mods makes it very difficult. But any trans shop can swap the direct replacement Super T10 and same for the rear set with any driveline shop. And after 35 years maybe it's a good time to overhaul that rear diff with new bearings, posi clutch-pak and seals.
Reality here, we're talking $2,500-$3,000 with new parts but remember your old parts are worth a few bucks to your friends here on CF. What does a TKO/5 cost before labor? After labor? And I think you still need a highway (low ratio) gear set too?
Now the real cost saver is to rebuild your stock T10 with the right gear set and find the appropriate rear. And I'll guess there's plenty of highway (low ratio) gear sets for cheap and that you could easily resell your 3.70 set. Now this could bring cost down to near $1000 and leave you with rebuilt trans and rear ready for another 20 years service.
Okay I'll shut up now but I couldn't resist this topic as it seems popular with the current fuel prices - thanks to Georgie B. And I've only rebuilt 2 Muncies in my life but it taught me to let a real transmission mechanic fix my transmissions just like we need a real soldier to fight our war on terrorism.

 

Kerry's as much a "real soldier" as I am a rocket scientist

 

Only a "rocket scientist" could bad mouth 3 purple hearts, a silver star and tour in the Delta!