[Mr Twister]

I have a 74 Trans Am with a 455 / 4 speed Muncie and 3:42 rear. I find the car enjoyable around town but highway driving is annoying. I got spoiled by my daily drivers with multiple overdrives. I know most of the people on this board are very nostalgic and like 4 speeds, but maybe the original poster should consider a TKX. I think it would add to a more positive driving experience. I know in my case its the perfect solution to my issues with the cars drivability.

[7D4 TA]

I found a super T10 from Richmond at a decent price I’ll be putting in with the 2.64 1 st gear. It’ll be a local car, no real long trips. I’ll have 27” tall tires, so combined with a 3.08 or maybe a little lower but nothing lower that 3.42 I should be fine. I just wanted input on the m21 with the 2.20 1st gear but it’s definitely not staying. Looking for a fun cruiser, nothing more.

[Formulajones]

Originally Posted by scott70

The 3.27 first gear with a 3.08 rear sounds like a good combo but yes not what he’s asking about. If someone can afford it though the tkx would be my choice. What are you going to spend on a nice m20?

Mgarblik is pretty much spot on. Out here I see them regularly for $800 to $1500. Some claim rebuilt but are they really and by who? Did they just do the minimum? Some guys don't even want you pulling the side cover to have a peek. So you really can't be sure what your getting. And if you have to rebuild it, not counting labor you can spend several hundred in parts.

It's pretty much why I just keep what I have and don't go out of my way sourcing 4 speeds, and save that process for the correct type restorations. Most everyone these days that actually want to drive their cars just go 5 speed. The cost isn't much more when you really get down to it and it opens up the cars ability and makes the whole driving experience better.

[jhein]

Originally Posted by scott70

I have now a tkx 2.87 first gear and 3.31 rear,,,its much more pleasurable on take offs compared to the m21 but even though that sounds like a big jump in 1st gear it actually feels normal. I wouldnt want it any taller.Not geared too low. So i would imagine a m20 compared to a m21 would feel nicer on takeoffs but its not going to feel like a big change but with a 3,08 rear i would definitely go with the m20 at the least. Its still going to feel a little tall in 1st gear. I think the tkx comes in a 3.25 first gear,,wonder how that would be.

I think it's a 3.27 1st gear in that TKX and that would be a nice combo with a 3.08 gear. I have the same TKX and rear gear as you do and I agree with everything you said.

[Formulajones]

Just to add the other really annoying thing with muncies, st-10's etc.. is that most won't go through the trouble to do a case repair at the counter shaft. You won't know it's a problem till it's in the car and drive it a bit, it's common for them to leak there from just years of use and abuse. The cross pin doesn't fit tight enough anymore and with these things being 50+ years old the problem is more common than you think.

[jhein]

Originally Posted by Mr Twister

I have a 74 Trans Am with a 455 / 4 speed Muncie and 3:42 rear. I find the car enjoyable around town but highway driving is annoying. I got spoiled by my daily drivers with multiple overdrives. I know most of the people on this board are very nostalgic and like 4 speeds, but maybe the original poster should consider a TKX. I think it would add to a more positive driving experience. I know in my case its the perfect solution to my issues with the cars drivability.

I've said it before. Of all the modifications/upgrades I've done to the car, the TKX was one of the best. I know the OP was not considering that option but if it was within their budget, a 3.27 1st and a .72 OD would be the equivalent of having a M20 with 3.99 rear in 1st and a 2.21 in 4th. It's a huge improvement in driving pleasure.

[72projectbird]

I've had TAs set up with a few different engine and trans combos, and it really isn't the big of a deal to me what it has when it comes to street driving. If we're talking about a car that's going to see the track 99% of the time, of course we should be scrutinizing every gear ratio possible, but something that's just a street bruiser/cruiser I feel it's not the big a deal.

If it were me, I'd throw the M21 you already have in it.

[RAIIIJudge]

my builder is almost finished w/ a 461 that was started nearly a year ago. besides waiting for porting to be finished then pistons and cam .. it's been a haul.
car's original m20 was popping out of 3rd on deceleration so I had transmission rebuilt w/ "Italian" masiero m22 gears but w/ wide m20 ratio. car currently has a 12bolt w/ 3.73s. previously wasn't too great on the highway ha but super fun around town which'll be mostly where it'll be living.
to say I'm looking forward to getting motor back in would b a huge understatement ; ) im not against going to lower numbered gear next spring but will drive as is this fall for sure.

[mgarblik]

Not to hijack the thread, but related. A number of people in this thread have done the change to a TKX. Is anyone willing to disclose the "real total cost" to make the conversion?. I know you can buy the transmission alone for $2800.00. But that's just the tip of the spear. Once you modify the crossmember, have a driveshaft made, figure out the transmission mount, buy a new clutch with fine splines and all related components. Then the shifter and whatever is needed to go with it. Also a working speedometer. Are we talking more like $4500.00 if you do most of it yourself? I like the idea, just haven't been able to pull the trigger.

[Formulajones]

It depends on the car. I can do a typical f body or a body for $3500-ish. It depends on what the owner wants.

I can shorten driveshafts and rebalance cheaper than new shafts, but if you want a new shaft we may as well upgrade it to seem less steel tube and better ends so it'll at least take a little abuse. Those shafts run $600-ish with solid Spicer joints.


Clutches I can just simply put a 26 spline disc in and leave the rest of it if it doesn't show issues, that's about $100 for a disc. I find most owners want to change the whole clutch, now you're getting into $500-$600 additional. Then they want to add hydraulics when the mechanical is perfectly fine.

Cross members I modify unless you want something aftermarket.
Speedo is easily handled with a short cable extension and adapter for the Ford style speedo gear. Some guys just want to change out the whole thing or use a gps setup for a fancy speedo, all that stuff just adds cost. Most of it isn't necessary.

We are talking about 4 speed cars here, much cheaper to do that swap.

For instance my 69 Z28 is a factory m22 car. Since we drive it everywhere including my wife dailying it fairly regularly, I wanted the 5 speed to mainly cut down on the wear and tear. It's a simple drop in with no modifications.
Since it was a fine spline I didn't touch the clutch. I didn't want to modify the original driveshaft so I had a nice steel shaft made with solid joints $600. I didn't want to modify the factory cross member so I bought a drop in aftermarket piece, $300. A simple speedo cable extension and a round bar shifter to look like the factory piece pops up in the stock console perfectly. Didn't cut a thing on the car. I had it all done in a day. At the time the tko was $2200. I was in the whole thing with tax and all for $3400-ish and considering what it did for the car it was well spent. The 2.87 1st gear really woke it up and the .64 5th allows me to cruise 75-80 mph at 2300. Darn thing knocks off 21 mpg and is super nice on long trips.
I own other 5 speed swaps that cost more as they get more involved but again, I'd gladly spend $4500-$5000 to do these swaps just because the driving experience isn't even a comparison to anything less. I still have another one I'll do when I get around to paying attention to that car more. It's another 4 speed so pretty straight forward.

When I can tie up $2000-$2500 in a Muncie and it doesn't improve anything it just makes more money sense to do the upgrade.

Ive even gone the auto overdrive route on some of our other cars and kick myself for not doing those sooner. That gets a little more spendy.

[Mr Twister]

The TKX is $2895 everywhere. The best deal is free shipping and $70 summit bucks at Summit Racing. (The 10% coupon is not valid for transmissions) If you have an existing manual trans, 4k should get it done.

[scott70]

Yes total costs can vary on what you change. Instead of modifying a driveshaft which I’ve done before , I bought a 700.00 Denny driveshaft…. So more money. I also went new billet flywheel and clutch ,,, more money over using what you got. Adjustable bell housing dowel pins. New shifter, used my factory Speedo cable.. Energy suspension had the correct height trans mount for the A body..Yep I’ve got over 4 k but it can be done cheaper.

[Formulajones]

Originally Posted by Mr Twister

The TKX is $2895 everywhere. The best deal is free shipping and $70 summit bucks at Summit Racing. (The 10% coupon is not valid for transmissions) If you have an existing manual trans, 4k should get it done.

Yeah that's the problem with everything anymore. It's all climbing in price, and it's not just new parts, it's swap meet parts, used stuff, nothing is immune anymore. So the longer you wait the more its going to cost. I fully expect tkx transmissions to surpass $3000 in the future, but you'll also be paying more for muncies too, not just to buy them but to rebuild them as well. The car hobby isn't for the faint of heart anymore.

[Murf]

I just put a 2.88 first gear ST10 in my wife’s car. 3.07 rear & 27 inch tires.
It finally drives like we wanted it to. Nice around town & 70 mph is OK on the highway.
It’s a 9-9.5 to 1 comp 455 with 230 / 236 hyd roller. Couldn’t send the dough for an overdrive. I would not have liked a 2.20 first gear at all.

ETA, if it were me. I’d sell the Muncie & get a trans with lower first gear. Hey wait, that’s what I did. ��

[Scarebird]

Originally Posted by scott70

Until the 454/455 came along wasn’t it recommended /required from Gm that it was 3.90 and up for the m21 trans?

Most likely - my M21 equipped 442 had 3.90's...

Did not seem like an issue 40 years ago.

[AG]

I just rebuilt and installed a 3.07 12-bolt in my friends '65 A-body with a Muncie M20 and a 462/RAIV cam and the car drives fine. No issue with takeoff in first gear.

[GOAT8U2]

The M20 with 2.52 1st is higher than us auto TH400 with 2.48 first gear. Seems like a nice comprise is M20 and then if you're still on the factory rear end, you probably need to change the axles at some point. Rock out some 3.73s etc and you'll be real happy with the tires spinning like the rest of us.

[mgarblik]

Thanks for the pricing information. Very helpful. The car I may eventually swap to a TKO is a 62 Catalina. So no drop-in parts for that one. Currently a 10 spline input Muncie. They have a very narrow trans tunnel for the Slim Jim trans so even a Muncie is pretty tight in there with the shifter hanging off the side. The exhaust goes over the cross member so it's tight as well. For a big car, not much room under there. Even the clutch linkage is jammed in tight because of the rear steering gear and linkage. Something to think about though. Would love the OD with the 3.42 axle.

[Scarebird]

Originally Posted by mgarblik

...The car I may eventually swap to a TKO is a 62 Catalina...

IIRC Tremec no longer makes the TKO, just the TKX - no issue as the TKX is stronger and fits where the TKO won't.

[mgarblik]

Originally Posted by Scarebird

IIRC Tremec no longer makes the TKO, just the TKX - no issue as the TKX is stronger and fits where the TKO won't.

Thanks. That was a mistake. I meant TKX. It looks like it would package easier and has a bunch of different shifter position options.