[Johnny406]

I have been building a new engine for my race car and it's coming along nicely. With that said, I will be pulling out the 463 soon and will at a minimum freshen it up and dropping the compression and I may very well replace the rotating assembly with a 4.5 stroke 488 rotating assembly that I have to install in my 81 T/A street car. I know the weak link in this is the original B/W T-10 tranny in the car. It has the weak 3.43 gearset to help get the wimpy 305 sbc moving.

I'm already very careful with the 406. When I have raced it a few times, I've done it on real street tires, driven around the water box and have only lightly hazed the tires.

The current 3.42 8.5 10 bolt is stout with 30 spline Eaton Posi and Yukon axles, tubes stitch welded, perches reinforced and a stud girdle and the driveshaft has stout Spicer 3R u-joints.

My question is, would I be better off finding a close ratio M22 or a cast iron T-10 or try to have my current tranny beefed up and re-geared? I'd like to keep it old school and a 4 speed if feasible. The 488 really sounds fun as a street brawler but...

[ponjohn]

I don't think either option will hold up with sticky tires.

Might be time for a Liberty or Jerico if you're committed to the 3rd pedal.

[tom s]

2X John

[Rocky Rotella]

For the money involved, this seems to be a pretty effective solution.

https://www.hotrod.com/articles/insi...r-engineering/

[HWYSTR455]

With around 500-550hp/ftlbs, Muncie units would only last me around 15-24k miles before a rebuild was mandatory. Getting close to those miles, shift quality drops off exponentially. Street tire use.

Supercase and M23 are marginally better IMO. The case isn't the only problem, the main shaft bows in use, wearing stuff like the case, bearings, gears, sliders, etc.

The APT tko-600 extreme is a good option, rated at 1000ftlbs, but I need some time with the one I bought to say whether or not that rating is valid. Should have that car on the road this coming summer.

It's not just the trans you're going to need to worry about, the 8.5 is going to be strained. It's not 'if', it's 'when'.

I say freshen up the trans you have and build a beef rear, like a Moser 12 or S-60. Once your wallet recovers, spring for a trans.

Not sure if this is an option for you, but you could run a TH400 to save some money. A decently rebuilt TH400 will survive and is not too expensive, as long as you don't go overboard on a converter.

Remember that power will find the weakest link, so either R&R/upgrade current stuff or keep a very close eye on things. There's no free lunch.

.

[455rebel]

I had a cast iron T10 behind a 500hp small block. No problems, fun as a barrel of monkeys
No problems, But never had sticky tires on it. I bought it used, replaced the brass rings and bearings, put bout 30K on it before crash! Also had a 12 bolt with Moser axels.

[HWYSTR455]

There's other factors than just HP/TQ, such as vehicle weight, rear gear (manipulation), etc, so just straight HP/TQ is not a good weighing factor.

You get a car that weights 4300lbs with 276 rear gears and 500hp, compared to a Vega with a 454 with 500hp at 3300lbs and 456 gears, it's 2 totally different situations.


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[Skip Fix]

I think Larry Navarro's ST-10 broke just street driving behind his 455 . Second or third gear not even a power shift.

[HWYSTR455]

I tried ST-10s and had no luck, broke faster than the Muncies, and didn't shift anywhere near as nice.

I tried everything to get them (Muncies/ST-10s) to live, talked to tons of 'experts', and all told me you just have to keep rebuilding them or go to a stronger trans.

The best experiences I had were with M-20/21s, using 'selected' cases, iron mid-plates & side covers, fresh main shafts, and quality gears, sliders, and bearings. Blueprinted, with good clusters/countershafts.

The load on the main shaft not only bends them, but it also eats countershafts and makes the pin wobb out the case where it passes through. You know when that happens, the pin leaks where it passes through the case. No way to fix that except to replace the case. Supercases help, but doesn't stop it from happening, it just takes a little longer.

Once the mainshaft is bent, and the case leaks, it's done. Usually you can salvage some gears and some other hard parts, but that's about it.


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[ponjohn]

Do the newer transmission shift like the Muncies?

The few I have driven don't seem to be friendly to powershifting such as the TKO.

The M21's I had in my nearly stock GTO would shift with a slight depression of the clutch very fast.

[amcmike]

[HWYSTR455]

I LOVE the way Muncies shift, you can go easy, you can go hard, you can flat hammer them and they shift. But, that abuse does accelerate wear. If you get used to one, you basically only need the clutch to start off for 'normal' driving, you can just slightly let off and shift at lower RPMs.

Does anything else shift like them? Not that I have found, but you can get used to just about any transmission with some time behind them.

The TKO-600 need work to shift very good, they shift 'good' right out of the box. The older ones had problems, especially with high RPM shifts, but most of that has been worked out, and what hasn't been worked out, builders can put the finishing touches on them. A lot of problems also came from people putting gear lube in them, which is a no-no.

The original Doug Nash 5 speeds shifted pretty good, but sometimes you can get 'lost' while working them, and it takes a sec or two to get back on track. The road race guys know how to work them, or at least the older-timer road race guys.

Blockers/synchros are made to be disposable, and usually need attention at particular intervals, but not a big deal. Drain & change like every 4 oil changes on 'abused' manuals and they live longer.


.

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[Skip Fix]

The late model asphalt car I had picked up years ago uses a Muncie -but they are not banging gears that often.

I have a "race" Nash 5 speed I'm going to try in the 65 GTO project when I get there. It was originally an NHRA stocker "4 speed" as it had 4th and 5th 1:1. Mopar input and output splines. Converted it to 26 spline GM. Swapped in 2.80, 2.22,1.77,1.33,1.0. Straight cut gears might be a little noisy! You had better have a GOOD quality snap ring pliers to take it apart!

[pokey1]

Ran my M20 in my GTO since 1976 with 3:90 gears. Combination I put together in 1997 dynod at 487 HP at the crank and 537 FT LBS of torque. One in it now (built in 2016) dynod (chassis) at 530 hp and 570 Torque at rear wheels without the nitrous. Tranny held up good but never ran good sticky slicks.. to afraid. In 2018 I finally bit the bullet and sold all those parts and went with silversport T56 Magnum. 2.97 first, 2.10 second, 1.46 third, 1.00 fourth, .74 fifth and .63 sixth. Now has 4:11 gears and 28 inch tall tires. Drives awesome and worth every penny. Works real nice for low rpm's driving on street and 75 miles an hour at 2200 rpm on the highway.

[tom s]

They made a ST-10 that NASCAR used years ago.Iron case,iron mid plate and hi nickle gears.Came in a 2.64 first gear only as I remember.Tom

[72LuxuryLeMansLa.]

Originally Posted by pokey1

Ran my M20 in my GTO since 1976 with 3:90 gears. Combination I put together in 1997 dynod at 487 HP at the crank and 537 FT LBS of torque. One in it now (built in 2016) dynod (chassis) at 530 hp and 570 Torque at rear wheels without the nitrous. Tranny held up good but never ran good sticky slicks.. to afraid. In 2018 I finally bit the bullet and sold all those parts and went with silversport T56 Magnum. 2.97 first, 2.10 second, 1.46 third, 1.00 fourth, .74 fifth and .63 sixth. Now has 4:11 gears and 28 inch tall tires. Drives awesome and worth every penny. Works real nice for low rpm's driving on street and 75 miles an hour at 2200 rpm on the highway.

That sounds like the definition of FUN!

[pokey1]

Originally Posted by 72LuxuryLeMansLa.

That sounds like the definition of FUN!

Hoot hoot.. oboy it does...

[Johnny406]

What about using a Ford toploader? I do have a 9" housing that was in a 2nd Gen F-body hill climb car.

[Skip Fix]

The early Pro Stock guys used Top loaders and Hemi transmissions as they were stronger than the GM transmissions.

[Jay S]

It seems like the Pontiac 11 inch bell housings used in the mid to late 60s big cars had a top loader bolt pattern on them. IRC Pontiac uses a top loader 3 speed in some of there big cars and the 3 and 4 speed trans pattern are the same. I think there are 2 top loader Ford patterns. Not totally sure on that. IRC, tremec made the top loader for ford, and tko600 is based of that design.

There use to be (may still be going, I have not been there in years) a manual transmission class at a local 1/8 mile track near me that a lot of the GM guys used A-833 transmissions and toploaders. In the early 80s you could find some overdrive A-833s in ford and chevy pickups, they use hyd clutches. There are some possibilities there as well.

It takes some investigating and adapting. But the top loader and the a833 both work. It is nice to just by something new, but those are the more budget friendly options. We run 2 A-833s, 2 ST10s and an M22.

Rocky had a cast iron st10 with the cast mid plate and the 2.6x low gear in his car. I don’t know if it survived?