[Bart42]

Working on a body off restoration and I am investigating manual transmission options. I currently have a M21. Looking to go from a 454 to a 496 or 505 engine. I am concerned about the increased torque effect on a manual tranmissions. I am willing to cut up the tunnel to go with an overdrive situation.

With the torque numbers I have seen with the 496 plus BBC, what manual transmissions are out there the can easily handle 600-700 lbsft of torque.

What actually do the torque ratings on a tranny mean? Are they a never to exceed number or is there a margin of safety?

This is to be a street car.

Thanks,

Bart

 

[MEJ1990TM]

Is it going to be a street car that sees any track time, or is it going to be just a street car? That will make a huge difference. If you are going to be putting out that torque, but never using it that M21 would last just fine.

 

[Bart42]

Is it going to be a street car that sees any track time, or is it going to be just a street car? That will make a huge difference. If you are going to be putting out that torque, but never using it that M21 would last just fine.

Well never say never, but any track use if it ever happens would be very small. If I did change my mind and started racing it, what trannies would I need to look at? I am trying to do this once, so looking at my options and besides I'm an engineer and I like to make sure I have plenty of leeway in my selection.

 

[Scotch]

I have and recommend Rockland Standard T56s. (www.rsgear.com).

I have their 'Son of Tranzilla' T56 in my heavy (3,700lbs) '67 wagon, and with 500ft-lbs and 545hp at the flywheel, I beat on it pretty hard and it's been flawless. They rate it at 750 ft-lbs, but I think vehicle weight and purpose has a lot to do with it too. I mean, 750ft-lbs in a Vega on the street is one thing, while 750 ft-lbs in a Caprice on slicks at the drags is another.

I think the 'Son of Tranzilla' would be fine for you, but the regular "tranzilla" T56s are even stronger (and more pricey).

I use all stock LT1 hydraulics for the clutch. LT1 bellhousing too. I chose a CF DF clutch/flywheel and Hurst shifter. I had to cut the trans tunnel out to just past the rear trans yoke (almost into the back seat floor area) which was more than I thought I'd have to cut, but it worked out just fine. I use an ATS crossmember and ATS slave cylinder adapter plate, and it hooked up perfectly to stock pedals.

Best mod I've made to the wagon. The big Baer brakes are a close second, though...lol!

 

[wark67]

Auto Gear M22 W will handle 600 lb ft. and probably more. It was my choice after shelling my M22 Muncie

 

[70GS455]

I understand a Super T-10 with an iron case, iron midplate, and high-nickel gears can handle alot also. It is what I plan to replace my M-21 with.

 

[MEJ1990TM]

I'm not familiar with the T56, but from what I have read both Super T-10's and the new Auto Gear M22's will take quite the beating. Another one to look into might be a Ford Toploader. One of the guys around here ran the Toploader in a '66 Chevelle that was running low 10's. It never broke on him.

 

[Bart42]

What is the difference in a standard T56 and the Tremec T-56 Magnum that Keisler and others are offering? Anyone have any experience with them?

 

[KeislerJeff]

To put it simply, the T56 Magnum is the next evolutionary step in the T56 line. It has received a revised shifter mechanism similar to the TKO offering 2 shift positions right out of the box without need of purchasing additional parts.

The internal parts have also been redesigned to offer much more hp capacity over the older T56. T56 carried a 450 lb. ft. torque rating where the new T56 Magnum carries a 700 lb.ft torque rating.

Just like TKO, these ratings are based on continuous input, not maximum input. We have tons of guys running as much as 400 hp over the stated ratings of these trannys. Since you say you`re building a street car it really doesn`t matter how much power you have, you won`t be hooking it up.