I know that there is a difference in the ratings for these, but I have mostly dealt with thirdgens and was wondering if there actually seems to be a strength difference between the 2 in practice. My cousin has one out of a 93 and I was just wondering if it would hold up as good as one out of a later car. If the the later ones actually do seem to hold more power does anyone know what parts are weak and if they can be replaced with the later parts?

Ben

 

93 T-56's are rated 50 ft.lbs. higher than 94+

 

Are you sure? I have always heard the opposite(mostly on thirdgen.org). If that is the case was it only the G92 cars that were rated higher or was it both trannys in 93?

Ben

 

I've heard the same... that the 94 up were stronger due to longer 1st gear... 2.66 for 94 up vs 3.2x for the 93...

The went with a bigger rear diff on 94(3.42) vs the 3.23 and there is where they gained the advantage...

 

Well, the G92 cars had a different ratio than the other 93's so would that kind of put them in between? I think the gear ratios kind of went like this. If it is because of the gearing of first gear then I would assume that the G92 cars wouldnt be as weak as the normal 93s

M28 M29 94+
3.36 2.97 2.66 1st gear
2.07 2.07 1.78 2nd gear
1.35 1.43 1.30 3rd gear
1.00 1.00 1.00 4th gear
0.80 0.80 0.74 5th gear
0.62 0.62 0.50 6th gear

Does anyone know for sure how to tell if a transmission is the M28 or M29 without the option codes? I believe the car that it came in had 3.23 gears origionally if that makes a difference.

Ben

 

If it came out of a car with a 3.23 then it's the M29 gearset (2.73 came with M28)

 

Cool. Anyone have any answers to my first question about how they handle power. What exactly was the stock rating on the M29 and does it actually seem to be weeker than the later ones when used or is that just by rating?

Ben

 

I just bought a new M29 T56 from Chevrolet for my project car, and it's going behind ~660 horsepower and 580 lb-ft. of torque.

Borg Warner's rating system is a little misleading, since they rated the T56s (from everything I've heard or rear) for 24 hours continuous power handling. In other words, they'll handle a lot more for shorter periods of time, especially when the car is already in motion. To answer your question, the G92 is nominally rated at 400 lb-ft. and the '94-up is rated at 450.

As with any transmission, it's your use of the car that will probably determine the longevity of the transmission. If you have 700+ lb-ft. of torque and you're launching repeatedly on slicks, you're probably going to break something sooner or later. As soon as you beef up the rear end and driveline, it'll probably be the transmission. But if you make 700 lb-ft. of torque and use your car predominantly on the street and don't subject the car to abusive launches, you'll probably be just fine. There's a big difference between shocking the drivetrain with a lot of torque from a standing start (especially on slicks) and subjecting it to the same amount of torque while the car is in motion.

That said, I seriously doubt that you'll have any problems with the G92 (2.97:1 first) T56 compared to a "standard" '94-up 2.66:1 first gear model. Remember that the G92 gear set is the same as the Z06 Corvette's, (through fourth gear) and no one is complaining about breaking their M12 T56 that I've ever heard.

 

My car as an M28 and I am pushing well over 600 rwhp without any problems. Lets see how it does at the track this year when I launch it hard on slicks.