Best manual Transmission?

My 98 mustang made 620hp through a 3650 tremec and never had any problems w/ it.

I have no issues with my t56

I have a TKO 600 and it is a beast. 350 tq to the wheels and I can launch it all day at 5k rpms with no problem. My buddy has a 600 rwhp stang with the same tranny and hasn't had any issues.

the TKO transmissions are junk! they are hard as hell to get into 3rd under a load. my buddy broke 2 before swapping to a Viper T56.

the T56 is a better trans without question. shifting is as smooth as you can get. the Viper spec T56 will hold just about anything you can throw at it. IIRC D&D has NEVER seen a busted Viper spec from any that they have ever sold.

what are the issues with the T56 you have heard? i dont know of anyone that has problems unless you are making over 600, and then you just need an input shaft

BTW my Viper T56 has been great for almost 4 years now

AntiRice98 said:

I have a TKO 600 and it is a beast. 350 tq to the wheels and I can launch it all day at 5k rpms with no problem. My buddy has a 600 rwhp stang with the same tranny and hasn't had any issues.

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Actually, since we're talking about transmissions and durability here, just a quick clarification: You're not putting "350 tq to the wheels." That figure obtained from a dyno run is actually a computed value of what the engine would be producing to make the HP observed at the wheels.

If your engine is making 350 ft-lbs and your TKO600 1st gear is 3.27:1 and your rear axle ratio is, say, 3.73:1 then the torque "at the wheels" is more like 350*3.27*3.73 or 4269 ft-lbs. Even if your dyno run was done in 4th gear (1:1) then the torque out of the trans is the same as the engine but the axles still see a 3.73x multiplication for 1305 ft-lbs. And if you are revving to 5000 and dumping the clutch then the torque at the hubs will spike much, much higher as the momentum of the flywheel is suddenly dumped into the machinery.

When it comes to transmissions, this is really a tough thing: high RPM clutch drops are probably what's going to hurt the trans in the worst way. Think about the instantaneous shock load on the input shaft, the teeth on the input shaft and cluster shaft gears etc as the energy of 30-lbs of steel flywheel spinning at 5000RPM (not to mention the inertia in the crankshaft and damper etc) is suddenly channeled into that itty bitty input shaft...

And if you've got a solid hub on the clutch disc it's just that much worse.

It's amazing any of these transmissions take the abuse they do

trinity_gt said:

Actually, since we're talking about transmissions and durability here, just a quick clarification: You're not putting "350 tq to the wheels." That figure obtained from a dyno run is actually a computed value of what the engine would be producing to make the HP observed at the wheels.

If your engine is making 350 ft-lbs and your TKO600 1st gear is 3.27:1 and your rear axle ratio is, say, 3.73:1 then the torque "at the wheels" is more like 350*3.27*3.73 or 4269 ft-lbs. Even if your dyno run was done in 4th gear (1:1) then the torque out of the trans is the same as the engine but the axles still see a 3.73x multiplication for 1305 ft-lbs. And if you are revving to 5000 and dumping the clutch then the torque at the hubs will spike much, much higher as the momentum of the flywheel is suddenly dumped into the machinery.

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Yeah, but the torque the transmission sees has nothing to do with the rear gear ratio. Transmissions are generally rated with engine tq because that is the torque input to the transmission.

I believe the 350 torque mentioned above was put in terms of rear wheel tq because that is how it was measured and it lets the reader understands that the number represents tq after drivetrain loss and not before.

When people use the rwtq term, it is implied that it is a number representing the engine tq that makes it back to the wheels after losses if all gears were 1:1.

Rickyll7 said:

Yeah, but the torque the transmission sees has nothing to do with the rear gear ratio. Transmissions are generally rated with engine tq because that is the torque input to the transmission.

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The torque input to the trans, yes, though the torque at the output shaft is most certainly dependent on the selected gear ratio. It's also important to note that while the theoretical torque input into the trans is the maximum torque produced by an engine, there are shock loads many, many times that "smooth" level produced by things like high-RPM clutch dumps (amplified if you've got traction via sticky tires) and solid clutch hubs etc.

Still, I know what you're saying in terms of how manufacturers typically rate a transmission at in terms of torque input.

I believe the 350 torque mentioned above was put in terms of rear wheel tq because that is how it was measured and it lets the reader understands that the number represents tq after drivetrain loss and not before.

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It's just a peeve of mine when I see quotes of "rear wheel torque" framed as if that's what's actually at the rear wheels. I just think it pays to fully understand this concept and why, for instance, the input shaft to the transmission can be such a comparatively thin shaft while, as we move further back along the drivetrain, components get heavier and more robust on out to the wheel hubs.

i have a 97 gt that means i have the t45 right?? i know it needs a rebuild or new synchros because when you slam it from 1st to second or 2nd to 3rd it grinds, but now when driving normal.