Tremec TKO 500 or T-5 tranny

[MFPvette80]

I'm still sorting through the options for converting my 1980 from the stock TH350 auto to an overdrive manual. Most of the kits offered include a TREMEC TKO 500 gearbox, but there is one that uses a T-5. It's a less costly option. Anybody have a comment on the difference between these two transmissions. My engine is an LM-1 crate motor with a mild cam and headers, so it's proabably pushing around 325 HP.

 

[Crimson Thunder]

Do you drive your car hard?A stock T-5 was only rated at 300 ft-lbs of torque.I'd spend the extra money on the Tremec.Good luck with your project,the TKO-600 is on my wish list as a future project for my car.

 

[Hib Halverson]

Both the T5 and the TKO-500/600 are made by TREMEC.

The T5 is a "medium-strength" trans. The TKOs are more heavy duty. The T5 is lighter and shifts nicer. The TKOs are heavier and shift a little more heavily.

You have to decide how much torque your engine will generate, what the axle ratio will be and how much traction you will have at the rear.

I'd say the T5 would be marginal with a 325-hp engine making 350-370 lbs/ft. However, if the car is not raced and the tires on the back are not real sticky, the T5 might be ok.

On the other hand, if you're going to drive hard and put some wide tires on the back, then the TKO is better.

 

[MFPvette80]

I've got 255's on the car so grip is pretty good. I'm not in the habit of beating up the vehicle. But then, it hasn't had a manual before either . The T-5 kit I'm considering is from American Powertrain. They modify the standard T-5 to beef it up for use up to 400ft/lbs of torque. I think that should be plenty since I'm not planning any further engine upgrades. The rear end is still aluminum, and I don't want to leave it and a couple of twisted half-shafts in a pile somewhere.

 

[Hib Halverson]

I've got 255's on the car so grip is pretty good. I'm not in the habit of beating up the vehicle. But then, it hasn't had a manual before either . The T-5 kit I'm considering is from American Powertrain. They modify the standard T-5 to beef it up for use up to 400ft/lbs of torque. I think that should be plenty since I'm not planning any further engine upgrades. The rear end is still aluminum, and I don't want to leave it and a couple of twisted half-shafts in a pile somewhere.

Even a modified T5 would be marginal. Also, if this company says they beef-it-up such that it's input torque rating is 400 lbs/ft, ask them to provide test data supporting that along with the specifics of the modifications. I'd be really interested in what they have to say.

Also, your rear end is not aluminum. Only the diff case is aluminum. In side is the Dana 44 rear axle assembly used on 85-up C4s with manual transmissions. All I'd do there is disassemble it, inspect all the parts, replace any limited slip parts or bearings as necessary, then put it back together and use a good synthetic lube. With 255 tires and a driver who sometimes runs the car hard, the weak spot in the driveline will probably be the T5 and not the axle.

 

[MFPvette80]

I knew the diff case material changed in 1980, but I was unsure of what else changed. It's good to know that the rear end gears are stout. I've replaced the lubricant and additive, and everything looked good with the original 3.07 gear set. With the TH350 I never had to worry about tranny failure. Something to consider now though. My neighbor has a stock T-5 in his '85 Firebird Formula that he has dual tubos on. He had it on the dyno at nearly 500 hp. He has not blown up his T-5... yet. I'll send more details on the American Powertrain offering soon since I'm going to call them today. The kit is a new product from them that they rolled out at Carlisle last weekend. Lot's of folks showed interest including myself.

 

[MFPvette80]

I spoke to the fellow at American Powertrain and got the scoop on the T-5. While most of what they do is proprietary, upgrading of internal parts is a big part of the improvement process. They have also tested the unit beyond the rated 400 ft/lbs. I've got a kit on order and will post the results of the install in a couple of months.

 

[Hib Halverson]

If I was told what they do was "proprietary" and they did not provide the test data before the sale, I'd have not made the purchase.

 

[MFPvette80]

The fellow I spoke with did provide details on which internal components were replaced, the materials used, and how the testing was performed. I didn't feel that it was my place to pass this information along since they considered it a trade secret. I hope they'll publish additional information in the future. Needless to say, they answered my questions and provided a good warranty, so I went ahead with the purchase. Time will tell, and I plan to provide plenty of objective feedback.