[76TA462]

For an original 4-speed 1976 Trans Am, does the drive shaft tunnel need to be modified for a 5-speed Tremec TKO. Thanks.

[pontiacmark]

My understanding is that it does not. You could also check with American Powertrain or Silver Sport Transmissions.

[Hooter]

I pulled one from a 79 TA and the tunnel had not been modified. Putting it in my 74.

[David Jones]

No mods needed.

[Tim john]

Fits in a 69 Firebird without any modifications.

Tim john---

[PDC]

Got one in my 73 TA - no tunnel mods.

[Wick]

Have one in my '75 with no mods.

[ta-kid]

You will have to change the front yoke to a ford one and shorten the driveshaft though.

[tom s]

If you get a GM Tremic it has a 26 spline input.Tom

[Cliff R]

PM Rocky Rotella if he doesn't see this and respond to it. He's running an OD in his TA and pretty sure he'd done at least one magazine article on the swap/install........Cliff

[76TA462]

Thanks all. Happy 2020.

[Formula8]

No tunnel mods on mine. That said, I ended up using the Ford Racing aluminum driveshaft as it was the correct length for me using the supplied Cobra trans yoke. As the aluminum driveshaft has a significantly larger OD then the factory steel shaft, my driveline alignment needed to be spot on, otherwise the rear of the shaft would rub up against some of the bracing. I use a ratcheting tie down around the frame to "tweek" the driveline over a bit to get it centered perfectly, bolt the crossmember in place then take out the tie down.

[76TA462]

With the real-life comments (thanks), I started sorting out everything I would need if I do the swap to Tremec. Had it mostly figured out, but not getting some clarity about the TKO500 vs TKO600. My 455 engine dyno-ed 542tq and 535 hp. Since then I upgraded the fuel delivery and ignition systems and the seat of the pants dyno showed a huge improvement. The engine build should have been closer to 600 tq and hp anyways. Looking at the Tremec website they say the max torque for the TKO500 is 500, and for the TKO600 its 600. So, I figured on the TKO600 using the one with the 0.64 ratio for fifth. I have 3.23:1 rear gears and 27-inch tall rear tires. One supplier had no comment, and the other is highly recommending the TKO500 because of the overall gear ratios providing a better overall performance and good all-around cruising. There was no real feedback on the TQ question. Any real-life recommendations here? Wouldn’t want to spend the zillions and end up breaking something. Thanks.

[tom s]

I have a 500 behind a 450 HP 455 and a 600 behind a 500 HP 421.The 500 has the 3.27 first and the rear is a 3.31.The 600 is the .64 OD with a 3.90 in the back.The 500 is perfect for street driving in my application.In the 421 I would like to go to a 3.64,not sure if the 3.42 would work with my cam.The 455 has a SPII and the 600 has a OF.FWIW,Tom

[76TA462]

Thanks. I might be over thinking this. Seems the TKO 500 is geared best for street application like my car. However, I built the car to drive it and do pound on it off and on when outside the city. With my torque in the 575 range (engine) , I am starting to think that I shouldn't be worried about damaging the TKO 500. Does that seem right. I would get a 600 tq plus rated clutch though. I have been using the TH400 for mannnny years now, but do remember that when I had the OEM 4-speed and emissions weak 455 (1976) I never broke the tranny but sure broke a bunch of forks and burned out a few clutches. If I go Tremec I will use the hydraulic set-up :>)

[tom s]

Depends on tires,big sticky tires will be a issue.A tech at Richmond told me all trans MFG have at least a 20% fudge factor.I raced my 500 for a season with 28X10 full M/T slicks and never broke it.Twisted the bolts holding my 9.3 dana posi together but trans held up with 5000 plus launches.It was a few years later when the 600 came out and I replaced the 500.Tom

[76TA462]

Good to know. I run Nitto NT555G2 285/40/18 in the back and will only go to a street slick at best. Tom, why did you swap to a 600 from the 500?

[Formulajones]

It's pretty close either way you cut it. The 500 works well for people that have numerically low rear gears and don't want to change them. That's where the 3.27 first gear works nicely, and slightly less overdrive of .68 for guys that have something like a 3.23 or even a 3.08 rear gear. In the end it works out similar.

I like to run the 600 and that's the one I swap the most, and works well for guys that have 3.55 and up rear gears. The .64 overdrive works well with that.

Currently swapping a Z spec cobra T5 with 2.95 first gear and .63 overdrive. Basically same trans that McLeod is selling. I actually like the gear ratios of this trans better, much closer at 2.95/1.95/1.34/1 when compared to the TKO600. Currently using a 3.27 rear gear with this one but not good enough for my taste so a rear gear swap to either 3.55 or 3.73 will be next.

[JSchmitz]

Originally Posted by tom s

Depends on tires,big sticky tires will be a issue.A tech at Richmond told me all trans MFG have at least a 20% fudge factor.I raced my 500 for a season with 28X10 full M/T slicks and never broke it.Twisted the bolts holding my 9.3 dana posi together but trans held up with 5000 plus launches.It was a few years later when the 600 came out and I replaced the 500.Tom

X2 on the tires. Also the rear end gear ratio.

[Formulajones]

You'd have to really be doing something to break a TKO. A lot of failures are driver or clutch adjustment issues. As Tom stated he's had a lot of success racing them, as have 1,000's of others. The 600's are put behind 9 and 10 second cars and used quite often in the stick classes. Very rarely do you see a broken one. Does happen but not high up on the worry list.

On a street car that doesn't have suspension set on kill and likely spins anyway, the trans would last many years of trouble free service.