[Caster1]

Hello guys. Longtime lurker with a few posts here. I'm looking for real world feedback on the TKX, preferably behind a high TQ Pontiac. I own a 66 GTO with a 461 stroker stand dyno'd at 560hp/570tq. Running a ford 9" rear end with 3.25:1 gears. The TKX is rated to 600 lb ft which should be OK but I really like having a bit more room for error...lol.

My car is a hobby/driver with over 11K miles in 4 years. I do not baby the car and have exploded the M20 (lasted about 500 miles after engine) and an M23Z (which was since rebuilt by Jody Haag with the upgraded 9310 alloy headset). I find my self on the highway REALLY wanting an OD gear, which has led me to the TKX.

I would appreciate real world advice from anyone that has a TKX in a Pontiac.

Thanks!

Tommy

[Formulajones]

Tremec actually rates this stuff a bit on the conservative side, probably for a few reasons. I've talked to a few suppliers in person and they've all expressed being very comfortable installing them behind 700+hp/tq applications without worry.

They've been used in dragstrip applications for years and proven to be pretty darn durable in those scenarios.

You could also order one from Liberty with strengthened upgrades if you're really worried about breakage, but I doubt you'd put a dent in a stock one with 560 hp/tq.

[Scarebird]

I like mine, only "issue" I have was the reverse switch having this goofy pair of studs instead of a 2 bladed plug.

[Formulajones]

You can use a round female terminal crimped on a couple wires easily enough. I've done that in a pinch. Most car guys have an arsenal of wire terminals on hand.

Easiest solution is to just order the weather pack plug that Tremec offers with the trans if you just want plug and play.

[lfdsteve]

Originally Posted by Scarebird

I like mine, only "issue" I have was the reverse switch having this goofy pair of studs instead of a 2 bladed plug.

Mine came with a rubber booted pigtail…

[Formulajones]

Most supply it when ordered in kit form. If you piece meal the trans obviously you'll have to order the connector and any other add on you might need, like a speedo adapter for instance.

[gman005]

I put one in my 72 and I love it. It make around 600hp.

[tom s]

I was told they have a 20% fudge factor when rating gear boxes.FWIW,Tom

[Formula8]

I have a TKO which is similar and I can tell you what your dilemma is going to be. The overdrive. The problem is with likely any cam producing 560hp and 3.25 gears, your engine is not going to be all that happy with a .64 OD gear at speeds less than 70mph.

I was okay with my 464, solid lifter cam, 3.73's, .064 OD and a single plane manifold. Switched over to a factory intake and OD was still okay but 1st gear was useless. Put in the OF cam, first gear was useless and OD was a problem. Went to a shorter stroke, retained the OF and put the single plane back on. Now everything is fine except for OD. Added fuel injection and timing control and the car has improved all over but OD is still a little funky.

Bottom line is spend some time on the computer with simulations or calculators to make sure you order one with a gear spread that works for your intended driving.

[65madgoat]

Had a TKO behind a 461 motor like yours for 7 years with no issues with .82 OD ---- and now have the TKX behind a tad more stout motor and love it as well with I think a .68 OD as I wanted more overdrive this time with the bigger motor and 3:55 gears each time.

[64speed]

Tko600 with .64 overdrive. 26 inch tire, almost identical Wayne Sless motor you got and 3.70 gears. OD is great. Car just goes to sleep in 5th

[jhein]

I agree with the above comments about your 3.25 rear. A .68 OD will probably be too much (don't know what size tire you have). They also have the wide ratios with the 3.27 1st and a .72 OD but even that would be pretty tall, like a 2.34 rear in a 4 spd. If you're wanting to keep the 3.25 then you could get the 2.87 1st and the .81 OD. That would give you the equivalent of a 3.70 in 1st and 2.63 in OD. That's obviously very close to what I have with my 3.31 rear which would be the equivalent of a 3.77 in 1st and 2.68 in OD.

[Formulajones]

I run the .64 overdrive with 3.55's out back all behind a rowdy little DZ 302 and it works beautifully. It'll cruise at 35 mph in 5th without complaint. That thing has a 254 @ .050 camshaft in it, about 25 degrees more duration than most guys here run in there 455's!!

Bottom line, how the car acts is all going to be tune related. Timing and fuel are big factors in how the engine is going to behave at low rpm.

[Caster1]

Guys, Thanks for the replies. I'll work out the math on the 3.25 gear and OD. My real concern is the durability of the TKX. I plan to occasionally take the car down the track (hopefully at Norwalk) and mostly drive on the street. I don't baby the car, have exploded a M20 (not strong enough) and and M23Z (which was supposed to be strong enough, since rebuilt with upgraded allow headset). I like the thought of an OD trans, I spend more highway time than I thought I would in the car. Any horror stories out there ? Thanks!

[Singleton]

Originally Posted by gman005

I put one in my 72 and I love it. It make around 600hp.

Was the TKX in the car when your wheelstand photo was taken?

[R 70 Judge]

I looked into this myself last year. American Powertain has a cryogenic gear treatment that increases the torque capacity of the TKX from 600 lb/ft to 985 lb/ft for $1065.

They offer the same cryogenic treatment for the T56 magnum as well. That torque capacity goes up to around 1100 lb/ft IIRC.

Having two overdrives would be nice but it’s honestly kind of unnecessary unless you are doing 1/2 mile roll racing events. I am still leaning towards the cryo T56 magnum for the extra torque capacity since I will eventually be running a large single turbo setup.

[Formulabruce]

No matter What you do, for the Tremec to " live" you MUST., yeah its a MUST, make 100% Sure the transmission is Lined up with the Crank.. there are videos and instructions on this. Need to be UNDER .005 or warranty is VOID. The input shaft has ZERO play side to side. Your NEW crank BEARING will help your TKO live. .

[Half-Inch Stud]

Originally Posted by Formulabruce

No matter What you do, for the Tremec to " live" you MUST., yeah its a MUST, make 100% Sure the transmission is Lined up with the Crank.. there are videos and instructions on this. Need to be UNDER .005 or warranty is VOID. The input shaft has ZERO play side to side. Your NEW crank BEARING will help your TKO live. .

Hmmm, that explains to me why, longk ago i had seen a Muncie withe the input shaft nose broken off at the bearing. Wasn't mine, but did not think through how that could break in use.

Likely to Break shaft nose when Off-alignment and under load, and crank bearing is doing it job.

FWIW the 4L80 0.75 OD seems ideal with the 469 and 3.54.

[jhein]

Originally Posted by Half-Inch Stud

Hmmm, that explains to me why, longk ago i had seen a Muncie withe the input shaft nose broken off at the bearing. Wasn't mine, but did not think through how that could break in use.

Likely to Break shaft nose when Off-alignment and under load, and crank bearing is doing it job.

FWIW the 4L80 0.75 OD seems ideal with the 469 and 3.54.

I broke the input shaft off my T10 in my formula. It sheared off right at the base. I thought it was because of my awesome and powerful motor (lol) but now I think it was probably just misaligned.

[65madgoat]

Get your trans from Bowler if you are really concerned with breaking one.


https://shop.bowlertransmissions.com...e-transmission