Svante

Hi.. Ok the 4+3 finally gave up on me yesterday. For 375 miles it stood up for the turbo abuse but last night i made a 2nd through 3rd pull and it started rattling really bad then Bang!! So i rolled to a stop trying to at least having it moving to get home, but the first 3 gears are gone and reverse and 4th gear sounds like a rockcrusher. So i had it towed .. Anyway, do you have any idea of what gearbox to go with? I like to keep the stick so manual it is! What about the Tko 600? A 5-speed would have been great.

Thanks
/Svante

BrianCunningham

ZF's are pretty strong

they're are racing tranmission big $$$

what kind of torque you shooting for?

mn_vette

You can find a used ZF6 out of a 90's Vette and it should be pretty close to a bolt in. Those hold up very well. Sometime during '93 the switched from a black tag to a blue tag. The blue tags didn't hold up as well, but had less noise or something like that.

On a side note I have a McCloud clutch/flywheel setup for the ZF6 to a SBC setup. I had to get it special since my LT1 had a rear main conversion. Its used but in good shape if you are interested.

Svante

Ok! So the ZF's are more durable than the TKO 600 then? I have'nt dynoed it yet but it pulls real strong from 4500rpm and up, currently 17psi with a BW S400SX 75mm rated 1050hp. I spins the tires in 4th gear so i guess the torque is pretty high.

I removed the gearbox yesterday and it have cracked the housing between the counter and mainshaft and the gears are stripped

Thanks a lot for the reply.
/Svante.

Svante

Ok thank you! If i find a ZF i'll PM you further about the clutch/flywheel setup

/Svante

BlowerWorks

The 4+3 is a strong trans IF you disable the auto kick down. In the chip you can prevent auto kickdown. Then you use the button to shift under LIGHT load. greg

Svante

Yes i ran it with the OD unit disconnected, it's the manual unit that broke down on me :/ .. Question is what gearbox to go with that can accept the power from the engine.

Thanks

tpi 421 vette

I have a black tag ZF I have been abusing at the drag strip for years with nitrous, slicks and 4000+ rpm clutch dumps and never broke the trans. I have broke about everything behind the trans (before the Ford 9") but not the trans.

Svante

Sounds like a good choise! I dont want to buy a gearbox that looks like my old one after a while so i need something durable. Lenco seems to be good trannys as well, maybe not as good on the street but quick and easy if i like to take it to the track

How much torque are you putting out on your motor?

Thanks.

FrankieD

What clutch is available to handle 1000hp with a ZF6 tranny?

oldpro

i would call bill boudreau aka the zfdoc he blueprints theses trannys making them buillet proof. 602 319 6575. he is the absolute best with the zf tranny .

triantafilos scoumis

Still have your clutch forsale

c4cruiser

Try looking at the TKO 5-speed here This transmission is a bolt-in replacement for the 4+3. It's pricey but it does come with everything you need for the install. It's supposed to be good for up to 600 ft-lbs of torque for the TKO600 box. The 500 and 600 versions have slightly different gear ratios.

A ZF trans would work but you would have to find the components to install it into an early C4. Others have done this swap so use the Search function to find information about how it was done.

Brand-X

I think the ZF would be an easy retrofit (I run a ZF 6 speed behind a 383 w/16 psi boost). Try this guy for blueprinted trans for your power level:

http://www.zfdoc.com/index.htm

383tpimachine

G-Force built T56.

oldpro

I just had the zfdoc blueprint the tranny in my zr1 and I have never had a tranny that shifts as smooth and positive in my life. after looking at the guts of this transmission with bills mods it could handle the 1000 hp easy . it is an amazing piece.