The story so far, I bought a 1984 Vette with just over 90k on it about 8-9 months ago very stock just a few mods, K&N filter, very mild aftermarket ignition... Nothing special, well about three months ago while the wife was driving to pick me up from the airport the engine blew up. Really did a number, blew two golf ball sized holes through both sides of the oil pan along with many other smaller holes and a good sized crack in the bottom of the block. Wasn't very pleased at the time but I had been planning an engine swap so wasn't that concerned... Fast forward to now, ***** deep in this swap project to a 383 stroker that I know entirely too little about. (I have a good mechanic friend who has been taking care of this for me) ((Also I just returned from overseas and it was a bit of an issue trying to communicate)) anyway... My mechanic claims the motor will be putting just under 450 horse to the wheel, and my biggest concern is that 4+3 transmission. The overdrive hasn't worked since I bought it, whch was never a huge deal as I don't do much highway driving and it's mostly a daily driver and we plan on just bypassing the system altogether when the car is re-assembled. But now I'm concerned about the ability of the drivetrain to handle the massive jump in power. Has anyone been through this? Can the 4+3 handle that much HP? Or should I pull the tranny before we drop the engine in to try and save myself a headache? Thanks in advance for any help/suggestions, and I'll try to get pics of the car and new and old motors up soon.
-Luke

 

Those numbers (450 RWHP) are a little optimistic IMO...unless you dumped $10,000 (or more) into the build, you should expect maybe 350 at best.

HP don;t come too cheap or easy, except in a bottle but then its not true HP... its certainly not available to you all the time. Empty bottle...back to stock.

As far as the trans, just be certain to do the maint on BOTH the Trans units and it'll be fine. Calloway used the 4+3 on twin turbos.

Regarding the OD section, you need that and the computer program that runs it. Its part auto-OD and part manual. Without it, you will spin 3000+ rpm trying to cruise at 55 mph....you should be down around 1500-1800 for that speed.

Do some research on the 4+3 to learn the right way to drive it. Use it like a 4 spd with an OD that CAN be engaged and add gears from 2nd and up.; It also kicks down to a passing gear when the OD and computer are engaged. People bash it because they never learned how to drive it or that its actually 2 trans units bolted together. You have to change fluids and do the maint and its actually fun to drive..

 

Good news/bad news..........

The good news is the rear end will act as a protector for the trans. Bad news is it will blow up before the transmission does.

The Dana 36 model rear in the '84 will not stand that sort of torque.

A Dana 44 will bolt right in, small issues of different track, but no big deal. The later model C beam is not an easy install in the smaller spaces but can be done with a little patience. Been there done that.

Now you blow up the T10. Actually the T10 is pretty stout, but the OD unit makes any longevity problematical. I don't think OD will live through 450+Hp duty, but I have never broken one, so maybe some who have will chime in.

Lots of replacement options. There is a sticky in the Tech Topics that gives an accurate set of directions and does, don't, can't, and wont's for ZF 6 speed install.

The ZF is a brute. most people who break them don't know how to shift them. 450 Hp will not be an issue... Look into a guy called the ZF Doctor. He has a sight filled with info.

Lots of other after market stuff, but you will need to educate yourself on clutch hydraulics... This is important.

And understated that the Corvette is VERY specific application. It's an engineered piece and not following the design concept really can break a lot of stuff, fast.


good luck.

TJM

PS look at that a TKO swap thread with pictures, right there for you!!

 

Rear end and clutch will go first unless you already have trouble with the trans.

 

Just dont hoss on the tranny when your in OD and you should be fine.

 

Thanks for the input guys, little update- After reading more we decided to leave the O/D attatched and functional and I'm just going to have a tranny shop go through and rebuild if necessary.

@leesvet- I agree that 450 to the wheel seems very optimistic, but I guess I'll just have to wait until I can get it on a dyno. Also, when I bought the car I did try to use the O/D and it turned off by itself when I was cruising on the highway, felt like I downshifted from fourth to second, so I never tried to use it after that. Honestly it scared me and I didn't understand it so I just didn't use it. After reading about them on this forum though and learning how to use them "properly" I'm kind of excited to try it again.

@TJM- I have been torn between the two options of swapping the diff, or doing a solid axle swap... Any ideas on that? Also, what do you mean about clutch hydraulics? I apologize if thats a stupid question, I'm pretty new to all of this.

@BADDUCK- I just put a new "zoom" clutch in it, so I'm not too worried about that. From what TJM said though I'm worried about the rear end. How long do you think the stock diff will last for me? Moneys starting to run short and I'm going to have to wait a while before I could replace it.