Thinking of replacing my 4L60E with that trany. I don’t think the stocker will last long behind the 396 + n2o. I’ve scored the 4L80E cheep (less than a $100) and plan on rebuilding it with strong components and getting a good stall for it. Don't want to go to a th400 because of no overdrive. I know that the torque arm will have to be change (good excuse to get the spohn piece) what else needs to be done to get this trany to work? And where can I get the parts from?
Thanks

 

I've got that transmission in a full manual version--no electronics. I have had some problems with it that we are trying to get resolved (long story). When it was working right, I really liked it. There is a guy that has a 1200hp 427 SBC Corvette that has one of these. Check out his website. He lists the guy that built his tranny. His is all computer controlled.

http://www.montygwilliams.com

I am currently working with these people on mine:

http://www.transmissioncenter.net/highperflist.htm

My transmission is what they call "Quadzilla" in their product line.

 

How hard was it to fit, and what kind of problems? I'd certainly consider one rather the adding a GV to the TH400, as long as someone else got it to work first!

Rich Krause

 

Same issues as 4l60e ,only heavier.

 

It has the same ratios as the TH400 + a 0.75 OD, so I guess its almost identical and as strong. I don't know if the PCM can be made to control its functions or not. But I think jet makes a wirning harness and a computer to do that.
What about the cross member can the stock one work, will a new one needs fabing up from zero?

 

It wasn't as hard as you might think to make it fit. We did have to hammer on the transmission tunnel a little to make clearance for the transmission cooler line fittings. You also have to cut off a corner of the transmission housing, but that is something that has no function in this application anyway. For the crossmember, we used my M6 crossmember and welded on some extensions. This crossmember came closer to working than the A4 crossmember.

What kind of problems? The only thing I have to run to the transmission is a vacuum line to a modulator which controls line pressure. As I understand it, line pressure is generally regulated by the computer (or controller) but in this non electronic application, the modulator is controlled by engine vacuum. Since I have a supercharger, they told me to put a check valve in the line so that when the system changes from vacuum to boost, pressure will not get to the modulator. My theory is (and I don't profess to know anything about transmissions so all comments are welcome) that when boost kicks in and the check valve closes, line pressure drops as does clutch pressure. As a result, I have twice burned clutches. Rich, I talked to them yesterday and mentioned what you suggested in an earlier post about building it as a full race trans without the modulator and they said they would look into that. The guy I talked to wasn't the builder, so he didn't know.

As far as computer control, High Performance Transmissions has a unit and FAST also has a stand alone unit. I'm not sure if the stock PCM can be used for this trans. TCI might have something also. The problem is that these computer systems add another $1000 to the price tag plus a laptop, but if they can't fix me up with a full manual, I may have to consider going to electronics. This trans seems to work well for Monty Williams and he is pushing 1200hp and 1000 torque so the transmission itself should be plenty durable.

I should know something soon about what went wrong with mine and what I am going to do, so I will try to keep you guys posted.

 

David: Thanks! I'd like to do this myself, if it works.

Rich Krause

 

OK, I am reviving this thread to correct some things previously posted and let you guys know what was wrong with my 4L80E.

First of all, the guys that I bought the transmission from did an autopsy on the dead tranny and found that upon assembly, a band had been adjusted too tight. This, they felt sure, was the cause for the eventual failure. They rebuilt the tranny and sent it back and I just got finished installing it and it seems to be doing fine.

In an above post, I was mistaken about the function of the vacuum activated modulator. Running vacuum to this softens the shifts and supposedly makes the transmission more "streetable". They told me, however, that I could just plug it off, but that it would shift hard. Just to see, I plugged it off. Much better! 1-2 shift is pretty hard and 2-3 and 3-4 are not as hard, but immediate. So right now, I am happy with this transmission. I'll let you know if any other problems develop.