4T40E Modifications

[4x43100]

Hey guys, for my current project I need to remove the final drive from the 4T40E trans. I have looked over schematics for the transmission and final drive gear assembly and it looks like I can make it drive straight through by replacing the planetary gear set with a block that just transfers the power. I am assuming no body has had a need to do this before but I figured I would ask just in case.

I also want to install a posi traction differential unit. I know they are made for this transmission I was just curious if the whole trans needs to be disassembled to get to the diff or if there is any way to access it from the tail shaft. Thanks for any advice.

[1988GTU]

You might be the only person that I am aware of to entertain/try out that idea.

I have messed with the 45E which is essentially the same trans.
The clutch plate & friction load design is about the most cost effective path to take imo. The torsen diff is nice to think about, but cost just makes it not rational.

Are you putting down over 285 whp/wtq? Anything at or greater than those numbers seemed to make the 45E very unreliable and any fail very fast. Turbine shafts always broke aside from one input shaft rounding off. The longest trans that lasted was roughly 3k miles. It was a good core that was rebuilt, but sent all the shafts out for cryo prior to installation.
Never completely burnt up the clutches...

[4x43100]

I was planning on using this posi traction unit:http://www.engineered.net/eplsd.htm. I want the clutch pack design over the torsen gear design anyway to try and achieve the most positive lock possible with an automatic operation diff. I would prefer and electric locker but I know no one makes that for these transmissions.

On the note of strength, I am honestly not sure why the Malibu with a V6 ended up with a 4T40E instead of a 4T60E but regardless, the motor is bone stock right now. Eventually it may have some combination of heads/cam, turbo, and/or nitrous. Eventually it would be nice to have it north of 300hp. I figured I could deal with strengthening the trans once I started actually modifying the motor but I am hoping it will survive fine with a shift kit and maybe clutch upgrades. My thinking behind this is that there will be very little resistance one the powertrain due to the fact that it will be in a chassis that will probably end up being lighter than than engine and transmission combination.

[1988GTU]

I'm going to put more emphasis on that unreliable and failing part I mentioned above. If you are set on 300 WHP/WTQ I wouldn't waste the time and money on a 40E.

[4x43100]

Even when in a chassis that barely weighs anything? I am just applying the reverse of the rule that a high horsepower vehicle is going to need a stronger transmission the heavier it is, due to the increased inertia. With barely any weight to move, I feel like it would last much longer. Regardless I already have the 40E and I will see how fast this thing is with the stock motor. A cam and some head work should help out but not take it over 300HP. If I were to go to something other than a 40E would a 60E bolt up with similar electronic controls?

[1988GTU]

I dont know what "chassis that barely weighs anything" means to you.

300 WHP & WTQ is over the number provided as a guaranteed failed point. Good luck!

[4x43100]

Well the chassis it is going in is from a golf cart. So legitimately sub-500 pounds. However if your saying that it will fail regardless, would a 60E bolt up mechanically and electronically? It would obviously be stronger but how much bigger in size is it?

[1988GTU]

Its not much larger and would be the same level of effort to make work as the 40/45E.

[4x43100]

Okay so what about electronics compatibility? I read at one point every different gear ratio combination of 4L60E had a different connector so I am guessing none would work with the 4L40E connector?

[3400-95-Modified]

4L transmissions are not the same as 4T's... So don't get that confused when your looking for a transmission, the L is for a RWD application.

And yes the plugs are different but some of the ECU's have a calibration that would work with a 4t60e so it all depends on which computer you plan on using and then picking the proper BIN and having a 4t60e trans plug to wire to the proper pins if your using a custom harness.

[4x43100]

Wow ya I know they are different I don't know why I said L instead of T. I am hoping to use the stock PCM and modified stock wiring harness. Just out of curiosity, a 4T80E wouldn't bolt up to a 3100 correct? I could check it eventually but I have a 4T80E from a 98 Cadillac Seville with the 4.6 Northstar.

[1988GTU]

80E will bolt up, but will require some alterations to the trans bell.

[4x43100]

The modifications would be to make a bump for the starter right? The Northstars have the starter in the valley so it doesn't have a bump on the side.

So I have been looking at used 4T60Es and see a pretty wide range of prices. What would you guys say is a fair price for a used unit? Also does it matter what year or is it going to be hard to find one with the same connector regardless?

[1988GTU]

The modifications would be to make a bump for the starter right? The Northstars have the starter in the valley so it doesn't have a bump on the side.

So I have been looking at used 4T60Es and see a pretty wide range of prices. What would you guys say is a fair price for a used unit? Also does it matter what year or is it going to be hard to find one with the same connector regardless?

It has been a long while since I messed with the 80E stuff. FWIR, there will be a bolt hole on the bell.h ear not used and I think the Bell will need some material removed where the starter will mount on the block going into the trans. The 80E is a big beast and much heavier overall. So if you are worried about lbs and space, I'd explore just the 60E and 65E.

3400-95-Modified is the 60E guru for most if not ALL of your indepth 60E questions.

As far as price goes. I would have to ask if you are looking for trans in working order, rebuilt trans, good core, "junk" unknown condition trans, or New (not likely found) .

If you are asking for a salvage yard type that is handed to you and has a 30 day warranty, I pay no more than 250 a trans (FWD) OTD. Some are DOA, some are in need of attention, some are recently rebuilt stock units. Never know until you get it apart/in the vehicle.

[3400-95-Modified]

98 or 99 trans is the best to go for, had the best internals to start with. Just a matter of finding the good ratio. I can post up the tag id numbers chart later or just search Google, it will tell you which drive/driven sprockets it has plus diff ratio.