drptop70ss

I picked up a complete 1995 LT1 with an S trim supercharger on it, supposedly a 500+HP to the wheels engine. Engine is rebuilt with forged internals and tuned for an 4L60E.
I want to drop this engine into one of my project cars, should I even attempt to run a stock 4L60E trans? I do not plan on racing, just big smokey burnouts on the street and generally having fun with it. What are you guys doing with your transmissions? Other options are going T56 or a TH400 but would like to use the 4L60E since the PCM is already setup, not sure what I would have to change to the program to go T56. I could also go 4L80E, but again not sure what would be needed to change in the program or wiring. I have tuner cats and am not scared of wiring work but would need the pinouts. Any real world input?

Kevin Blown 95 TA

Here's what I've figured out about it. You need a healthy transmission with a good 3rd clutch setup and get it programmed to not downshift into second when you stomp the gas. I believe that shifting out of 3rd into 2nd and back into 3rd quickly during a boosted kickdown kills the 3rd gear clutches, and you have enough power to not need to downshift into 2nd, cool 60 mph interstate burnouts notwithstanding...And I think the hyjinx on the street are more likely to destroy the transmission than a straight race from a stop through the gears 1-2-3 for reasons I already mentioned. So you need the transmission set up correctly for hardware, then get someone that knows what they are doing to program it and you might be able to keep it together for a while. If you have a 58 mm throttle body, you have to program it for that, too, since throttle position is referenced in many of the tables and everything happens earlier with a 58. If you decide to get rid of it, changing to T56 program is relatively easy. The other auto options are a little more involved.

drptop70ss

Thank you, excellent information. Going over the options I found what I think I need to switch to the 4L80E, but I think the T56 will be more fun, and I have the parts on the shelf so what the hell may as well go 6 speed.
Is it possible to change the parameters of the A4 program to run the M6 correctly? (reverse lockout solenoid working, not looking for shifter in park, etc). I can get a 1995 M6 bin file to use to upload to the PCM but want to make sure I can transfer the custom work that has already been done with the engine.

Kevin Blown 95 TA

Yeah, it is easy to reprogram. There is a choice for auto in the switch table and usually another one in the chassis section and then you just have to setup your gear ratios correctly, etc for whatever rear end you have if you change it. You'll also probably want to reprogram (disable) the CARS which is the 1-4 skip shift. I did one a long time ago and don't remember having any trouble getting it to work correctly. The only thing was getting the reverse solenoid wired and the brake switch hooked up - I think there was something different there for auto vs manual since the auto shifter had a solenoid on it. I can't remember all the details, but A4 to M6 is relatively easy other than just doing all the work. You might even find a write-up on it if you do a search. The person I did it for had downloaded an excellent step-by-step that someone was nice enough to put together which even detailed which pigtails to buy to get it wired up correctly and how & where to make the hole for the shifter.

97WS6SCharged

It's also beneficial to use the highest capacity transmission cooler you can fit with a fan if you really intend to do burnouts with it.

blown94

I kind of disagree that a 4L60 will not hold up behind a supercharger. Now, I'm speaking properly built trans of course. I build them myself, and I tried a few transmission with different clutches and as with everything, there is a recipe for success. For me, it was a combination of both building the trans to hold the power, and also like Kevin stated, programming the shift points to your driving style. I found myself manually shifting my car a lot due to stock programming being far from optimal, and eventually I decided I was just going to fix this the right way. It took me about 6 tries to get it close, then lots of seat time and memory skills to get it spot on so that the car will downshift with the correct amount of pedal, but also so it would not double down shift, then shift back up quickly. Once I was done, it drove like a completely different car. I basically got rid of the dead spots, and I programmed my converter clutch to come on earlier, and stay on through shifts, but make sure you have a quality converter for this. I threw 10 lbs and 125 shot@mine with synthetic fluid, also a very important factor. Fluid was cherry after much street and track use. Definitely add a large cooler, and a larger pan.

Kevin Blown 95 TA

That is interesting. If the converter is locked all the time you are running through the gears, it wouldn't stay in the higher rpms which is what a stall converter is supposed to do. And it would certainly shift harder under boost instead of absorbing some of the hit form the gear change. It is really behaving like a manual transmission in that case. So what is that like for performance? and do you feel it is hard on your drivetrain and tranny parts?

drptop70ss

Well just to update I found a great deal on a GM rebuilt 4L80E, it is rebuilt to stock but I figure it will have a better chance of living than the stock 4L60e.

blown94

Absorbing the shift = slipping in my book, which defeats the purpose of a shift kit in the first place, don't you agree? This is actually a trick I learned from the diesel guys. A converter coming on and off under full acceleration is not the greatest thing for it in the first place, but a performance converter is built to withstand the abuse much more than a stock one. Also, if you look at the program, or if you're able to see/feel it, you will realize that it goes off before the shift, then comes back on after the shift, so it's not really "absorbing" anything. If anything, it's creating a flare instead. The stall of the converter is basically meant for launching, but does play a small role@other times, most of which I feel are part throttle pedal position changes or downshift wot situations, which it still functions the same the way I have it set up. On the wot up shifts however, it's a different story. You gain the "lost" ponies that a stick would have, as the converter is "slipping" whenever it is not locked. When you are in a full throttle run, the converter in my opinion is not really hindered by the lockup staying on in the respect to keeping the engine in its rpm range of that's what you're thinking. I don't believe it to be any harder on drive train components, in fact I think it relieves some of the stress of firm quick shifts, and works well together.

Kevin Blown 95 TA

Well, maybe it is a little confusing to say "I programmed my converter clutch to come on earlier, and stay on through shifts" because, there are switches for unlocking the converter both on upshifts and downshifts, so that can be disabled through programming. And your sig shows a non-lockup converter, so it is hard to understand what you are talking about.

blown94

Yeah, right now the car is down. Dropped a valve 3 years ago and pulled the engine to swap my 383 in, and, well, life happened. Now I have a 6 month old and 2 bike crashes later, time and money are tight, so the engine is sitting in a bag. I was running a non lock up converter for awhile cause the stall matched my setup better than the lock up converter that I had, I bought another 3500 lockup for this new setup but never got back to it, YET. It's coming though, stay tuned.

The program was set up to unlock at the points I felt it lugged the engine down, however under acceleration, I set the speeds at which it would lock to gain those extra ponies slipping through the converter, essentially making it like a stick, yes. I feel is really no different than clutchless shifting, aka power shifting, a standard transmission. If anything it's less harsh like I stated, because under normal programming, the converter unlocks before the shift, causes a slight flare in rpm, then shifts, then re applies the lock up. As where keeping it on maintains power transfer as the trans quickly shifts. Now like I said, this is a performance transmission, and I'm not saying this would be a good strategy for a stock 100k mile trans at all! If one had a stall converter, I'm assuming the trans is built to handle power, but IMO, I still believe it to be no more "harsher" on drive train parts. The lock up clutch just needs to be able to handle the load. But un locking and locking repeatedly under full throttle is almost as abusive IMO.

hulettsz28

drptop70SS: you'd be suprised what the 4L60E can handle. I think you'll be fine for a while, but it will certainly reduce the lifespan. Either way you should update this thread with your results.

For what its worth, I have the B&M shift kit and a stall, would estimate low 400hp. The mechanic who helped with my build said we'd be sweeping the transmission up after my first lap around the block. That was 2006. I put probably 3000 miles on it first few years after the build, beating the **** out of it always.

Worst case it pops and you rebuild. Either way you're going to have fun.

Congrats on the purchase and good luck with it!

hulettsz28

Also note I'm on a street tire. If you're hooking up, you may need a broom and dust pan sooner than later.

drptop70ss

I actually picked up a GM rebuilt 4L80E with stock converter for cheap, so I am going to use it. Already reprogrammed the PCM to control it, just have to do some wiring when I get to that point. This is going in a 1951 Ford F1 pickup on street tires, basically a smoke machine since there is no real weight on the back of the truck.

blown94

Well, no weight = no traction = no real load on the trans. You would have been fine with a 4l60e. They can handle 500 if built properly, more if done perfectly. I had et street tires on mine and ran 7.42 on the old setup with 7 psi and a shot of nitrous. Properly built, cooled, and synthetic fluid will help keep these transmissions alive. I'm HARD on my trans. Broke a front planetary ring gear right off the shaft. I attribute that to an already weakened component. 3-4's burnt up once, the builder had the clutch pack too tight, and I told him that was going to happen, but he assured me it was fine, lol. The one I have now had the trans go HD kit installed and I set that one up myself with a z-pack and some other upgrades. Haven't had a problem since, and my car was roasting tires in first, slipping the nitto drags into 2nd sideways, and chirping into 3rd, on a stock 10 bolt with only solid pinion spacer installed