My Experience with the 4T60-e and Forced Induction

[Schmieder]

Here is some in field experience regarding the 4T60-e in a 96 GPse 3100 boosted to 5-10psi (variable throught the months) but torque is more logical to referrence.

Now, I know the torque calculations done by the PCM are only as accurate as the MAF Sensor. But I spent a LONG time tuning that MAF and I believe I have it tuned very well. My rail press and injector flow rates are true meaning the MAF is true (good enough anyways).

So now to the trans...

The 4T60-e was rebuilt and had roughly 30-40k miles of easy driving. Fluid was good and filter clean. The trans was in great shape. A 14K BTU Cooler with cold fluid bypass was installed pre-radiator ATF cooler.

The 4T60-e survived 1 year of brutal driving (having fun) at 300-320 ft/lbs Trans Delivered Torque. ATF remained good, no indications of burned fluid. ATF temps hovered around 160-200*F through the year.

A few days ago the boost was kicked up to 10psi again. I am getting roughly 400-430 ft/lbs at 10psi. I didn't expect so much torque at 10psi. (other mods besides boost such as crank scraper, custom exhaust, cat delete, ect) The ATF is showing signs of stress with a mild but noticeable burnt smell. But over all temps remain ok. It now has a rattling which fades when warm. Some slip at high load now. All this occured after a handful of WOT runs spaced out over a day.

So the trans is on its way out. I expected this eventually. I am surprised I got a little more then a year of serious trans abuse at 300-320 ft/lbs trans torque.

The 4T60-e, it can handle 300-320 ft/lbs for atleast a year. But it seems to die fast at anything near 400 ft/lbs. I may have had longer time had I stayed at 300-320 ft/lbs max. It is again back to 300-320 and isn't showing any worsening of condition. But the cold start rattle remains now.

Looks like I will be doing a 5-speed swap soon. It was on my list anyways so I think I was subconsciously killing my autotrans on purpose. But I won't let this data go to waste.

Conclusion: I had good experience with 320 lbs torque on the 4t60e. I had rapid deterioration at 400 ft/lbs. The MAF may have been off a tiny bit, but anything less then 1% translates into no more then 3-4 ft/lbs difference.

So there ya go. A good condition 4T60-e can handle 320 lbs with a GOOD cooler installed for some time with a punishing driver. Never pass 320 as it seems to be a logically concluded torque limit.

oh, btw, I am on day 18 no cigarettes cold turkey! I FEEL GREAT

[3400-95-Modified]

Somewhat of a vital piece of information would be what did you use to rebuild this trans? Was it 100% stock? If so you have not found the limits of it. That would be like doing a stock rebuild on a 65e and cutting it off where it fails then, but there are so many more parts to make it last much longer.

If its 100% stock then ok yes that answers the question to those who only plan on keeping it the way it was from the factory (which is quite pathetic)

I've got about eight 12 second passes on my trans plus multiple 13's and its holding up quite well... I have to give some attention to my LSD since its close to 4yrs old and many daily miles on it, but the rest is fine.

[Schmieder]

Somewhat of a vital piece of information would be what did you use to rebuild this trans? Was it 100% stock? If so you have not found the limits of it. That would be like doing a stock rebuild on a 65e and cutting it off where it fails then, but there are so many more parts to make it last much longer.

If its 100% stock then ok yes that answers the question to those who only plan on keeping it the way it was from the factory (which is quite pathetic)

I've got about eight 12 second passes on my trans plus multiple 13's and its holding up quite well... I have to give some attention to my LSD since its close to 4yrs old and many daily miles on it, but the rest is fine.

Yeah, bone stock. Actually, it was rebuilt at a professional shop. But I believe it was a standard rebuild. I never once believed that trans would survive very long. I am planning to swap in a Getrag 5 speed soon, when it gets warm out again. As of right now it still pulls hard so the trans isn't completely dead. I just noticed a dramatic increase in symptoms of a dying trans when I hit 400 some ft/lbs.

I agree, a 4t60-e is not a performance trans 100% stock. But it is nice to know the 4t60-e can handle 320 lbs for atleast a year under punishment.

The ONLY mod on the trans is the cooler. Besides tuning shift points and TCC.

Btw, what would a rattle indicate? I am sure its the Trans Housing where the reattle comes from.

What did you do to your trans to allow it to last so long under such track runs?

to those who only plan on keeping it the way it was from the factory - Just the other day someone asked me for tips building a turbo with stock block internals and stock auto tranny. It seems many people attempt to cut costs by ignoring the trans if they are planning for lower boost amounts.

I think being able to boost the trans stock up to 320 ft/lbs isn't bad at all. I would recommend 280 ft/lbs max but that is still 100 ft/lbs greater then factory 3100 L82. There can be effective FI 3100 running on stock trans. But for people like you and me, plus many others here, it is silly and I agree 100% with what you said.

BTW, how much torque can a stock Getrag 5-Speed handle? Is there a difference of Getrag and Muncie? Or are the the same trans?

[pocket-rocket]

to those who only plan on keeping it the way it was from the factory - Just the other day someone asked me for tips building a turbo with stock block internals and stock auto tranny. It seems many people attempt to cut costs by ignoring the trans if they are planning for lower boost amounts.

That's just dumb. If you decide you have the money to boost it, you need to have the money to have supporting mods done. The transmission is the link between the engine and the tires, so if it gives out in the middle of no where, you are stuck walking. Going fast isn't cheap. Even RWD V8 guys know to put some money in the transmission and they have huge aftermarkets compared to us which equals cheaper go fast parts prices. That's just my $.02 though...

[3400-95-Modified]

That is quite impressive for a stock rebuild I have to admit.

I used Raybestos Stage 1 red clutches, Borg Warner hard parts, I replaced all the valves in the valve body for the hardcoated ones to prevent side loading, I also replaced a few of the valves for ones that boost line pressure. I installed the Gill Younger shift correction kit, I shimmed all my accumulators to increase shift pressure and shorten shift time as well as doubled up on the springs for the 1-2 shift. And I run an adjustable vacuum modulator so I can bring the line pressure up higher.

So far all of those things have helped quite a bit. I also have a HUGE trans cooler and I do not run it through the regular radiator cooler since I'm running a 3k stall converter, that alone genrates quite a bit of heat.

As far as your rattle, it depends on when its happening. I've had one trans lunch the low roller sprag and that made some rattles, but also eventually jammed and broke the race rendering 3rd and 4th gear useless... I had to drive home in 2nd on night from school.

I'm not sure on the torque that a 5-speed can handle, but I know one guy with a 5-speed in a Beretta that ran 122mph run at 12.5 with 14lbs of boost or something on a completely stock 3500... He broke a counter weight off a crank on one engine and I think threw a rod on a second.. But the trans still lives on. He also had his pressure plate modified to hold a but load of torque, I was originally a Spec Stage 3+ clutch that was improved... at least holding wise.

I've done what I can with the knowledge I have on the 60e, Jeff from EP can build a better one but at this time I can't afford that so I've gone as far as I can which seems to be working so far.

I did start with a 100% stock clutch set with the other noted mods when I was running N/A and I saw some black slip marks on one of the packs when I took it apart to install the Raybestos clutches, so I'm glad I did those and hope that they hold up much better. I'll find out soon on how they look now but overall the car felt great before I put it away this year.

[AleroB888]

The 4T60-e survived 1 year of brutal driving (having fun) at 300-320 ft/lbs Trans Delivered Torque. ATF remained good, no indications of burned fluid. ATF temps hovered around 160-200*F through the year.

A few days ago the boost was kicked up to 10psi again. I am getting roughly 400-430 ft/lbs at 10psi. I didn't expect so much torque at 10psi. (other mods besides boost such as crank scraper, custom exhaust, cat delete, ect) ......

lol .... Freezing cold Winter air + 10 lbs boost must translate into a horrendous amount of tire spin, probably even during the 1-2 shift, which can't be doing a tranny any good I would guess there are spikes in torque output that make it especially critical for a turbo car to control boost as the shift point is approached. I think a Roots blown setup is more "forgiving" in that respect, since the torque curve tapers off toward the shift point. In my case the (delivered trans) torque curve is 310-320 over a broad range. But there is also a spike in torque output when the pedal is floored from a standing stop, of 352, before the TPS even reaches 100%.

As far as stock trannies going out, it is usually going to be a more or less gradual process, depending on the abuse, but generally you will be able to drive it home.

[bob442]

Turn up the APC pressure 10% on your tuner and it will last, and aftermarket frictions are avalible so that thing would have lasted longer

[3400-95-Modified]

If you know anything about a 4t60e you'll know that pressure is NOT controlled by the ECM, only when the shift happens, not even shift time. Its not like the 65e or 45e. And only aftermarket frictions are the Raybestos Red's aka Stage 1's

[pocket-rocket]

As far as stock trannies going out, it is usually going to be a more or less gradual process, depending on the abuse, but generally you will be able to drive it home.

The first one in the 91 went out after pulling into Chicago for the car show (~100 miles from home). It was fine on the highway all the way there, then when we got into town it would start acting like it was in neutral and not want to go but would eventually catch and start going, so I babied it. Eventually it wouldn't move at all after that. When we went out to check it out it would move around until warm. Once it was warm it would do nothing. Luckily it doesn't take long enough to pull onto a car trailer for the thing to warm up. When the second one went, it did the same thing, so I would use it to run the garbage down in our mobile home community to keep the fluids circulated until the 5 speed swap began. One day the diff blew apart, lol. And no, I was not the ritualistic peg-legger that wore the pin down. I didn't like making it peg leg, even before I knew it was bad for it.

[AleroB888]

The first one in the 91 went out after pulling into Chicago for the car show (~100 miles from home). It was fine on the highway all the way there, then when we got into town it would start acting like it was in neutral and not want to go but would eventually catch and start going, so I babied it. Eventually it wouldn't move at all after that. When we went out to check it out it would move around until warm. Once it was warm it would do nothing. ......

Now that you mention it, I had a '93 Corsica V6 auto trans that did the same thing, I was told the TC solenoid was sticking when hot.

[pocket-rocket]

I thought TC solenoids killed the engine at idle in gear, kind of like dropping the clutch on a manual while in gear at a dead stop.

[AleroB888]

I thought TC solenoids killed the engine at idle in gear, kind of like dropping the clutch on a manual while in gear at a dead stop.

Yeah, that's right, but it would work ok until it got hot, then I'd have to shut it off, let it cool, and I could drive it again for a short distance.

[Schmieder]

Not the TC Solenoid as it drives better warmed up. In fact, the trans now slips at 50%+ throttle when the ATF is cool. I generally don't dog it while the systems aren't up to operating temps. But all in all I can feel the trans disengaging at throttle when cold. When warmed up it grabs fine and looses the rattling.

So symptoms are, slips when ATF cool and rattles. Symptoms gone when fully warm.

But I can say the ATF fluid burnt up fast when I was pushing 10psi (in freezing weather, lol)

Well, over the past year the ole 4t60e took my punishments. But I am swapping it out for a Getrag 282. Before the Getrag is installed I want to beef it up to withstand 550-600 ft/lbs. Spec Stage 3 or 4 clutch and.....whatever else I discover along the way.

I have two options for my aging 4T60e. (1) Sell it for whats it's worth or (2) Pump up the boost and let her die in a blaze of glory.

Or (3) Weld it to my washing machine...lol

[pocket-rocket]

I personally like 2 and follow up with 3. But that's me.

[Schmieder]

I will definately have to video record option 2. Multiple cams, one in cab, one on sideline, another mounted in the engine bay.

One a side note, having a multi-cam system on the car with a touch screen display in the cab would be cool. I would want a few in the engine bay with a switchable light for viewing while driving. Plus a few others like one to cover the underside, one per wheel and the typical back up cam.

I would also like an electronic switch which controls two valves. One for intake and the other for exhaust to bypass the turbo setup 100% at the flip of a switch. Not simply opening the wastegate as a form of boost control as the intake still passes through the turbo. Should the turbo fail and spit oil a disable switch with full bypass would be convenient and look cool in the dash. Ultimately I need a switch board mounted on the roof just before the sunroof to control various circuits. i.e. gauges on/off, ignition retard on/off, water/meth injection on/off, turbo on/off, force EGR close switch, force radiator fans on/off, ABS on/off.

As you may see, I love control. Plus its a convenience. Imagine being able to disconnect the battery through a heavy duty switch in the trunk and an electric trigger in the cab to disconnect the battery while driving. 99% of the time the switches won't be used but the 1% of the time I need to diagnose or control a system in the car it will be nice to have....and it looks cool too.

This car will definately be one of a kind when I'm done with it. At that point, should I tech it out I would have to show it off at a few auto shows.

I personally like 2 and follow up with 3. But that's me.

Or I could hollow it out and grow tomato plants in it. Make the worlds largest smoking pipe......AHHH a bird feeder, yes thats it. With a fountain mounted on the top of the feeder!!! Mount the sucker right in my front lawn.