Learn Me - GM 4l65e, rebuild, options etc.

Anyone rebuild one of these? 4l60/65? What kind of HP will they really hold?

Swap to a 6L80? Will the PCM run the 6l? Reflash?

Ditch the auto and T56 swap?

Sorry I know nothing of these and you guys are always a wealth of knowledge!

I have.  My current one has taken much drag strip abuse at ~487 crank hp.  This year i’ll reallY be pushing it with 550-560.  It’s a questionable “rebuilt” unit that was in a van when i got it, and the were the kind of place that would do the bare minimum and call it rebuilt so long as it drove far enough for them to never see it again.

Matt Happel of the Sloppy Mechanics runs 4l80e's in all his drag cars. I *think* if you add a cooler they can be bashed on near-endlessly, but I would find and message him for his opinion. Here's his youtube channel.

In reply to Patrick :

Good to hear. I'm looking to push 600 if I can. Which I think will be really limiting the lifespan.... 

In reply to GIRTHQUAKE :

Yeah the 80's are supposed to be much stronger, but I have not idea if the stock PCM for a 65 will run it. 

There are a few specialty tools to rebuild one, all of which i made by looking at the pictures in the book when i got to that point.  The worst part was assembling the 3-4 clutches without cutting the seal, which i did, twice.  I went to the trans shop and bought a seal and they put the piston in for me.  There are tests for clutch pack travel that you do with compressed air before you put the assemblies back in, pay attention to these.  

You can dial up line pressure and dial down shift times to help reduce clutch pack slipping basically making an electronic “shift kit” in the tune.  On this one i set the 1-2 and 2-3 shift times to 0, so it shifts as fast as is mechanically possible.  It barks tires on 1-2.  When i blow up this one i have another that’s got 25k on it, so we can test a known low mile one

600 hp won't kill it, the torque it requires to get to 600hp will.

4L60/65E computers won't run a 6L80.  The 6-speeds of this family have their own PCMs and accept data from the ECM to run.  There are aftermarket ways of using sensors and a crapload of wiring to get the 6L to function, but in stock form they more or less separate the transmission control from the engine control.  Different animals.

A T56 would be fun until about your 15th time grabbing second gear and dumping the clutch.  Again, the HP won't do it, but the torque will.

The real question is.... do you actually need OD?  I'm not kidding.  I used to do a lot of Caddy 500 stuff, and everyone paid the big bucks to get some kind of overdrive behind it to handle the torque.  What they failed to realize is that the 500 makes so much low end grunt, it is totally kosher to stuff a 2.73 ring gear in the back and use a TH400 or a Powerglide.  My point is that it makes no difference if you have OD or not, it matters about the torque curve, the ratios, and the rear gears.

I guess I'm asking... where is the 600hp coming from?  If it's a 2.0L 4-cyl screaming at 13,000 RPMs, that is a big difference from a 13L diesel spinning at 1850 rpm.

Patrick said:

There are a few specialty tools to rebuild one, all of which i made by looking at the pictures in the book when i got to that point.  The worst part was assembling the 3-4 clutches without cutting the seal, which i did, twice.  I went to the trans shop and bought a seal and they put the piston in for me.  There are tests for clutch pack travel that you do with compressed air before you put the assemblies back in, pay attention to these.  

You can dial up line pressure and dial down shift times to help reduce clutch pack slipping basically making an electronic “shift kit” in the tune.  On this one i set the 1-2 and 2-3 shift times to 0, so it shifts as fast as is mechanically possible.  It barks tires on 1-2.  When i blow up this one i have another that’s got 25k on it, so we can test a known low mile one

Cool, I watched a youtube and now im in expert :D /s

It definately made it seem a little more DIY'able, I have never been in a auto trans so it took a bit of the mystery out. Sounds like I could probably do it if I take my time and slowly assemble things. Looks messy tho!

The PO says 2nd and 4th slip, which makes sense as I think they share a clutch pack?

Curtis said:

600 hp won't kill it, the torque it requires to get to 600hp will.

4L60/65E computers won't run a 6L80.  The 6-speeds of this family have their own PCMs and accept data from the ECM to run.  There are aftermarket ways of using sensors and a crapload of wiring to get the 6L to function, but in stock form they more or less separate the transmission control from the engine control.  Different animals.

A T56 would be fun until about your 15th time grabbing second gear and dumping the clutch.  Again, the HP won't do it, but the torque will.

The real question is.... do you actually need OD?  I'm not kidding.  I used to do a lot of Caddy 500 stuff, and everyone paid the big bucks to get some kind of overdrive behind it to handle the torque.  What they failed to realize is that the 500 makes so much low end grunt, it is totally kosher to stuff a 2.73 ring gear in the back and use a TH400 or a Powerglide.  My point is that it makes no difference if you have OD or not, it matters about the torque curve, the ratios, and the rear gears.

I guess I'm asking... where is the 600hp coming from?  If it's a 2.0L 4-cyl screaming at 13,000 RPMs, that is a big difference from a 13L diesel spinning at 1850 rpm.

Power is from a L76 6.0LS. Hopefully with added turbos.

OK no 6L's got it. 4L80e an option? 

I guess I could not need OD, but this thing has a high rear end gear already, 4.10's. I think OD would be good wiht that. 

4L80/85E is an option.  Many of the LS trucks got one, so they are out there.  You can use an older one as well, you'll just need a special TC and one bolt hole won't line up on the bellhousing, but no worries.  Take your pick of nearly any 2500-3500 GM truck pre 6L80 years and you'll almost certainly find a 4L80/85E.  Then, for simplicity you could get the ECM from the same truck.  There are many possible differences in ECMs; for instance a drive-by-wire vehicle won't always be compatible with a cable throttle since often times the ECM doesn't have the driver for a IAC.  As long as you have compatible hardware, a tuner can do nearly anything with the tune.

I agree with 4.10s needing OD unless you have really big tires.  So, unless it's going in a super light car that could tolerate 3.08s, go with the OD plan.  If all your torque comes in by 3000 with the hairdryers and the car is 3000 lbs or less, you could easily ditch OD and regear the rear for highway cruise.  As it is, I think you'll have significant traction issues with 4.10s.

You could actually build a 4L65E to take the abuse, but you'll open up the really big wallet AND the 3.06:1 first gear will be absolutely useless with 4.10s.  700r4/4L60/4L60E/4L65E all have that super low first and the largest ratio split 1-2 shift of any automatic.  Even if you got it to hold together, a first gear final drive of nearly 13:1 is just pretty ridiculous.  I currently have 4.10s in my Impala SS with a 4L60E.  Just taking your foot off the brake, it shifts to second almost right away.

My coworker has a trailblazer SS with ~700hp on the 4l65/70/whatever comes in those. The comment about torque is critical. If you don't need excess torque, don't make it. Torque breaks parts and also corresponds to cylinder pressure which correlates to heat which correlates to chances for detonation.  

To me, the amount of torque you 'need' mostly depends on the vehicle weight and how much traction is available. 

But basically a 4l60 et al will hold enough torque to make anything it ever came in  fast. 

In reply to Curtis :

The truck is stock with 4.10's and a 4L65e. Its 5400lbs, not light by any stretch. Looking at "built" options for the 4L65 range from ~2600 to 5k$ it seems..... 

Looking at HP Tuners, for ~$400 it looks like I can have full access to the PCM. Flashing to a 4L80 shouldn't be too difficult. 

Vigo said:

My coworker has a trailblazer SS with ~700hp on the 4l65/70/whatever comes in those. The comment about torque is critical. If you don't need excess torque, don't make it. Torque breaks parts and also corresponds to cylinder pressure which correlates to heat which correlates to chances for detonation.  

To me, the amount of torque you 'need' mostly depends on the vehicle weight and how much traction is available. 

But basically a 4l60 et al will hold enough torque to make anything it ever came in  fast. 

The big thing that goes (other than clutches) is the input drum.  They get hairline fractures where the shaft goes in.  If you're lucky it shows up as a flare/slip, but if left unchecked they .... um... explode.  With malice.  Hardcore.  Age will do it behind a stock 4.3L, but they don't last long north of 450tq.  Billet is the way to go.  Wish I still had the picture of a supercharged Camaro we worked on with a heavy shift kit and the ECM defaulted to full pressure.  He caught a 1-2 shift with traction and we had to extract a large chunk of the case poking up through the tunnel.

They CAN last if you don't have excessive traction, but anything north of 450tq, I strongly suggest a billet input drum.

In reply to Curtis :

Seems the "big built" trans runs 4200$ for the 65. Yikes. 

The seller of the truck I'm looking at isn't wanting to budge on his price.....ggggrrrr

The big thing that goes (other than clutches) is the input drum.  They get hairline fractures where the shaft goes in.  If you're lucky it shows up as a flare/slip, but if left unchecked they .... um... explode.  With malice.  Hardcore.  Age will do it behind a stock 4.3L, but they don't last long north of 450tq.  Billet is the way to go.  Wish I still had the picture of a supercharged Camaro we worked on with a heavy shift kit and the ECM defaulted to full pressure.  He caught a 1-2 shift with traction and we had to extract a large chunk of the case poking up through the tunnel.

They CAN last if you don't have excessive traction, but anything north of 450tq, I strongly suggest a billet input drum.

I might have given the wrong impression. I was suggesting  (or trying) that a built 4L60/65/70 could take a lot. I wouldn't trust a stock one past 450tq either, so i agree with you there.  

In reply to Vigo :

Yeah stock one is already dead at stock power levels lol 345hp 380 torque (crank I assume)

It's got unknown pistons, forged rods and crank, 44lb injectors and valve springs done. 

Vigo said:

The big thing that goes (other than clutches) is the input drum.  They get hairline fractures where the shaft goes in.  If you're lucky it shows up as a flare/slip, but if left unchecked they .... um... explode.  With malice.  Hardcore.  Age will do it behind a stock 4.3L, but they don't last long north of 450tq.  Billet is the way to go.  Wish I still had the picture of a supercharged Camaro we worked on with a heavy shift kit and the ECM defaulted to full pressure.  He caught a 1-2 shift with traction and we had to extract a large chunk of the case poking up through the tunnel.

They CAN last if you don't have excessive traction, but anything north of 450tq, I strongly suggest a billet input drum.

I might have given the wrong impression. I was suggesting  (or trying) that a built 4L60/65/70 could take a lot. I wouldn't trust a stock one past 450tq either, so i agree with you there.  

Gotcha.  They are fun when they blow though 

In reply to Curtis :

Fun :D That has many definitions. 

Looks like the 4L80 isn't a simple swap, needs a custom output shaft, they are available, but $800!! Grrr. 

It's my opinion that building up a 4l60 is a better deal than making mods to install a used stronger unit that's of unknown actual current condition. And once you talk about rebuilding the 'stronger' unit then you are definitely right back to just building up the 4l60. 

I did 'watch' someone convert a 'trollblazer' from a 4l60 to 4l80 this spring. It needed a driveshaft, crossmember, adapter harness, tune changes, etc etc. All to hold an amount of power that a built 4l60 would have held anyway. I think the 4l80 is sort of overhyped. Not that it cant do what it can, but i think it gets talked about so much that people who don't need it want it anyway and just end up making it a hurdle they didn't really need to jump. 

java230 said:

In reply to Curtis :

Fun :D That has many definitions. 

 

Looks like the 4L80 isn't a simple swap, needs a custom output shaft, they are available, but $800!! Grrr. 

Not simple, but just get a 4L80E yoke, the right U-joint, and shorten your shaft.

In reply to Curtis :

It's AWD....weird output shaft I guess. 

But that truck sold :(