4L60 or 6L80 when buying used

[SoNic67]

I know "friend price" for a run of the mill 4L60E rebuild at the transmission shop down the road is about $1600 assuming the core is usable.

Probably those are the ones that end up later on YT as examples of how not cut corners when rebuild a transmission.

 

[01rangerxl]

Probably those are the ones that end up later on YT as examples of how not cut corners when rebuild a transmission.

Actually I think this guy is pretty good and that was an actual friend deal. Particular vehicle was an 05ish 2wd Tahoe. I remember it having a leak that he fixed no questions shortly afterwards, but otherwise it has been fine and that's going on two years now.

Saw a nice square Explorer outside of his shop tonight, it's definitely an old truck place.

 

[Exhaustgases]

I don't think it matters for unknown history. The specific abuse of transmission (high temperatures) and neglect (no fluid changes) can render any statistics irrelevant.
4L60E, being longer in service, was revised multiple times (so all the design "surprises" were taken care of in factory) and also has more chances to be correctly rebuilt, because shops are more familiar with it. But even that is not a given.

A bit of history for 4L60E and internals, from a GM transmission repair guru (Richard Crich), that explains that not all the 4L60E are the same:

And a video for 6L80E (where he claims that the TQ is the weak link on those):

I like this guy he is very knowledgeable, but like many other folks doing work on various mechanical things on youtube I'm not impressed with the handling of the parts, the dragging a pick or screw driver over the valve body and a few other such things that are done with out care. I would love to get to drag that new billet engine block he showed awhile back all over that transmission tear down table, and flip it around etc.
He drives me nuts when he calls the stator support, a stator, he should know the nomenclature by now.
Here is a sharp guy as well, and he doesn't throw the parts around.
I'd hate to be doing a factory stock full concours restoration, and have the gouging and scratching, denting etc that Richard would add to the outside of my transmission case. And saying nothing about the same on the inside of the same. I guess most people just don't care about their stuff or know any better. I just know that he would not be allowed to overhaul a helicopter transmission. No screw drivers allowed prying in an aircraft transmission or engine.

 

[clinebarger]

Here is a sharp guy as well, and he doesn't throw the parts around.

I'd hate to be doing a factory stock full concours restoration, and have the gouging and scratching, denting etc that Richard would add to the outside of my transmission case. And saying nothing about the same on the inside of the same. I guess most people just don't care about their stuff or know any better. I just know that he would not be allowed to overhaul a helicopter transmission. No screw drivers allowed prying in an aircraft transmission or engine.

That Reverse Input Drum bushing gave your guy hell....Even had to take a hammer to it. I liked that he tried to use a Arbor Press as I hate bushings getting hammered in!!....But his press is too small/wrong style for transmission work.

I don't like running awls/screwdrivers across machined surfaces either, But I'm sure he flat files his Cases & Valve Bodies. I've seen FAR more violent transmission builders.....He likely learned all that from his mentor, My mentor was pretty slam/bang happy & he teased me non stop when I did things differently, No doubt about him being a VERY good transmission man I just try not to pick up bad habits from people no matter how good they are.
One thing I see Richard do that might make you cringe......Banging the Forward Sprag against the table to release the Sprag Race, That is & always will be the best way to get the Race off.....Trying to pry if off is a good way to bend the sheetmetal oil deflector/dam.

When you see a trans man use a screwdriver to remove snap rings.....He's not really prying on anything.....He likely has a notch ground into the tip allowing him to "Hook" the snap ring, Flip it out of it's groove & pull the end up spiraling the snap ring out of it's groove.
I have several flat blade screwdrivers with the "Notch" mod, And I have a small trim tool that I ground down & use exclusively on 700R4/4L60E for the Forward Clutch & 3-4 Clutch snap rings.

Helicopter Transmissions probably isn't a fair comparison.....There are likely specific tools for every overhaul step. Don't throw stones 'til you've been in the business for awhile Making Money at it. I'd likely trust Richard over your guy as I believe in the old saying "If you can't make a living at it....Teach"
He referenced factory clutch clearances, Which you would think IS the right thing to do? NOT when it comes to a 4L60E!
You can/should run the 3-4 clutch at .020"-.025" clearance.....Trust me, Once it has 20 or so cycles....It will have .030" to .035" worth of clearance.
Same with the 2-4 band.....It like's .040" to .050" clearance which requires an extra long aftermarket Servo Apply Pin that you grind to fit. It's ridiculous how sloppy GM was with Band Clearance, Don't think I've ever seen a stock unit have under .100" clearance.


We as Transmission Builders overhaul subassemblies that were NEVER meant to be overhauled, Take the 4L60E Reverse Input Drum.....GM never intended for you to replace the Bushings, If the bushing are worn....Replace the drum. That's why there are no J-tool/Kent Moore bushing drivers.

When the 6L80E was first introduced....No separate Case Bushing existed much less a driver for it, GM wanted you to buy an entire Case at some ridiculous price.

If we blindly followed the manufacturer recommendations....Stock 4L60E builds would cost 3 times or more of what they cost now & it would be cheaper to buy a crappy SRTA rebuilt unit from the dealer which is exactly what the manufacturer wants!!

Yes....There are universal bushing driver sets & they have their place, I have 5 different kits myself that don't cover half the bushings I install. I even have the T-0220 kit that's suppose to be made for 4L60E's....It's trash!

That's when you got to machine your own on a lathe, I'm not a pro machinist so it takes me forever to make, test, tweak a single driver. I used to machine them from steel & switched to aluminum for faster/easier machining & tweaks. Of coarse aluminum won't hold up to pounding bushings in with a hammer but not an issue with a Arbor Press.

This is a bushing driver I made years ago for the Front Reverse Input Drum Bushing.....Works great & drives the bushing squarely to the right depth every time.
You have to take in account for the bushing ID to shrink when installed....Or you get what happened to the Instructor, A stuck driver. But has to be a close enough fit to prevent bushing distortion & belling. I also machine Stops in my drivers to prevent bushing depth issues...Either to proud or to deep.