As title says, anyone ever rebuild one at home?

Looked at a few kits, some with torque converter some without.

From Jasper or NAPA, they run in the upper $2k range.

Rebuild kits seem to run in the $3-700 range.

I've always wanted to do one and have a 4l80e that needs one, but you need a big clean bench to do it right, and I don't have one. I've watched so many "precision transmission" tear-downs on youtube, I feel like i could do it.

my biggest take away from all the videos is knowing what/how to check for worn internal parts that need replacing once you tear it down.

One shop local to me, and have not heard one good thing about them...

No but it looks like a cool project on 4l60e atleast. Some of those other get expensive quick and I wouldn't want to risk the $$ and fuck it up.

Definitely put the 3rd gear Zpack and a corvette servo in.

If my transmission guy doesn’t stop dragging his feet I may be leaning how to build a 4L80 soon

I've done 3 now, about to do a 700r4 and another 4l60e probably this year.  It's not hard, biggest thing is paying attention to the details.  can't really have the "eh, that's good enough" mentality or you risk all neutrals.  

Hell, my friend rebuilt his on the side of the road during Power Tour last year

One of our old techs was a trans rebuild guy for like 14 years. The other side of our shop was Buick/GMC. They would pull them out and he would rebuild them in like 30 minutes, it was crazy to watch. As above, he knew every burr to check, every Denali part you needed, all that little stuff.

Wet bench, every part you pull out goes in order. Then back together with the same parts or new parts. There’s tricks about soaking clutches and greasing this but not that, it’s a bit of old school magic.

I got a buddy that does them often. He's done 3 or four for me, we're pretty close and he doesn't ask for anything except I buy parts. I generally slip him $100 he doesn't want to take. I do stuff for him too but it can't be too hard if you know what you're doing.

Only time I ever spent more than ~$400 was on a Sonnax input housing with billet input shaft. Parts are available to build a pretty tough 4l60/5. I beat the snot out of mine but it's billet front to back now.

It is a fools errand.   If you don't have a dyno to test prior to install, you may end up pulling it multiple times to see what you missed or fucked up.  I have had top pros fuck up transmissions twice three times. Sometimes a brand new hardened part will crack for no reason at all.  They have to eat the second R&R.

Hughes Performance Transmissions  is what you seek.


I will build a car from the ground up with no fear.  I do not rebuild transmissions, and I will only install them one time.

I've had a "top pro" built trans last one trip down the track and started puking ATF at the staging lanes for the next trip. Pump seal failed, converter bushing walked out, took out the whole thing. They do test on a Dyno before shipping them out but maybe they should have run this one a little longer/harder.  They took care of me very well and I've had no issues since. I've used them before and would use them again.  Fortunately in & out is very easy on this car.
Attached File

I probably averaged 2 a month when I was a Chevy tech. Where in PA? I still have some tools.

No, but I put everything from sonnax in mine except the hardened input shaft and carrier.

Will probably do that when I put in a 600hp LS1 or LS3.

I did quite a few when I worked at Cadillac. It's not rocket surgery.

Replace the reaction sun gear with a new GM or better unit and upgrade to a five gear planetary.

If you can assemble an AR properly, you can rebuild a 4L60. It's just heavier and takes a little longer.

I have a newly rebuilt one that I ruined the pump on by not seating the torque converter properly on during installation. The company sent me a replacement but never picked up the fresh rebuild that I broke the pump on.
I should install a new pump and have a spare transmission.

NEPA, pike county

Bummer, I am down in Lancaster.

Built a couple of my own, worked in an engineering firm where we rebuilt every automatic in production at one time or another. It's not nearly as hard as building a manual trans IMO. Most - not all - manuals need more time pressing things apart/together, and if you've ever installed the counter shaft on a M-20/21/22, it takes a deft touch to get it in there without one of the 3,876 needle rollers getting cocked on you.

Does the 4L60 have the variable vane pump? I forget which GM trans has it, but you darn sure want it primed as best you can before you start the engine. Those pumps, if you start them dry and cold just once, lose 20% of their baseline performance for good. If I had one disassembled in front of me, I'd remember the things we did, but it's been 25 years or so......

A while back, yes.

I bought the ATSG books.  YouTube was not a thing back then.

Are you able to make some tooling?  2x4 and all thread plus nuts and washers, bolts in the 2x4 if needed for pressure in the right two or three spots, etc.  You will need the ability to stretch, guide, and squeeze the nylon seals.  I used hose clamps.

It worked in the end, after total disassembly and replacing all clutch packs.  I did not need to replace bushings.

I have, it sucked, trans worked but had a funny noise at idle in gear when stopped.  I later became a professional mechanic. My coworker of 15+ years working on fancy german cars needed to rebuild his.  I told him to buy one  in a crate, he argued. He rebuilt it, it cost him about the same as buying complete.
500 miles in pump failed,  he replaced it, about 500 miles later it stuck in gear.  He tore it down found a planetary failure, spent another few 100.00 , new torque converter went though everything.  
Put about 2000 miles on and the pump started leaking again.

The tools and tricks to do it once are silly to buy and learn.  Unless you just really want the bragging rights buy one complete.
I'm a ase master tech with all kinds of add on certifications. I'm a 20+ year porsche master tech.
I own a truck with a 4l60e, if the trans broke I'd buy a crate trans

Repaired does NOT equal " Rebuilt "

pulled down to an empty case and inspecting/replacing any worn or broken parts and then upgrading others while in there seems pretty much like rebuilt.  So where do you draw the line?

Hot tank, white gloves clean room, and then dyno testing.  That is rebuilt. New pump, furnace brazed converter, beefed up parts where the stock are insufficient.  

I have toured Hughes Transmission twice.  They know what they are doing.


Locally, Gallo Tranmission rebuilt a 700R4 for me.  Bow Tie Overdrive really fucked it up and there were very few salvageable parts, including the ruined case.  My new one shifts right and it is perfect.  The first question they asked me at tear down was if it had ever shifted right.  That would be a nope.

My first transmission was an early 700r4 in my c4 vette.
That's just a 4l60 with a mechanical valve body and a computer controlled over drive/converter lockup.

It wasn't bad, i bought a how to dvd off of ebay, converted it to a file ao i could watch it on a tablet computer.

I also had the factory service manual as a general reference.

My first attempt worked great, but i had the pump rotor explode on me after like 4 or 5 thousand miles.

I used a no name pump rotor that came from the kit.
And i had my pressures boosted for some F1 quality quick shifts...

That took out the pump housing.
Replaced it with a later model pump that i had to setup the fluid pathways for my earlier transmissions.
That i had to use the factory service manual and the original pump to figure out.

It got a billet pump rotor and a looser/higher quality converter with the second go around.

I also didn't need the video the second go around, but my 84 factory service manual had a typo, the forward sprag had the freewheel examples arrows pointing the wrong way!

Man the transmission does some weird shit when the sprag is in there backwards!

I saw in someone elses 86 manual, the arrow was pointing in the other direction... lol
The earlier "lip seals" are stupid, what a pain in the ass.
I upgraded everything as i had more info, and the hard parts are all upgradeable.
I love gm for that kind of mindset.

I ended up replacing everything except for the case, valve body, and the input drum with the later stuff.
Shimmed endplay to perfection, and reinforced the input shaft/drum.

It has been going well ever since.

Lessons from that
Earlier shit shimmed.
Like converter spacing.
Watch out for falling washers, catalog everything.
Air test everything, use transmission assembly lube/gel, don't get shy with it.
The blue stuff worked great in the summer and winter.


And about a year or two ago i did a 6l80 from my tahoe.
Upgraded everything that needed it, focusing in boat hauling.

Absolutely wonderful transmission.
Documentation wasn't great, selectives for clutches are not available, they use selective snap rings instead.

Better stuff available now, anoying!

I got mine pretty much perfect, parts cost alot more than the 4l60.

I learned don't touch the converter lockup in the tune unless you really understand it.
New info just came out about it this year, like reducing allowed slippage also raises the lockup pressures.

And an aftermarket converter like mine with more than one clutch can put lots of hydraulic pressure on the thrust bearing if you don't also reduce lockup clutch pressures...

Fun stuff overall, but I'm a dork like that.

If/when I take the plunge, it will be for my back up vehicle.  2003 1500 silverado 4x4 with about 250k.

As mentioned,  it was rebuilt once before by a previous owner.

I would like to upgrade it a little better then stock, but do not need a performance build.

5 gear planetary.

HD reaction sunshell.

I did the 5 pinion planetary gear after the pump exploded.

At the time i understood that the aftermarket ones weren't good, you want an oem.

I got a low mile unit from a trailblazer, along with the rest of the upgrades it had at the rear of the transmission.
(Ebay)

Atsg manual went over the upgrades gm had over the years pretty well, sonnax and transgo to fill in the spaces.

I saw transgo started publishing their documents again on their website.
For a while they had it locked down.