Personally, I don't think I'd rely (solely) on the GM service manual for this; IMHO, GM tended to needlessly duplicate some illustrations, while omitting others that might help the reader.
In other words...I've seen better written service manuals (and I'm not referring to Chilton / Haynes - I would not try rebuilding a 4L60 using the 'general' Trailblazer/Envoy repair manual, as they don't go into enough detail.)
I just came across a good reference - google "4l60e rebuild manual", and you should get a returned link to the
ATRA rebuild manual. A much better reference than the GM service manual, IMO. I'm not posting the direct link due to potential copyright infringement issues, but you shouldn't have trouble finding it at the top of the result listings.
Another frequently used manual is the
ATSG rebuild manual. Some of us have them from installing a TransGo corrective shift kit we purchased online (mentioned below) - however, I don't know of a site that has the contents online, as with the ATRA manual.
A couple (ok, a lot!) of pieces of advice, especially if you've never done this before.
- I'd recommend the second pair of hands for removal / install, since you've never done this before.
- A transmission jack (you can get them at Harbor Freight) makes the job much easier - the trans weighs a couple hundred pounds. Do NOT expect to be able to lower or raise the case without something supporting it, and
fasten the trans to the jack!
- As you mentioned, reviewing beforehand to see the tools / help you need is essential, and keep from hurting / killing yourself (or the trans.)
- Having a clean, organized, and sufficiently sized workspace makes the job easier and ensures a better chance of success. Label & bag your parts where needed - there are a ton of parts in the 4L60e, and many look similar. You do
not want to mix them up.
- There's a video series on YT showing disassembly / reassembly of the 4L60 - it's 10 videos of each, but I highly recommend it (search on 'Project 4L60e') The instructor speaks a bit slowly, but if you can get over that, there's some *very* good info there. Another good one is Hiram Gutierrez' installation of the TransGo kit that I mention below; it's an hour or so, but worth the time. Hiram's various trans videos are golden, IMO.
- Raising / securing the vehicle off the ground at all four wheels (not just the front ones) is better.
- If you have 4WD, you'll have a front driveshaft & transfer case to deal with, as well as the rear driveshaft. More work, but certainly doable. Do yourself a favor and remove the xfr case *before* removing the transmission - much easier (lighter) & more room to work that way. If you leave the transfer case attached to the transmission, you're talking an extra 100 (?) lbs of weight when you bring it down / put it back up.
- When you're removing / reinstalling the trans, securing the tailshaft output (e.g.; latex glove, etc.) helps keep the new (and old!) fluid inside the trans & helps prevent a puddle of fluid on the floor.
- If you're rebuilding it, you may as well address the weak areas of the trans:
- Hardened sunshell assembly (Sonnax makes one; there's another called a "Beast") Don't reuse the old one. The newer GM shells are supposed to have undergone some hardening, but I'd still use a Sonnax / Beast. I have a Beast in mine.
- HD clutches / steels (Raybestos & Aldo make good ones). Also, a new HD 2-4 band by either. I have the Raybestos 'Hi-Energy'; the Kevlar bands are a bit harsh for daily street use, per the F-body boys.
- Eliminate PWM activation of TCC (either via a PCM tune or mechanically - many of us have gone the mechanical route through a TransGo corrective shift kit (orange box; not the blue 'HD-2' kit; but since you'll have the trans out of the truck, take a look at it, if you're interested)
- 'TC Performance' on eBay carries 'all in one' kits (the TransGo 'orange' kit above w/ added goodies) to address the TCC & other valve body issues. If you can, get at least the kit with the hardened separator plate & gaskets, and if you can get the one with the good Sonnax pinless accumulators, even better.
- Use all new filters, solenoids (A / B / force motor), gaskets, etc. A 'master rebuild' kit gives you most of what you need, other than specialized / strengthened parts.
- If you want to put in an improved 2nd servo for better holding power on the 1-2 shift, now's the time to get that, too (although not absolutely required). Many of us have the 'Vette servo' from TC Performance's kit (he sells different ones; some have it, some don't)
- A careful examination of your pump / vane assemblies is good. Taking them to a trans shop for bench test is better. Putting in a new quality pump (or rebuilding the old one) is best, depending on how miles on the existing / how long you're keeping the vehicle (regular duty / 10-vane is fine; there are 13-vane as well, but you'll find as many people saying 10-vane are good enough)
- When putting in the new (not 'reused', not 'rebuilt') torque converter, it takes THREE seating actions (you'll read about this, so I won't go into it here.) If you have less than 1/4" distance from edge of TQ to case edge, you don't have it seated properly. Failure to do so will destroy your pump and force you to drop the trans again to repair / replace). Also, strapping the torque converter down once seated is advised, so it doesn't have the potential to slide forward & unseat itself while you move the trans into place & reconnect to the engine. Seated properly, it shouldn't move, but I'd rather be more careful than less.
- If you're planning on towing, a converter with a little higher stall speed (3200 and up) can be helpful. You don't need a 'race' converter.
- Priming the converter with 1 quart of fluid before installing can be a good idea (vs. running it empty until the pump fills it at startup)
- GET A TRANSMISSION COOLER, and install it along with the new trans. Doesn't have to be huge. The stacked plate versions are the most efficient (although you cannot 'overcool' a transmission, so size it for what you need, 'worst-case' - boat? trailer? plowing?)
You need that fluid temp below 200F on a hot day or under load; below 180F is even better. They're not hard to put in; there are even adapters / kits which eliminate having to cut & reflare the fluid send / return lines. Remove your grille and put the cooler right in front of the A/C condenser for best results (you can pick passenger or driver side). Check out @GMTMan's thread on how he did his (I have the same one).
- Speaking of fluid, use a good quality Dexron VI - at least a semi-synthetic, if not a full-syn. Dexron VI is semi-syn by nature. 'SuperTech' (e.g.; Walmart brand) isn't a 'good quality' fluid in my book, unless you're dumping the vehicle (and if that's the case, you wouldn't be doing all of this) 12 qts to fill the 4L60 on a full rebuild. You'll want 2-3 extra to go along with that dozen, for various lubing / assembly tasks, and 'just in case'
- Finally, if you want to go 'all-out', the last 'weak' area, relatively speaking, is the planetary gear, which is a 4-pinion assembly, stock. 5-pinion planetaries are available; they were first put into the 4L65e. They're a bit spendy, and planetaries don't fail often. Up to you. I had the option to go with one in mine, and it's the one thing I didn't choose to upgrade. We'll see if I made the right decision.
If you go through with this, you would be doing a real service to do a write-up for the site (including pics; a multi-part thread as you progress is fine, too - and you can ask questions on stuff you're not sure on. One of our newer members who works in the trade appears to know a lot about transmissions - way more than me, I'd guess. Hopefully he doesn't get p!ssed off that I volunteered him.)
Because of accumulated mileage, there are more and more members here encountering issues with their transmissions (the 4L60 is a pretty good trans, IMO, but it's stock service limit is about 200K or so). Put in items like I list above, and the new one should outlast the engine.
Don't expect to be done with this in 'a weekend', unless you have a LOT of help, or you've done a rebuild of another A/T before. To do it right takes time & care, especially for a novice (no offence intended). I paid $2100 to have mine rebuilt w/ good parts, with the goal of towing heavy, but I didn't have the room or a helper to do it properly (and at the time, I didn't know everything I listed above.) I did get a 2yr warranty, at least, and it has worked flawlessly since being rebuilt.
Expect to be in the neighborhood of $500-$800 in parts, unless you have a mechanic friend who can source parts cheaper.