[sherlock9c1]

Well, after getting out of the 4L60E game due to needing to focus on young children at home about a decade ago, I've slowly slid back into it. And accumulated far more tools this time around, so it's worth me to recoup the investment. Plus, local guys keep finding me and asking me to build for them. So, this thread will be where I stick all of the build photos. I'll go deep on the first few and then just catalog the differences and findings on later ones.

 

[sherlock9c1]

i've been meaning to post about tearing down, going though and DIY shift kit on the '96 4L60E unit that came with my LT1. it was rebuilt about 12 or 13 years ago by a supposed "guru"

I've been building these transmissions for 19 years now; I thought I knew what I was doing back then too... I've learned a LOT since then.

Either way, always enjoy your posts sherlock, especially the 4L60E stuff. hopefully you don't mind my interjections, the more info the better!

As long as we can agree to disagree. I learned early on that there are a lot of different 'recipes' out there; if the clutches hold and the hard parts don't break, that's all that matters.

 

[sherlock9c1]

I got my hands on a local core. This was out of a 2003 5.3 2WD truck. Owner "ran it until it didn't go anymore." I disassembled it; everything was shot. The valvebody tested terrible on my Sonnax vacuum tester. I did notice a big gouge across the case that looked factory. Who let this get past QC?

I'm not sure the paper gasket could seal that.

Also found the usual 2nd gear apply checkball lodged in the spacer plate. Fitzall VB-101 to the rescue (if I ever need to save that plate). When this happens, 2-1 downshifts will never happen quickly because the 2nd gear circuit has to exhaust through the little orifice rather than the big opening where the checkball normally vacates.

 

[sherlock9c1]

As of October 2022 I was working on my wagon's original transmission and for my buddy Spencer's '97 C1500 5.7 2WD pickup.

Here's a look inside the rear of the stator shaft which presses/bolts into the center of the pump. Notice the three holes on the right side; those are the feed holes for the input housing's pistons. This bore must be perfectly smooth. If the bushings get too worn, the input housing will start grinding on this surface, ruining it.

There's a bushing in the end that's been removed. The fastest way i've seen to remove this was to take an air grinder with a long tube-shaped stone and grind just about through it in one area, then easily pry it out.

Sonnax wide rear stator bushing about to get pressed in. Notice how much rougher the pump casting is in this pic than the last one; this is a '96 10-vane pump; the one above is from Spencer's '97; it's a 13-vane pump, super smooth casting. Huh. The '96's casting number was G-20; the '97 was G-39. Just for reference.

 

[sherlock9c1]

When you try to maximize the learning curve advantage...

Let's replace the three seals on the reverse piston. This piston gets applied by two different circuits, hence the three seals. No lip seals here; it'd be impossible to get them all in if so. Removing the old ones with a pick. After 26 years they were noticeably stiffer than the new ones.

With transmissions, always check the snapring edges to see if they are tapered in one direction. The 4L60E ones are not, but I've seen some Chrysler ones that are, and the bigger edges should always face down. I always check becuse of OCD.

I gently tap the piston down into place with the wooden end of a hammer, then compress the springpack and install the snapring. Just work the snapring around the perimeter until it snaps into place. I hate getting this one out during disassembly.

 

[sherlock9c1]

Here's a closeup of the rear needle bearing properly installed in the bottom of the case.

These needle bearings are directional; they MUST be installed in the proper direction. Follow the thrust surfaces.

Incorrect:

Correct:

Another angle: incorrect:

Correct:

 

[sherlock9c1]

Rear ring gear installed:

Notice the two stake dots. This keeps the output shaft tight, which helps during reassembly while you're trying to install the snap ring.

First thing to install in the reverse clutchpack is the wavy plate.

Then start stacking the clutches, paying attention to the tang at the bottom on the steels. It MUST be in this position for them to fit properly.

(above) This was my '96 wagon's stock clutches. At 145k they looked fine, so reuse them.


New clutches going into Spencer's transmission. Always soak them before installing.

It's smartest to install the rear planetary before installing the 4 clutches and 4 steels. When done, they should be about this high. Notice the witness mark in the case from where a needle bearing got dragged around. Battle damage. Cosmetic only. Keep moving.

Time to install the rear support center that comes with the Sonnax SmartShell. This is the most expensive sunshell on the market; far stronger and better engineered than the famous "Beast," but it also takes the load off the rear planetary's center needle bearing, eliminating a design weakness. That needle bearing cannot be replaced without disassembling the rear planetary assembly, which is a major undertaking. Just rotate this center section down into the center overtop of the old one.

 

[sherlock9c1]

Time to install the anti-clunk spring.

It goes here.

Install center support by pressing down and turning the center to align the lugs. The spring will "click" once it's fully installed.

Install the snap ring. This is the correct way to have it installed.

Do not leave the left end hanging as in this picture! You can shove it with a screwdriver to rotate it and get it fully supported.

 

[sherlock9c1]

Sonnax smartshell next. Look at the heat treating of the tangs that connect to the reverse input drum. No mushrooming or bending on these guys like you'd see on a high mileage stocker.

Every needle bearing goes for a dip before I install them.

Properly installed. Notice the spline area is doubly reinforced. This design has survived repeated AWD 11-second drag strip launches.

Check the rear sun gear splines for a tight engagement together. You don't want any looseness here.

Sun shell and rear sun gear installed. Copper washer was standard up until 2003 or 2004 when GM went to a needle bearing here for less resistance. You'll also need a later design front ring gear assembly if you switch to the bearing; the design is different. Personally for stock and mild builds I think the old design is fine.

 

[sherlock9c1]

Oh, and here's the rear sun gear; stock bushing is up top; kinda skimpy. Sonnax makes a wider one. Or you can sneak two stockers in the bore. Your choice.

Sonnax on left; stocker on right. I put all the Sonnax upgraded bushings in all my builds; They're inexpensive and it doesn't take any extra time.

 

[sherlock9c1]

Front planetary needle bearing (between that and the ring gear) installed correctly.

Incorrect:

I always check the front sun gear to make sure it turns freely on the output shaft. This is good practice for any bushing before you install the component.

Output shaft installed through the bottom, snap ring goes on. It is not directional.

Snap ring in, all ready for the front sun gear.

 

[sherlock9c1]

Unfortunately, something was binding on the 96's geartrain. Turns out the rear sun gear was tight on the front ring gear housing. I tried pressing it in a little farther in case it wasn't fully seated, but that just made it worse.

I tried dressing it with a file but no go. A buddy loaned me his wheel cylinder hone which I'll try. If that doesn't work, I'll just press it out and press another one in. I wonder if I mushroomed it while driving it in. Always smart to freeze your bushings before installing them.

 

[sherlock9c1]

@buickman1 the geartrain is basically identical; the pump is similar; the case and valvebody are quite different. When I was first learning on these, I relied heavily on the GM factory service manual and the ATSG rebuild guide. I'm sure there are some youtube guides as well that may be helpful.

One major design limitation on this family of transmissions is that they don't have individual line pressure taps for each circuit, so troubleshooting must be indirect. I'm not aware of a way to add this without major machine work, and even then, it would likely be custom to one particular transmission. Ah well, useless griping.

Personally, any idiot (including myself when I started) can go through the gear train and do a proper job with a universal spring compressor and a bushing driver set, both of which are not terribly expensive. But it takes a lot more tools and resources to make sure the pump and valvebody are optimal. Thus, buying a remanufactured valvebody and pump may be wise if yours are high mileage.

1. Pumps need to be flat, smooth, and have less than 2.5 thousandths clearance. They can only be repaired in a lathe. The boost valve can be replaced just by removing the pan, but the pressure regulator valve requires a sonnax 77917-TL reamer and the pump must be disassembled to do it. You also need a pump alignment tool for the '96-up pumps during reassembly.
2. Valvebodies need the proper vacuum test equipment and most of the Sonnax replacement valves require reamers that get pricey fast.

 

[sherlock9c1]

Always rebuild the 4L60E in subassemblies. Don't take everything apart and stack all 1100 parts on a table like the youtube guys do; that's showboating. Let's start with the reverse input drum; it's right behind the pump. The snap ring comes out easily, then the 4 clutches and steels come out, with a "belleville" spring plate at the bottom. 99% of the time these never wear and can be reused if the transmission hasn't had coolant contamination and the friction material isn't flaking off. These still had the original printing on them from 1996.

Spring compressor installed, snap ring comes out.

Install two new lip seals with the lips facing towards the bottom of the drum.

Reinstalling this piston can be really tricky. GM slightly staggered the inner seal height so it goes on first, then the outer seal. I bought a tool from BET performance that takes care of the inner seal.

The TransTec Lip Wizard is handy for the outer seal. Insert it into the gap, roll it all the way around with VERY GENTLE downward pressure, and it will slide down into place. DO NOT press hard here; you'll kink the seal and have to massage it back to the proper shape.

The 'belleville' spring is obviously different; only has four spline groups. Install it coning up in the center. I did see a half-ass rebuild without this spring. So it can work, but I wouldn't.

 

[sherlock9c1]

This was a pic of Spencer's transmission with fresh clutches. Very little clearance (maybe 0.020"?). I didn't measure because I've done enough of these that you know what's acceptable and what's not for a non-wearing clutchpack like this; this transmission goes into reverse just fine, even with the rear case checkball removed (another backwoods mod that was common back in the day). The '96 wagon's reused clutches had similar clearance.

Last pic is the drum wear from the sunshell. New drum on left, 145k original on right. To me this is not super critical; I'm far more concerned about the side surface quality where the 2-4 band rides. Deep scoring or a low spot in that area is reason to replace with a new drum, IMHO.

A word on refurbished reverse input drums: I've seen shops just "resurface" them with a sanding disc in an air tool. There's no guarrantee of flatness. Some shops with put them in a lathe and true them that way, but then the diameter is smaller; how much smaller? Do you need a longer servo pin? Sonnax makes one (the 77787-02K) you can custom-grind to fit perfectly, and it's o-ringed out the wazoo (in typical Sonnax fashion), but you're halfway to the cost of a new drum. So unless you're installing the Sonnax 77911-03K super-hold 2nd gear servo that comes with that pin, I'd just buy a new drum. Below is the new drum going into Spencer's truck. New drums also come with bushings pre-installed. If you do them yourself on an older drum, note that they are different diameters, and sometimes they are only chamfered on one side; if you don't install the chamfers facing up, you'll never get the drum to go over the teflon seals without damaging them during reassembly. Just a heads up.

 

[sherlock9c1]

Very cool; unfortunately I have replaced 3 Impala transmissions but I never saw “how the sausage was made”.

Yeah, I know a number of guys with cars like yours that rightly got frustrated. Keeping a 4L60E alive behind a modified engine is doable, but requires additional clutch area, clamping pressure and programming to work correctly. Take away any of these, and it doesn't last.

 

[sherlock9c1]

Let's build out the input housing. Thee are there clutchpacks in here, the overrun, forward, and 3-4. The pistons get installed in opposite order. First thing to do is replace the green o-ring that goes in a groove in the center area.

Next, install the 3-4 piston. These come in every 4L60E rebuild kit ever. In this pic, it's already installed, so I'm holding a second one for reference. These drop in easy with a little Assembly Goo.

The 3-4 clutch apply "basket" drops on top of it, followed by the return spring and snapring. I used my snapring compressor to secure it; not worth a pic.

Next up is the forward (outer, with tabs) and overrun (center) piston. I like to install these together into a big steel dish and then lower the whole assembly in. GM went to bonded steel pistons in place of aluminum in 1997; the aluminum forward pistons were prone to cracking if all five teeth weren't EXACTLY level, and the lip seals could blow out if you looked at them wrong (that's what happened on my Impala). Gently work it in and the bonded seals will behave.

 

[sherlock9c1]

Next up is the forward/overrun return spring. This is different than the old style, it has a lower metal retainer ring. GM P/N 24206085. Snapring goes on as normal. As of 2022, it's pretty hard to find original B-body 4L60Es in the junkyard, but if you do, these new pistons are yet another reason not to trust one that's still factory original.

The first thing to go in is one of the overrun steels. There's only 2 steels and 2 frictions in the overrun clutch on 4L60Es... if you manually downshift, this is all there is to bring the engine revs up, so do them a favor and add a little throttle when you downshift.

Don't forget to add the rubber seal to the end. This completes the lube circuit between the input shaft and output shaft.

 

[sherlock9c1]

Here are the rest of the overrun clutches and steels. Easy peasy. On this build I reused the steels since they were fine, with no evidence of heat damage or coning.

Needle bearing soaked and installed into the middle. This is the correct orientation. It rides between the input housing and the forward sprag (most people just call it "the sprag.")

Original sprag on left, updated "29-element, dual cage sprag" on right. Personally, I think the stock sprag is fine for stockish builds; I've only seen them fail in one of the 25 I've been in. The upgraded one is less than $50 as of 2022 so it's a cheap upgrade though. Sharp-eyed observers will notice I actually have the new one backwards in this picture.

Once you reassemble the sprag and reinstall it, insert the front sun gear and turn it counterclockwise. The sprag should freewheel that way but lock together if you turn it clockwise. If not, flip the sprag elements over, otherwise you won't have 1st and 2nd without manually downshifting to rely on the overrun clutches.

This is the correct orientation.

 

[sherlock9c1]

Next up is a thick plate with a dimple that separates the overruns from the forward clutches. Just drop it in.

Install the wavy plate.

Then, 5 steels and 5 frictions, starting with a steel. Always have a steel against a wavy plate or spring plate.

Forward clutches fully installed. I've circled two areas; the upper area shows the sprag assembly fully seated against the needle bearing. The lower area shows correct total height of the forward clutches. It just "looks right" - you can check with feeler gauges after the plate goes on, but I like to use my calibrated eyeball as a secondary QC as I go.