After a very short career in towing, I'm now rebuilding my 210,000 mile 4L60E.

I experienced what I now know was slipping in the torque converter lockup. I managed to limp home in low gears.

Dropped the pan to do an exchange and filter. Lots of fine metallic particles, no chunks.

Since this incident, I've added a cooler and another ~1,400 miles without the trailer. If OAT is cold, I can get on it (as much as a 2006 Chevy TB can get on things) and cannot make her slip. As soon as it starts warming up outside, it will reliably slip in OD. Despite this she can climb no problem in 2-3. Oil was "aging" at the start of the trip, black by the end. Got a P0894 once, which I could clear and reliably keep away providing I baby the shifts.

Objectives:

• Make this vehicle tow capable again. Get another 5,000 good towing miles + 30,000 general miles.
• Try not to spend all my money.
• Learn more about transmissions and get a successful rebuild under my belt.

Disassembly inspection:

• I expected to find nothing inside the transmission, since my research pointed to the Torque Converter.
• Most things looks great:
  • Gears all look new. Vertical slip on pinions well within spec.
  • Frictions look like they have plenty of meat on them. Not glazed as far as I can tell. Steels uniform appearance.
  • Reverse input drum looks good. Original machining lines across full band. 0.0015" feeler is no-go at the center of the band.
  • Pump seems good too. 0.0015" feeler will drag between the rotor and a straight edge. There is one small casting defect on the flat, but I don't think it's significant (not under the vanes, no trailing striations)?
• Only issue I found is that the 1-2 (I think) check ball is working its way through the plate, although not quite stuck yet.
• TCC bore not inspected.
• Did not do a pressure test prior to disassembly.

I think (hope?) everything is probably fine with the internals, the only issue is the lockup clutch is tired from 210k of soft shifting.

Question

(I'm sure I'll come back to this thread with further questions, but for now

Do I even need to replace these frictions? They look fine to me and as far as I can tell I've not had any issues with functions outside of OD. (I did get a couple of harsh 1-2 shifts one time just before I disassembled)

Why do they look so good after 210k? (Or is my inexperience showing here and they actually look like trash?)

 

At that mileage, it is quite possible the transmission has been rebuilt before - unless you know the entire history of those miles. You will hate yourself later if you don't do a thorough rebuild.

Rick

 

Just do a full rebuild and address the LEAKS they will and do exist trust me , BORE PLUGS FWD AND REV A MUST, NEW OR EVEN BETER ORRINGED END CAPS FOR THE CONVERTER REGULAR VALVE AND 4-3 VALVE, ONE OF THE MANY WAYS TO FIX THE CONVERTER REGULATOR VALVE WEAR, REMOVE AND RESEAL THE INOUT DRUM, ORINGED BOOST VALVE, TEFLON OR ORINGED BAND PIN A MUST . Clean up really well inside as with these really all trans but in particular these cleanliness is next to Transmissions Godliness lol. At least check all bushings for good fit . I used to preach change all but with so many issues with NEW ones of late and fitment I now say check and change as needed, Too tight when changing is an easy enough fix but like on my last unit I put 3 new bushings in the same spot before I got one that actually was a better fit than the original it was argh. Parts tolerances have been terrible of late even among several name brands so don't assume NEW all good .
REMAN parts like input drums are sometimes a much but do not again assume they are right, I have had several of late that when I tested for leaks were actually worse than the original and ended up removing shaft and resealing at least one of them even that was not possible and these are from places you would think would be good like wits or global .
Kit type or clutch type for a stock or stockfish rebuild not particularly important more a matter of builder preference. Input sprag a must . Strongly suggest the slightly oversized AFL valve from GLOBAL . New solenoids and Wiring harness a must IMO ,
But I stress most of all FIX THE LEAKS. in the 3-4 clutch and servo feed circuits with that number of mile you will have leaks. Even the leak at the band pin in case because of the way fluid is fed can result in premature 3-4 clutch failure along with in particular the FWD abuse valve bore plug i have measure literally several 1000s of erosion wear on these and even with NEW bore plugs they still leaked more than I cared for thus why I started making ORINGED PLUGS.
Hope this helps and good luck with your build.

 

Thanks for the replies, @B52bombardier1 and @FranksCustomTrans!

@B52bombardier1, I think that's what I needed to hear. I don't know the history, but I agree these look younger than 210k. No evidence someone has been in here before, other than aftermarket filter and maybe missing dipstick depth limiter bracket (not sure if one should be installed or not). I'll replace frictions, but keep steels.

@FranksCustomTrans, agree there must be leaks. My budget is going to force me to be a bit more selective than your recommendations though. I will do the Sonnax TCC ream + expensive tool, but I can't really afford to replace solenoids and harness (I'll get these on the vehicle if I notice problems). I'll put new molded pistons in but probably keep the input sprag (it seems fine).
I'll inspect the AFL, but I can't afford the tool to fix it if there are no obvious issues. I have none of the AFL symptoms (Southpaw Autoworks AFL Video).
I had planned to replace all bushings, but what you say about parts is concerning Will look into o-ringed plugs and anchor.

Thank you for the detailed reply and advice! Your experience is hugely appreciated.

 

Personally I would opt for this for the Converter regulator valve for a single build an save the money https://transgo.com/product-details/4l6-iso-3/ then get this from global which requires no tool . Order one of these from global https://globaltransmissionparts.com/...wibxs2bV6FYHfI and yes call them you can order just 1 not expensive. and use money saved for a sprag , shift solenoids and harness . But your choice . bushings I would inspect and replace as needed. ORINGED PLUGS - And these for the two bore plugs. no one but me make the orringed ones but these will do. Dont get them from ebay but rather when you call global for the afl valve they will have these . I prefer them over the transgo ones. You can probably however get all from global when you call .
Just suggestions of how i would handle it .Also you can get a new GM VB plate for around 15 dollars.

 

Or you could sweet talk Frank into putting together a kit to address the leaks. One stop shopping.

I will get persecuted for this, but you can go to Whatever It Takes' website and look up what the thickness of those frictions should be and if only worn a few thousandths I would reuse. Keep in mind if a friction is worn .002 and you have a 5 friction pack that is .010 overall. This is only if you are building this unit for yourself, if building for a customer replace all frictions. The rosin in those frictions has cured and if they were going to fail, they would have do so by now. You just need the verify how much they have worn.

 

I'd recommend using the "gently oversized" AFL Valve from Central Valvebodies. It's $25, and I've used it on every 4L60E I've opened up, because the factory valves NEVER pass a vacuum test.

 

Save your money on buying a reamer tool that you will be unlikely to ever use again. Take that money and your valve body to a local and reputable transmission shop and let them bring its measurements back to a stock specification. Then you rebuild the transmission from there.

Rick

 

Thanks all! I can't overstate how valuable your advice is.

After some thinking and back and forth with the wife (who would love this to fail so she can justify a new car - (honestly, managing this is like half the job)) I've come up with the following BOM. Sorry @FranksCustomTrans , please don't be mad, it's hard to justify > $1 K on an amateur build that could blow up before I get it off the ramps.

• Fitzall TCC Valve. (Not sure how I feel about PWM defeat, but I'm not aware of any other options that preserve PWM outside of the Sonnax. Can upgrade to Sonnax on the vehicle if this fails. This build is for towing, so maybe bang-bang is better? idk)
• Overside AFL from GTP (globaltransmissionparts.com/4l60e-4l65e-4l70e-afl-valve-gently-oversized-seals-existing-bore/)
• BW Hi Energy Band from GTP (old one looks great, but I tweaked it on disassembly)
• Cheap Torque Converter from Scamazon for $199. (amazon.com/GM92SS1-4L60E-4L65E-Torque-Converter-Warranty/dp/B07J4XQYG1)
• Cheap seal kit (amazon.com/KP33900EF-REBUILD-OVERHAUL-CLUTCH-PISTON/dp/B01GU2LUMS) (WILL fit the teflons with the proper tool)
• OE spacer plate from ebay (would buy from GTP, but they don't have OEM)
• O-ringed plugs.
• Tools & fluid
• REUSE: Bushings (if fit is good), frictions (if gap in spec), steels, accumulators, solenoids, harness, pressure switch, servos, pistons, hard parts, sprags

This comes out to $558 after tax, vs. $1,033 for a proper job that I think Frank would approve of.

I am willing to pull it all back out if this fails. I have high confidence in the TCC+AFL failure diagnosis and subsequent TC destruction. Appearance of the frictions tells me other circuits are good.

@B52bombardier1 , only one local shop. They weren't interested in just doing the VB. They want the whole thing. This is my only car so I can't travel for it, cycling range only.

@dixiebandit69 , solid advice. Absolutely will do.

@bbond105 , building for myself and willing to pull it out again if I need to. Will attempt reuse if gaps are good.

@FranksCustomTrans , 4L6-ISO-3 almost made the BOM, but this part confuses me: "GM remanufactured SERTA transmissions usually have valve bodies that have been machined to allow the use of a larger .472” diameter TCC regulator and isolator valve. Over time those wear out the bore the same way the originally valve did, again leading to the same complaints." It makes it sound like it will not fit an OE valve body, but only a SERTA (Service Replacement Transmission Assembly) remanufactured transmission.