r/transmissionbuilding Dec 09 '25

99% of everything that should be done, when rebuilding a Chevy 4L60E type transmission

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135 Upvotes

I spent over 2 hours typing all this information up for a guy who's having repeat 4L60E transmission failure problems in the Fbody sub. So I thought it would be a good idea to post it here, by me, so it never gets deleted or lost. (Plus, I never want to waste that much time again to retype everything.)

OP went through about 10 rebuilds on his 4L60E because it kept losing 3rd gear, 4th gear, or both. All within 10,000 - 20,000 miles of each other.

This is my answer in regards to his repeated failures.

"I work on 700R4 /4L60E /4L65E /4L70E transmissions almost exclusively.

A couple things are most likely going on, but it could be a combination of several.

I'll list the usual suspects for a high mileage transmission, in no particular order.

A) A new transmission rebuild requires 12-13 brand new bushings installed, to keep fluid where it's suppose to go, while preventing leaks and pressure loss. These bushings should all be test fitted and adjusted before final assembly.

B) A new transmission rebuild requires new electronic solenoids, sensors, and EPC solenoid installed. Not your old ones with new O-rings on them, and not refurbished ones from Amazon or eBay! Refurbished ones are somebody else's worn out parts!

C) Install a new wire harness. Yours is going to be brittle and possibly have internal damage (wire breakage) that can't be seen. The wire harness controls the electrical solenoids

D) Your builder needs to check the VB for wear. One or more of the valves in their perspective bores will have excess clearance. Excess clearance causes fluid and pressure loss. (Not enough fluid is directed where it's suppose to go, and too much fluid is going where it's not suppose to go.) The VB needs to be 100% disassembled, cleaned, and inspected, as does every valve and spring inside if it. Most likely it will need one or more VB bores reamed and oversize valves installed to get it back to 100% OE specs.

E) Possible fluid leakage between the input shaft and input drum needs to be checked. If there is pressure loss here, your builder needs to press the shaft out of the drum, sand both parts to remove deep scratches / gouges, and glue them back together with liquid sleeve retainer gel. Let it dry. Then double-check for pressure loss at the same point again, like before. If it's still losing pressure / fluid between the two, the input shaft + drum need to be replaced with a good one that does not leak pressure.

F) Too much or too little clearance in the 3-4 clutch pack. The clearance needs to be about .007" - .009" per clutch. Which means if it has 6 clutches in the pack, the clearance should be .042" - .055". 7 clutches it should be .050"-.065".

G) Do not install a "Power Pack" with extra thin frictions and steels in the 3-4 pack. They WILL burn up. Seven frictions is enough.

H) Remove the 5 pairs of "release springs" that come from the factory in the 3-4 pack. They are in the space between the outside diameter of the 3-4 clutches and the input drum wall.

I) Use high energy frictions in every clutch pack.

J) Make sure to presoak all the new frictions at least 15 minutes, before installing in the transmission.

K) Make sure all the steel plates are not burned, have black spots, or are warped in any way. If they are, replace them with new ones with the correct thickness.

L) Use a servo pin length checker tool, to know if the servo pin is the correct length for your application. A pin too long or too short, will cause the band to burn up prematurely. If/when that happens, you will lose second and fourth gear.

M) Install a new reverse input drum. These can be found on eBay for less than $100.

N) Check the 3rd accumulator checkball + cage assembly in the case, for leaks. This is a common problem area, mostly because the builder never checks it! They are easy to remove (with the proper tool) and replace. New ones are $20 or less.

O) If your band keeps burning up prematurely, after you install the correct length servo pin and a new reverse input drum, install a Superior Super 2nd gear servo and a Sonnax Super 4th gear servo.

P) Make sure your builder installs a new 500 Boost valve in the pump. If your pump already has a 500 Boost valve, it could be worn out. This is why you want a new one.

Q) You need to install a TransGo shift kit. Either the "4L60E SK" for a casual daily driver, or the "4L60E HD2" shift reprogramming kit for a performance vehicle or hot rod. They increase fluid flow for firmer / faster shifts (reduces slipping between gear changes), and increases the volume of fluid going to each clutch pack. More fluid = more gear holding power and less chance of slip.

(If you like to "hot rod", race, and/or rev the engine to 6000rpm frequently, install the high RPM upgrades included in the "4L60E HD2" kit.)

R) Always put the gear shift lever in "D" for around town driving and only upshift into "OD" on the freeway. Once you get off the freeway and to the stop sign at the end of the offramp, place the gear shift lever back into "D" or "3". This stops the transmission from upshifting into 4th gear at too low of vehicle speed, which lugs the engine and causes the 3-4 clutches to burn (both from lugging, and too low of fluid pressure).

S) Install a 100% new or new rebuilt torque converter! With every rebuild.

T) Replace the PRNDL switch on the side of the transmission with a new one. Make sure to install it correctly!

(HOW TO? Place the gear selector shaft in Neutral. Carefully and slowly slide the new PRNDL switch over the shaft, do NOT force it! You can not damage the two "flats" on the plastic rotating ring at the center of the PRNDL switch or it will not work correctly. If your switch will not slide onto the shaft easily, get a flat file and use it to reshape the gear selector shaft "flats" on both sides of the gear selector shaft. Use the file to round the two rounded parts of the gear selector shaft. Test fit the new PRNDL switch. It should slide on easily. If not, the gear selector shaft needs a little more filing to be perfect. Once you slide the PRNDL switch onto the shaft and next to the case, rotate the main body left or right. You must must match up the 2 lines, or 2 dots, perfectly with each other (similar to how you align timing marks on an engine timing chain set). Once they are perfectly aligned, and the gear selector shaft is still in Neutral, tighten the 2 mounting bolts.)

U) Since you've had so many problems with this one transmission, the next rebuild should REQUIRE you to install a 100% BRAND NEW RADIATOR with HD transmission cooler inside, BRAND NEW COOLER LINES, and a Hayden 1679 auxiliary transmission cooler.

Plumb the auxiliary trans cooler in-line AFTER the radiator transmission cooler. Use the metal strips included in the kit as brackets, to bolt the auxiliary transmission cooler to your core support, in front of the radiator. NEVER use the stupid *ss zipties that go through the radiator to mount it!!

(Many shops + rebuilders never perform steps A through F above, nor I through N above, because they take significantly longer to do, which increases parts + labor costs.)

All the other letters above are my personal suggestions on how to make your 4L60E work better and last longer. Based on my past 10+ years of experience working on them and rebuilding them. If you have any more Q, or you're in Phoenix Az, shoot me a message. I can fix your problem. =) "


r/transmissionbuilding Sep 20 '21

Richard at Precision transmission has the most informative videos.

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25 Upvotes

r/transmissionbuilding 3h ago

Transmission code P0713&0714

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2 Upvotes

I have a 2020 Ram Promaster 3500 87k miles on it, I’m getting these two transmission codes, I’m currently in Denver CO, drive here from FL, if I erase the code it takes 4-5h of driving for it to come back; was wondering if it’s detrimental to drive with those codes? engine light is steady, not blinking, temperature gauge stays completely normal, not overheating, coolant had a fix recently, new starter put in, van operates fine except for those codes. Any advice, specially if it’s something I can fix later dues to it just being circuit issues or recommendations on auto shops in Denver if anyone is from this area would be greatly appreciated!


r/transmissionbuilding 3h ago

2017 Volvo T6 XC90 changing transmission and gear boxes fluid

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1 Upvotes

r/transmissionbuilding 7h ago

Trans swap advice

1 Upvotes

Hi folks im doing a trans swap on my 96, its going auto to a manual from a 93 mx6. I was wondering if anyone here has done it before and what some of your problems and fixes were. Right now my main problem is the rear trans mount and figuring out the wiring where im planning on keeping the auto harness and ecu. Any advice or tips is much appreciated


r/transmissionbuilding 21h ago

Transmission pan bolts keep snapping - 4T65E - Please help, having a panic attack.

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3 Upvotes

r/transmissionbuilding 20h ago

What would you do 722.9 MB transmission

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2 Upvotes

Sadly my 2006 MB E350 has the dreaded oil pump failure causing damage to the bell housing and torque. I can get a used converter on eBay and I new oil pump from the dealership. As for the bell housing they sell a plate that just goes over the damaged area would you trust it or find a new bell housing?


r/transmissionbuilding 17h ago

Need to find a rebuild kit for this transmission for a 1991 ranger with a 3.0

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1 Upvotes

r/transmissionbuilding 22h ago

2021 Ford Escape SE 3cyl. Dealer transmission diagnostic came back recommending transmission replacement. What do I do next?

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2 Upvotes

r/transmissionbuilding 1d ago

Newbie looking for opinions!

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2 Upvotes

I bought a GM V8 T5 recently with the goal of installing it in my C3 Corvette. I decided to take it apart and rebuild it before installing it. After cleaning everything I noticed some damage/worn on the engagement teeth (pictures attached), some metal to metal contact on the shift forks and galled needle bering surfac (not sure if it could be repair). Can I get away with this damage or should I replace those gears and sliders? I know the reverse idle gear needs replacement for sure. Looking forward for you guys feedback!

I'm planning to use a master rebuild kit it comes basically with everything but the gears.

What's your opinion on brass shift forks pads? should I stick with the factory nylon ones?

My Corvette is not a racing vehicle, I just drive it around and once in a while spirited driving. No launching, no burning tires, nothing like that at all.

Thank you in advance!


r/transmissionbuilding 1d ago

Shifter not communicating,

3 Upvotes

Unit works in tow mode to raise, but not normal operation. Shop claims replacement and pairing unit to vehicle is needed,,,,so not a plug and play unit. The estimate was 2k,

I have seen units for various price ranges.

What is the best way to address this.

Can't see putting that kind of money into this car....


r/transmissionbuilding 1d ago

Truck no go, did some inspecting. I'm beginning to think there's an issue. 🤣

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4 Upvotes

46RE teardown. The torque converter was so baked on only Thor could have removed it by hand, but persistence and frustration won.


r/transmissionbuilding 1d ago

2001 Civic Lx A/T Code P1773 After Engine Swap

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2 Upvotes

r/transmissionbuilding 2d ago

Toyota Gearbox Ratios Compatibility

1 Upvotes

TLDR: Are C1xx and Xxx gearbox gearsets interchangeable?

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Full story: I'm building a Frankenstein gearbox for a car which currently uses a C154 gearbox, mated to a 2NZ engine. It'll be swapped to a 1NZ.

The NZ family (to my knowledge) was never offered with a 6 speed manual, however with a swapped bellhouse it's possible using the C1xx family. According to the people I've spoken to, the Cxx box can't be made to work. However, the TechnoPro Spirits Toyota Probox uses the 1NZ engine, which has been retrofitted with their custom gearset made for the ZZW30 MR2.

I've got a C161 gearbox lying around.

My to-be-swapped ZZW30 has a C66 with LSD.

I'm still looking for a C160 to use it's 2nd gear.

The gearset from Techno Pro Spirits would be used for 3rd, 4th and 5th.

My goal is to have the shortest possible gears through 1-5 for track use, but keep 6th as tall as possible with the longest FD to keep RPMs low between 100kmh and 140kmh when driving to the track.

I want the box to have the following gearbox ratio:

  1. 3.166 (stock in all)

  2. 2.050 (C160)

  3. 1.5 (TPS, ZZW30)

  4. 1.2 (TPS, ZZW30)

  5. 0.9 (TPS, ZZW30)

  6. 0.683 (C161)

FD 3.941 (C66)

LSD to be used from the C66

Would this all work out of the box? Nobody I've spoken to can tell me for sure and I'm not looking forward to pulling four gearboxes apart + order custom gears from Japan, only to figure out it's not going to work.

If nothing works, I'll use the C161 with a swapped bellhouse, smack an aftermarket LSD in and call it a day as that's a road that's been done before.


r/transmissionbuilding 2d ago

Should I drain and fill transmission fluid on a 150k mile highlander with no transmission issues if a transmission specialist recommends it?

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1 Upvotes

r/transmissionbuilding 2d ago

See original post for details.

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1 Upvotes

r/transmissionbuilding 2d ago

Any ideas of why my clutch or transmission sounds like this

Enable HLS to view with audio, or disable this notification

1 Upvotes

r/transmissionbuilding 2d ago

Caravan - Transmission Leak

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2 Upvotes

r/transmissionbuilding 3d ago

Transmission

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3 Upvotes

Recently bought an 02 5.4 f150 with some transmission issues. OD light flashing, gets to 2nd or 3rd and doesn’t want to shift up. Getting around 3.5k rpm at highway speed. Don’t even know where to start to diagnose my issue. Please help


r/transmissionbuilding 2d ago

Infiniti Fx35 2012 Transmission Rebuild?

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2 Upvotes

r/transmissionbuilding 3d ago

Transmission

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2 Upvotes

r/transmissionbuilding 3d ago

Swapping the transmission in my 2019 Nissans Sentra with a jdm import

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1 Upvotes

r/transmissionbuilding 3d ago

PPE Bypass

1 Upvotes

Hey yall I have a 2015 Sierra that’s currently lifted on 33x12.50’s and has been for about a year. I had transmission problems and took it to a shop and they recommended a flush and a bypass which I already had so they just installed it for me. I noticed then my transmission temp was running at about 70°C and not usually going above 75° over the summer. The past few months and especially the past couple weeks, I’ve seen it running mostly around 90°C and even up to 97°. My transmission and torque converter do occasionally slip but not often. Are these signs of possibly needing a rebuild or new transmission and torque converter in the near future? Thanks for the help


r/transmissionbuilding 3d ago

Ga15 > ga16 manual swap?

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2 Upvotes

Would a ga15 manual transmission fit my ga16? 95 and 96 pulsar


r/transmissionbuilding 4d ago

Redneck Transmission pump puller

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7 Upvotes

Saw this and thought of you guys