4l60E slipping/being erratic.

[04Z71w]

The 4l60e In my z71 is slipping and being erratic at times. Some times it starts off in 2nd then around 20mph drops into 1st and takes off then back into 2nd. Some times it just starts in 2nd gear and stays put until I let off the gas then get back on it to feather it into 3rd. It's stupid. I can still shift manually through the gears and reverse works fine. Most of the time it hunts for a gear that will engage. It has 277k miles so I'm assuming my trans is rubbish. Supposedly it had been rebuilt before I bought it but no proof to back up that claim. That being said, I'm not a gm person and don't know a ton about the 4l60 other than they are finicky and useless after so much use.

Yes, it has proper fluids and a recent filter change.
I'm thinking about getting a stage 1 built 4l60E from monster transmission and got a quote for 1686.00 out the door. The install I can do myself.
Is that a reputable builder and a decent price? I need a transmission that is built enough to handle maybe 380hp as I'm just going to do cam/header/ported 862 heads and a tune. It's not going to be be total daily driver but will be used for small road trips and camping.

 

[PNWYukon]

You should scan for codes, it could be the valve body or solenoids. 4L60E is a great transmission, but the band and clutches wear out. If your transmission was rebuilt, then it should not be acting up.

If you personally did the trans filter, how did it look? What was on the pan magnet?

I would look for somewhere else than Monster Transmission.

 

[rockola1971]

I second that problems are likely in the valve body. Sticking or jammed valve(s). Possibly a bad solenoid. BUT....the damage may have already been done. What color is the fluid and does it smell burnt?

 

[Bill 1960]

Just a comment on performance mods and road trips, which used to be my strategy. Over time I figured out when you’re far from home a stock powertrain is less likely to break. And a lot easier to get repaired when it does.

Good luck whichever vendor you choose. I got a GM reman myself.

 

[04Z71w]

You should scan for codes, it could be the valve body or solenoids. 4L60E is a great transmission, but the band and clutches wear out. If your transmission was rebuilt, then it should not be acting up.

If you personally did the trans filter, how did it look? What was on the pan magnet?

I would look for somewhere else than Monster Transmission.

Sorry for the reply...well it wasn't rebuilt per say more or less got told the transmission had 600 worth of repairs but couldn't tell me for what so I'm assuming that was bull crap or does not want to admit the repairs didn't work.

No codes for the anything transmission related.
Didn't see anything in the trans pan that would be alarming at all and the fluid was a red color but looked fairly clean and not low. It has 277k miles with the original engine and trans and no idea what the past history or maintenance was on the drive line. Engine runs flawlessly. In fact I'm surprised how lively and smooth the engine runs its just the trans acting up. I'll just take it to a place near that knows all about ls and the 4l60e.

On the highway it runs great in upper gears so guessing 3rd and 4th are fine. It will cruise nicely at 70 @2k rpms and shift down to 3rd getting on the gas. 1st and 2nd might be just on the verge of going.

You should scan for codes, it could be the valve body or solenoids. 4L60E is a great transmission, but the band and clutches wear out. If your transmission was rebuilt, then it should not be acting up.

If you personally did the trans filter, how did it look? What was on the pan magnet?

I would look for somewhere else than Monster Transmission.

 

[04Z71w]

Just a comment on performance mods and road trips, which used to be my strategy. Over time I figured out when you’re far from home a stock powertrain is less likely to break. And a lot easier to get repaired when it does.

Good luck whichever vendor you choose. I got a GM reman myself.

I've pretty much scrapped my plans for any power adding mods for this thing aside from the shorty headers I got free on a trade for some other parts I had for another car. I'm sure a stocker 4l60 with upgraded OE parts will do fine. I may pull it out myself and open it up to take a gander because it looks like there might be an oil leak from the rear main seal. There's oil dripping from that area down the oil pan around the oil filter and onto the ground. It's not a lot of oil but it's enough to warrant a fix that or it's the oil sending unit which I know is located back of the engine at very top above the rear main seal. I'm going to diagnose that this weekend.....I rebuilt my 68 mustang with less issues than this Tahoe lol.

 

[04Z71w]

I second that problems are likely in the valve body. Sticking or jammed valve(s). Possibly a bad solenoid. BUT....the damage may have already been done. What color is the fluid and does it smell burnt?

Transmission fluid color is a medium dark red and does not smell burnt and it is full upto OE specs. That was the first thing I checked.

 

[YukonRog]

Sad to say, that's why they call them 4L"Slippy" transmissions, LOL. The $600 you mention was probably mostly in labor and done from the pan. I'm thinking your problems will lead to a replacement. I've done a lot of research lately on transmissions and have seen/heard a lot of negative things about Monster Transmissions. Although I find it odd that several builders in my area use their Sunshell and Planetarys in their builds. I'd take the time to do your own research and make your own conclusions. I found a shop that is rebuilding mine for $1900 and giving me a 2yr unlimited mileage warranty. He's been in business for decades and has lots of glowing reviews.
I also considered doing the work myself but I've conceded I'm just too old and tired to that anymore. But in my searches I found a plethora of transmissions. Rebuilt and Remanufactured. Make sure you understand the difference. Lots of scams out there too. And you have to consider the supply chain delays. I was quoted 4 weeks by several. Good luck and let us know what you decide.

 

[04Z71w]

Sad to say, that's why they call them 4L"Slippy" transmissions, LOL. The $600 you mention was probably mostly in labor and done from the pan. I'm thinking your problems will lead to a replacement. I've done a lot of research lately on transmissions and have seen/heard a lot of negative things about Monster Transmissions. Although I find it odd that several builders in my area use their Sunshell and Planetarys in their builds. I'd take the time to do your own research and make your own conclusions. I found a shop that is rebuilding mine for $1900 and giving me a 2yr unlimited mileage warranty. He's been in business for decades and has lots of glowing reviews.
I also considered doing the work myself but I've conceded I'm just too old and tired to that anymore. But in my searches I found a plethora of transmissions. Rebuilt and Remanufactured. Make sure you understand the difference. Lots of scams out there too. And you have to consider the supply chain delays. I was quoted 4 weeks by several. Good luck and let us know what you decide.

I've done tons of research so far and that's exactly what I'm worried about....all the scams and junk. I've crossed Monster Trans off the list along with Jegs because they have bad reviews from multiple people with the same issue. There a few shops here that specialize or at lest claim to specialize in 4l60 and everything LS related. I've never had a Chevy or dealt with anything Chevy but I have always liked the NBS z71 that being said I'm researching up all I can. There is a place not to far that can rebuild mine anywhere from completely stock specs for 1890.00 ( thats with installation ) to 2800 for a stage 2 build. He even sent me a list of the parts and part numbers they use which was pretty cool honestly. Probably will be the place I go to. I don't mind a stock unit as long as they use updated parts that are none to fail on 4lslippys...lol...I'm good although I might just go stage 1 incase down the road I do want to add mo powa. My 68 mustang started life as a 289 then got the power bug added a 390 then added more power to that 390 and now the c4 is at its limit.

 

[PNWYukon]

If you are going to replace check out this one:

4L60E Transmission M30 93-14 GMC Chevy Cadillac Buick

4L60E M30 transmission. Not just a rebuilt 4L60, every unit has been completely remanufactured with performance upgrades.

spprecision.com

 

[04Z71w]

If you are going to replace check out this one:

4L60E Transmission M30 93-14 GMC Chevy Cadillac Buick

4L60E M30 transmission. Not just a rebuilt 4L60, every unit has been completely remanufactured with performance upgrades.

spprecision.com

Saw them through searches and its priced right. I just have to decide if I want to do the install or not. I can but don't want to lol.

 

[04Z71w]

Well dropped trans and replaced the rear main along with the oil sending unit...what a PITA! while the trans was out I replaced the valve control body and 1-2 and 3-4 solenoids, new filter, flushed and refilled...must of down the trick. No more erratic shifting or gear hunting. Only thing it does now is hang a little high In rpms before it shifts but definitely a huge improvement over what it was. Now that fall is setting in time to tear into the suspension and get all that mess sorted out. My kids call it the bounce house on wheels haha.

I'm going to definitely keep an eye on the trans though. If it starts acting up I'll replace in the spring. Just needs to hang in there till then.

 

[PNWYukon]

Well dropped trans and replaced the rear main along with the oil sending unit...what a PITA! while the trans was out I replaced the valve control body and 1-2 and 3-4 solenoids, new filter, flushed and refilled...must of down the trick. No more erratic shifting or gear hunting. Only thing it does now is hang a little high In rpms before it shifts but definitely a huge improvement over what it was. Now that fall is setting in time to tear into the suspension and get all that mess sorted out. My kids call it the bounce house on wheels haha.

I'm going to definitely keep an eye on the trans though. If it starts acting up I'll replace in the spring. Just needs to hang in there till then.

You replaced the entire valve body?

Did you inspect the separator plate?

Did you inspect the accumulator pistons and springs?

 

[04Z71w]

You replaced the entire valve body?

Did you inspect the separator plate?

Did you inspect the accumulator pistons and springs?

Separator plate, accumulator springs and pistons all replaced. Separator plate replaces with an oem unit and used sonnax pistons/springs. I didn't do those parts. Made a call to a local builder here and did some trading for him to come over take a look and see what else I might be over looking. I've never gone into a 4l60e so it was an experience. All I know is it was pretty damn dirty inside there so not sure what in the hell the previous owner did. Wrestled with the damn thing going back in. Have to replace the catalytic converters and y pipe they sit in now. They were all rusted out and dented up pretty bad.

 

[04Z71w]

On a happier note I did sell the 22s that came on it when I bought for 1400.00 over the weekend.

I'm not sure if the timing belt has even been changed and its sitting at 288k miles. Should I change it when I replace the oil pump I already have? Even though it seems to be operating fine its nice knowing there's fresh parts in there.

 

[PNWYukon]

On a happier note I did sell the 22s that came on it when I bought for 1400.00 over the weekend.

I'm not sure if the timing belt has even been changed and its sitting at 288k miles. Should I change it when I replace the oil pump I already have? Even though it seems to be operating fine its nice knowing there's fresh parts in there.

Like many of us on here, it is a matter of course to replace parts that are 15+ years old. It is really how much you want to do for updating versus waiting until something breaks.

I have not heard about timing chains breaking, but it depends on what the previous owners did to it. Hotrodding etc. Based on how rough your transmission was, I would be changing parts on the engine out just to know they are new. If you are going to tear into the engine you might as well do it all!

 

[Colby_e32]

Have you considered doing a corvette servo?

My 2001 tahoe with 250k miles or so started to flare shift 1-2, and 2-3, sometimes didnt want to shift on the interstate. I installed a corvette servo over 20k miles ago, no more flare shifts, nice solid firm shifts into 1-2, and 3-4. Helped a ton for drive ability, and has been giving me great results. as with anything I know it will eventually fail, but for now its a go!

As for timing chains, and oil pumps, I wouldn't worry about the timing chain, seen several 350k+ trucks still running strong, with all oem stuff. Oil pumps typically dont fail either, its usually just the pickup tube o-ring that gives everyone so much trouble.

 

[04Z71w]

I don't mind spending time on replacing parts even if they are still working peace of mind not being 15 years old lol. This is more of a restoration/fun project. I have a strong belief when everything goes electric tahoes of the old will be worth some money. Or I could be wrong and we're stuck with gas hogs paying 20 dollars a gallon for. Who knows. It's gonna be fun though!

I'll skip past the timing chain and oil pump for now then. Only thing I'm doing to the engine is putting on rebuilt heads/gaskets and such. More of a basic engine refresh. Compression in all cylinders was pretty much right on the money. I did a new trans mount this weekend I'm changing out the motor mounts and time permitting I might start on the front suspension. There's a lot of rocking movement and the mounts look like trash.

 

[swathdiver]

Glad you did the valve body repairs, those prices seemed too cheap to me to get anything of decent quality and how in the world does the trans guy know what needs changing until he actually sees the internals laid out before him? Ever watch Precision Transmissions on youtube? They do 4L60 tear downs all the time. Learned a lot about them from those videos!

 

[04Z71w]

Have you considered doing a corvette servo?

My 2001 tahoe with 250k miles or so started to flare shift 1-2, and 2-3, sometimes didnt want to shift on the interstate. I installed a corvette servo over 20k miles ago, no more flare shifts, nice solid firm shifts into 1-2, and 3-4. Helped a ton for drive ability, and has been giving me great results. as with anything I know it will eventually fail, but for now its a go!

As for timing chains, and oil pumps, I wouldn't worry about the timing chain, seen several 350k+ trucks still running strong, with all oem stuff. Oil pumps typically dont fail either, its usually just the pickup tube o-ring that gives everyone so much trouble.

A corvette servo never crossed my mind honestly. This is my first GM product ever owned so I'm catching on. I'll definitely look into it though.