4L60E Hard Shift Problem

[Guardsman]

Here's the bulltein from GM about the problem with the 4L60Es. A lot of people have asked about it, the problem where the 1-2 shift feels like you're getting rear-ended, and you may get a code 1870.

http://www.thenebula.com:9001/servle...ppModel=Camaro

Perhaps this could be added to the Tech Section??

[SuprSpdDB7]

link isn't working 4 me

[Guardsman]

hmmm....I'll see if I can find it again. One of the guys on here had the link to the website, that's how I found it....

[spddmn]

Not working for me either, but my car does the same thing (97 bird, 4L60E) I originally thought it was the B&M shiftplus that caused this but i dont think so anymore, by the way, I have a B&M shiftplus for sale if anyones interested. send me an email at nashnorris@excite.com

[lifeguardinme19]

I had read the GM bulliten on 1-2 hard shift about a week ago. I found it while looking for a different problem I'm having with my A4. If I remember right, the 1-2 hard shift has something to do with the valve body. I'll try to find it again and post it for you guys

[DrFix2Fly]

Code P1870 is Transmission component slippage. It's a common problem to 4L60e valve bodies 98+ with Ec3 programming. The problem is caused by wear in the TCC (torque converter control) valve bore. The valve computer engages the torque converter lock up clutch slowly and gently by modulating the valve rather than engaging it in one move like the 700R4. This eventually wears out the bore allowing pressure leakage on the apply side of the valve, the torque converter clutch slips and if you are over 60 mph, your compter sees a slip condition. At this point it trys to compensate by applying full pressure all the time to all functions. This explains the hard shift and the whirring sound which is your pump working in high pressure mode. If this condition happens once, your computer will simply apply full pressure. If it happens in two sequential ignition cycles (or is it twice in one cycle?) it will give you the SES light and high pressure mode. I also belive it may be caused by the Jet SCU 2000 which many of us have used to correct speedometer readings, but that's another scenario. The repair for this condition is from Sonnax. Your tranny shop will remove your valve body, ream out your TCC bore and install a sleeve and new valve. For more information check out the sonnax site.

[Tyler F]

I"ve had this problem since I got my car last year, but the hard shift problem is only when its cold. Is that still the same problem, and am I heading for a tranny rebuild if I don't do anything about it?

[DrFix2Fly]

Typically this problem occurs at operating temperature. Call a few tranny shops and listen to what they tell you.

[Guardsman]

Basically what DrFix2Fly said, the problem is in the torque converter clutch apply valve.

I've also seen that the leak develops on the exhaust side of the piston, but it wouldn't surprise me if it leaked right through the piston, with the parts that GM uses.

The valve is called a pulse width modulated valve. It's there for all of the average Joe's who don't want to feel the car shift.

Because of the leakage, there isn't enough pressure to keep the torque converter clutch (tcc) locked up. So, two things happen, slippage, and heat. The slippage causes the PCM to throw a code, and command max line pressure, and, as said above, that's the hard 1-2 shift, and the whistling sound is the pump.

The heat gradually destroys the transmission. About 5,000 miles before my engine finally threw a code because of the problem, I flushed my trans, and filled it with Redline High Temp ATF. When the guy took the tranny aprt to rebuild it, the Redline was torched, that's how hot it got.

One of the fixes is to either bore the valve and sleeve it, or install a new valve body.

The route I went was to have the valve bored and sleeved, and also got rid of the pulse width modulated valve control, and converted it to a straight on-off lock up. In addition, the kit that had that also had fixes for a lot of other problems with the 4L60E (lag going into first and reverse, etc.).

If you're paying for your transmission yourself, don't even waste your time with the dealership, they're going to charge $1800+ for a new trans that will very likely have the same problem. My car got a new transmission a few hundred miles before I bought it, and it bit it about 50,000 miles later.

Superior Transmission parts (that's the company I got my parts from) and a few ther companies sell the fix kits for the 4L60Es, and they can be installed as part of a rebuild, a good tranny shop should know where to look, and how to get the stuff.

While I was at it, I also had a corvette solenoid, mild shift kit, heavier duty clutch packs and band installed.

[DrFix2Fly]

Thanks for adding to my explanation Guardsman. I wish I knew you when I needed a VIN number to flash my 99 PCM to. Funny thing about the SCU 2000 and my other explanation to the slip condition. Jet stopped asking me follow questions about their product and how I had it installed. During my troubleshooting with my tranny shop, if we drove the car with the Snap-on analyzer attached with the SCU 2000 disconnected and the rear gear changed to 3.42, we actually got negative slip. Connect the SCU 2000 and the slip goes away until the condtions are right. I will keep the board posted as to how I resolve this potentially expensive problem with Jet.

[Ted]

I just recently got the code 1870 on my car. And I get the hard 1-2 shift after I drive a long time on the highway and then come to a stop after doing so. How much is this generally to fix? Does it cost as much as a transmission overhaul?

[DrFix2Fly]

Read the explanations above and then open your wallet about $500 for a sonnax valve.

[Guardsman]

Ted,
At this point, I'd say to just get the transmission rebuilt. By the time it has thrown the code, the internals are probably pretty well baked. For the fix kits, and the labor (you will have to pull the transmission to do it, unless you only do the valvebody), you're looking at several hundred dollars.

If you get it rebuilt now, you're probably looking at $1500 or so, depending on where you are, more if you have the shop pull and install the tranny.

Basically, you're better off just biting the bullet, and getting the whole thing rebuilt, that way you have all new parts. If you spend a few hundred dollars now to fix just what's wrong, and the tranny dies a few months later, you'll be stuck paying for everything twice.

[Ted]

Let's say I don't get it taken care of. What am I looking at here? Like how long is the transmission going to last etc... I've seen trannys go for cheep for our cars. Like $300. WOuld it be easier to buy a semi decent used one and put it in my self? I've had a tad bit of tranny experience when we dropped my friend's M6 out of his LT1, it didn't seem to hard to take the whole thing out. What do you guys think? I'm trying to sell the car soon. And theres not a whole lot wrong with it really.

[Guardsman]

If you're just going to sell it, then, yeah, your best bet would be to toss a cheap tranny in it. How long it will last, who knows? Depends on how hard you drive it, how long it feels like lasting, etc.