84CUCV
3/4 ton status
like there is a shift kit in it. all stock truck. any ideas? thanks
CK5
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4L80E shifting HARD
- Thread starter 84CUCV
- Start date
what year truck??my truck can shift hard if its programed to through a handheald
84CUCV
3/4 ton status
1991 all stock
i couldnt tell you mines a 98 and unless there is something worng with the trans its all in the computer
My 91 crew cab developed a HARD shift and it was something called a "PCM". Fortunately, for me the trans was under warranty so the shop fixed it. I do remember it had a code for it in the computer. I have a 91 manual if you can pull any codes.
84CUCV
3/4 ton status
ok thanks i will pm you when i get it done
Don't some automatics go into a panic or safety mode when they sense slipping? Then shift like it was a full throttle shift all the time to prevent more damage? Maybe I am just making stuff up but I think I remember reading about this a while ago
Jason4x4
1/2 ton status
Most later model auto's will go into limp home mode, which usually consists of stuck in 3rd gear.
MaxPF
1/2 ton status
If slippage is detected in electronically controlled GM trannys the PCM will max out the line pressure. The result: hard shifts.
Is your fluid level good?
Is your fluid level good?
I have a 91 Sub with a 4L80e in it. When I purchased it about 6 months ago it had a hard shift from first to second. I kind of let it go at that. About a week ago it started to slip a little off the line. Once the revs got to about 1000 it would start pulling. I parked it and got a filter and some fluid. Once the fluid and fliter were change the shift was smooth and nice. The slipping was still there so I ran it by a shop a couple of days ago.
The tranny guy took it for a quick spin but ask me if my check engine light work. I said it did and he just turn the key on to see that it did. He seemed kind of puzzled and I ask why. He said that the 4L80s normally never go south and if they do they normally have a code.
Long story short he said the forward clutch pack must be about fried for it to even start to slip a little. So my assumption is that the hard shift was the tranny trying to prevent the slippage.
I was going to post on here asking if anyone had a nice link to shop manual. I was considering trying to rebuild it myself. If all I need are seals and clutch band/plates they the kit is only $265 bucks compaired to the 1200 a shop wants to do it.
The tranny guy took it for a quick spin but ask me if my check engine light work. I said it did and he just turn the key on to see that it did. He seemed kind of puzzled and I ask why. He said that the 4L80s normally never go south and if they do they normally have a code.
Long story short he said the forward clutch pack must be about fried for it to even start to slip a little. So my assumption is that the hard shift was the tranny trying to prevent the slippage.
I was going to post on here asking if anyone had a nice link to shop manual. I was considering trying to rebuild it myself. If all I need are seals and clutch band/plates they the kit is only $265 bucks compaired to the 1200 a shop wants to do it.
Should be able to get a rebuild manual written by ATSG. Picture quality was junk before, but I bet they are much better nowadays. I don't believe the later GM shop manuals cover rebuild of the trans, most dealers apparently farm out their trans work, or simply swap the trans.
84CUCV
3/4 ton status
1200 to rebuild a 4l80e? a guy at work payed 1800 for his.
i hope to good the trans is not on the way out.
i hope to good the trans is not on the way out.
Fwiw, it was $1700 to build mine. 
$1800 - $1700 for about 300 to 400 in parts. I need to learn how to do trannies and make a nice side income.
I'm not to sure but a guy I work with used to do them so I might have him over for a training session soon.
They are not really all that hard to work on they just require a fair amount of specialized tools and a good service manual
on a side note this is some solid sig material
I agree, either sig or income, it's all good with some jack and coke! I don't think there is gonna be much work going on this weekend. I'm breaking down a gallon bottle right now!
