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Discussion Starter · #1 ·
Sorry if in wrong spot. Transmission forum link didnt work for me.

My 94 3500 auto 4x4 doesnt have reverse. Im thinking of getting a trans from a picknpull or similar place because i dont have the 1 grand plus to get it rebuilt. What years will work or works best?
 

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You might try googling "4l80e reverse doesn't work". IIRC, it's basically installing a slightly longer reverse pin to compensate for the reverse band wearing.

Not a permanent fix, but makes it work for some time without a lot of effort and you can save up for a rebuilt one or take your time to find a working transmission.
 
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Yeah the reverse pin thing is a problem with the 4l80e. Fairly cheap, easy fix. You don't have to pull the trans. Just unbolt the servo from the side of the trans and install the longer pin. There are utube vids on how to fix. . There is a kit with the extender for the pin and all the gaskets on ebay for cheap Look up, 4l80e reverse fix. As said above it will get you by for a while. All the fix does is make a moderately worn reverse band work. but it is still wearing out and will need repaired eventually.
 
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Discussion Starter · #5 ·
Thanks alot guys. Ive been looking and hadnt found that yet. Il give it a shot and hope for the best
 

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Discussion Starter · #6 ·

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do that google search I posted, lots of youtube videos showing how to do it.
 

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Discussion Starter · #9 ·
Posting this just incase some else is looking for this at somepoint.
Finally got time to install this pin extension kit for the reverse servo this past weekend. Wasnt too hard. Just pulled the trans pan and then pulled the valve body because you cannot get the reverse servo off with the valve body on, atleast on my year trans. Then pulled the reverse servo and installed the extension. The extension adds .225 of a inch onto the pin and we ended up grinding about half off till it felt like it just barely touched the band when installed. Then put everything back together. Luckily for me it worked and i now have reverse again. Sorry for no pics but ehen i get working i dont think about them. Sorry for the long post on a old thread but want to out this info out there.
 
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Posting this just incase some else is looking for this at somepoint.
Finally got time to install this pin extension kit for the reverse servo this past weekend. Wasnt too hard. Just pulled the trans pan and then pulled the valve body because you cannot get the reverse servo off with the valve body on, atleast on my year trans. Then pulled the reverse servo and installed the extension. The extension adds .225 of a inch onto the pin and we ended up grinding about half off till it felt like it just barely touched the band when installed. Then put everything back together. Luckily for me it worked and i now have reverse again. Sorry for no pics but ehen i get working i dont think about them. Sorry for the long post on a old thread but want to out this info out there.
Thanks for that update :thumb:
 

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1996 K3500 6.5L TD dually F
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Wanted to bump this thread for personal interest and importance : NOTE (as some have stated): The job seemed so easy….
In the 4L80E valve body, that reverse piston pin —added length— is NOT a permanent fix, and it won’t work if your rear band is toast. (I forget where I read this here on DP.)
That’s what the extra length is intended to APPLY— and if the rear band is broken, it may be a waste of time.
Try testing your rear band FIRST!
It’s applied in ManFirst gear and REVerse; since REV is untestable, maybe ManFirst (1) can address the band. Drive forward to 25mph, and shift over to ManFirst (1). The engine should rev and the rear band would normally slow the truck by compression. If it won’t slow the truck and your tach doesn’t move, the REAR BAND is broken or worn out! Then any pin lengthening is futile, and an overhaul is required to install a new rear band— unfortunately, one of the last things that has to be removed.
I ordered the pin kit before I learned to test the rear band, and (maybe) this saved me much time and aggro.
Yeah, I’ll have to have an overhaul done. But I don’t look forward to that cost— fully-rebuilt 4L80E trans 2 years and 6000 miles ago…. so when do we give up the ghost to the scrapyard? NEVER? :whistle: 💪
 
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Wanted to bump this thread for personal interest and importance : NOTE (as some have stated): The job seemed so easy….
In the 4L80E valve body, that reverse piston pin —added length— is NOT a permanent fix, and it won’t work if your rear band is toast. (I forget where I read this here on DP.)
That’s what the extra length is intended to APPLY— and if the rear band is broken, it may be a waste of time.
Try testing your rear band FIRST!
It’s applied in ManFirst gear and REVerse; since REV is untestable, maybe ManFirst (1) can address the band. Drive forward to 25mph, and shift over to ManFirst (1). The engine should rev and the rear band would normally slow the truck by compression. If it won’t slow the truck and your tach doesn’t move, the REAR BAND is broken or worn out! Then any pin lengthening is futile, and an overhaul is required to install a new rear band— unfortunately, one of the last things that has to be removed.
I ordered the pin kit before I learned to test the rear band, and (maybe) this saved me much time and aggro.
Yeah, I’ll have to have an overhaul done. But I don’t look forward to that cost— fully-rebuilt 4L80E trans 2 years and 6000 miles ago…. so when do we give up the ghost to the scrapyard? NEVER? :whistle: 💪
"…. so when do we give up the ghost to the scrapyard? NEVER? :whistle: 💪" Good words to live by, and not just for our old trucks.:)
 
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1996 K3500 6.5L TD dually F
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Wanted to bump this thread for personal interest and importance : NOTE (as some have stated): The job seemed so easy…. (snip)
…. But I don’t look forward to that cost— fully-rebuilt 4L80E trans 2 years and 6000 miles ago…. so when do we give up the ghost to the scrapyard? NEVER? :whistle: 💪
UPDATED: Asked the trans mechanic who rebuilt my 96 4L80E, and he said, “unless the rear band is outright *broken, it’s usually the servo is cracked.” So, with dropping the pan and servicing, I’ll replace the rear servo altogether, (save the pin if reusable).
Then re-assess. I’ll be saving-up for the worst.
 

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UPDATED: Asked the trans mechanic who rebuilt my 96 4L80E, and he said, “unless the rear band is outright *broken, it’s usually the servo is cracked.” So, with dropping the pan and servicing, I’ll replace the rear servo altogether, (save the pin if reusable).
Then re-assess. I’ll be saving-up for the worst.
I’ve been down that road before a few years ago on a 03 4L80E in a GM truck for a guy I know not far from me.Basically I hooked up a pressure gauge to the pressure tap above the large weather pack connector and while in reverse the gauge showed 300 psi so I knew it wasn’t a oil pressure problem.The band was worn in this transmission but I added on I would say 3/8” to the pin and tapered the end nicely.

I had a digital dial indicator mounted upside down to measure servo pin travel after I modified it and with the help of a modified servo cover.I came up with .161” travel which is what sonnax said was within specification.So with that taken care of I used new acdelco valve body/case gaskets and reverse along with manual 1 engine braking was on the money.It turned out perfectly.

I told the guy to use 4 low when backing up a hill with a load in the back to reduce wear and tear on the reverse circuit.It was heavily loaded with sand all the time with a huge snow blade up front.Snow clearing is hard on transmissions which is why they don’t last if neglected.
 
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