4l80e rebuild gone wrong...

TubeTruck · Jul 11, 2024

Looking for some help here before I pull the tranny again. Transmission has 250k+ miles on it and wore out enough to strip the output shaft splines going into the t-case. So I decided it was time for a rebuild and upgrade. Bought a rebuild kit with red Alto clutches and all the fixings, and a Transgo HD2 kit. Watched all kinds of videos and dug into it. Pretty straight forward. I skimped on the solenoids (actually it didn't even cross my mind to replace them, lol). Got the whole thing back together and in. Started it up and put it in gear. You can hear the internals spinning, and placing it in park it bounces the parking pawl. Bought a pressure test kit. 90 psi in park and all forward gears, 120psi in reverse. I know it should be 150 and 275-300. Using a hand pump I pumped tranny fluid into the pressure port. Fluid poured out from around solenoids A & B, the shift solenoids at the back of the valve body. Bought an electrical kit and replaced the solenoids. Same issue. I'm guessing internal leak, but I thought I would ask in here if anyone had issues like this.

Catbox · Jul 11, 2024

Nick @NickTransmissions would be the one to ask.

He has many videos on the TubeYou as well, perhaps peruse those as you wait for a response.

NickTransmissions · Jul 11, 2024

TubeTruck said:
Looking for some help here before I pull the tranny again. Transmission has 250k+ miles on it and wore out enough to strip the output shaft splines going into the t-case. So I decided it was time for a rebuild and upgrade. Bought a rebuild kit with red Alto clutches and all the fixings, and a Transgo HD2 kit. Watched all kinds of videos and dug into it. Pretty straight forward. I skimped on the solenoids (actually it didn't even cross my mind to replace them, lol). Got the whole thing back together and in. Started it up and put it in gear. You can hear the internals spinning, and placing it in park it bounces the parking pawl. Bought a pressure test kit. 90 psi in park and all forward gears, 120psi in reverse. I know it should be 150 and 275-300. Using a hand pump I pumped tranny fluid into the pressure port. Fluid poured out from around solenoids A & B, the shift solenoids at the back of the valve body. Bought an electrical kit and replaced the solenoids. Same issue. I'm guessing internal leak, but I thought I would ask in here if anyone had issues like this.

Sorry to hear you're having trouble with it...These units can be a bit finicky however you need to take that stupid HD2 kit out of that transmission and put it on the shelf (can't even recommend you sell it as it would be knowingly passing all of the problems it creates onto someone else). Those sandwich style spacer plates they come with as well as that pressure relief mod create more risk/problems than they solve...You can dual feed internally since you have the transmission apart and it's a vastly superior method for upgrading the holding capacity of the direct clutch.

Did you:

> Replace the boost valve with a Sonnax 4L80E-LB1 (I don't like Transgo's valves either for these or the TH400s)
> Perform a case air check prior to bolting on the valve body
> Vacuum test the valve body and pump stator support
> Check the forward drum for sealing ring groove wear (very common in these units)

You can check out my 4L80E Youtube playlist - I have a tear down and inspection video (prob the most detailed out there on the net atm), two complete rebuild series, one focused on daily driving/mostly stock while the other is a street/strip build up. I also have videos on vacuum testing the valve body, installing Sonnax zip kit corrective parts as well as testing solenoids, etc.

4L80E

All 4L80e - related videos

www.youtube.com

Bextreme04 · Jul 11, 2024

TubeTruck said:
Looking for some help here before I pull the tranny again. Transmission has 250k+ miles on it and wore out enough to strip the output shaft splines going into the t-case. So I decided it was time for a rebuild and upgrade. Bought a rebuild kit with red Alto clutches and all the fixings, and a Transgo HD2 kit. Watched all kinds of videos and dug into it. Pretty straight forward. I skimped on the solenoids (actually it didn't even cross my mind to replace them, lol). Got the whole thing back together and in. Started it up and put it in gear. You can hear the internals spinning, and placing it in park it bounces the parking pawl. Bought a pressure test kit. 90 psi in park and all forward gears, 120psi in reverse. I know it should be 150 and 275-300. Using a hand pump I pumped tranny fluid into the pressure port. Fluid poured out from around solenoids A & B, the shift solenoids at the back of the valve body. Bought an electrical kit and replaced the solenoids. Same issue. I'm guessing internal leak, but I thought I would ask in here if anyone had issues like this.

The bold part makes me question what you got going on here. Are you saying you can hear stuff spinning but the truck won't move? And that you went to put it back in park and you had the grinding bounce from the park pawl? That sounds an awful lot like you have the T-case in neutral. The only way that the park pawl can be bouncing is if the output shaft is spinning. If the output shaft is spinning... you should be moving. If you aren't moving... the problem isn't in the transmission.

I've also never heard of a transmission going bad causing an output spline to get stripped. Stripped spline would be from something bad happening in the T-case most likely...

NickTransmissions · Jul 11, 2024

Bextreme04 said:
The only way that the park pawl can be bouncing is if the output shaft is spinning.

The pawl never makes contact with the parking lugs on the output planetary when not in park unless the little pawl return spring was not reinstalled or installed it incorrectly and it's fallen, sitting in the pan. It's also possible the guide plate bolts were not snugged / torqued, worked loose and fell into the pan. That could result in the pawl spring falling out and allow the pawl to make contact with the lugs on the output carrier.

That said, T case can certainly be in neutral; I would think he'd place it in gear before trying to drive it but who knows.

@TubeTruck - What drivability symptoms do you have as nothing you mentioned in your first post mentions anything about movement or lack thereof. You just talk about hearing noises...

Also are the pressures you provided at idle or stall?

TubeTruck · Jul 12, 2024

Alright, a lot to answer here..

NickTransmissions said:
Sorry to hear you're having trouble with it...These units can be a bit finicky however you need to take that stupid HD2 kit out of that transmission and put it on the shelf (can't even recommend you sell it as it would be knowingly passing all of the problems it creates onto someone else). Those sandwich style spacer plates they come with as well as that pressure relief mod create more risk/problems than they solve...You can dual feed internally since you have the transmission apart and it's a vastly superior method for upgrading the holding capacity of the direct clutch.

Did you:

> Replace the boost valve with a Sonnax 4L80E-LB1 (I don't like Transgo's valves either for these or the TH400s)
> Perform a case air check prior to bolting on the valve body
> Vacuum test the valve body and pump stator support
> Check the forward drum for sealing ring groove wear (very common in these units)

You can check out my 4L80E Youtube playlist - I have a tear down and inspection video (prob the most detailed out there on the net atm), two complete rebuild series, one focused on daily driving/mostly stock while the other is a street/strip build up. I also have videos on vacuum testing the valve body, installing Sonnax zip kit corrective parts as well as testing solenoids, etc.

4L80E

All 4L80e - related videos

www.youtube.com

I didn't get a chance to pressure test it. I didn't have a way to do it at the time, but I do now, so that was going to be one of my tests before I pulled it. I installed the transgo stuff, the only Sonnax piece I installed was the rear bushing. So no to the Sonnax boost valve. I haven't seen anything about vacuum testing. I'll have to look into that. I learned about not using the HD2 kit after I rebuilt it, when I was looking to a solution to the problem, lol. Jake's says I can keep the HD2 kit, but don't do the relief mod, which I had already done. I'll probably pull the valve body out and tap the relief hole for a set screw.

Bextreme04 said:
The bold part makes me question what you got going on here. Are you saying you can hear stuff spinning but the truck won't move? And that you went to put it back in park and you had the grinding bounce from the park pawl? That sounds an awful lot like you have the T-case in neutral. The only way that the park pawl can be bouncing is if the output shaft is spinning. If the output shaft is spinning... you should be moving. If you aren't moving... the problem isn't in the transmission.

I've also never heard of a transmission going bad causing an output spline to get stripped. Stripped spline would be from something bad happening in the T-case most likely...

So the output shaft was extremely wobbly when I took it apart. The rear bushing was almost non-existent. The wobbling caused the output splines and t-case input splines to wear down and eventually strip.

But yeah, the sounds. So I start the truck in park, no sound. I put the truck in gear, Rev or Fwd, and I can hear the internals spinning (maybe something is loose inside?). Rev it a bit and no movement. It doesn't even try, like it's in neutral. Put it back in park and it grinds the pawl. I'll check the t-case again. I rebuilt it for the second time now, but what you said about it spinning makes sense.

The pressures I listed are at idle. I revved it a little bit they don't change much. And the truck doesn't move at all.

Edit: I know I manually checked the t-case to make sure it worked before I put it back in the truck.

TubeTruck · Jul 12, 2024

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Bextreme04 · Jul 12, 2024

NickTransmissions said:
The pawl never makes contact with the parking lugs on the output planetary when not in park unless the little pawl return spring was not reinstalled or installed it incorrectly and it's fallen, sitting in the pan. It's also possible the guide plate bolts were not snugged / torqued, worked loose and fell into the pan. That could result in the pawl spring falling out and allow the pawl to make contact with the lugs on the output carrier.

That said, T case can certainly be in neutral; I would think he'd place it in gear before trying to drive it but who knows.

@TubeTruck - What drivability symptoms do you have as nothing you mentioned in your first post mentions anything about movement or lack thereof. You just talk about hearing noises...

Also are the pressures you provided at idle or stall?

The highlighted part of his statement that I was referring to specifically says that he get the pawl bouncing after putting it in drive and then returning it to park. That to me sounds like what you get when you are messing with 4wd and put the transfer case in nuetral with the trans in drive, then you have no way to stop the output shaft without grinding some things and if you try to pop the trans into park you will get the grinding pop and the pawl shaves some of the lugs off trying to engage them. If t-case is in gear and the rear end is healthy, the output shaft should not be spinning when the truck is stopped and you should not "hear things spinning in the trans" and there should be nothing for the pawl to "bounce on". This sounds like a classic case of either transfer case destroyed/in neutral or the rear end.

Bextreme04 · Jul 12, 2024

TubeTruck said:
Alright, a lot to answer here..

I didn't get a chance to pressure test it. I didn't have a way to do it at the time, but I do now, so that was going to be one of my tests before I pulled it. I installed the transgo stuff, the only Sonnax piece I installed was the rear bushing. So no to the Sonnax boost valve. I haven't seen anything about vacuum testing. I'll have to look into that. I learned about not using the HD2 kit after I rebuilt it, when I was looking to a solution to the problem, lol. Jake's says I can keep the HD2 kit, but don't do the relief mod, which I had already done. I'll probably pull the valve body out and tap the relief hole for a set screw.

So the output shaft was extremely wobbly when I took it apart. The rear bushing was almost non-existent. The wobbling caused the output splines and t-case input splines to wear down and eventually strip.

But yeah, the sounds. So I start the truck in park, no sound. I put the truck in gear, Rev or Fwd, and I can hear the internals spinning (maybe something is loose inside?). Rev it a bit and no movement. It doesn't even try, like it's in neutral. Put it back in park and it grinds the pawl. I'll check the t-case again. I rebuilt it for the second time now, but what you said about it spinning makes sense.

The pressures I listed are at idle. I revved it a little bit they don't change much. And the truck doesn't move at all.

Edit: I know I manually checked the t-case to make sure it worked before I put it back in the truck.

You either have a trashed transfer case or rear end. If you are hearing things spinning and it is grinding going into park... the transmission is going into gear and spinning the output shaft. I would block the wheels and set the parking brake, then put it into gear. Get out of the truck and see if your driveshafts are spinning. If not, your transfer case is in neutral or put together wrong. If they are, you have something really wrong with your diff or transfer case depending on what is spinning.

Bextreme04 · Jul 12, 2024

TubeTruck said:
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That didn't happen because the output shaft was wobbly. They are all wobbly and free floating. It should have been held steady by either the output bearing on the rear housing in a 2wd or it gets held steady by the input on the T-case in a 4wd. I have NEVER seen a 4l80 32 spline gear strip like that. The only way I can think that something like that would happen is if something locked solid in the T-Case or rear end... but even then I would have expected something else to physically shear before the output spline would strip like that. What T-case are you using... and how is it adapted to the 4L80?

Ricko1966 · Jul 12, 2024

I don't have everything on every vehicle,so this may not apply. But if the speedometer drive is in the transmission put it in gear give it some gas and see if the speedometer registers. If it does I'd be looking at the transfer case.

Nasty-LSX · Jul 12, 2024

Wow man that sucks!!

TubeTruck · Jul 12, 2024

Bextreme04 said:
That didn't happen because the output shaft was wobbly. They are all wobbly and free floating. It should have been held steady by either the output bearing on the rear housing in a 2wd or it gets held steady by the input on the T-case in a 4wd. I have NEVER seen a 4l80 32 spline gear strip like that. The only way I can think that something like that would happen is if something locked solid in the T-Case or rear end... but even then I would have expected something else to physically shear before the output spline would strip like that. What T-case are you using... and how is it adapted to the 4L80?

NP205 with twin stick and rail mod. I'm using the ORD adapter. I'll check the transfer case when I get home.

Bextreme04 · Jul 12, 2024

TubeTruck said:
NP205 with twin stick and rail mod. I'm using the ORD adapter. I'll check the transfer case when I get home.

Round pattern 205? Or did you modify a figure 8 to have the long input? I have a stock 205 Figure 8 with the short input as it originally had a TH400 in front of it. I'm using the stock adapter with a Northwest Fab adapter plate and cut down a 2wd output shaft to fit the required 4-7/8" length. I don't think I've ever seen a 205 input shaft go that for onto a 4L80 output shaft to have stripped it that close to the trans.

NickTransmissions · Jul 12, 2024

TubeTruck said:
Alright, a lot to answer here..

I didn't get a chance to pressure test it. I didn't have a way to do it at the time, but I do now, so that was going to be one of my tests before I pulled it. I installed the transgo stuff, the only Sonnax piece I installed was the rear bushing. So no to the Sonnax boost valve. I haven't seen anything about vacuum testing. I'll have to look into that. I learned about not using the HD2 kit after I rebuilt it, when I was looking to a solution to the problem, lol. Jake's says I can keep the HD2 kit, but don't do the relief mod, which I had already done. I'll probably pull the valve body out and tap the relief hole for a set screw.

So the output shaft was extremely wobbly when I took it apart. The rear bushing was almost non-existent. The wobbling caused the output splines and t-case input splines to wear down and eventually strip.

But yeah, the sounds. So I start the truck in park, no sound. I put the truck in gear, Rev or Fwd, and I can hear the internals spinning (maybe something is loose inside?). Rev it a bit and no movement. It doesn't even try, like it's in neutral. Put it back in park and it grinds the pawl. I'll check the t-case again. I rebuilt it for the second time now, but what you said about it spinning makes sense.

The pressures I listed are at idle. I revved it a little bit they don't change much. And the truck doesn't move at all.

Edit: I know I manually checked the t-case to make sure it worked before I put it back in the truck.

Yep, plug that VB with a set screw.

When was that picture of the stripped output shaft taken? Is that it's current state or was that taken prior to you rebuilding the unit?

4l80e rebuild gone wrong...

TubeTruck

I'm from Boston. Deal with it.

Catbox

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NickTransmissions

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4L80E

Bextreme04

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NickTransmissions

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TubeTruck

I'm from Boston. Deal with it.

4L80E

TubeTruck

I'm from Boston. Deal with it.

Bextreme04

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Bextreme04

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Bextreme04

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Ricko1966

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Nasty-LSX

TogetherforeverCovid19

TubeTruck

I'm from Boston. Deal with it.

Bextreme04

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NickTransmissions

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