80e Pressure Drop During 1-2 Shift = Cooked Clutches
03-21-2015, 05:33 PM
#41
My shop builds HUNDREDS of 4L80E's a year. I wouldn't rebuild a transmission that had burnt 1-2 clutches and still air checked good for free. I would charge for the repair because it points with great certainty to a low fluid condition. Especially on a unit that dyno'd good and by your own admission made proper pressure in the truck, except on WOT 1-2.
Your fluid level was low during your WOT runs. You glazed the intermediate clutches by doing so. So until they are replaced, you will have a soft WOT 1-2 shift as mentioned previously. The reason you didn't cook them completely out of the transmission is likely because FLT used a good clutch material.
I can't even grasp the concept of why a customer thinks they can run a transmission low on fluid and it should be OK, and if not it should be the builder's fault.
Would you say the same thing if you spun all the bearings in your engine because it was 2 qts low during WOT? I highly doubt it.
The rod bearings in an engine rely not so much on the pressure as the hydrodynamic wedge created by the oil.
A transmission ABSOLUTELY relies on the pressure to create the force required to clamp it. If it's not there, the clutches slip, and once they slip they are ruined.
As I mentioned previously NO builder can build a transmission that will live without proper fluid level. It's doesn't matter how much you pay for it, how well it was built, how popular or reputable the builder is, what the internet consensus is on the builder's abilities, or how many times they repair it due to your mistake.
It seems to me that you owe FLT for one rebuild and need to pay them for another.
03-21-2015, 05:35 PM
#42
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I can't answer that for sure, however, it's probably assumed when you're playing at this level that this stuff is understood. There are quite a few critical steps in installing a transmission including the torque converter clearance, using the correcting trans line fittings, proper fluid level, etc. Any of those can result in a failure, and we have seen several cases of these on this forum over the years.
03-21-2015, 05:41 PM
#43
I can't answer that for sure, however, it's probably assumed when you're playing at this level that this stuff is understood. There are quite a few critical steps in installing a transmission including the torque converter clearance, using the correcting trans line fittings, proper fluid level, etc. Any of those can result in a failure, and we have seen several cases of these on this forum over the years.
It IS assumed that whoever installs the transmission knows the critical installation steps and they also assume the responsibility that it is done correctly. It is completely beyond the transmission builder's control.
We have seen so many failures due to installation issues (with fluid level being the most common) that I wrote a packet that ships with each transmission addressing every aspect of installation I could think of that causes failure. Since we began sending these out, the failures have been reduced tremendously.
A transmission company shouldn't have to send out a pop-up book to ensure our product is installed correctly but we have pretty much resorted to that.
I also don't feel liable when a product fails that is obviously an installation issue. It's not our responsibility AND we took extra steps to educate the customer/installer of the critical checks.
03-21-2015, 05:44 PM
#44
The 1-2 shift circuit can be improved greatly on a 4L80E, but that depends on the valve body design. We see intermediates come back with little or no hot spotting after years at 1200-1500 RWHP.
03-21-2015, 05:47 PM
#45
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My statements weren't based on an opinion. They were based on fact that you have confirmed by your posting.
My shop builds HUNDREDS of 4L80E's a year. I wouldn't rebuild a transmission that had burnt 1-2 clutches and still air checked good for free. I would charge for the repair because it points with great certainty to a low fluid condition. Especially on a unit that dyno'd good and by your own admission made proper pressure in the truck, except on WOT 1-2.
Your fluid level was low during your WOT runs. You glazed the intermediate clutches by doing so. So until they are replaced, you will have a soft WOT 1-2 shift as mentioned previously. The reason you didn't cook them completely out of the transmission is likely because FLT used a good clutch material.
I can't even grasp the concept of why a customer thinks they can run a transmission low on fluid and it should be OK, and if not it should be the builder's fault.
Would you say the same thing if you spun all the bearings in your engine because it was 2 qts low during WOT? I highly doubt it.
The rod bearings in an engine rely not so much on the pressure as the hydrodynamic wedge created by the oil.
A transmission ABSOLUTELY relies on the pressure to create the force required to clamp it. If it's not there, the clutches slip, and once they slip they are ruined.
As I mentioned previously NO builder can build a transmission that will live without proper fluid level. It's doesn't matter how much you pay for it, how well it was built, how popular or reputable the builder is, what the internet consensus is on the builder's abilities, or how many times they repair it due to your mistake.
It seems to me that you owe FLT for one rebuild and need to pay them for another.
My shop builds HUNDREDS of 4L80E's a year. I wouldn't rebuild a transmission that had burnt 1-2 clutches and still air checked good for free. I would charge for the repair because it points with great certainty to a low fluid condition. Especially on a unit that dyno'd good and by your own admission made proper pressure in the truck, except on WOT 1-2.
Your fluid level was low during your WOT runs. You glazed the intermediate clutches by doing so. So until they are replaced, you will have a soft WOT 1-2 shift as mentioned previously. The reason you didn't cook them completely out of the transmission is likely because FLT used a good clutch material.
I can't even grasp the concept of why a customer thinks they can run a transmission low on fluid and it should be OK, and if not it should be the builder's fault.
Would you say the same thing if you spun all the bearings in your engine because it was 2 qts low during WOT? I highly doubt it.
The rod bearings in an engine rely not so much on the pressure as the hydrodynamic wedge created by the oil.
A transmission ABSOLUTELY relies on the pressure to create the force required to clamp it. If it's not there, the clutches slip, and once they slip they are ruined.
As I mentioned previously NO builder can build a transmission that will live without proper fluid level. It's doesn't matter how much you pay for it, how well it was built, how popular or reputable the builder is, what the internet consensus is on the builder's abilities, or how many times they repair it due to your mistake.
It seems to me that you owe FLT for one rebuild and need to pay them for another.
As far as me owing FLT, very funny. First of all, and as mentioned previously, I am a total novice to all this, Chuck is well aware of that and Chuck never told me to over fill past the fill line and by not doing so would glaze the clutches as you believe. Because of that alone, how am I responsible? Not to mention, it says, "DO NOT OVER FILL" right on the dipstick + I never insisted he rebuild the first one for free. I simply told him what happened and he said he would warranty it - simple as that. You making the statement that I owe them for two transmissions is uncalled for.
Last edited by L8ERBRO; 03-21-2015 at 07:12 PM.
03-21-2015, 05:56 PM
#46
So please explain why the pressure drop is still there, I'm curious about that one.
As far as me owing FLT, very funny. First of all, and as mentioned previously, I am a total novice to all this, Chuck is well aware of that and Chuck never told me to over fill past the fill line and by not doing so would glaze the clutches as you believe. Because of that alone, how am I responsible? Not to mention, I never insisted he rebuild the first one for free. I simply told him what happened and he said he would warranty it - simple as that. You making the statement that I owe them for two transmissions is uncalled for.
As far as me owing FLT, very funny. First of all, and as mentioned previously, I am a total novice to all this, Chuck is well aware of that and Chuck never told me to over fill past the fill line and by not doing so would glaze the clutches as you believe. Because of that alone, how am I responsible? Not to mention, I never insisted he rebuild the first one for free. I simply told him what happened and he said he would warranty it - simple as that. You making the statement that I owe them for two transmissions is uncalled for.
Chuck isn't responsible for your fluid level. You paid him to build a transmission and he did so. Anything he did beyond that was a courtesy. I'm sure he rebuilt it as a courtesy too.
I will bow out and discontinue my tech assistance, as it seems you have it all figured out.
03-21-2015, 05:57 PM
#47
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There is always a slight drop at the moment of the shift. The clutch apply piston moves and the volume of fluid required causes a pressure drop as the regulator takes a moment to catch up.
The 1-2 shift circuit can be improved greatly on a 4L80E, but that depends on the valve body design. We see intermediates come back with little or no hot spotting after years at 1200-1500 RWHP.
The 1-2 shift circuit can be improved greatly on a 4L80E, but that depends on the valve body design. We see intermediates come back with little or no hot spotting after years at 1200-1500 RWHP.
If there is always a slight drop at the moment of shift, why does my 1-2 WOT shift have a very lengthy 20psi drop and the others do not?
Why is there no drop on the 1-2 under part throttle?
03-21-2015, 06:00 PM
#48
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03-21-2015, 06:10 PM
#49
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For someone who has built hundreds of transmissions, you SHOULD be able to at least show your intelligence of the 80e and answer my questions. As I have absolutely NOTHING figured out...I'm an admitted novice here.