4l80e direct clutch failure
Thread Starter
Joined: Sep 2007
Posts: 4,188
Likes: 292
From: woodbine, md
4l80e direct clutch failure i finally got my 2005 4l80e apart, (i bought it as a core to rebuild) and all looked good except the direct clutches, they were shot-what might have caused this to fail, anything that i need to look for, maybe a computer related thing orig-i will be rebuilding it with a transgo manuel shift kit, and i believe they have diff springs to install in the direct clutch-maybe the kit will address some of this-also the sun gear looks like it had some good use, but i think it will be ok
the prices for the tool to do the 4th clutch sure seem high (i have one of the pieces) for some plastic stuff, lol
the prices for the tool to do the 4th clutch sure seem high (i have one of the pieces) for some plastic stuff, lol
Don't take my word for it since I am not a pro builder, but I am doing the same type of work on a 1995 4l80e. I am installing Alto 031756HP kit for the direct clutch it has 7 thinner steel & friction plates to replace the 5 standard pieces without modifying the drum. The transgo-3 kit does include new springs for the direct clutch. I believe the transgo kit also feeds both chambers of the direct clutch, but I think that it is done in the valve body, not like an older TH400 where you leave one of the seal rings out. Again, I am not an expert. I am curious what other people have to say about the alto frictions.
The Alto frictions are "OK" but the stock 4L80E frictions are better.
I also don't care for using the thin steels of the Alto PowerPacks.
It's been proven time and again that thin steels will cause the pack to go away much faster than using fewer frictions with thicker steels.
Ask any of the sponsors here why they don't use the Alto PowerPack in the 3-4 clutches of the 4L60E....
I'm sure they all tried them back in the day before there were other options.
The Hi energy material was developed for the 4L60 trans because of the weak 3-4 clutch design. It was later used on the other transmissions like the 4L80E.
You can easily get 6 clutches using the .077" "forward" steels in the 4L80E direct drum. 2005 core should have the molded piston in it.
5 clutches are enough for 800+ HP in a TH400 or 4L80E anyway.
One thing to keep in mind about adding clutches, although you are getting more friction area (theoretically greater torque capacity) you are also adding to the frictional losses (drag) in the trans when that clutch pack is being driven through.
The direct clutches are being driven through in 1st gear at 185% of engine rpm. 6000 rpm is about 11,000 rpm differential between the frictions and steels. In 2nd gear it is engine rpm, and in 3rd they lock so the drum spins with the forward drum at engine rpm.
Your core was probably used in a heavy towing application and the directs are what are going to go away. The Transgo kit addresses this by dual feeding the drum.
On a TH400 or 4L80E you MUST dual feed the drum for it to live above ~500 HP, despite what some would tell you here.
I also don't care for using the thin steels of the Alto PowerPacks.
It's been proven time and again that thin steels will cause the pack to go away much faster than using fewer frictions with thicker steels.
Ask any of the sponsors here why they don't use the Alto PowerPack in the 3-4 clutches of the 4L60E....
I'm sure they all tried them back in the day before there were other options.
The Hi energy material was developed for the 4L60 trans because of the weak 3-4 clutch design. It was later used on the other transmissions like the 4L80E.
You can easily get 6 clutches using the .077" "forward" steels in the 4L80E direct drum. 2005 core should have the molded piston in it.
5 clutches are enough for 800+ HP in a TH400 or 4L80E anyway.
One thing to keep in mind about adding clutches, although you are getting more friction area (theoretically greater torque capacity) you are also adding to the frictional losses (drag) in the trans when that clutch pack is being driven through.
The direct clutches are being driven through in 1st gear at 185% of engine rpm. 6000 rpm is about 11,000 rpm differential between the frictions and steels. In 2nd gear it is engine rpm, and in 3rd they lock so the drum spins with the forward drum at engine rpm.
Your core was probably used in a heavy towing application and the directs are what are going to go away. The Transgo kit addresses this by dual feeding the drum.
On a TH400 or 4L80E you MUST dual feed the drum for it to live above ~500 HP, despite what some would tell you here.
Some advance warning: The instructions included with the transgo kit are not great, but I think (hope) I was able to make all of the modifications correctly. If it ever stops snowing in portland I will have a chance to test it out on a chassis dyno. I don't think I can put 800 to the rear wheels, but I will be disappointed if I can't get over 500.
TransGo's instructions are better than most on the market so I'm not sure why you would say they aren't great, they are usually pretty specific.
I've used their kit in the 4L80E many times without issue...
I've used their kit in the 4L80E many times without issue...
What is done exactly to make the 4l80's dual feed the drum ???
Some advance warning: The instructions included with the transgo kit are not great, but I think (hope) I was able to make all of the modifications correctly. If it ever stops snowing in portland I will have a chance to test it out on a chassis dyno. I don't think I can put 800 to the rear wheels, but I will be disappointed if I can't get over 500.
The Alto frictions are "OK" but the stock 4L80E frictions are better.
I also don't care for using the thin steels of the Alto PowerPacks.
It's been proven time and again that thin steels will cause the pack to go away much faster than using fewer frictions with thicker steels.
Ask any of the sponsors here why they don't use the Alto PowerPack in the 3-4 clutches of the 4L60E....
I'm sure they all tried them back in the day before there were other options.
The Hi energy material was developed for the 4L60 trans because of the weak 3-4 clutch design. It was later used on the other transmissions like the 4L80E.
You can easily get 6 clutches using the .077" "forward" steels in the 4L80E direct drum. 2005 core should have the molded piston in it.
5 clutches are enough for 800+ HP in a TH400 or 4L80E anyway.
One thing to keep in mind about adding clutches, although you are getting more friction area (theoretically greater torque capacity) you are also adding to the frictional losses (drag) in the trans when that clutch pack is being driven through.
The direct clutches are being driven through in 1st gear at 185% of engine rpm. 6000 rpm is about 11,000 rpm differential between the frictions and steels. In 2nd gear it is engine rpm, and in 3rd they lock so the drum spins with the forward drum at engine rpm.
Your core was probably used in a heavy towing application and the directs are what are going to go away. The Transgo kit addresses this by dual feeding the drum.
On a TH400 or 4L80E you MUST dual feed the drum for it to live above ~500 HP, despite what some would tell you here.
I also don't care for using the thin steels of the Alto PowerPacks.
It's been proven time and again that thin steels will cause the pack to go away much faster than using fewer frictions with thicker steels.
Ask any of the sponsors here why they don't use the Alto PowerPack in the 3-4 clutches of the 4L60E....
I'm sure they all tried them back in the day before there were other options.
The Hi energy material was developed for the 4L60 trans because of the weak 3-4 clutch design. It was later used on the other transmissions like the 4L80E.
You can easily get 6 clutches using the .077" "forward" steels in the 4L80E direct drum. 2005 core should have the molded piston in it.
5 clutches are enough for 800+ HP in a TH400 or 4L80E anyway.
One thing to keep in mind about adding clutches, although you are getting more friction area (theoretically greater torque capacity) you are also adding to the frictional losses (drag) in the trans when that clutch pack is being driven through.
The direct clutches are being driven through in 1st gear at 185% of engine rpm. 6000 rpm is about 11,000 rpm differential between the frictions and steels. In 2nd gear it is engine rpm, and in 3rd they lock so the drum spins with the forward drum at engine rpm.
Your core was probably used in a heavy towing application and the directs are what are going to go away. The Transgo kit addresses this by dual feeding the drum.
On a TH400 or 4L80E you MUST dual feed the drum for it to live above ~500 HP, despite what some would tell you here.
Perhaps the problem is that I don't have training on automatic transmissions. The instructions tell what modifications to make, but it give any indication of why holes are being drilled or plugged.
For example:
Step 22: Install hollow sleeve on short end of the 1-2 servo pin. Push servo assembly firmly into case. Sleeve must be below flush with case. If flush or above flush don't use it.
In my case, the sleeve did fit below the level of the case, but what does it actually do, and will the transmission still work the same if it is left out?
Also, the instructions don't say anything about the lockup function. I am not sure if I can just apply constant 12 v dc to the PWM solenoid, it may not be capable of 100% duty cycle without overheating.
Again, I am not an expert on these transmissions, perhaps that is the real problem.
For example:
Step 22: Install hollow sleeve on short end of the 1-2 servo pin. Push servo assembly firmly into case. Sleeve must be below flush with case. If flush or above flush don't use it.
In my case, the sleeve did fit below the level of the case, but what does it actually do, and will the transmission still work the same if it is left out?
Also, the instructions don't say anything about the lockup function. I am not sure if I can just apply constant 12 v dc to the PWM solenoid, it may not be capable of 100% duty cycle without overheating.
Again, I am not an expert on these transmissions, perhaps that is the real problem.
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Most of the Transgo (and other valve body) kits on themarket are not geared towards the novice.
Transgo sells some kits that include a video (and I believe you can download the video now online) for the commercial market.
The reason for each modification doesn't need to be explained IMO. It IS nice to know, but sometimes if you give too much information the novice builder will foul it up by trying to overthink it.
TransGo's instructions are usually pretty clear as to what to do and how to do it. They can't teach basic mechanical skills and shouldn't have to as far as drilling holes, removing valves, etc.
Their -2 kit (auto) for the 4L80E has gotten much less complicated in the last year or so for the installer.
The sleeve on the 2nd servo is to tighten up band clearance for quicker band apply when using manual mode. The trans will work fine without it (it works without it in stock configuration right?)
Dual feeding can be accomplished by several methods. The TransGo kit is one method and the only method to do so without diassembling the transmission.
The PWM lockup solenoid, put a resistor in the supply side to reduce voltage so the solenoid will last longer.
Transgo sells some kits that include a video (and I believe you can download the video now online) for the commercial market.
The reason for each modification doesn't need to be explained IMO. It IS nice to know, but sometimes if you give too much information the novice builder will foul it up by trying to overthink it.
TransGo's instructions are usually pretty clear as to what to do and how to do it. They can't teach basic mechanical skills and shouldn't have to as far as drilling holes, removing valves, etc.
Their -2 kit (auto) for the 4L80E has gotten much less complicated in the last year or so for the installer.
The sleeve on the 2nd servo is to tighten up band clearance for quicker band apply when using manual mode. The trans will work fine without it (it works without it in stock configuration right?)
Dual feeding can be accomplished by several methods. The TransGo kit is one method and the only method to do so without diassembling the transmission.
The PWM lockup solenoid, put a resistor in the supply side to reduce voltage so the solenoid will last longer.
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Verdad Gallardo Thread Starter
Joined: Sep 2007
Posts: 4,188
Likes: 292
From: woodbine, md
Jake, if you need to reduce voltage to the PWM, does that mean the orig computer doesnt use +12, but something less?
what voltage would work-i bought a pigtail so i wouldnt have to cut up an old wiring harness i have, just in case i go FI someday
i am adding a switch to my brake pedal, and then just an off/on switch for the converter-i thought about wiring it to a Hobbs switch, so in boost it would disc also, in case i forgot
guys, have a great holiday
what voltage would work-i bought a pigtail so i wouldnt have to cut up an old wiring harness i have, just in case i go FI someday
i am adding a switch to my brake pedal, and then just an off/on switch for the converter-i thought about wiring it to a Hobbs switch, so in boost it would disc also, in case i forgot
guys, have a great holiday
Staging Lane
Joined: Jul 2005
Posts: 56
Likes: 0
From: usa
I've found a few torque converters that claim to hold 1,000HP locked.
Closed ex-Sponsor Account
Joined: Dec 2008
Posts: 434
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From: Az
It is nice to have the capability to lock during shifts, but in some instances the benefits of the torque multipication from the unlocked converter after the pull down in engine rpm, can help the overall E.T.
Hey guys, I'm dan dan the nascar man.. I've worked with 900hp race car motors for years.. But i'm not so good when it comes to transmissions... See I kept the first truck i ever bought and its now of sentimental value to me.. Its a 98 siverado 1500 ext cab z71 pickup.. Well, its now my project truck and the goal is to get rid of the weak 4l60e and 243c transfer case and put in a 4l80e with a 261/3 c transfer case. I am currently working on building the engine and so far i have a fully forged eagle assembly capable of 1500hp, splayed block, a snail for each bank and dart iron eagle heads (iron heads run cooler and prevent detonation which = less timing and more hp) I do not know much about automatic transmissions! I am hoping you guys could walk me through what I will need in hard parts for my transmission.. I am assessing this truck on high boost to make 750-800whp and about 850-900torque.. it will be a low speed engine making a ton of torque.. I'm assessing full torque will be made under 3,000 rpm and hold a straight line till about 4,500 rpm and fall slow.. hp peak will be about 6,200 rpm if any other information is needed please let me know.. I'm looking at a spur cut planetary now! Never knew transmission parts could be so expensive! A 4sps is a piece of cake to build! lol Thanks in advance!
