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3-4 clutch pack burn-up 4L60E
i rebuilt this trans a little over a year ago and its back ,the first time i built this trans (bench unit) it went about 50 miles and burnt up 3-4 clutch pack i tore this thing back down went throught it and reset it up again i found the valve in the 1-2 accumilator bushing had stuck. fixed that and rebuilt trans again ,now a year later its back same thing 3-4 clutch pack burnt up. went back through it again but i see no apparent problems,looking for some suggestions i may have missed? ive rebuilt several of these with no problems. the owner said he was driving it and started see smoke out the back of the truck and so he pulled over and checked fluid it was very low so put fluid in it and drove on home by the time he got home he had no 3-4 gear . not throwing any codes.
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also should add i find no apparent leaks anywhere and trans was full when i recieved vehicle at shop. looking for some major componets to really look at or things to look for . im not a shop just helping a friend out .
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also, with repetitive 3-4 clutch burn up id be looking at the clearance the 3-4 clutches were set at and, make sure theres no leakage in the input drum on the 3-4 circuit. next, id hook up a line pressure gauge hooked up along with a scan tool to make sure that the EPC solenoid is working correctly and giving proper line pressure, and has proper line rise. and last, make sure tcc is working properly, without it, your building up heat which can lead to venting, which can lead to fluid loss, which can lead to clutch pack/transmission failure. see where im going with this??? on average, you going to want to see maybe 50 rpm slip or less with 60% or less duty cycle on the tcc during command. hope this helps. |
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Did you reinstall the 5 3-4 "load release springs"? If so, you'll have repeated 33-4 failures. What was the clearance set at? What clutches and steels did you use? Did you air check the 3-4's through the pump? Teflon input shaft rings? Worn inside pump stator/stator bushings? Did you install a new 3-4 accumulator piston in the case, or atleast check the pin wobble in the old one? Worn boost valve sleeve? Is the band burnt, too? Is the converter clutch locking up?
Frank |
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3-4 Load Release Springs
10sec70 - please tell us more. You asked - "Did you reinstall the 5 3-4 "load release springs"? If so, you'll have repeated 3-4 failures."
I'm following this thread because my 4L60e is failing for the third time too - I would describe similar symptoms. I assume from your statement that these springs should be left out during reassembly?? I don't know if the tranny guy who rebuilt mine knows this, and would like to understand the reason. Thanks! |
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one works for a shop that has a standard 3 year, 50,000 mile warranty on domestic, and 2 year, 24,000 on imports and, its not a national chain shop and, his units last without a problem. clearance on the 3-4 clutches are critical as well, i set mine anywhere from .015-.025 for factory replacement and to manufacturers specs on aftermarket. Last edited by tnsmith10; 12-03-2011 at 06:02 PM. |
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You'll NEVER have an issue leaving the load release springs out. However, you can run into issues when reinstalling them. Hydramatics theory was that the 3=4 clutches are trying to centrifically apply at higher RPM's, which is BS. It was GM's attempt at putting a Band Aid on a bullet wound. The 5 sets of springs force the top and bottom pressure plates apart when the clutches aren't applied. The problem is, fluid pressure can't overcome these springs quick enough to put full clamping force on the clutches. I have 4L60E's running high 9's at over 140 NPH and many being shifted above 7000 RPM's. I have NEVER reinstalled load release springs since 1993 which is when I thought ALL builders learned their lesson, but apparently not. I don't have 3-4 clutch failures in my '60E's...Even after years in 12,11,10,and even 9 second cars.
Now, the reason I left this board once before was because of other "builders" arguing facts. I'm not going to subscribe to all the sensless pissing contests this time. I've SPECIALIZED in 4L60E transmissions since 1993. I know them inside out and upside down. I've done things with these transmissionsthat most only dream of. If the other "builders" here would pay more attention, instead of arguing or trying to prove me wrong, they might actually learn something. As I said, I'm not here to argue, so I'll put it simple... If you disagree with my theories or build practices, atleast be able to show me a 4L60E that you've built that runs faster than 9.7 @ 142 MPH, and has lasted for 7 years, or one being shifted at 7200 RPM's. I'm sure there are people out there who would argue with the way Rick Hendricks engine shop builds engines... Those are the guys not winning championships...LOL Frank |
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the atsg manual that I have says to leave em out...
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Frank |
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its not always a matter of who is right or wrong but, trying to help give as much info or help that can help fix someones problem. so youre a specialist on the 4l60e, great, the site can use your help. fast cars and having a 700/4l60e in them that stays together is cool but, not all of these trans are getting put on the strip and on factory rebuilds, its quite possible to build these units with the load release springs installed and they last. as i mentioned in my prior post, i have a close friend of mine who puts them back in on every build and his trannys live well past the 3 year/50,000 mile warranty. so, its different than what you would do, it doesnt mean its wrong. |
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The ATSG 4L60E Update Handbook states that you may re-use the 3-4 release springs if you're using the .106" thick
steel plates along with the 7605 Borg Warner high energy lined plates. Of coarse the one piece apply plate must be maintained along with the proper backing plate. |
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one thing ive leaned no 2 tranny rebuilders build one exactally the same we all have our tricks and mods if it work you get the same results i leared and still learn alot from reading and talking to other mechanics and the ones i see that think they know more and dont keep up on the info are the ones that have combacks more frequently i used to work with a guy like that but back to the 4l60 as for the springs i use them but i set my cleaence under .25 i like about .10 when there that tight the spring help keep them apart i ask in a ealier post is the tv cable coreect being a bench job u need to find out how the cable is mounted
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Frank |
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correct about the cable i dont know why i didnt see the e at the end off the 4l60 in the post
but ive never had a problem with 3-4 burn up in a 700 or 4l60e i use the thick steels ive built them for trucks vettes fbodies i give u none of them were 10sec cars. i check the clearence then make sure i slide the plantary in it a make sure it will turn |
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