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Old 06-23-2018, 02:14 AM   #1
shootracing22
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Join Date: May 2016
Location: Gulfcoast, MS
Posts: 57
4l80e Rear case bushing

Short Question:
Is the rear case lube circuit on a late model 97-2003 4l80e sufficient for rollerizing the rear case thrust washer with a TH350 bushing?

Early models a lubed through the shaft late models are lubed through the case. Being that this is a 4wd unit the tail shaft bushing or-face is blocked adding little more volume to the rear case thrust bearing and output shaft bushing.

Plus I am thinking that the rear bushing that centers the case thrust bearing needs some type of path for the oil to migrate to the rear case thurst roller. I have seen this mod made and some discussion on lube circuit but clear direction what is the best practice for the late model 4l80e.


Long story for anyone interested:
I have a 1989 v3500 Chevy 4x4 square body crew cab that I swapped in a 12 valve Cummins and a stock 4l80e that was pulled from a low mileage 2003 box van. The Cummins is currently making in the neighbor hood of 400hp and 1100ft lbs of torque at a very low RPM (max torque is usually made in the 2000rpm range). I am using a TCI EZ TCU by Fast to control it.

I haven't pulled it apart yet and needless to say the stock transmission did not last. Under full throttle 1st gear pulled strong, 2nd felt like it slipped, the converter lock up was not as firm as it once was and with the converter locked the truck didn't set you back like it once did. Now its not making any line pressure after idling in the yard I want to attempt to build if right this time around. I plan to go with a tripple disk converter tuned and built for the Cummins powerband.

My main goal is dependability with crisp shifts with out being to harsh since this is often used for the occasional under 10k light towing daily driver often ran in Over drive, and I am hoping the 4l80e is capable of this.

I recently ordered a Stage 5 kit from Jakes Performance with a valve body re-calibration kit that blocks off the accumulators. I plan on using the ATRA manual for most of the rebuild.

If my 2003 4l80e is stock rear case lube accumulator feed that lubes the rear case bushing isnt sufficient I read some builders find it necessary to block the accumulator feed lube tube and run a early intermediate shaft and out put shaft? Just want to make 100% sure this is correct before I go through the trouble

My plans are to run the Sonnax Smart-Tech Overrun Clutch Valve Kit Part No. 34200-40K. Running this kit will help with my late model overrun clutch will hold up or would it be wise to swap it to a early model larger overrun clutch? I have heard about one high HP application that it did well using this Sonnex kit did well in one of Jakes builds.

Any addtional parts or tips would you recommend for my build that is not included in the kit?

In advance I greatly appreciate any help. Like most people I am on a budget, my trucks is more of a hobbie I enjoy tinkering with but want to build it right. I built a few transmissions in the past and feel confident I can build this one by being thorough and paying close attention to detail.

I found this article though it dosnt address the lube circuit question it does address causes for thurst bearing failures due to load. I am going to try to apply this article to my build.

http://www.gearsmagazine.com/magazin...4l80-rebuilds/

Heres a picture since most of us like pics
__________________
2006 GMC X-cab Z71 5.3LS
1994 GMC 1500 LWB 2wd
1989 Chevy Crew v3500 4x4 12 valve Cummins swap
http://www.4btswaps.com/forum/showth...-for-feed-back
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