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Rebuilding a 4L80E

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Location
Ca
Thread starter #1
Alrighty guys. So I am in the process of swapping a 12v cummins into my truck & I'd like to rebuild the 4l80e that's in the truck as it has 210k on it & I believe it just needs a rebuild period.

I purchased a torque converter from a local shop (D&P Products) & had it set up for my application. He welded a bead around where the clutch likes to crack & he put better? clutch material on it. Really not sure if that's what he said, but I remember him saying that the clutch material comes off due to the clutch being too smooth where the material mounts, so he roughens it up j then uses some machine to apply the clutch material. I don't mess with this stuff, so it was cool to see. Anyways, he said it would hold the power level of a stock or mild cummins, so we'll see.

Moving on, I also purchased a rebuild kit from another local company (Transparts Warehouse) & they helped me pick a kit that would hold up to the swap. The gentleman from D&P recommended a stock rebuild instead of upgrading to Red Eagle as he said I would break a shaft before slipping a clutch. The difference in price was $100 or so, & to me, the extra insurance to me was worth it. So I got a "level 2 deluxe red eagle kit".

Now here's the thing: I'm not a transmission specialist. I'm a DIY mechanic. I work for the Air Force as an aircraft hydraulic technician. I've done so big stuff on my cars. I can pull transmissions & engines, I've rebuilt some stuff. Transmissions? Never done one. I always said I would pay someone to rebuild my transmissions.

Welp, nothing ventured, nothing gained right? I am going to attempt to rebuild this transmission myself as I would like to learn how. It's way outta my comfort zone which is another reason I want to do it myself. If someone else can learn & do it, so can I. So any tips, tricks, tools, etc that you can think of that I'll need would be extremely helpful! I'm purchasing an ATSG manual to help me along as well as youtube videos & other internet write ups.

Yeah. I'm pretty nuts. Also never rebuilt an engine before & here I am rebuilding the 12v. But that's another story...
 

WarWagon

Well it hits on 7 of 8...
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AZ
#3
So put upgraded shafts in the 4L80E. The input shaft is known to snap although I never broke one myself. Good call on the upgraded frictions because, yes, you can slip it to complete burn up without breakage.

The Torque Converter as you presented it sounds like a turd. Marketing hype? They, OEM TC clutch, slips then the damage happens so upgraded TC clutches are good, but, a rough clutch surface - YUCK. Stall speed and the converter itself is critical to getting power, no extreme heating, and vibration free performance. First you need to select the stall speed as mentioned above. Then you need a good converter because there is a lot of krap ones out there that don't work well, vibrate, overheat the trans oil, slip the weak lockup clutch, all while not working worth a damn.

I would suggest you get up to speed on converters starting here then decide on what you really need:
https://www.converter.cc/The_Truth_s/21.htm

Ask me how the proper stall converter gets the anemic big turbo 6.2 of mine up to "turbo light off RPM" and then lights the tires up. I have videos of a 2000 RPM launch and then the tach sits above 3000 max HP RPM through the gears till I let off. The OEM lower stall converter would lug the krap out of the engine belching smoke while not getting out of it's own way in an attempt to get to 2000 RPM to light the turbo. Yes I use a Yank Converter, no you don't have too. But the info is free and makes all the difference in the world. Note: Cummins is a lower RPM luggable diesel vs the 6.2 /6.5 engine so keep that in mind when looking at stall speed as well as your turbo setup.

 
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Location
Ca
Thread starter #4
Thank you for your advice! As I'm sure some of you have found out, I dont know much about Torque Converters & transmissions in general. Still learning as I go. I honestly don't know if what I said is what the gentleman at the transmission shop said. I probably misunderstood him.

The cummins is a 1996 12v p pump. It's at the machine shop now. I'm just doing a rebuild with very slight upgrades. New injectors, new governor springs, delivery valves, fuel plate, etc. Turbo will be stock, as well as intake & exhaust manifold. My truck has a 4" diamond eye exhaust now so I'll adapt that to the motor as well.

Back to TC's, what would ya'll recommend? I don't plan on drag racing the truck, nor really towing as of this moment. Mainly just for yard work & as a fun truck (no, I dont mean rolling coal fun, I think that's stupid) to go up to Tahoe & get around the mountains with.

When I lived in Colorado, the truck was my winter rig which it will continue to be when I move back.
 

WarWagon

Well it hits on 7 of 8...
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Location
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#5
I would call Dave at Yank Converters with as much info as you got about the rig, trans, engine, mods, etc. and ask him what he would suggest. Lake Tahoe... What kind of mountain grades are we talking about to get there from your place?

When the converter is locked up the "stall speed" is out of the equation. Unlocked on a grade is where the converter can shine as well as getting things moving. With a Cummins the GM converter may be too high of a stall. But I am guessing.
 

Sand

Active Member
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Location
Canada
#6
A local torque converter rebuild shop put mine together for my H1 Cummins swap. I haven't run it yet but he said the 4l80e converters are not a really low stall unit. He put in a good clutch and billet piston. Tightened up some of the clearance inside and hand recurved the tips of the turbine and tig welded them in place to give me as low a stall as possible. He thinks it will be in the 1400 -1600 rpm zone.
 

FellowTraveler

Well-Known Member
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Nature Coast
#7
A local torque converter rebuild shop put mine together for my H1 Cummins swap. I haven't run it yet but he said the 4l80e converters are not a really low stall unit. He put in a good clutch and billet piston. Tightened up some of the clearance inside and hand recurved the tips of the turbine and tig welded them in place to give me as low a stall as possible. He thinks it will be in the 1400 -1600 rpm zone.
For what I have gathered stall speed of any converter will rise as modifications increase torque output and peek torque rpm's.

A custom billet unit is costly and can be built from scratch for 1000-1200 rpm stall however; it must be noted that when using such low stall speed converters you can forget jack rabbit acceleration from a stop.....and your trans will run much cooler extending it longevity.
 
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