Was about to disassemble the center support and noticed these missing teeth that look like they have been broken off. Should I be alarmed or will the other 40 teeth that are left hold just fine for another lifespan?

 

It almost looks like it was manufactured with the teeth missing.

 

"siu automotive's" 6l80e overhaul on youtube states 1 tooth should be missing and thats where the snap ring ends should meet but no mention of the 3 missing teeth on the opposing side. I have drained the pan and didnt see anything of this sort just the mess of TC material as usual. They do seem to be on exact opposite sides from each other so maybe your right.

 

Your absolutely correct! I didn't think to check the part any further after disassembly today I was more focused on getting everything clean. It's clear as day with the low sprag removed just didn't look quite right. It was such a small surface area of material showing looked like it had been broken but now I see it's the casting surface finish.

 

I have not had the pleasure to get into a 6L80. My experience with transmissions in the past tells me that the missing spline to the housing may line up with a lube hole for the roller/sprag itself. Some of that is actually done on purpose...

 

They can be finicky......

 

You are also correct sir, I will make sure to line these up when reassembling.

 

What areas of this model do you consider finicky? Unit had 200k on it. Pump was in bad shape so it has been sent off for resurfacing and the 1-2-3-4 piston was cracked resulting in a toasted clutch pack which will be replaced with the sonnax upgrade. The 4-5-6 clutch pack were also toasted I can only assume this is mainly due to the bad design of the apply plate which the customer does not want to upgrade. Vacuum testing showed the valve body to be barely above sonnax's replace standard. I will be installing a TransGo Valve Kit Valve Clutch Select & Torque Converter Clutch TCC which includes the #2 and #3 shift valves and the TCC regulator valve as well as a transgo SK-6l80 shift kit. All the valve body end plugs will be replaced with o-ring style.

Being this is the first 6l80 I have ever attempted to rebuild just wanted to ask for any pointers as I want this to work out great for my customer who is investing 2 grand into this build. I will be tuning out DOD and converter lockup gears 1-4 and may be modifying pressure tables slightly but that decision is still in the air.

Also does anyone have any tips for installing the pistons in this unit? I sometimes have trouble with the reverse/low pison in 4l60's so I came up with the trick of wrapping the pistons seal with thin clear packing tape to pull the gasket in towards the piston while installing. I apply the tape backwards so it doesnt stick to the piston and have the bottom edge of the tape pulled upwards to ease the removal process after it makes it into the bore all the way. I leave one end of it sticking up so I can slowly pull it out from the piston/bore with plenty of trans fluid so I does not stick to any surfaces. Have done this 10+ times with no issues and always manage to get all the tape removed without it tearing and leaving any inside the assembly. I have tried this with 4l80 4th clutch piston and it doesnt work well with the tighter clearance and sharper edges so I usually work that one in with a thin slim jim I put a curved smooth edge on and have managed to get it assembled without tearing the seals or paying $500 for a plastic assembly sleeve. These 6l80 pistons seem they will be much trickier judging from a test run I did putting the 3-5-R/1-4 drum back together to do a leak/drum crack check.

 

The TransGo parts and o-ring end plugs are a good discission. I don't recall any of the pistons being hard to install but then again, I have never had any problems with the 4L60 low/reverse piston, just lube them up and tap them in with a long 3/8 extension.

If you are only charging $2000 for parts and labor to rebuild a 68L0 you are eighter getting parts a whole lot cheaper than I am or you are seriously under charging. I was told in a trans seminar by Gil Younger's brother, I think his name was Fred, that you need to charge twice as much so that if you have to go back into the trans that you won't lose your butt. I have never charged that much but I keep that in mind and at the very least charge enough that it will cover all of the parts twice if God forbid I would have to go back into it. This was just a side hustle for me and not my primary income, so I was okay if I lost some my labor.

 

Clutch clearance and and tuning. Both of these have to work together for proper shift timing. The TECHM can adjust for slight improper clutch clearance but can only do so much

Last, internal leaks. Mainly in the pump and stator

From my experiences.....which is way less than most on this forum