Transmission Upgrade/Update for a 2008

91RS

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I've seen a number of people here talk about rebuilding and/or updating parts of their 6L80, automatic transmissions are one of the few things I don't know a lot about. I bought my 2008 thinking it was going to need a transmission and I ended up replacing the filter and resetting the adapts and have been driving it for 4 years. It has never shifted super nice even after having it tuned and with 157k on it I've been considering replacing or rebuilding it as preventative maintenance. I know there are some updated seals and other parts that came in 2009 (IIRC) and I've seen some people use Sonnax's Zip Kit which looks like something I'd be interested in but I can't seem to find a good list of the parts that would need to be replaced to upgrade this transmission. I don't know if I should just buy the Zip kit and then order a GM seal kit and clutches for my year and go with that or order Sonnax upgraded parts but I don't know what I need. I don't know if I should go ahead and replace the TEHCM or just buy the rebuild kit Sonnax sells for it.

I've also seen a lot of talk about an "upgraded" torque converter but haven't really seen where people are getting these from. I do NOT want an aftermarket converter. I put a Yank 3200 stall in my TBSS because the TBSS forum said it was a "must have" and I absolutely HATED it and I will never do that again. I might be ok with a slightly higher stall but I want it to be able to function exactly like the stock converter. Seems like the CTS-V/ZL1 torque converter may fit the bill but I'm not sure if the flex plate needs to be changed also. I don't tow much but I still want to be able to tow if needed. I also would be interested in doing a torque converter in my 2013 to prevent failure. I saw a thread Doubeleive started about torque converters I'll read through as well.

Lastly, will tuning be needed for any of these things? Specifically, the torque converter with a different stall?
 

Geotrash

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I've seen a number of people here talk about rebuilding and/or updating parts of their 6L80, automatic transmissions are one of the few things I don't know a lot about. I bought my 2008 thinking it was going to need a transmission and I ended up replacing the filter and resetting the adapts and have been driving it for 4 years. It has never shifted super nice even after having it tuned and with 157k on it I've been considering replacing or rebuilding it as preventative maintenance. I know there are some updated seals and other parts that came in 2009 (IIRC) and I've seen some people use Sonnax's Zip Kit which looks like something I'd be interested in but I can't seem to find a good list of the parts that would need to be replaced to upgrade this transmission. I don't know if I should just buy the Zip kit and then order a GM seal kit and clutches for my year and go with that or order Sonnax upgraded parts but I don't know what I need. I don't know if I should go ahead and replace the TEHCM or just buy the rebuild kit Sonnax sells for it.

I've also seen a lot of talk about an "upgraded" torque converter but haven't really seen where people are getting these from. I do NOT want an aftermarket converter. I put a Yank 3200 stall in my TBSS because the TBSS forum said it was a "must have" and I absolutely HATED it and I will never do that again. I might be ok with a slightly higher stall but I want it to be able to function exactly like the stock converter. Seems like the CTS-V/ZL1 torque converter may fit the bill but I'm not sure if the flex plate needs to be changed also. I don't tow much but I still want to be able to tow if needed. I also would be interested in doing a torque converter in my 2013 to prevent failure. I saw a thread Doubeleive started about torque converters I'll read through as well.

Lastly, will tuning be needed for any of these things? Specifically, the torque converter with a different stall?
I haven't rebuilt a 6L80 but I have rebuilt a ZF 5HP24 on the bench. And I had a similar set of questions before I did it. Here is what I learned:

1/ "Banner" kits will give you new clutches and steels, as well as a bunch of other things you'll need to rebuild the transmission such as seals and some bearings/bushings that are considered wear items. They are sold in different levels, and the premium kits will also include things like redesigned pistons, clutch drums and valve body components where known weaknesses exist.

2/ Zip or shift kits from Sonnax and Transgo will usually only include parts designed to fix known weaknesses in the original design or manufacturing. Such as more durable check balls, redesigned valve body components, etc.

Sometimes, vendors will also sell additional components not included in the kits. For the ZF, a known weakness was the A-clutch drum, so there is a company that makes a redesigned one and it wasn't available in any of the kits from the bigger manufacturers. So it's a research project every time.

For the 6L80, this kit will have everything you should need, including valve body parts and updated pistons. If you want to roll your own though, @Just Fishing just finished a full rebuild on his and can likely help you with a detailed parts list.

On the TC, my transmission shop sourced a factory unit from their preferred nationwide supplier CVC (model BU60FHD) that was rebuilt with a billet housing and a stronger lock-up clutch. So it has the factory stall and dimensions but is stronger and more durable.
 
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Just Fishing

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Yeah, so far my home rebuilt 6l80 is working fantastic.
biggest pitfall would be the return pistons.
you need to press them in, and be very mindful of the lip seals.
I had one try to catch and tear on me while pressing into place.

I used these "blue" pistons, sold me on the "Resists tearing".

I don't see too much mention of them being used, so i was a little wary.
but so far so good.

I also used an obscene amount of trans gel for reassembly.
I feel like it was half a tub :jester:

When going to air test the unit after assembly I got some very weird results.
I ended up pushing transmission fluid into the transmission in order to break it up/dissolve the assembly gel.
Once I did that it passed the air checks. :peace:

When doing the bushings, I used this bushing driver kit.

Lots of the same drivers with different names, but they all appear to be the same.

Pretty much you want to stack them to support the inside of the bushing, and then drive with the larger part.
Some of the pieces i used were perfect.
Others were a tiny bit loose.
I resolved that by using a perfectly cut piece of electrical tape (super 33 and super 70 depending if I needed more or less thickness)...

then the installed depth, I used a digital caliper set to measure depth before i removed the bushing.
both with the driver installed on the top of the original, and where it sat in the part.
took lots of pictures for my reference.
And marked bushing orientation.

Lots of attention to detail.

Hardest part i had was trying to get the clutch clearances using a dial indicator into what the spec should be.
from the factory, they were very loose.

One of them the 2-6 clutch.
Instructions say that it should fall with in x range.
And if you don't get that then you assembled it incorrectly as there are no selective snap rings available for it. :jester:

Well disassembled and reassembled 10x and it was too loose each time.

I had decided to replace the 1-2-3-4 5/r drum due to a roller bearing and a seal that I couldn't source separately.
So i had some left over snap rings.

Then summit racing sent me a 6l90 drum with a 6l80 part number by mistake.

So i had extra snap rings to work with...

Longer story short, the snap ring in that drum was a tad longer, and had more tension, however it fit the 2-6 drum perfectly.
In spec and i gave my self a
1ise923pan1nirttejiohxqoucywds8pgl4qukx7&rid=giphy.gif


It's a fun transmission, but expensive.
Ebay was my best friend for parts.

selective snap rings are confusing, so I did lots of searching using dial indicators, my hand-held digital caliper, and the current snap rings to figure out the proper thicknesses.

If your transmission was like mine and working perfectly before tear down w/o any failed clutches, then you could probably get away with just measuring clutch clearances before removing them from the drums.
then you would have a reference #



Don't cheap out, and plan on a new pump.
I sourced my housings in amazon.
then sourced the pump rotor kit on ebay after amazon left me hanging for a month and wouldn't let me cancel the order "preparing for shipment bs"

And I/m me or @ me if you need help/questions.
 

Just Fishing

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for the 1-2-3-4 drum also, if you replace it (and you probably should)
measure the height of the drum vs the old one.

Apparently, there are more than a few that hit the market with the wrong pn on the box.
I got the correct one from amazon in the end...
 

Just Fishing

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I've seen a number of people here talk about rebuilding and/or updating parts of their 6L80, automatic transmissions are one of the few things I don't know a lot about. I bought my 2008 thinking it was going to need a transmission and I ended up replacing the filter and resetting the adapts and have been driving it for 4 years. It has never shifted super nice even after having it tuned and with 157k on it I've been considering replacing or rebuilding it as preventative maintenance. I know there are some updated seals and other parts that came in 2009 (IIRC) and I've seen some people use Sonnax's Zip Kit which looks like something I'd be interested in but I can't seem to find a good list of the parts that would need to be replaced to upgrade this transmission. I don't know if I should just buy the Zip kit and then order a GM seal kit and clutches for my year and go with that or order Sonnax upgraded parts but I don't know what I need. I don't know if I should go ahead and replace the TEHCM or just buy the rebuild kit Sonnax sells for it.

I've also seen a lot of talk about an "upgraded" torque converter but haven't really seen where people are getting these from. I do NOT want an aftermarket converter. I put a Yank 3200 stall in my TBSS because the TBSS forum said it was a "must have" and I absolutely HATED it and I will never do that again. I might be ok with a slightly higher stall but I want it to be able to function exactly like the stock converter. Seems like the CTS-V/ZL1 torque converter may fit the bill but I'm not sure if the flex plate needs to be changed also. I don't tow much but I still want to be able to tow if needed. I also would be interested in doing a torque converter in my 2013 to prevent failure. I saw a thread Doubeleive started about torque converters I'll read through as well.

Lastly, will tuning be needed for any of these things? Specifically, the torque converter with a different stall?

My converter is a double disk unit.
I got it from circle D
Sold as a "Truck/hd" upgrade vs stock.

But they do not offer it any longer.
it was replaced by a triple disk version.

You don't need to go this route, but I didn't want to lose capacity and towing ability, so I wanted to stay with a larger sized converter.

My converter was about $700 if i remember correctly.
and this triple disk went up a little since i was last looking at them early this year.
 

Just Fishing

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And as for tuning,
I did some to mine, but the converter I purchased said no tuning required.
but I lowered my allowed slippage from 20% to 10%
and I think I'll go even lower soon enough.

I would suggest asking the converter manufacture questions about what sort of changes are suggested/required.
I suspect you might end up needing to tweak the pressures a tad and the slip %

that's pretty easy, but I am curious what they suggest myself.
 
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91RS

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The Circle D does look like the way to go for a bulletproof converter. The CTS-V converter doesn’t make much sense after you have to pay the core charge and buy a $350 aftermarket flex plate to use it. But maybe it isn’t even worth doing at all. Maybe I’ll just get new OEM converters and be done. They’ve lasted 157k and 171k miles. The 08 is already tuned so I’m sure the slip has been reduced or turned off and I’ll probably get the 13 tuned to disable the AFM and hopefully not need to do a cam and lifters any time soon so the transmission can be tuned also.
 

Geotrash

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The Circle D does look like the way to go for a bulletproof converter. The CTS-V converter doesn’t make much sense after you have to pay the core charge and buy a $350 aftermarket flex plate to use it. But maybe it isn’t even worth doing at all. Maybe I’ll just get new OEM converters and be done. They’ve lasted 157k and 171k miles. The 08 is already tuned so I’m sure the slip has been reduced or turned off and I’ll probably get the 13 tuned to disable the AFM and hopefully not need to do a cam and lifters any time soon so the transmission can be tuned also.
It’s really worth taking a look at the CVC overhauled units with the stronger lockup clutch and billet housing. Keeps the factory stall and bolts right up, but should outlast the original by a long shot. And only slightly more expensive than OEM.
 
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91RS

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This one? Their web site is awful. This is the only one that says billet anything when I search for “6L80 torque converter.”

 

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