Rebuilt 6l80 Fluid Question

The summary - I had a local shop rebuild my 6l80 and it now has about 12k on the rebuild. After warming up it tends to shift harder from 1st to 2nd and 2nd to 3rd. However, it is more pronounced up and down between 1st and 2nd. It has done this pretty much from the start, they tell me it is because of the new valves, etc makes the trans shift firmer.

My question, they put in BG trans fluid. I have read on this board and others that the trans shift process is better when the low friction AC Delco fluid is used. I am contemplating having it flushed and have the AC Delco fluid put in to see if it smooths out the shifting.

Any feedback is appreciated.

Thanks
Tim

What are the warranty specifics? Is it still under warranty and, if so, are there requirements for fluid changes by the same shop?

BG does not Dexron VI compatible fluid. Part number 316. Is this what they used on yours or one of the many others?

Use a Group IV synthetic DexronVI. I recommend LubeGard's DexronVI.

Marky Dissod said:

Use a Group IV synthetic DexronVI. I recommend LubeGard's DexronVI.

COMPLETE Full Synthetic ATF - Lubegard

www.lubegard.com

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Thanks. I didn't even know lubegard had their own actual fluid. Once my supply of ac delco runs out I'll have to try some.

Plimbob said:

The summary - I had a local shop rebuild my 6l80 and it now has about 12k on the rebuild. After warming up it tends to shift harder from 1st to 2nd and 2nd to 3rd. However, it is more pronounced up and down between 1st and 2nd. It has done this pretty much from the start, they tell me it is because of the new valves, etc makes the trans shift firmer.

My question, they put in BG trans fluid. I have read on this board and others that the trans shift process is better when the low friction AC Delco fluid is used. I am contemplating having it flushed and have the AC Delco fluid put in to see if it smooths out the shifting.

Any feedback is appreciated.

Thanks
Tim

Click to expand...

What specific valves did they say were installed that made it shift harder?

Also what is "BG" fluid? Dex6 should have been used.

I'd get in touch with the rebuilder and ask what they recommend. Sometimes a firm shift is desired to reduce wear. That Dexron VI is a really thin fluid and I wonder if that might be causing some of the failures on the newer trannys.

tom3 said:

Sometimes a firm shift is desired to reduce wear.

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True to an extent but you dont shift-calibrate these transmissions mechanically like the old two, three and four speeds.

All the calibration work is done via tuning, usually with HP Tuners or similar software. Which is why I would like to know what "valves" were installed to increase firmness, per that shop's explanation. All the aftermarket 6L valve body/hydraulic "performance" kits are really to correct pattern issues/failures that have their roots in the hydraulics. Most often that means getting rid of harsh shifts, not introducing them...The shift points, speeds, apply and balance presssures, bleeds, etc can all be adjusted as required by electronic tuning, as Im sure you already know.

I dont think that shop did everything it was supposed to as there shouldn't be any harsh up or down shifts after a rebuild, outside of the first few drive cycles as the TEHCM settles in and adapts fully to the driver's habits, style, etc...And that may be what's happening here...

waiting on the OP to respond back...

Gents -

Here is what I know:

The BG fluid is an after market supplier of fluid and additives and the shop tells me the fluid in the unit is Dex6?

I believe they put in Sonnax valve body, upgraded thermostat and a Billet TQ.

I don't know if they tuned the TEHCM. I was contemplating a call to Blackbear to discuss tuning.

Thanks for everyone's input.

Tim

Plimbob said:

I was contemplating a call to Blackbear to discuss tuning.

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Not enough people think like Plimbob.
Not only do they not understand how wrong they are,
they are actively disinterested in learning why they should.