Silverado 6L80E Transmission Thermostat Delete

Grumpy Bear · July 31, 2020

23 hours ago, rav3 said:

Can anyone give me the link to JohnA "full series on this mod"?

CamGTP · July 31, 2020

10 hours ago, dieselfan1 said:

Do you go to BIR?

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Nope, went to the 1/8th mile in Grove City.

BIR is to far away, going to Grove City is just over an hour from Rogers.

dieselfan1 · July 31, 2020

Nope, went to the 1/8th mile in Grove City.

BIR is to far away, going to Grove City is just over an hour from Rogers.

Never knew there was a dragstrip there. Looks good.
No crowds.

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truckguy82 · August 2, 2020

On 7/31/2020 at 4:01 PM, Grumpy Bear said:

I can take an educated guess. Warm fluid is less viscous and spinning parts in a less viscous fluid takes less gross power. That's the theory. Most lubricating oils however are 'slickest' around 160 F ish so it doesn't play out. Worse, in the winter it takes longer for the fluid to heat with a zero min flow bypass thermostat. Net/net a failed plan but one that earn points with the EPA, CARB etc. It's the cheapest way possible to fail at a plan goal. Unless the goal is to fail the transmission and build shop invoices. Then they hit that nail square on the head.

I’ve read all your logic on this thermostat being worthless. And it does make sense, and it’s possible. But on the flip side, that would mean an entire team of engineers are complete morons. This thermostat is on one if the highest gross revenue vehicles in the world. Surely there was many calculations and people involved when deciding to add this thermostat.

My guess

-80% chance there is an advantage and we don’t know about it

-10% chance they are intentionally trying to reduce life of the transmission.
-10% chance they are all morons

Maybe we should get to the bottom of it and class action them if it was devious in nature. I would be pretty pissed if that was the case. I’d take a week off of work and dos attack whoever was responsible.

rav3 · August 2, 2020

40 minutes ago, truckguy82 said:

I’ve read all your logic on this thermostat being worthless. And it does make sense, and it’s possible. But on the flip side, that would mean an entire team of engineers are complete morons. This thermostat is on one if the highest gross revenue vehicles in the world. Surely there was many calculations and people involved when deciding to add this thermostat.

My guess

-80% chance there is an advantage and we don’t know about it

-10% chance they are intentionally trying to reduce life of the transmission.
-10% chance they are all morons

Maybe we should get to the bottom of it and class action them if it was devious in nature. I would be pretty pissed if that was the case. I’d take a week off of work and dos attack whoever was responsible.

Thank you your response Senior Enthusiast! As a retired Plastics tooling engineer, I can appreciate your comment. I'm sure there were many engineering's working on this solution. With that said....WE do NOT know what the upper management directed these engineers to do. I feel that they would not want a shorter transmission life; how ]ever, most things like this are added so as to improve either emissions or MPG. These are being driven by political directives, not longevity of a car or truck. At least they made the thermostat housing out of aluminum but all in all, it added weight & another item to fail. Bottom line, IMO, I feel transmission fluid last longer at a lower temperature that at a higher one. It's the laws of thermodynamics.

Flame on guys......

KARNUT · August 2, 2020

With just about everything new on these trucks geared toward fuel mileage. The temperature being controlled by a thermostat in the transmission would be a bad thing according to some. But a costly maintenance and repair cylinder deactivation system is good. Interesting.

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Grumpy Bear · August 2, 2020

2 hours ago, rav3 said:

Thank you your response Senior Enthusiast! As a retired Plastics tooling engineer, I can appreciate your comment. I'm sure there were many engineering's working on this solution. With that said....WE do NOT know what the upper management directed these engineers to do. I feel that they would not want a shorter transmission life; how ]ever, most things like this are added so as to improve either emissions or MPG. These are being driven by political directives, not longevity of a car or truck. At least they made the thermostat housing out of aluminum but all in all, it added weight & another item to fail. Bottom line, IMO, I feel transmission fluid last longer at a lower temperature that at a higher one. It's the laws of thermodynamics.

Flame on guys......

I know personally two design engineers, (both now passed on) whose job it was to design the parts they were given to design to last 'just past' the warranty period. One from the now defunct Zenith and the other from BMW. You remember Zenith who's slogan was, "The Quality goes in before the name goes on". :crackup:

True research in the manufacturing arena hasn't happened in decades. There is no interest in refinement for the sake of excellence but there is a great interest in development for cash. Companies don't make products. They make means to separate you from your cash. Bentley uses VW platforms to build profit margin in a mark that built it's reputation on excellence in design. The Buick LaCrosse and the Cadillac XTS are identical platforms and power trains. Different sheet metal and interior appointments separate two cars that are 20K + different in price. The Impala was the low margin fruit of that tree and was loped off.

"New and Improved" today is marketing, not engineering and manufacturing.

Now catch them in it! :crackup:

Eddie 70 · August 5, 2020

I did the transmission thermostat flip. We took my truck to Knoxville tonight. Ran around a little. We stopped by Chick-Fil-A and sat in line for a few minutes. The trans temp got up to 158*F while in line. That was the highest I saw during the whole trip. We live about 5 miles away from Chick, the temp dropped back down to 153*F before we got home. So it is cooling and maintaining pretty cool. I am pretty happy with that outcome so far. I'll still do my 15k mile one gallon transmission fluid change. It's cheap enough and easy enough and may help. It cannot hurt.

rav3 · August 5, 2020

PROGRESS UPDATE:.....I just did the transmission thermostat flip as above that eddie70 did. Pretty simple change. Had to clean the snap ring area on top as it was corroded. Flipped the thermostat & put it all together. Just an FYI, my '17 has the small retainer plate holding the 2 transmission lines in & a small screw holding the retainer plate to the thermostat housing. This retainer plate is not symmetrical. The screw hole is offset to one end so if the screw wont start in the threads, rotate the plate 180 deg. The transmission fluid temperature was reduce to 145*F. It did go up to 147 once but immediately went back to 145F. Out side temp was 80F and most driving was backroads at 45 to 55 MPH. Normally it would have been about 170 to 185F. so about a 40 to 45 deg. reduction in fluid temp. I'll keep an eye on it to make sure this is the normal. From what I've read, this is about the new normal with this modification.

Hope this helps others.

flyingfool · August 6, 2020

usually high temp thermostats are emmisions devices... and they are not built for longevity or fun power in mind.

just wondering out loud, but does flipping the t-stat cause any flow reduction in the cooling line VS just deleteing and pluging the bypass?

Edited August 6, 2020 by flyingfool

2kwik4u · August 6, 2020

There is an aspect that nobody has touched on yet.......Consistency. Trans temps just under the operating limit of the fluid, with adequate reserve cooling provide the most consistency you can get, with the least amount of viscosity possible. It's likely the best compromise available so that the same configuration can be run in Miami, and Anchorage year round. It might not be the BEST solution for either of those climates, but it's the best compromise between the two when all aspects are considered.

The transmission shifts WILL change with fluid temperature changes. There are internal passageways that allow that fluid to move from place to place and apply or release clutches that change the gear ratios. If this fluid is consistently at the same temperature, then the control algorithms that maintain pressure, actuate clutches, and route fluid don't have to make as much of an adjustment, and the programming can be more easily defined, and subsequently result in better and more consistent performance to the user.

IMO, If you aren't overheating the transmission fluid (200deg +) for extended periods of time, there is ZERO benefit to cooling it any further, or messing with the system at any level. You are doing the modification for the sole purpose of making yourself feel better about the temp reading you're seeing. Excessive heat kills a transmission. Read that again. Excessive is the operative word there, and 192deg (88deg C) is not excessive. Combined with NOT changing shift parameters (such as clutch slip timing, shift timing, line pressures, etc) you are messing with a VERY well tested formula that we only have anecdotal evidence on.

Remove it at your own risk, if your transmission fails under warranty, and this is found during tear down, I would bet they'll deny you coverage, and with good reason. They can't warranty against all possible modifications, and we can all agree fluid temp is an important parameter to transmission life, regardless of where you fall on the temperature spectrum. You messed with a proven formula, and you only have some guys on a message board as backup for that decision. A few guys on a message board does not an engineering team make, and I'm certain more than a few people looked at the system overall at GM and made the decision to include the thermostat. Maybe it was an accounting thing, maybe it was a legal thing, Maybe the mechanical guys put it there to make the programming guys life easier. Maybe the design was so far down the path that it would have cost more to remove it than to keep it. We don't know.

Grumpy Bear · August 6, 2020

55 minutes ago, 2kwik4u said:

Remove it at your own risk, if your transmission fails under warranty, and this is found during tear down, I would bet they'll deny you coverage, and with good reason. They can't warranty against all possible modifications, and we can all agree fluid temp is an important parameter to transmission life, regardless of where you fall on the temperature spectrum. You messed with a proven formula, and you only have some guys on a message board as backup for that decision. A few guys on a message board does not an engineering team make, and I'm certain more than a few people looked at the system overall at GM and made the decision to include the thermostat. Maybe it was an accounting thing, maybe it was a legal thing, Maybe the mechanical guys put it there to make the programming guys life easier. Maybe the design was so far down the path that it would have cost more to remove it than to keep it. We don't know.

I don't do FUD.

Fear Uncertainty and Doubt.

I do physics, chemistry and math.

I don't guess.

I do rational and reasonable.

I measure once and cuss twice.

6L80-E didn't drop out of the sky in 2014 the first year the thermostat was placed in service. HD models since still don't have this thermostat. The hydraulic circuits are not moving slave cylinders a six feet. They are applying pressure to switches from micro inches to fractions of an inch. Ditto clutch packs. Flow restrictions are not an issue.They do this from the fluids pour point to the hottest part of the worst desert on the planet. They have to or you don't leave the drive when it's 40 below. On a really cold day it may lag a shift getting some heat in her but by 104 F all TCM parameters are satisfied. Just like they were in 2013 when they didn't have a thermostat. 104 F is the lower SAE viscosity specification. If it doesn't work right there, it doesn't work. Period.

In my area, Norther Illinois, 90% of the working people commute less than 20 miles to work with a minimum of 8 hours between shifts. During the winter it is not unusual for the fluid temperature to never reach 100 F in that distance and to NEVER reach the 192 F thermostatic set point at a distance of 100 miles or 2 hours.

In your world the 6L80/90-E would not operate correctly north of Missouri in the winter. It couldn't be tuned. You could only use AC-Delco fluid and the torque converters of the beast would be solid as a rock. Are they? :crackup: The major transmission builders such as SONNAX live on the shortcomings of OEM engineers...like the torque converter clutch. Like the 4-5-6 clutch apply piston. Like the SONNAX pressure regulation spring (TransGo). Like overheating them for the EPA and CARB. Like......Like..... Black Bear and others like them would be out of work.

I don't wait for OEM engineers and warranty scares destroy my equipment and THEN fix it. :wtf:

I don't guess, I measure...for several years before the delete. The Keebler Elves did not design this transmission. There is no magic factory......

Edited August 6, 2020 by Grumpy Bear

2kwik4u · August 6, 2020

@Grumpy Bear

How does your truck Perform in Death Valley in the summer? What about Winnipeg in the winter? How about Miami in the spring? Have you towed a trailer in those areas? What's your data on SAE J2807 test? Do you have any reliability readings on an 80% loaded quad cab 4x4 over 100k miles of east coast driving?

Weird......I don't either. Honestly, we're having an unarmed battle of data here. NEITHER OF US, knows exactly what it's supposed to do (as the engineers designed it, the programmers coded it, or the testers reported it) at any level of confidence. Unless we distill it so far as to say "make the truck move forward" we're picking the fly poop out of pepper. Because we simply do not know.

You have only a few data points from one region. You simply DO NOT have the data set to make those assertions as facts. They are opinions based on anecdotal evidence. I would take the Pepsi challenge with your data vs GM's data every day and twice on Sunday. Talk about Dispersing FUD, your claims are based on opinion, NOT FACTS. You in fact do deal in FUD sir.

Since anecdotal evidence is what you seem to like. My transmission DOES NOT work properly when it's cold. Shifts are firmer, and faster. Properly is VERY subjective, and you can't even pin that down with data. At this point I'm clearly not going to change your mind, and honestly don't really care. I just hope others consider the fact that both of us are dispensing opinions that are worth about as much as the electrons that display them.

Grumpy Bear · August 7, 2020

2 hours ago, 2kwik4u said:

Since anecdotal evidence is what you seem to like.

Well ain't you all that.

Where did I go to school? What field(s) of study? Who did I work for? What did I do there? What is my life experience? You know where I've lived? How did you come by your conclusions? Assumptions? Assumptions.....really bad ones. Ones only genuine ignorance can make.

What I like are results! I'm getting the results I'm after. I always have and for nearly 70 years. Mine shifts effortlessly and smoothly at any fluid temperature I allow it. Think I'll continue in my ignorance of scientific method and engineering. Seems to get in the way of results.

You need a new handle.

rav3 · August 7, 2020

4 hours ago, 2kwik4u said:

There is an aspect that nobody has touched on yet.......Consistency. Trans temps just under the operating limit of the fluid, with adequate reserve cooling provide the most consistency you can get, with the least amount of viscosity possible. It's likely the best compromise available so that the same configuration can be run in Miami, and Anchorage year round. It might not be the BEST solution for either of those climates, but it's the best compromise between the two when all aspects are considered.

The transmission shifts WILL change with fluid temperature changes. There are internal passageways that allow that fluid to move from place to place and apply or release clutches that change the gear ratios. If this fluid is consistently at the same temperature, then the control algorithms that maintain pressure, actuate clutches, and route fluid don't have to make as much of an adjustment, and the programming can be more easily defined, and subsequently result in better and more consistent performance to the user.

IMO, If you aren't overheating the transmission fluid (200deg +) for extended periods of time, there is ZERO benefit to cooling it any further, or messing with the system at any level. You are doing the modification for the sole purpose of making yourself feel better about the temp reading you're seeing. Excessive heat kills a transmission. Read that again. Excessive is the operative word there, and 192deg (88deg C) is not excessive. Combined with NOT changing shift parameters (such as clutch slip timing, shift timing, line pressures, etc) you are messing with a VERY well tested formula that we only have anecdotal evidence on.

Remove it at your own risk, if your transmission fails under warranty, and this is found during tear down, I would bet they'll deny you coverage, and with good reason. They can't warranty against all possible modifications, and we can all agree fluid temp is an important parameter to transmission life, regardless of where you fall on the temperature spectrum. You messed with a proven formula, and you only have some guys on a message board as backup for that decision. A few guys on a message board does not an engineering team make, and I'm certain more than a few people looked at the system overall at GM and made the decision to include the thermostat. Maybe it was an accounting thing, maybe it was a legal thing, Maybe the mechanical guys put it there to make the programming guys life easier. Maybe the design was so far down the path that it would have cost more to remove it than to keep it. We don't know.

@2kwik4u...Good input here. You sound like an engineer with good logic.