A6 / 6L80 Trans Problems - Help Please
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
The trans tune is wrong!!
The tables for the trans need to make the trans keep the line pressure up in anticipation of the next shift or the car will redline in every gear.
If the trans is tuned right the engine rpm's should raise when the trans down shifts ,if it doesn't then the trans needs the computer reflashed so it maintains a load on the engine.You should see engine drag engauged when slowing down at times, if the trans is set up right .You will burn up the trans if you keep it the way it is.
Call Chuck Cow he knows about this problem.
The tables for the trans need to make the trans keep the line pressure up in anticipation of the next shift or the car will redline in every gear.
If the trans is tuned right the engine rpm's should raise when the trans down shifts ,if it doesn't then the trans needs the computer reflashed so it maintains a load on the engine.You should see engine drag engauged when slowing down at times, if the trans is set up right .You will burn up the trans if you keep it the way it is.
Call Chuck Cow he knows about this problem.
With the greatest of respect, all of these elaborate explanations about how the transmission works off of torque input and line pressure is fine- I get that- but what I simply can't wrap my head around is why the shift speeds are clearly significantly less than what the maths says they should be??
BTW: I have a modified tune in my truck and I have beat the hell out of if for the last 5 years, towing my 10,000lb enclosed race car trailer and my boat and launching it on a full hit of nitrous, etc. I have 100s of nitrous passes on this truck, most with the TM turned off. I even burned up the clutch in a 1000hp rated Yank converter, and it's still going strong - so go figure? Maybe the Vette 6L80E transmission is weaker somehow??
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
What you are missing is that the mph commands the shift. In my logs the shift is commanded at the mph I set every time. Now, when the shift completes is another story. It takes a certain time to complete (based on many settings and variables) and in a car with big power, especially in lower gears it can be quite a few mph until it does. The trigger speed needs to be below where you want the actual shift. How much is trial and error as it varies.
Tuning these transmissions is not for the novice or faint of heart...
Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 411
From: Montreal
St. Jude Donor '13
I'm talking about STOCK GM tunes!! I haven't touched these tables. So WTH is up with that?
With the greatest of respect, all of these elaborate explanations about how the transmission works off of torque input and line pressure is fine- I get that- but what I simply can't wrap my head around is why the shift speeds are clearly significantly less than what the maths says they should be??
BTW: I have a modified tune in my truck and I have beat the hell out of if for the last 5 years, towing my 10,000lb enclosed race car trailer and my boat and launching it on a full hit of nitrous, etc. I have 100s of nitrous passes on this truck, most with the TM turned off. I even burned up the clutch in a 1000hp rated Yank converter, and it's still going strong - so go figure? Maybe the Vette 6L80E transmission is weaker somehow??
With the greatest of respect, all of these elaborate explanations about how the transmission works off of torque input and line pressure is fine- I get that- but what I simply can't wrap my head around is why the shift speeds are clearly significantly less than what the maths says they should be??
BTW: I have a modified tune in my truck and I have beat the hell out of if for the last 5 years, towing my 10,000lb enclosed race car trailer and my boat and launching it on a full hit of nitrous, etc. I have 100s of nitrous passes on this truck, most with the TM turned off. I even burned up the clutch in a 1000hp rated Yank converter, and it's still going strong - so go figure? Maybe the Vette 6L80E transmission is weaker somehow??
Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 411
From: Montreal
St. Jude Donor '13
Okay. That makes sense. I went back and looked at the modified tune from my truck where we had to modify the shift times downwards to get it to stay of the limiter (7200!) after I put 4.10 gears in my truck. I remember that we had to bump the 1-2 shift speeds down to 18MPH! to get it to shift at all on the nitrous. But I know it's doing like 37 MPH when it shifts. In fact, from what I've seen, it will shift at around 6500 off the spray and like 6900 on the spray, so what you're saying about other variables makes sense.
Tuning these transmissions is not for the novice or faint of heart...
Tuning these transmissions is not for the novice or faint of heart...
My last testing had my shifts starting dead on the mph set...
They completed this much higher....
1-2 set 30 shift 38
2-3 set 52 shift 62
3-4 set 88 shift 98
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
The one thing that I noted is that in my car with the stock tune the trans temps could get over 200 degrees, whilst my truck, even towing with the Yank in it, has never seen over 185 degrees, since it has an HD cooler. I really think we underestimate what high temps do to clutches in a transmission, because if the ATF is that hot, the clutch pack is likely to be much hotter.
Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 411
From: Montreal
St. Jude Donor '13
According to everything I've read it's supposed to be the 80. It's an AWD truck though, so maybe they put a 90 in it? I'm amazed that it's lasted this long too. The truck only has 33,000 miles on it, but they have been some very hard ones!
The one thing that I noted is that in my car with the stock tune the trans temps could get over 200 degrees, whilst my truck, even towing with the Yank in it, has never seen over 185 degrees, since it has an HD cooler. I really think we underestimate what high temps do to clutches in a transmission, because if the ATF is that hot, the clutch pack is likely to be much hotter.
The one thing that I noted is that in my car with the stock tune the trans temps could get over 200 degrees, whilst my truck, even towing with the Yank in it, has never seen over 185 degrees, since it has an HD cooler. I really think we underestimate what high temps do to clutches in a transmission, because if the ATF is that hot, the clutch pack is likely to be much hotter.
High temps are the biggest killer of these trannies.
Thread Starter
Pro
Joined: Jun 2000
Posts: 635
Likes: 0
From: McMinnville TN
Some interesting discussion going on here. Thanks for the input.
Track update: Took the car to the track Friday night. I had made some changes to tire sizes and shift RPM in the tune, and had driven the car around a bit to try to re-learn.
The car shifted "better", but still hit the rev limiter on every pass, and every gear.
Now, I only got 3 passes in due to two separate oil-downs on the track that took over an hour each to clean up. They were bad. On the first one, I was in the burnout box when the car ahead of me threw a rod out the bottom of the pan at the finish line. The second time, I was first in the staging lane when an engine let go off the starting line.
So, only 3 passes, but I did have my best/quickest times ever! I also had three consecutive 1.50 60' times.
I think I may just need to invest in HP Tuners, but I do have some questions about which version I need to purchase. My Intune just doesn't have the capability to make the adjustments that I apparently need to get this trans working right. I would appreciate your input on what I need. Do I only need the 6110, the 6011, or is the 6021 needed? I have no idea.
Thanks for all the input!
Track update: Took the car to the track Friday night. I had made some changes to tire sizes and shift RPM in the tune, and had driven the car around a bit to try to re-learn.
The car shifted "better", but still hit the rev limiter on every pass, and every gear.
Now, I only got 3 passes in due to two separate oil-downs on the track that took over an hour each to clean up. They were bad. On the first one, I was in the burnout box when the car ahead of me threw a rod out the bottom of the pan at the finish line. The second time, I was first in the staging lane when an engine let go off the starting line.
So, only 3 passes, but I did have my best/quickest times ever! I also had three consecutive 1.50 60' times.
I think I may just need to invest in HP Tuners, but I do have some questions about which version I need to purchase. My Intune just doesn't have the capability to make the adjustments that I apparently need to get this trans working right. I would appreciate your input on what I need. Do I only need the 6110, the 6011, or is the 6021 needed? I have no idea.
Thanks for all the input!
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Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 411
From: Montreal
St. Jude Donor '13
Getting HPT is the way to go because you will never get it right without logging the runs. As far as I know there is only HPT and HPT pro. You want the pro version so you can log and make changes.
Supporting Vendor
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2024 C6 of the Year Finalist - Modified
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Basically the general rule of thumb is that the quicker the car launches (whether because of gears, high stall converter, more power or a combination of all three) the more lead time you need to give it, making the difference between commanded and actual shift larger than it usually would be.
Former Vendor
Joined: Nov 2005
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From: Ossining New York
St. Jude Donor '07-'08-'09-'10-'12-'13-'14
Thank you!
The trans tune is wrong!!
The tables for the trans need to make the trans keep the line pressure up in anticipation of the next shift or the car will redline in every gear.
If the trans is tuned right the engine rpm's should raise when the trans down shifts ,if it doesn't then the trans needs the computer reflashed so it maintains a load on the engine.You should see engine drag engauged when slowing down at times, if the trans is set up right .You will burn up the trans if you keep it the way it is.
Call Chuck Cow he knows about this problem.
The tables for the trans need to make the trans keep the line pressure up in anticipation of the next shift or the car will redline in every gear.
If the trans is tuned right the engine rpm's should raise when the trans down shifts ,if it doesn't then the trans needs the computer reflashed so it maintains a load on the engine.You should see engine drag engauged when slowing down at times, if the trans is set up right .You will burn up the trans if you keep it the way it is.
Call Chuck Cow he knows about this problem.
Cars not shifting at WOT can be for many reasons.... and not even in the trans calibration.
Give me a shout and I'll get it going for you.
Chuck CoW
Le Mans Master
Joined: Apr 2013
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Likes: 1,118
I just took a look at one of my recent passes and the 1-2 shift is commanded for 15MPH but doesn't actually happen until 25MPH.
Basically the general rule of thumb is that the quicker the car launches (whether because of gears, high stall converter, more power or a combination of all three) the more lead time you need to give it, making the difference between commanded and actual shift larger than it usually would be.
Basically the general rule of thumb is that the quicker the car launches (whether because of gears, high stall converter, more power or a combination of all three) the more lead time you need to give it, making the difference between commanded and actual shift larger than it usually would be.
Supporting Vendor
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2024 C6 of the Year Finalist - Modified
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So it looks like it's about a 10mph "margin" for the 1-2 shift? That's what I'm seeing from all of the tunes I've looked at too. I had to do a bit of tweaking on this to my brother's car's TCM tune yesterday to try to get it to shift at the right RPM. Thanks for the guidance guys, because this had me stumped for a bit.
Le Mans Master
Joined: Apr 2013
Posts: 5,376
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Wow! That IS a big gap. It's similar to the modified tune for my truck as well, which has 4.10 gears with a 31.9" tire (which is close to a 26.1" with 3.42s). This is the tune that we did when it had a yank PT3200 converter in it. I looked at that last night and the shift speed is set at 18mph and I know it shifts 1-2 at around 37mph.
Thread Starter
Pro
Joined: Jun 2000
Posts: 635
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From: McMinnville TN
I went ahead and ordered HP Tuners Pro. It will be here tomorrow (Wednesday). I'm not touching the engine tune, but if there is anyone here that could shed some light on how to get started with the trans tune, I would appreciate it.
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
Pro
Joined: May 2009
Posts: 611
Likes: 3
From: Milwaukee WI
St. Jude Donor '13
I went ahead and ordered HP Tuners Pro. It will be here tomorrow (Wednesday). I'm not touching the engine tune, but if there is anyone here that could shed some light on how to get started with the trans tune, I would appreciate it.
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
I've used ECS to remote tune via efi live and then hp tuners. After I did a circle d stall install circle d highly recommended Patrick G do the trans program since he has a lot of experience tuning for their converters. Having dealt with both, they both are excellent resources if you find the learning curve too steep.
Race Director
Joined: Sep 2007
Posts: 16,557
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
I went ahead and ordered HP Tuners Pro. It will be here tomorrow (Wednesday). I'm not touching the engine tune, but if there is anyone here that could shed some light on how to get started with the trans tune, I would appreciate it.
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
37 mph 1-2 & 6700
72 mph 2-3 & 6700
114 mph 3-4 & 6500
The corresponding scanned shift speed and rpm is:
47 mph 1-2 & 6650
85 mph 2-3 & 6700 (sometimes it reads 84 mph around 6650)
127+ mph 3-4 & 6500 (I normally trip the lights in 3rd, which is why the +)
I'm running the same size DR (Hoosier)and a 2.56 gear. I don't bother changing anything to compensate for tire size from stock, since I don't care what the speedometer reads at the track. I have the rev limiter set at 6900.
Those scanned numbers were from my last pass. It was a 10.92 @ 125.26 with a 1.52 60' set in 2100'DA. Since I'm just a bolton and you're FI, I'd suggest you drop back about 2 or 3 mph from my numbers before making your first pass. Also check your rev limiter to see where it's set. Assuming you get a clean full pass, then check your scan to find the max rpm in each gear and adjust the tune mph to get the shift to occur closer to your desired rpm.
Have fun playing with your new toy, but don't make radical changes and always doublecheck any tune change to avoid fat-fingered keystrokes.
Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 411
From: Montreal
St. Jude Donor '13
I went ahead and ordered HP Tuners Pro. It will be here tomorrow (Wednesday). I'm not touching the engine tune, but if there is anyone here that could shed some light on how to get started with the trans tune, I would appreciate it.
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
I have never used HP Tuners before. This will be a new experience for me, and I sure don't want to ruin my trans by making a stupid mistake due to lack of experience.
It looks like I need to lead the 1-2 shift by at least 15 MPH in order to get it to shift where I want it to, but I don't know the MPH that I want it to shift. Maybe 10 or so for the 2-3 shift. What is a good starting point for my car? How do I "fast learn" the trans at the track? I will be at the track Friday night trying out the changes.
So many questions. I appreciate your help.
Thanks!
The first thing I would do is measure the actual height of your tire, and change that in hpt so that the speedo will be correct. Doing that will automatically change shift points so you don't want to do it after you get things right.
I would lower the shift speeds more than you think needed, and start there. Log a run (so you see where the shift is commanded, and where it actually happens) and then you can raise them bit by bit until it changes where you want it too.
There are a few basic rules you should follow. If you change the WOT shift mph, you should match the 100% shift column in the main mph table.
Once you get HPT up and going, if you need any help or have questions, feel free to ask.
This is one of the most informative threads I've ever seen, particularly because of the input from obviously competent tuners. Thanks for sharing guys, I am learning a lot on here.
Thread Starter
Pro
Joined: Jun 2000
Posts: 635
Likes: 0
From: McMinnville TN
HOXXOH - Yes a 2.56 diff. Yes, I understand that I can cause more harm than good by changing things that I don't understand. Thanks for the baseline MPH and RPM points.
Realcanuk - I realize that I won't learn this powerful software in one day. Probably will never scratch the surface of what it can truly do. I am looking forward to trying to work out my shifting issues, but I know that I DON'T KNOW anything about tuning a trans. I will just be working with shift points and MPH for now. Thanks for the offer to help. I will definitely take you up on that if you don't mind.
I got the software today. Going to get it installed on my laptop and start looking it over. I assume (but I'm asking)...Do I need to go pull the current tune from the car and see what the current settings are? I wouldn't know where to start without doing that, correct?
Thanks for all the help and input. I REALLY appreciate it!
Stacey
Realcanuk - I realize that I won't learn this powerful software in one day. Probably will never scratch the surface of what it can truly do. I am looking forward to trying to work out my shifting issues, but I know that I DON'T KNOW anything about tuning a trans. I will just be working with shift points and MPH for now. Thanks for the offer to help. I will definitely take you up on that if you don't mind.
I got the software today. Going to get it installed on my laptop and start looking it over. I assume (but I'm asking)...Do I need to go pull the current tune from the car and see what the current settings are? I wouldn't know where to start without doing that, correct?
Thanks for all the help and input. I REALLY appreciate it!
Stacey
Last edited by smaynor; Apr 30, 2014 at 09:29 PM.