Transmission Problems On 4l60e Equipped GMC Truck

07 CC Sierra · September 1, 2008

Mike ,what about the NBS 4L60E 2-1 downshifiting bump ,when stopping at the light?
I had that problem in my 2007 ,but my 2008 is perfect...

BTW my name's Luiz Diaz...

Slip yoke maybe?

C & A s Dad · September 2, 2008

Ok, one more question.

In reference to the "Tow in 3 or D" question, you stated to run up speed enough for converter lockup. That I understand, but will the coverter lock up in 3 also, or only in D.

C

Sorry for not getting to this question earlier. I would have to connect the scanner to your truck and find out if the torque converter clutch solenoid is activating in 3rd gear. You might be able to watch to see if there's an RPM drop at partial throttle, but that might be hard to detect. I tried to look it up on alldatapro and I'm not finding any good info.

I know my 02 Yuk XL does not allow the convertor to lock in 3rd with the TH Mosw engaged. I had always thought it did but I checked it towing this weekend and the convertor never locked while I was in 3rd with the TH on.

C & A s Dad · September 2, 2008

I'm getting the impression these transmissions are rather fragile. Is that really the case? It's making me reconsider purchasing a TT or doing any tuning. I would like more power, but this makes think it'll just strip this gear quicker.

I would not worry about it. There are litteraly millions of these trans on the road in GM Trucks and many of them last 200,000+.

If you plan to tow, either add an external cooler (stacked plate) or upgrade the one you have considering where you live. Service the trans, I recommend syn fluid. Add a trans temp gauge like the Aeroforce Interceptor, tow in 3rd with the T/H engaged and enjoy your truck.

You need to research max TT length for your Tahoe. Their shorter wheelbase does limit your trailer length.

Outbacker · September 2, 2008

Anyone have any experience with the Tru Cool tranny coolers? Is the stock cooler that comes on the GMT900 an example of the tube and fin style?

Good discussion.

satori · September 2, 2008

I'm getting the impression these transmissions are rather fragile. Is that really the case? It's making me reconsider purchasing a TT or doing any tuning. I would like more power, but this makes think it'll just strip this gear quicker.

I would not worry about it. There are litteraly millions of these trans on the road in GM Trucks and many of them last 200,000+.

If you plan to tow, either add an external cooler (stacked plate) or upgrade the one you have considering where you live. Service the trans, I recommend syn fluid. Add a trans temp gauge like the Aeroforce Interceptor, tow in 3rd with the T/H engaged and enjoy your truck.

You need to research max TT length for your Tahoe. Their shorter wheelbase does limit your trailer length.

Good to know about the TT length, thanks.

As for the reliability of this tranny, what you're saying is the impression I'm starting to get after "wasting" this whole weekend reading this board.

At first I read enough to make me nervous, but the more I read, the more I'm comfortable with it. In fact, I'm pretty much ready to order a tune from wait4me. I'm now convinced the tranny will be fine.

I do have 4.10 gears and the factory HD aux trans cooler. I don't know what the quality of that one is though.

I don't remember the context of the post, but I remember someone here telling a guy his tranny already comes with synthetic. When did that start? Mine might already be synthetic?

Edited September 2, 2008 by Satori

Mike Diaz · September 2, 2008

So does anyone know if this sun gear has been upgraded in the new models GMT-900?
Just curious if it is across the board, I know GM made some changes to the trannys and was wondering if a better one was actually installed?

I think they may have, but I only dealt with transmissions that were 2003 and older since most newer trucks were under factory warranty when I worked there.

Mike Diaz · September 2, 2008

GREAT info in this topic. I remember back in high school, my auto shop teacher preaching about coming to a COMPLETE stop before shifting gears. Most of us thought it wouldnt do much (if any) damage. Sounds like he was right!

Have you had any 6 speed GM trannys (6LE 70/80) or something like that in for repair? I'm sure there aren't as many out there as the 4 speeds since the 6 was only in Denalis and SUV's. 2009 year available in the 1500's.

I could have sworn I remeber someone saying the 6 speeds were mostly selnoids.

What do you think about their build quality comared to the 4 speeds?

Thanks!

Solenoids have always been a problem on 4L60E transmisions. I don't know much about 6L80E's.

C & A s Dad · September 2, 2008

I'm getting the impression these transmissions are rather fragile. Is that really the case? It's making me reconsider purchasing a TT or doing any tuning. I would like more power, but this makes think it'll just strip this gear quicker.

I would not worry about it. There are litteraly millions of these trans on the road in GM Trucks and many of them last 200,000+.

If you plan to tow, either add an external cooler (stacked plate) or upgrade the one you have considering where you live. Service the trans, I recommend syn fluid. Add a trans temp gauge like the Aeroforce Interceptor, tow in 3rd with the T/H engaged and enjoy your truck.

You need to research max TT length for your Tahoe. Their shorter wheelbase does limit your trailer length.

Good to know about the TT length, thanks.

As for the reliability of this tranny, what you're saying is the impression I'm starting to get after "wasting" this whole weekend reading this board.

At first I read enough to make me nervous, but the more I read, the more I'm comfortable with it. In fact, I'm pretty much ready to order a tune from wait4me. I'm now convinced the tranny will be fine.

I do have 4.10 gears and the factory HD aux trans cooler. I don't know what the quality of that one is though.

I don't remember the context of the post, but I remember someone here telling a guy his tranny already comes with synthetic. When did that start? Mine might already be synthetic?

Mike,

I can help you with your questions.

Your truck does not have syn fluid. GM began using Dex VI in late 06 if I am correct but I know they were not using it in 05.

Your OE cooler is a stacked plate designed cooler and is an excellent overall cooler. IMO it is too small for high heat climates such as the Southern parts of the US. This is why I upgraded mine to an 11 x 11 x 3/4 unit. Your is apprx 5" x 11" x 3/4". I will be happy to send you some pics of mine installed in case you consider upgrading. I would need you to send me your e mail address in a Private Message.

If you have the 4.10 gears you will be pleased with the towing capacity of your truck. You will want to use 3rd with the TH mode. This will keep your Revs right in the 5.3's sweet (2300 to 2800) spot when you are driving between 55 and 65. If you get a tune, be sure you tell them you are towing and are looking for extra tq in the low to mid range. More HP and TQ at 5500 RPMs is not going to help you tug that camper.

C & A s Dad · September 2, 2008

Anyone have any experience with the Tru Cool tranny coolers? Is the stock cooler that comes on the GMT900 an example of the tube and fin style?

Good discussion.

Bob, I could be wrong but I believe Tru Cool was the orginator of the Stacked plate cooler and held the patent for years. I think they still produce them for several other companies such as Hayden. I cannot swear to this but I can tell you they are an excellent product. This would be an excellent choice for you considering where you live becuase they offer several models with built in thermostats. This lets the cold thick fluid bypass the cooler until it gets warm. This is not an issue where I live.

I do recommend the 3/4" thick models as they offer more efficient cooling than the 1.5" thick models. GM stopped using the thicker models in 99 with the 800 series trucks.

I just towed my camper this weekend and the outside temps were only in the mid to upper 80s. I was pulling bigger and longer hills than I had ever pulled before and my trans temp peaked at 158 for a few minutes but ran low 150s most of the time.

gvbhunt · September 2, 2008

Ok, one more question.

In reference to the "Tow in 3 or D" question, you stated to run up speed enough for converter lockup. That I understand, but will the coverter lock up in 3 also, or only in D.

C

Sorry for not getting to this question earlier. I would have to connect the scanner to your truck and find out if the torque converter clutch solenoid is activating in 3rd gear. You might be able to watch to see if there's an RPM drop at partial throttle, but that might be hard to detect. I tried to look it up on alldatapro and I'm not finding any good info.

Just FYI, the TC does not lockup when in tow/haul mode. Here are charts from HPTuners showing engage/disengage speeds for the TC in both normal and performance (tow/haul) for my 4L70e.

rjirvine · September 2, 2008

WOW! This is a great thread. I have a 2000 NBS Silv 4x4 and bought it with 91k miles. At 100k miles I dropped the pan and changed the filter. I filled it up, ran it around the block a few times, and drained the fluid/filled it back up. (basically half of the fluid).

Would it be a good idea to drain the fluid every 15k miles (which would be half the fluid in the system)? I am under the belief that the fluid has "cleaning properties" and you dont want to do it too much, but figure I should change the fluid every 15k and fluid filter every 30k? Of course, I'm looking at preventative MX on my truck as I plan on keeping it a long time.

compulynx · September 2, 2008

Maybe I missed it, but I have still not seen an answer as to whether the converter will lock up in "3" , or only in "D" I see where it won't in T/H mode, but what about in regular "3"?

Also, I could swear I have seen my 2008 converter lockup in T/H. After the 3/4 shift, I would then see the RPM drop again......

C

Edited September 2, 2008 by compulynx

satori · September 2, 2008

I'm getting the impression these transmissions are rather fragile. Is that really the case? It's making me reconsider purchasing a TT or doing any tuning. I would like more power, but this makes think it'll just strip this gear quicker.

I would not worry about it. There are litteraly millions of these trans on the road in GM Trucks and many of them last 200,000+.

If you plan to tow, either add an external cooler (stacked plate) or upgrade the one you have considering where you live. Service the trans, I recommend syn fluid. Add a trans temp gauge like the Aeroforce Interceptor, tow in 3rd with the T/H engaged and enjoy your truck.

You need to research max TT length for your Tahoe. Their shorter wheelbase does limit your trailer length.

Good to know about the TT length, thanks.

As for the reliability of this tranny, what you're saying is the impression I'm starting to get after "wasting" this whole weekend reading this board.

At first I read enough to make me nervous, but the more I read, the more I'm comfortable with it. In fact, I'm pretty much ready to order a tune from wait4me. I'm now convinced the tranny will be fine.

I do have 4.10 gears and the factory HD aux trans cooler. I don't know what the quality of that one is though.

I don't remember the context of the post, but I remember someone here telling a guy his tranny already comes with synthetic. When did that start? Mine might already be synthetic?

Mike,

I can help you with your questions.

Your truck does not have syn fluid. GM began using Dex VI in late 06 if I am correct but I know they were not using it in 05.

Your OE cooler is a stacked plate designed cooler and is an excellent overall cooler. IMO it is too small for high heat climates such as the Southern parts of the US. This is why I upgraded mine to an 11 x 11 x 3/4 unit. Your is apprx 5" x 11" x 3/4". I will be happy to send you some pics of mine installed in case you consider upgrading. I would need you to send me your e mail address in a Private Message.

If you have the 4.10 gears you will be pleased with the towing capacity of your truck. You will want to use 3rd with the TH mode. This will keep your Revs right in the 5.3's sweet (2300 to 2800) spot when you are driving between 55 and 65. If you get a tune, be sure you tell them you are towing and are looking for extra tq in the low to mid range. More HP and TQ at 5500 RPMs is not going to help you tug that camper.

Thanks, there are a few other things I want to do before upgrading the oil cooler. No rush since it might be a while until I buy a TT. Really tapped into the savings to get the Tahoe.

I should probably change the tranny fluid and filter though. It has 72000 on it, and I don't see any tranny service on the service history.

And more low end torque is a definite requirement of any tune I end up getting.

gvbhunt · September 3, 2008

Maybe I missed it, but I have still not seen an answer as to whether the converter will lock up in "3" , or only in "D" I see where it won't in T/H mode, but what about in regular "3"?

Also, I could swear I have seen my 2008 converter lockup in T/H. After the 3/4 shift, I would then see the RPM drop again......

C

If you mean if the selector is in 3rd then yes, it should. The only thing that I know of that is disabled (different from when it is in "D" but in 3rd gear) is AFM, that will not work if the selector is not in "D"

Also it is possible that you have a different tranny than mine. I think that the trans makes less heat when the TC is locked so maybe if it is a 4l60e then they do it to cut down on heat?? Mine is a 4l70e. Just a guess on that one.

irengineer · September 3, 2008

Maybe I missed it, but I have still not seen an answer as to whether the converter will lock up in "3" , or only in "D" I see where it won't in T/H mode, but what about in regular "3"?

Also, I could swear I have seen my 2008 converter lockup in T/H. After the 3/4 shift, I would then see the RPM drop again......

C

There is no hard and fast rule that applies to every model year or even every engine / trans / axle variant. When the TCC locks up is controlled by the calibration in the TCM / PCM (depending on whether the trans controller is standalone or integrated with the engine controller - newer trucks are standalone). Generally they all have a typical pattern for apply release, but there's nothing saying they couldn't have been cal'd differently from one year to the next. If you see a 2-300 rpm drop after the 3-4 shift the TCC is applying.