rijrunr

My 2010 6.2 converter started slipping after a shot of nitrous. Before that, it everything worked fine. The fluid was clear and no problems. After a run, the fluid became dark. The tranny temps are still fairly cool considering the convertor is slipping at 50% (according to the transmission guy who tested it). However, he recommended replacing the who tranny, even though he couldn't tell me what else is wrong. Another shop told me the same thing even without looking at it. No one can really give me a reason why, other than the pumps are known to be crappy. Seems like the pump in mine would be good if it is staying cool. Especially under the conditions. I'm driving this thing 140 miles plus daily. I do have the pressure all the way up with the slippage to keep me going. I just had a circle D triple disk delivered and need to get it installed, but don't want to spend more money than I have to nor do i want to drop the tranny a few weeks after installing the converter. Not sure what to do. 2C is very welcome here....

rijrunr

Anyone have any feedback?

TechGM

I would not replace the whole trans. converter slippage is not enough reason to replace whole trans. The trans tech that looked at it should have looked at TCC slippage and commanded 100% PWM. To see if that would help bring down the converter slippage. This helps tell if its just because the clutches in the converter are slipping or if there is a line pressure or solenoid problem. I have replaced a few converters in the 6L80's and 90's. Never heard much about these pumps being garbage. Only time I have to replace pumps is when metal from converter scores pump body. Go ahead and drop the pan on your truck. Look for fine metal debris in the pan. Feels like gritty like sand. If you don't see this I'd simply replace the converter and put a new filter in.

However, if you do see metal in pan. Pull trans and tear it down completely to find exact cause of failure and what other, if any, components need replacing. 1-2-3-4 clutches are known to burn up.

rijrunr

Thanks for the reply. I just finished dropping the pan and changing the fluid. There was some elements stuck to the magnet. And I some film
Washed off when I cleaned the pan. The fluid was black and did smell some. I started it and got it to temp. Drive it around the block and it seemed to shift way better. I'm going to take it for a ride to get the converter to lock and see what happens.

TIM Z

iTrader: (12)

Can you shed light on what / why 1-2/3-4 clutches burn up in these units ?
Are they factory Borg Warner ?
Would raising the pressures help them live longer ?

I'm trying to learn these 6speeds , I want to add power to my truck , and want to know what trans mods are needed . I see some guys having great luck with these trans and bolt ons or forced induction with proper tuning .

Thanks

TechGM

These 6 speeds are quite unique. There's no real telling why the 1-2-3-4 clutches burn up and I'm not saying like there's one in my stall every week nor every month. What I think is issue is that the 1-2-3-4 clutches are almost always applied during the harder load conditions. For instance, when you are driving around and the truck is in 3rd gear, the 1-2-3-4 and the 3-5R clutches are applied to make 3rd gear range possible. 1-2-3-4 and 2-6 clutches make 2nd gear, etc.

I believe that simply raising line pressure would help these units when doing performance mods. But, everything has to be tuned together. I've heard of P0101 MAF sensor code popping up due to raised line pressures due to MAF sensor being one of thee most important inputs to the TCM to control shift timing and feel. Oh and better torque converters! I'm not happy with the factory torque converters lately.

rijrunr

These are pictures of my 6L80 pan with more than 100K miles. The fluid turned black and had a slight burn smell after the 125 shot. Prior, it was clean and nothing wrong. I'm not sure if this debris at the magnet is excessive or not. Maybe you could shed some light on this. The last comment seemed to be in line with what the local shops are telling me. I don't think they have a full grasp on this transmission. They all tell me they have no idea how to tune it.

TechGM

That pan and magnet look good to me. That's usual for a vehicle with 100k miles. Also a heads up for everyone. Where GM manufactures these transmissions and most of their trans they have rust inhibitor put on a lot of internal parts that when these vehicles see some mileage it turns fluid into that dark brown color. No reason for alarm. That's why at 30k miles some people complain about their fluid being dark in color.

Ok, I'm getting a little off subject and going in different directions. The most difficult thing with the tuning of these transmissions is due to the control valve assembly, aka TCM. It's the brown colored part bolted to top of your valve body. Everything is housed in this unit. Shift solenoids and pressure control solenoids. And these are all connected by a lead frame design. So no more wires, which means no more just changing out pressure control solenoids for more line pressure. If I honestly was to build a 6L80 I'd simply put a better torque converter in it. Transmissions constantly adjust shift feel and timing through ECM inputs. The TCM will compensate fluid pressure through its TAP cells for the giving load situations and adjust to get the best shift possible. We can always change out springs in valve bodies but that only helps with shift feel and apply. Not holding, which is the most important. Holding is only going to come from line pressure.

Sorry for long reply. I need to stay on point. If your converter is still slipping under lockup and load then you will need to replace it. Also if you plan on removing trans to replace converter, prior to perform a couple of hard accelerations from a stop or rolling low speed to see and feel if any of the gears feel like they are slipping. That way you'll have a better idea on if you should go further into trans while its out, or can you just get away with new converter.

rijrunr

Never mind the long reply. This is good Stuff!!!! This information could turn into a 6L80 sticky... So I'm assuming that's why some of that in the pan was stained that brown color? Your explanation of the TCM balancing the pressure may explain why the shifting smoothed out, cause I bumped the pressure all the way up to counter act the slippage. I can still feel the converter grab a little when it locks, but I already have the triple disk replacement. I'm wondering if I should go ahead and set the pressure back or leave it, based on your previous post.... I'm going to see if I can feel the clutches slipping.

I forgot to ask..... If the TCM automatically adjusts pressure, what happens when you manually set shift feel and pressure setpoints? I'm thinking these are one in the same??? I have a Diablo intune and you can adjust shift- softer/firm.

TechGM

I don't think anything crazy would happen because if you manually set shift firmness/soft the trans is just going to do what it is told by your tune. Just make sure it is tuned correctly that way you don't accidentally end up causing more harm than good.

Also remember too that since you changed out that older thinned out fluid with new fluid, the trans will be readjusting shift feel and timing to accommodate that new fluid. Every time a shift happens the TCM looks at it and determines if that was a good shift? Was it completed in an adequate time? Does it need to make fluid pressure adjustments to improve that shift? And so on.