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View Full Version : rear axle max torque and rear prop shaft numbers



mtnman
June 16th, 2006, 02:52 AM
I'm wondering if i can safely "up" my Rear axle Max torque (B6616) and Rear axle prop shaft (B6618) numbers to get more torque from my 2500HD. Has anyone experienced "upping" these numbers with positive results? Right now I'm stock with the following :

B6616 -10,000 (max allowed here is 41943040, which is a long distance from 10k)

B6618 = 2731 (same max allowed here as above)

It appears this "max allowed" number (41943040) arent really tailored to one specific
parameter)

Does anybody have person experience with 6.0 liter trucks on these numbers?

technical
June 16th, 2006, 05:45 AM
Yes. My OS must be slightly different considering the max values are a bit higher (2006 2500HD 6.0). Nevertheless, I set those values first to 50% of the max, then 75% fo the max value. I noticed much improvement. The vehicle doesn't bog when you stomp on it now. I still have to log some data to determine if the values should be modified from where I have them now, but I need to get the tune on my Camaro finished first. :)

mtnman
June 16th, 2006, 06:28 AM
You've set {B6616} and {B6618} to 75% of your max (which is greater than 41,943,040) ? Wow, I didnt think it would be safe to bump the values up that much. How long have you had these settings programmed into the PCM and how much do you stomp on it? Which tranny are you running? I cant remember if the allison is available for the 6.0 liter, although I think its not.

mtnman
June 16th, 2006, 06:47 AM
technical,

I found your previous post on this matter (http://forum.efilive.com/showthread.php?t=2677&highlight=rear+axle). I'll follow suit, slowly incrementing the values for the sweet spot.

technical
June 16th, 2006, 09:03 AM
I have the 4l80E with the 4.10 axle. I was really hesitant to go that high with the settings, but then I realized just how much bog the truck had. I didn't want to kill the TM entirely since it might make the truck a bit of a handful in wet weather. So far it has been working out pretty good.

Another note: I left the torque reduction stock. I saw no need to apply more torque during a shift. I also increase the line pressure for the upshifts to decrease wear on the clutch packs. Then I lowered the partial throttle shift pattern to maximize fuel economy. Now the truck can get into a higher gear faster yet still apply the torque required to get moving. I did similar things for preformance or tow/haul mode, but focused more on what was needed for pulling a load.

mtnman
June 16th, 2006, 12:28 PM
Did you set all parameters to the same value? Both max prop shafts and axles?

technical
June 17th, 2006, 04:10 PM
Yes I did, but I haven't had the chance to check the 4WD operation. It probably won't make much of a difference since those components can handle the torque from the drivetrain.