travelingman

My sons o6 48 re laidown, upon disasembly we found the front band friction
material almost completely gone an the front drum siezed together . All other clutches an mateing serfaces although showing some signs of blueing the friction material was fine an the blueing only slight . This truck has 80000k
an has towed a 40' camper quite often . The fluid had been changed at normal intervals an the bands adjusted at the dealer . The only power upgrades a Bully dog set on tow economy . The only question I had was did he always operate the truck in the tow haul mode when pulling the camper.
He said since you always have to reselect that on each startup there were
many times he would forget,but would always select it in the moutains or when pulling hard . So other than this towing the truck was never power
braked or drag raced or abused . Although I would say he is known to have
a heavy foot an from a 59 yr olds perspective leaves from all standing stops
more agressively than nessasary . What is the most common cause of a failure like this ? A fue days prior to the failure the truck showed signs of not
shifting as well in 1st to 2nd sorta hunting but not every time . Was that the band on its last go an it caused the rest of the system to wipe out ?

no_6_oh_no

Front band and front clutches (directs) take the brunt of abuse from the TQ. ANY added power just hastens the end without upgrading a few internal parts.

Its hard to tell if the band caused the problem or the direct clutches. Quite likely they are both symptoms of the added power coupled with low OE line pressures for NVH purposes.

What you have is the typical failure that could have been avoided with $300 in trans upgrades. Chalk it up to experience and go forward.

Take a look at this thread for the minimal upgrades needed. https://www.dieseltruckresource.com/...t-t287620.html

travelingman

Thanks no 6 I know your right an it sounds like you use your trk the same as he does . We,ve got the truck at the dlr right now an will most likely end up with a rebuilt unit from them under warranty . But these upgrades will need to be done
to prevent this from happening again shortly after we get it back .
Do you know what actually takes place when tow haul is ingauged ?
My son an I were wondering if the Bully Dog changes the shift points an lockup , an tow haul changes
the factory settings would the two not be working agaist each other ?

no_6_oh_no

AFAIK none of the programmers will change the shift settings and shift points. All they do is add power. The changes you feel are from the extra power at less throttle and THAT will help accelerate the demise of the trans.

The non-TH and TH shift points and lockup are programs in the TCM portion of the TCU they are set to work with stock power. When you increase power it takes less throttle to do the same work so it modifies how the trans reacts. The big problem is now you have enhanced TQ and the shift points and TV pressure are shifting right where the TQ can exert the most force. What happens is the extra TQ slips the clutches and bands which eventually causes failure.

Running TH will help to a certain extent becuase it does flip the internal program to a more aggessive mode. Throttle valve pressure ramps faster which enhances line pressure at the shift point for less slippage. The gov solenoid controls the shift point so it slightly extends the shift point and allows the extra TV pressure to make the shift firmer with less slippage. TH also has a more aggressive lockup algorithm so more power is actually transfered to the wheels. That is at times self defeating becuase now the extra power can work at slipping clutches more.

To a point running TH all the time is beneficial as it extends the shift point and allows higher apply line pressures, but, with extra power and towing a lot it is still not quite enough to overcome the differences in the throttle position that allows it to shift to soon. Unfortunately the TH program is just not smart enough to adjust for all of the potential variables without some help.

In addition to the mods I mentioned in the other thread if he is towing a lot and driving the truck in a lot of slower conditions, under 60 mph where there can be a lot of shifting, upgrade the front band to rigid and get rid of the flex band and replace it with a rigid.

The stock flex band will NOT take the extra TQ and excess shifting without degrading faster no matter the line pressures or setup. I purposely used the OE band and after 80k of towing and a lot of slower speeds with a lot of shiting the band is shot. The original went over 100k BUT it was a lot of open road driving with little slow-n-go and slower speeds. The stock band is much better suited to open road constant speed use.

travelingman

Thanks NO 6 I appreciate your explanation of how it actually works. Sounds like you,ve spent some time on the subject .