Which Program Do I Perform?

Keith Browning · May 25, 2005

In comes a 2005 F350 4X4 with the snow plow prep package to have the 05B27 program performed. The customer also complained that the trans has a long delay when shifting into gear. I discovered metal grindings in the oil pan. So I removed and disassembled the unit and inspected the parts and son of a gun! One of the rear planetary pinions had walked out and ground down on the output shaft gear just like the 04B24 concern. This trans also had the "updated?" solid output shaft gear in it. The reverse clutch snap-ring hadn't budged.

I found it odd that the trans build date was 11-30-04 and still had the pinion shaft concern. After conferring with my service manager we ended up performing an overhaul with parts kits from both programs. Look out fellas, I guess nothing is straight forward anymore! /forums/images/%%GRAEMLIN_URL%%/eek.gif

bkalafar · June 29, 2005

Well, there are a couple of issues that would cause this to surface, even though the build date was outside of the recall. Because the reverse carrier is a "floating" design, there is nothing to prevent the centerline of the planetary housing to cock in relation to the centerline of the sun or ring gear. With driving conditions that have frequest directional changes, as seen in snow plowing, there appears to be an additional load applied to the pinion shafts. If the "rolled" over ends of the shafts were done to the minimum dimension, it's only a matter of time until the shaft pokes out due to the hammering effect of the helical gears. The other issue concerns the mechanical diode type one way clutch. As only one strut is applying when the clutch is holding (in N,P,1A,2A,1M and 2M), an additional cocking action can take place. On some units, the cocking is so bad that the pinion gears ends have come in contact with the splined teeth of the separator plates in the reverse clutch. Due to certain issues, there tends to be a lot of clearance between the mechanical diode and the case splines. As the diode chucks back and forth (rotating in the case) coupled with the end play in the reverse clutch (made worse with a waved snap ring), unless both ends of the snap ring are barbed and oriented properly, you'll be replacing quite a few of these.