Gear carnage

[dogg rescue]

My beloved uncle who could wreck an anvil in a sandbox was driving the superliner and said he heard a noise. I got in it and he'll you didn't even need the parking brake to hold it still. I knew this rear end wasn't healthy because of the amount of metal I drained out of it. It still makes me wonder if his foot slipped off the clutch pedal.

[gearhead204]

I would say that's more than a side steeped clutch pedal !  a dumped clutch pedal will usually result in a tooth or two being ripped out next to each other, if I had to guess that's some wheel hopping!   and or loss of preload thus causing excessive back lash, and improper tooth surface contact!  

Edited November 1, 2016 by gearhead204

[carlotpilot]

1 hour ago, dogg rescue said:

My beloved uncle who could wreck an anvil in a sandbox was driving the superliner and said he heard a noise. I got in it and he'll you didn't even need the parking brake to hold it still. I knew this rear end wasn't healthy because of the amount of metal I drained out of it. It still makes me wonder if his foot slipped off the clutch pedal.

at any rate damn sure don`t look good

[Hobert62]

Atleast there is no guess in what needs fixed.    Ouch. 

Edited November 1, 2016 by Hobert62

[Vladislav]

Looks like the teeth count could be done without diff removing this time. Just in a can with the oil drained.

[ranchhopper]

Looks like someone forgot to release the brakes and surprisingly that was the weak point in the drive line.

[cstaples]

Are they 4:64 ratio? Obviously there is catastrophic failure, however the 4:64s are more prone to gear failure due to the size of the gears and the contact area. They spall the hard face off and the end is near.

[dogg rescue]

Nope, as it turns out they were 3.87's the truck was originally speced to have come with 4:17 and I swapped them back in. All the 4.42's we ever ran seemed to be indestructible.

[kt_Engineer]

My best guess - One or two of the tooth on the pinion have been spalling (surface fatigue) for quite some time and the noise was ignored. Eventually the spall grew big enough that the tooth broke under load and got into the gear mesh. Once that happens that will take out bunch of tooth (in the mesh) in a jiffy. I have witnessed 10's of failures like these.

[dogg rescue]

One year later, same truck, different driver. He was starting a load on frozen ground, and said he was just letting out the clutch. The pic is of the back of the power divider.

[HeavyGunner]

Ouch 

[Mack Technician]

At least the through-shaft will be a little cheaper to fix? Be nice to see you on top of 200 series Mack diffs.

[kt_Engineer]

On 11/8/2017 at 9:56 PM, dogg rescue said:

One year later, same truck, different driver. He was starting a load on frozen ground, and said he was just letting out the clutch. The pic is of the back of the power divider.

This is a different type failure than earlier one. The thru-shaft failure occurs only when extreme amount of torque passes through it during shock loading/clutch dumping type scenario. Mack Power-Divider does a true 50:50 torque split due to unique CAM mechanism and thru-shaft can see more torque than a conventional inter-axle diff on Meritor or Dana axles (in wheel-slip and other scenarios).

[1965]

1 thing for sure; your clutch is good

[david wild]

Driveshaft and u joints too.