Eaton Rearends...?

[Goofyexponent]

I drive a 1979 Louisville....it has the 40 Eaton rearends. The rear tandem is the "new" fine spline hardware, and the front rearend is the "old" style coarse splines.

We are having a problem with the front axle and the through shaft breaking the coarse spline shafts. Up until yesterday, the truck broke 2 input shafts on the power divider, and two through shafts that the yoke goes on to on the back of the front rearend.

This morning while hauling a load, I stuck the truck into reverse and eased up on the clutch and heard a loud "pop"...there goes the power divider input shaft again! Had one of our other dump trucks towed me to the jobsite where i dumped the load and called the big wrecker to come get her.

I had that input shaft in the truck from the day it was new until now...and I am NOT ******* my gear....especially if it is not my own truck.

We are pretty puzzled as to what is causing these shafts to break. Any thoughts on what to look for? I am going to tear it apart tomorrow and IF the right parts show up this time I will have her running in no time.

 

[Captain Morgan]

I am guessing you are either having bearing failure or either getting some inferior replacement parts. First guess usually is a result of heavy foot on the loud pedal, but you already answered that one....

 

[Goofyexponent]

That's what my boss thought too the first time it broke...about the heavy foot. But 3 different drivers broke 5 shafts (3 input and 2 output), and I drive the big rig like an old man in a station wagon.

We decided to just rip the front pot out and axle shafts of the housing and replace it with the fine spline eaton we have out back. Then she will have the new fine spline gear throughout and it will never break a shaft again!

Everytime she broke a shaft, the boss said it was worth $1000 in parts alone.

 

[NJKen]

That's what my boss thought too the first time it broke...about the heavy foot. But 3 different drivers broke 5 shafts (3 input and 2 output), and I drive the big rig like an old man in a station wagon.

We decided to just rip the front pot out and axle shafts of the housing and replace it with the fine spline eaton we have out back. Then she will have the new fine spline gear throughout and it will never break a shaft again!

Everytime she broke a shaft, the boss said it was worth $1000 in parts alone.

Sounds like the answer. Where are the shafts breaking? If they are snapping rite at the base uf the splines you where getting beat shafts for sure. The fine spline setup reduces areas of stress (splines anent as deep) and are usually stronger.
Good Luck
Ken

 

[Goofyexponent]

for some reason she keeps snapping the splines off right at the bearing where they loose the support from the bearing. Both the input and output shafts seem to snap right there. What we can't figgure out is one of our other drivers, who beat os the same style rearends for years NEVER broke a single shaft, but 3 drivers who are easy as hell of the trucks managed to go through 5 different shafts....

 

[Freight_Train]

for some reason she keeps snapping the splines off right at the bearing where they loose the support from the bearing. Both the input and output shafts seem to snap right there. What we can't figgure out is one of our other drivers, who beat os the same style rearends for years NEVER broke a single shaft, but 3 drivers who are easy as hell of the trucks managed to go through 5 different shafts....

Well,there is your problem.She likes it rough!

 

[PackRat]

Is it possible that the power divider isn't unlocking? Or, if air pressure drops for some reason, it locks in randomly?

 

[Freight_Train]

My vote is wear on other parts over the years or maybe crappy non OEM parts.Maybe the gears have wear and play causing slack and a shockload to the shaft now?Maybe side support is gone due to wear on other parts?I would totally take the housing apart and check everything at this point.1000 bucks a snap,crackle,and Pop hurts in todays ecconomy!

 

[NJKen]

If its breaking rite at teh bearing it sounds like something is out of line. It could have been machined wrong rite from the beginning At this point I would change the whole thing if it where my truck. Down time is BAD
Ken