Live PTO rattle

[doug dirt]

I have a question about a rattle in the PTO when at idle.
2020 Kenworth T880 with Cummins and an allison rd4500 transmission.
When truck is at idle , there is an annoying rattle.
When rpm's increase almost all rattle if not all rattle goes away.
When pto is engaged and raising box , rattle completely goes away.
I have heard that it could be the lashing is out of spec.
I also have heard that combination of Cummins/Allison could have this happen.
I have never had an Allison automatic so I am open to people's opinion.
Thank you

 

[Coaldust]

Sometimes, it’s a feature of the creature. When all the resonate frequencies stack on top of each other. Then, She sings the song of her people. Changing the PTO idle speed up or down could help.

Or, the installer didn’t know what they were doing. I would check the backlash.

And keep a regular eye on those PTO mounting screws. They have a tendency to loosen. The latest hardware kits come with Nord-Locs.

 

[Coaldust]

 

[IceHole]

I have the same setup on a work truck, it's quiet. I hate the Allison though, constantly lugging the crap out of the engine and I have to manually command it a gear or 2 higher.
Seems to think 800 rpm is a proper rpm to shift to. Barely over idle!

 

[Truck Shop]

Oh don't talk bad about a allison--oh those are the gift to HEF.

I hate the Allison though,

 

[cfherrman]

Nobody I know checks the backlash when installing a PTO

Ice a trans tune might be in order, or if it's a old Allison your modulator is bad

 

[IceHole]

Nobody I know checks the backlash when installing a PTO

Ice a trans tune might be in order, or if it's a old Allison your modulator is bad

2021. Been to the shop 3x and got a "computer".
Was shifting so hard it was making the engine drive belt chirp

 

[Truck Shop]

Nobody I know checks the backlash when installing a PTO

I do.

 

[cfherrman]

Personally, it's also funny when someone blows a brand new pto and you can fish the directions out of the trash and show them.