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Deere Mack

Noisy PTO rattle with MP8's and Allsion Auto

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Hello everyone, I've talked to a few of you before about this problem.  I bought a 2017 GU713 MP8 Allison auto dump truck at the end of last year. The problem I had was the PTO rattle being very loud inside the truck. My dealer had made several attempts to quieten it with no luck.  I know now this is a known issue but today I hit major discovery. Every bit of the sound I was hearing was traveling up my shift or raise/lower cable. The sound is traveling up the cable like a speaker wire and blasting out of my control console.  I remove the cable from the PTO completely, bracket too and no noise what so ever...NONE!

So now, how do I fix this?  I'd love to hear some ideas.  My first thought would be convert to a electronic or air system and eliminate the cable, but I'm not sure whats out there.

Edited by Deere Mack

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I wonder if the air control valves would work. Not sure if sound would travel up an air line the same way.

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I don’t know if it would completely eliminate the noise but we changed out the pto on a truck that had a cable system to an air shift pto and the air shift is 100 tines better. Smoother, faster, easier, cable doesn’t freeze up in winter.

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4 hours ago, RobM626 said:

I don’t know if it would completely eliminate the noise but we changed out the pto on a truck that had a cable system to an air shift pto and the air shift is 100 tines better. Smoother, faster, easier, cable doesn’t freeze up in winter.

I feel like it would make a difference but not sure. I wonder if the air lines could act like fiber optic cables and carry the sound or if it's mainly the vibration from the metal cable carrying the noise.

Anyone out there have the same set up with air controls?

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Need to talk with a noise and vibration expert.

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11 minutes ago, Deere Mack said:

I feel like it would make a difference but not sure. I wonder if the air lines could act like fiber optic cables and carry the sound or if it's mainly the vibration from the metal cable carrying the noise.

Anyone out there have the same set up with air controls?

The air hoses that replaced the cables are hollow plastic 1/4” hoses. The cables obviously have a metal cable with a plastic sheath over them. There’s not really a medium for sound/vibration to travel with the air hoses

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I appreciate the information Rob.  I've got a good feeling about it all.  Been digging in on air control valves and looking at options.

If you don't mind me asking, do you remember roughly the cost of converting?

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No problem. I can’t gaurantee if it will get rid of your problem but like I said earlier. There’s a night and day difference between the two as far as ease of operation goes. This set up didn’t once freeze up this past winter and it engages the first time every time.

i think the total cost for the pto and air controls costed around 8-900. My in-house mechanic installed it so we didn’t pay labor. I changed out a pto that already had air controls and I paid over 1000 from the mechanic

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The information below shows how sound travels through different mediums.  Make notice to  steel vs Nylon or Polyethylene. Most air lines are made of nylon or polyethylene and even between the two of those there's a considerable difference. Looks like the polyethylene line wins my vote.

Mild Steel    3235 m/s

Nylon           1150 m/s

Polyethylene  540 m/s

Dry Air (can vary depending on humidity) 346 m/s

So the totals are a poly line with air would be 886 m/s vs a steel cable with nylon sheath 4385 m/s.  The math says the air control hoist valve vs a cable control should be a lot quieter.

🤔

 

Edited by Deere Mack
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Is the cable for engaging the PTO, or running the pump/hoist up and down.  I myself hate the air operated hoist,  and took it off my truck and replaced with the cable.  The air operated hoist doesn't have the same level of control/feathering  in my experience.  But the air operated pto is the way to go.

Edited by OldRedMack
Didn't finish my thought.

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39 minutes ago, OldRedMack said:

Is the cable for engaging the PTO, or running the pump/hoist up and down.  I myself hate the air operated hoist,  and took it off my truck and replaced with the cable.  The air operated hoist doesn't have the same level of control/feathering  in my experience.  But the air operated pto is the way to go.

It's the control cable for the hoist up & down. My PTO is air operated.  It may be a trade off, feathering capabilities or extremely loud jack hammer sound in cab. 

Don't forget I understand these trucks are known for the PTO rattle with the Allison auto. But the discovery is that it enters the cab through the Hoist control cable.  Remove the cable from the PTO and Bracket, tie it away and no more noise. The only way you'll here it is to roll down your window and hang your head out the cab.

If anyone out there has my setup with air operated hoist control please chime in.  Thanks!

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The setup I had was cable engage/disengage and cable up/down. I absolutely hated it. Now it’s air everything. And the set up is great. I know what you’re saying about the air not being as precise because the regular truck I drive is like that. I feel like the older the valves get they they get loose and leaky and aren’t as precise.

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19 minutes ago, RobM626 said:

The setup I had was cable engage/disengage and cable up/down. I absolutely hated it. Now it’s air everything. And the set up is great. I know what you’re saying about the air not being as precise because the regular truck I drive is like that. I feel like the older the valves get they they get loose and leaky and aren’t as precise.

I'm sure there's a lot to consider, brand, install etc. But I'd be very interested in hearing from someone with the MP8 and Allison auto with the air control.

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Ok, mine is the t310mlr.  So definitely apples to oranges, but I have noticed a new rattle sound in my truck and never thought about the cable.  I will have to check that out.

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I will pass this info on my my buddy who has 3 GU's with MP8/ Allison. I'm pretty sure he has the cable up/down controls. 

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4 hours ago, Mackpro said:

I will pass this info on my my buddy who has 3 GU's with MP8/ Allison. I'm pretty sure he has the cable up/down controls. 

If he wants to test it out for himself it will take about 15min to remove the cable completely from the pto & pump, even the line from the bracket so no part of the cable is touching. He'll be amazed,  I swear it was like I was in a different truck.

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Looks like I might make the change, got to see if it makes a difference.  Anyone that has one as loud as mine will understand and hopefully it'll work and help out some other guy down the road.  The air operated hoist control is new to me, I've always had the cable. Is there anything I should know or look for, or is it a just a bad idea for a tri axle dump truck?  Any info would be a help.  Thanks

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My buddy's newest GU is coming in with full air controls for the bed unlike his other GU's . His driver requested it due to thatsvwhat he's used to. We will see how it sounds when it gets here in a few weeks.

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Could you get a length of rubber gas line and run the cable through?   It won't eliminate the direct connection between the control lever and pto but may buffer the sound some.  Just a late night idea.   

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8 hours ago, Hobert62 said:

Could you get a length of rubber gas line and run the cable through?   It won't eliminate the direct connection between the control lever and pto but may buffer the sound some.  Just a late night idea.   

Good morning, I appreciate your suggestion. I've tried putting rubber everywhere imaginable. Put rubber o rings in between the pin connection at cable and PTO, thick rubber on and around the cable bracket and in between cable and bracket. I also put extra sound deadening material on the inside of my control tower.  I've been desperate to eliminate this problem.  lol  I think the only way to help with the cable would be to have some type of plastic connection between PTO and cable. Even then sound travels  through hard plastic fairly well.  Installing air shift next week with polyethylene lines, the quietest way to go.

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I would compare going to the air control over cable is like going from mechanical to electric controls on a loader.  Which would mean that a little bit of movement on the stick goes a long way.  Just remind yourself that it is completely different and you will get use to it pretty quickly.  Even though I don't like the air controls, if my truck rattled like what you describe then I would swap it out also.  

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