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kvkamp32591
Veteran Reader

JD 7720 combine transmission

I have a 7720 combine with a clicking sound coming from what I think is the transmission. It seems to be getting louder. The faster I drive the faster the clicking sound.  The sound is not synchronized with the output shafts of the transmission. Does anyone have any ideas what this may be or maybe a similar experience?

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6 Replies
Honored Advisor

Re: JD 7720 combine transmission

Could it be one of the final drives?  Maybe lift drive wheels off floor and have someone spin it over while you observe.  But be careful and never put yourself in danger.  Put your cellphone on a selfie stick to hold under there if anything.

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kvkamp32591
Veteran Reader

Re: JD 7720 combine transmission

I jacked it up.  The click is definitely in the transmission. I hear it when I spin either wheel.

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Honored Advisor

Re: JD 7720 combine transmission

A broken tooth in one of the gears?

 

https://axleaddict.com/auto-repair/Manual-Transmission-Noise-Diagnosis   

 

11. Transmission Makes a Clicking Noise

The clicking noise may happen in any gear range.

  • On a transmission, this could mean worn or damaged teeth on a:

    • countergear or cluster gear assembly
    • output shaft gear
  • On a transaxle, this could mean damaged teeth on the:

    • input shaft gear

Worn gears may not represent a real or immediate problem. However, if a broken piece is moving around between gears and other components, it can cause more damage.

 
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kvkamp32591
Veteran Reader

Re: JD 7720 combine transmission

After spending most of yesterday trying to figure out a plan of action when we need to be harvesting I decided to run it.  As with a lot of decisions in ag I won't know if that is right or wrong until later.  I ran it today.  When I quit tonight I pulled the plug and drained the oil out of the transmission.  I was a little surprised that the oil looked good and there were no filings or contamination that came out.

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Honored Advisor

Re: JD 7720 combine transmission

That`s good news, is the drain plug a magnetic one?   If it was me, I`d run it until it pukes and get another one from a salvage yard. 

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kvkamp32591
Veteran Reader

Re: JD 7720 combine transmission

That's the plan-at least for this season.

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