Bobcat 731 drive chain wearing on gear reduction

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campbell45

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Sep 16, 2023
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32
Hi guys,

I took my chaincase cover off to adjust the parking brake a take a look at things.
I noticed that the front chains are rubbing on what I believe is the gear reduction housing?
It looks like there are steel guides in front of the gear reduction, but it doesnt look like I can adjust them.

Thinking that the chains need replaced, I tried to feel if the front and rear chains are close to hitting the bottom of the chaincase - they are not!
I dont see anything mentioning adjustment or maintenance in the service manual - just how to replace the chains.
Does anyone have any advice? Is this concerning?
Thank you
Here is a video showing the wear and the amount of play.
 

laurencen

Well-known member
Joined
Oct 3, 2016
Messages
189
on the 743 we replaced the chains, no adjustment we picked up some half links and removed links until we reached a point any more the link would not reach
 

Rylo

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Mar 11, 2023
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on the 743 we replaced the chains, no adjustment we picked up some half links and removed links until we reached a point any more the link would not reach
I didn't know they made half links. Where did you get the half links? We have been waiting on a replacement chain from bobcat and running out of patience. We can hear the chain starting to rub on the casing.
Assuming the half link will still line up with sprockets without issues?
Thanks
 

laurencen

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Oct 3, 2016
Messages
189
any chain supplier can get half links, check with agg dealers, Princess Auto in Canada here has them for all chain sizes.
 

brdgbldr

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Jun 1, 2012
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1,133
Has anyone else seen the chain wear on the gear reduction like mine in the video?
I have not had this issue with my machines but I do know that this happens when the chains stretch and then sag. A lot of time you can hear a muffled "clicking" of the chain, while driving, from it rubbing.

There is a way to check if the chains are too loose. You can put the machine on stands and then, by hand, move the tires back and forth. They should only turn a small amount before the chain slack is taken up and they stop. It may be different for different machines but the limit that I remember was about 1-1/2" max. You should try to find the specification for your machine.
 
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campbell45

Active member
Joined
Sep 16, 2023
Messages
32
Thanks brdgblder.
There is no specification or maintenance check for chain play that I can find in both the owners and service manuals.
I did find that axle end play should be less than 0.013".

My end play varies between each axle, but generally I'm at 0.016" - so slightly outside of spec.
I also tried the method of rocking the tire forward and back. I have 1" of slack.
While doing this, I definitely hear the chain slapping the guide and gear reduction housing.

Not too happy about all this.
Sounds like a chain case rebuild is in my future.
 

laurencen

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Joined
Oct 3, 2016
Messages
189
you can check what size chain you have and buy it from any industrial supplier, your chain is likely stretched, get 4 split links and 4 half links, they are easy to change on the rear do not drop the chain its a royal pain to re thread

0.016 end play is OK if you have no leaks I would leave alone
 
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campbell45

Active member
Joined
Sep 16, 2023
Messages
32
Does anyone know how much chain I would need to replace all four chains? I'd rather not remove it all to find out. If I can attach the new chain with the old, that'd save me some time struggling to feed the new chain on.

Thank you for everyone's help
 

laurencen

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Joined
Oct 3, 2016
Messages
189
the back one is a royal pain if you drop it, we wired thro the links when we split the chains, ours (743) had no spilt link to remove and its tight getting a split link in on assembly
 

oiu789

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Joined
Dec 23, 2017
Messages
129
Some parts list will give you a link count, look around or talk with your BC parts guy to see if they can tell you!
 

laurencen

Well-known member
Joined
Oct 3, 2016
Messages
189
we just picked a couple lengths from local ag dealer, if you have the cover off mark the chain and count the links as you rotate it
 
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