Yanmar/F935 rubber coupler/isolator

[Bogart]

Hi, thanks for a great forum.

As you can see the new coupler is under stress when installed. Part of this is lack of clearance between the drive shaft and the flywheel and part is because the drive shaft connects at an angle rather than being perfectly straight. I am considering grinding off maybe .030 - .035 inch of the pads on one side. Will installing this way lead to premature failure? Looking for any suggestions or input on this situation.
Thanks again.

 

[kennyd]

Welcome to TBN

I think you need to find the root cause of the mis-alignment, such as worn motor mounts or driveshaft supports.

 

[Spudland_Dave]

I think you need to find the root cause of the mis-alignment, such as worn motor mounts or driveshaft supports.

Common "problem"...but those isolators arent really a problem, its more of a wear/consumable part.

That being said...mine isnt as tight as yours is...its not loose, but not tight enough to deflect the rubber like yours.

 

[zzvyb6]

Check for a broken or sagged enging mount. Mine is as straight as you could want but wore out anyways (F935).

 

[Spudland_Dave]

Check for a broken or sagged enging mount. Mine is as straight as you could want but wore out anyways (F935).

zzvyb6 is right, it SHOULD be perfectly straight...I bet thats where your misalignment comes from.

 

[Bogart]

Thanks for the input.
I shaved .020 off each pad. That helped a lot. I can't believe how much smoother the mower is. That old coupler must have really let the drive shaft wobble around. I will try to get it straight when I have time. I have a lot of grass I need to mow and I have to spend a lot of time on this machine to keep it going.
I was lucky to find the condition of the old coupler before it completely let go. I was under the machine installing the PTO clutch.

 

[kuboman]

You will find that the motor mounts have sagged. Mostly the rear ones. I had this problem with mine and it was the rear mounts. Having the alignment out that much also puts a strain on the input shaft to the transmission and it will eventually fail causing catastrophic failure. Big mess.

 

[canucklehead]

what should the isolator bolts be torqued to, both the bolts to the driveshaft, and the mounting bolts to the pulley? do you also need blue loctite?

thanks

 

[canucklehead]

another question...there is a raised "shoulder" on the isolator. does the shoulder go against the driveshaft flange and pulley (like in Bogarts pic), or does the flush edge of the isolator go against driveshaft & pulley. It could be put in either way, so which way is correct?

 

[Mechanos]

Hi, thanks for a great forum.

As you can see the new coupler is under stress when installed. Part of this is lack of clearance between the drive shaft and the flywheel and part is because the drive shaft connects at an angle rather than being perfectly straight. I am considering grinding off maybe .030 - .035 inch of the pads on one side. Will installing this way lead to premature failure? Looking for any suggestions or input on this situation.
Thanks again.

You are off by one bolt hole on the installation of your new coupler. Remove all the bolts, rotate the coupler 60 degrees and reinstall all the bolts. Of course, now that you've shaved some material off the new coupler, that might cause "new" alignment issues.