JD750 Flywheel and Starter Gears

   / JD750 Flywheel and Starter Gears #1  

Paul Campanis

Member
Joined
Dec 6, 2022
Messages
40
Tractor
John Deere 750 from 1982
Is it advisable to machine the gears on this flywheel making them narrower?
What I mean is to remove the material that is worn.
Perhaps this will cause more problems?

The other photo is of my starter gear. Should this be replaced or somehow reconditioned?

What is common practice in these situations?
About one in four key turns results in a bad noise.
It is not getting worse but I would like it to be right.

Thank you to everyone who is helping me fix this tractor that is used for a garden ministry to the sick and poor.
Your assistance and support are greatly appreciated. I am grateful for your help and for taking the time to support these efforts.
You have breathed hope into a hopeless situation.

Thank you!
 

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   / JD750 Flywheel and Starter Gears #2  
Machining is not advisable as it decreases effective mesh engagement. For the flywheel ring, you heat expand it off with an oxyacetylene torch then flip it over while it's still hot and it shrink fits back on as it cools. There are several YouTube videos on the process. The starter gear may be able to be flipped as well with a puller depending on design. Alternatively you may be able to purchase it separately without having to replace the whole starter assembly

Starter pinon gear is Deere part #CH12701 in case it's asymmetrical and you can't flip it
 
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   / JD750 Flywheel and Starter Gears #3  
After a bit of reflection, it is possible to machine a minimum amount off of the starter pinon gear using carbide tooling so long as you also fabricate a spacer to put behind it of equal height to the material removed AND the gear was through hardened from the factory. If the pinon was case hardened using a lower alloy (common especially for larger gears as stronger for shock loading) from the factory you would be machining off the case hardening and exposing a faster wearing surface which will not last as long.
So I would consider this only as a distant third choice in terms of preference if the first 2 aren't feasible
1st choice flipping the gear, 2nd replacing the gear or the entire starter unit, distant 3rd choice machining the pinon and adding a spacer
 
   / JD750 Flywheel and Starter Gears #4  
Do you also need to make sure the starter gear is sliding on the motor shaft freely?
If it’s not jumping out all the way before it gets up some speed, it will grind instead of meshing with the flywheel gear.
 

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