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post #1 of 26 Old 08-15-2019, 01:35 PM Thread Starter
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Best way to fix a bad bolt thread

The pto bolt on my 335 keeps coming loose. I have used thread locker like recommended. The fit between the bolt and the crank isn't all that great. Any thoughts how to get this bolt to stop coming loose?
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post #2 of 26 Old 08-15-2019, 01:57 PM
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Re: Best way to fix a bad bolt thread

What color thread locker have you tried.? I'm thinking the red stuff is what you want if all else fails..
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post #3 of 26 Old 08-15-2019, 02:06 PM
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Re: Best way to fix a bad bolt thread

Blue Loctite and a lock washer.

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post #4 of 26 Old 08-15-2019, 02:07 PM
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Re: Best way to fix a bad bolt thread

The cupped washer may have lost its tension. I would try replacing the cupped washer and the bolt and reinstall with thread locker. If you're not cleaning the bolt and bolt hole in the crank with carb cleaner or brake clean, I would do so.

Have you been able to get the proper torque on the bolt?
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post #5 of 26 Old 08-15-2019, 02:07 PM
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Re: Best way to fix a bad bolt thread

Almost sounds like the bolt is the wrong size or there’s wear on the threads of either the bolt or what it threads in to.
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post #6 of 26 Old 08-15-2019, 02:42 PM
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Re: Best way to fix a bad bolt thread

That bolt does need to be torqued to the correct setting. Most are a 7/16th inch bolt in either Grade 5 or Grade 8. The correct torque spec is 41 ft-lbs for Grade 5 and 58 ft-lbs for Grade 8.
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post #7 of 26 Old 08-15-2019, 03:45 PM
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Re: Best way to fix a bad bolt thread

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Originally Posted by Flaken View Post
That bolt does need to be torqued to the correct setting. Most are a 7/16th inch bolt in either Grade 5 or Grade 8. The correct torque spec is 41 ft-lbs for Grade 5 and 58 ft-lbs for Grade 8.
I just looked it up in my JD service manual. They call for 45 ft-lbs.
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post #8 of 26 Old 08-15-2019, 04:07 PM
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Re: Best way to fix a bad bolt thread

Do you have room for a longer bolt with a helper nut?


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post #9 of 26 Old 08-15-2019, 04:53 PM Thread Starter
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John Deere shows the bolt as m10 x 90 . I replaced it with a 100 mm but it still feels sloppy in the crankshaft. I have been using blue thread locker. Will try the red.
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post #10 of 26 Old 08-15-2019, 06:15 PM
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Re: Best way to fix a bad bolt thread

Where are you getting these bolts from? Just like the SAE bolts, metric bolts also have different grades. Standard grade is 800-830 MPa, next toughest is 1040 MPa and the step up from that is 1220 MPa. You definitely do not want to put a lesser grade bolt there and try to torque it to something it is not, hardened bolts are a royal PITA to get out when they break.
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post #11 of 26 Old 08-15-2019, 07:45 PM
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Re: Best way to fix a bad bolt thread

If you thought you knew about thread locker, take a looksee here: https://www.henkel-adhesives.com/us/...adlockers.html I've been using this stuff for 40 years, and never heard of a need to prime things. Yes, some Locktights require a primer! I just googled your issue and ran into this. I learned quite a bit in the last 20 minutes of internet rabbit hole diving!
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post #12 of 26 Old 08-15-2019, 07:46 PM
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Re: Best way to fix a bad bolt thread

Quote:
Originally Posted by rockyrude View Post
I have been using blue thread locker. Will try the red.
You might regret that decision at some point down the road if it works.


I would look at Loctite Form-A-Thread and ensure that you have the proper grade bolt, JD cup washer and torque the bolt properly before I used red Loctite.
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post #13 of 26 Old 08-15-2019, 08:42 PM
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Re: Best way to fix a bad bolt thread

JD says to always replace the cupped washer after each removal.
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post #14 of 26 Old 08-15-2019, 09:17 PM
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Re: Best way to fix a bad bolt thread

ASME says to replace all hardware when removed.
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post #15 of 26 Old 08-15-2019, 11:07 PM
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Re: Best way to fix a bad bolt thread

Most likely the torque shoulders on the top of the PTO clutch and the bottom of the traction drive pulley are beat up from the bolt coming loose. If these surfaces are not square to one another and smooth the PTO clutch will **** when tightened up. This puts a lot of imbalance into the equation and the bolt loosens again further beating up all the surfaces that need to be smooth and square.
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