Helicoil question

Patsdeere · Aug 22, 2018

Working on a jd, but in this case I don't think it matters. The front axle has a support bar that goes back to the main case and has a pivot point. The pivot pin is screwed into the main case of the tractor and is essentially a stud. Sadly the hole is near the bottom of the oil sump, so if it wallows out, all your oil ends up on the ground. Don't ask how I know

So what would be the best fix? Currently a 7/8 stud. Drop it out for a 1" or maybe slightly bigger new stud? Or helicoil and go back original size? Will a helicoil seal when below the oil level in the sump?

Thanks.

Steve@Advance · Aug 22, 2018

Without seeing it, hard to say.

A 7/8 rethread set will be expensive! Over sizing it to 1" would be less costly. Trying to hand drill and tap, keeping it straight will be a challenge either way!

As for leaking oil, either will hold oil if sealer is used AND the stud stays tight. If the stud moves, or has nothing to tighten securely against, it will leak and eventually wallow out the threads again.

Check Break · Aug 23, 2018

I don't think a helicoil will seal. These inserts made by Gard will do the job if you have 1.25" that you can utilize for the 7/8" insert.

http://gardspecialists.com/view.php?r=Gardserts.pdf&v=chptr See Page 13 for a 7/8" insert.

Ian Beale · Aug 23, 2018

I was told that helicoils don't stand up too well if there is a pounding action on the stud

JL Ray · Aug 23, 2018

I can't see a Heli coil sealing up and not leaking. They are basically a spring with formed threads on the inside and outside. I would think a machined up insert of some type will be best. Pictures would help.

Mike M · Aug 23, 2018

Oversize to the next size up if possible is the least expensive way. You may need to make a special step stud ? Got a lathe ? I had to do this on some drawbar support bolts. J B weld the new stud in. That should seal it up.

RESLLS · Aug 23, 2018

7/8 = 22mm
15/16 = 23.5mm
Could go metric. 24mm tap costs about $10. 15/16 about 30. Metric bolt about 4. Know it is not the best idea, but 15/16 might not have enough meat left to tap a thread if hole is wallowed out some. Do you have enough metal left for 1"? 24mm should work without going too big. I have done it the other way on a few jap bikes. Next bigger size was standard.

ss55 · Aug 23, 2018

Is the bracket held on by only one stud or are there more than one fasteners? If more than one, I would check the condition of the other fasteners, if one was moving the others may be ready to let go too.

Special taps for heli-coils can be expensive if only used one time. There are alternatives to helicoils: www.CarrLane.com/en-us/product/threaded-inserts or www.McMasterCarr.com

As for sealants, I would try Loctite.com first. They make sealants and adhesives for many applications.

You may not be the first person to have this problem on your model of tractor. Try posting this problem on the John Deere forum below and maybe add some some pictures to jog someone's memory.

Patsdeere · Aug 23, 2018

Yes have access to a lathe. figured I would make 1 end 1" and the other the original size so the original castle nut fits back on.

Patsdeere · Aug 23, 2018

I'm sure there is some banging as the support goes from the front axle to the housing to keep the wheels from folding under the tractor should it hit something really big/hard.

Barry Ayres · Aug 23, 2018

sounds like a jd d i just did mine i made a new stud with the inner end thread longer than original and tapered out in the last 3 or 4 threads used a die grinder inside the crankcase to flatten off the inner surface. the tapered portion of new thread would just tighten up in the old worn out hole i then loctite'd the stud in followed by a locking nut on the inside then when you assemble the radius arm pivot with its spacer tube and tighten outer nut the bad thread is under compression from the 2 nuts and therefore carries little weight. may have some photo's somewhere.
barry

Patsdeere · Aug 24, 2018

You nailed exactly what I'm working on.

Texasmark1 · Aug 24, 2018

If you smeared the bolt and the HC really good with Permatex #2 when you install the bolt I wouldn't worry about it. Otherwise you have 2 sets of threads to seal off rather than just one. It has proven itself over many 10's of years to stay slightly soft and resist dino products.

Helicoil question

Patsdeere

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Steve@Advance

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Check Break

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Ian Beale

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JL Ray

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Mike M

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RESLLS

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ss55

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Patsdeere

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Patsdeere

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Barry Ayres

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Patsdeere

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Texasmark1

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