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Help! Spun pinion nut?
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andy1canada
Posted 2020-10-18 11:18 AM (#7611)
Subject: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Stuck and could sure use an idea or two if any out there?

Got my new Rockwell pinion oil seal in and got the pinion shaft installed as it was.

Then set up to torque the yoke nut back on with my new fangled Milwaukee M18 1/2" impact wrench.

Braced the yoke with a stout pipe wrench with a 4 ft pc of pipe extending to the ground to keep the works from turning with an eye to getting to that 600 ft/lb torque spec for the nut.

Gave'er a good blast with the impacter then put my 600 ft/lb torque wrench on her and proceeded to put my 225 lb frame on it to try get to that 'click' out of the wrench. The nut turns... then turns more and more till I realize its gone a couple of revolutions when I get this terrible feeling in my gut.

Yes, bozo manged to strip the nut.

At least I hope its the nut and not the pinion shaft threads.

Any how, the nut just spins freely now and don't move in either direction. Thinking maybe some heat but worry about toasting the new oil seal.

Any and all ideas certainly appreciated.

Thanks!

Terry
#846
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BigRabbitMan
Posted 2020-10-18 11:26 AM (#7612 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?



Elite Veteran

10001002525
Location: Cottage Grove, OR
Big problem but don’t make it worse with heat!
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andy1canada
Posted 2020-10-18 12:48 PM (#7613 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Going to try a zip-disk cutting as close as I can to the threads without hitting them.

If that don't do it I'll see if I can get at it with a metal blade on my jigsaw, or, a small sawZall.

Found out it's a 1"-20 nut. Mine is a simple flanged nut with a flat washer. No lock nut or lock washer or cotter pin (?)

I'm hoping for a good outcome here as it makes sense that the nut would fail before the shaft in order to protect the pinion.

Should have changed out the nut as well I suppose.

Terry
#846

Edited by andy1canada 2020-10-18 12:49 PM
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B. Sitton
Posted 2020-10-18 3:42 PM (#7614 - in reply to #7613)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

100100100252525
Location: Ignacio Colorado
I have new yokes and pretty sure a box of the nuts.
Bill
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andy1canada
Posted 2020-10-18 7:04 PM (#7615 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Well I couldn't get my nut off today!

Ended up deciding to go with a metal cutting blade on my Fein (oscillating) tool; more surgical.

Bought two new blades ($33.00 smackers) and burned through them both. Tried cutting the nut through to the threads on opposing sides hoping a slight smack with a drift/chisel would part it; no go.

Don't think I cut through deep enough so I'm going to get another blade and take another whack at it when I get time.

Pisses me off that this happened.

Terry
#846

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LCAC_Man
Posted 2020-10-19 8:34 AM (#7616 - in reply to #7615)
Subject: Re: Help! Spun pinion nut?


Elite Veteran

50010010010025
Location: Oceanside, CA
If it is the correct rockwell crimped end lock nut you are going to burn through a lot of cutters...those things are incredibly hard. I've dealt with similar problems in the past. Get another nut and weld it to the top of the one that is on there then use a slide hammer to bring the stripped nut out to good thread so that it will walk itself out. You will likely be replacing the ring and pinion...(or having the pinion thread repaired).
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andy1canada
Posted 2020-10-19 8:55 AM (#7617 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Good idea Len but there's not enough of the shaft end thread sticking out to start another nut on it.

This pinion in mint and I have no plans to mangle it.

Easy as she goes.

Thanks,
Terry
#846
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LCAC_Man
Posted 2020-10-19 9:46 AM (#7618 - in reply to #7617)
Subject: Re: Help! Spun pinion nut?


Elite Veteran

50010010010025
Location: Oceanside, CA
I wasn't suggesting the new welded on nut be threaded to the pinion, just the opposite, you would use the welded on nut to thread into the slide hammer, the slide hammer would then pull the original nut out a bit allow it to bite on to some clean thread and walk off..
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dkarnath
Posted 2020-10-19 9:58 AM (#7620 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Elite Veteran

50010025
Location: Medford, OR
I wonder if you could put a come-a-long on the yoke, put some slight pull pressure to it, and try backing the nut out?? Red neck engineering...
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andy1canada
Posted 2020-10-19 7:27 PM (#7621 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Thanks you guys.

Got me going in a new direction. Cutting it off is the wrong approach.

I'll get my welder out when I can and try Lenny's idea.

That should give better purchase than my vice-grips did; bloody thing let go and I went flyin'...

Found some new yoke nuts locally so just gotta' lose this one and I'm back in the game.

Thanks,
Terry
#846
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andy1canada
Posted 2020-10-22 3:37 PM (#7622 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Tougher game than I figured...

Good news is - I got the pinion yoke nut off. Thanks Len - great idea!

Bad news is the shaft is stripped.

http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=191&p...

Not sure which way to go with this.

I don't imagine simply running a 1"-20 die over it a few times to clean it up would suffice.

I noticed the washer the nut snugs up to is about 1/4" thick; does it need to be?
A 1/8" washer would buy me back that much more thread, although maybe not enough. (?)

What about having the pinion machined down to say a 15/16" or 7/8" shaft?

Pulling at increasingly short straws now.

Can a guy even still buy these pinions, or, anyone got a used one in case all else fails.

Maybe it might be time to take a serious look at that 3.73:1 Rockwell I got from buddy Jay.

Was hoping to catch a break but no such luck.

Any advice greatly appreciated.

Thanks,
Terry
#846
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andy1canada
Posted 2020-10-22 3:55 PM (#7623 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Extreme Veteran

5002525
Location: Victoria, BC. Canada
Just got off the phone with my gear guy in Vancouver and he's advised that I can send the shaft out to have it ground, welded then re-threaded for a very reasonable fee.

Breathing easier already.

Also, he was aghast when I told him about the 500 - 600 ft/lb spec from the FMC manual on these yoke nuts. He rebuilds heavy and med-truck diff's for a living and swears that 350 - 400 ft/lbs would tons for this application.

Food for thought.

Terry
#846
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LCAC_Man
Posted 2020-10-22 3:58 PM (#7624 - in reply to #7611)
Subject: Re: Help! Spun pinion nut?


Elite Veteran

50010010010025
Location: Oceanside, CA
I hope that works for you, being able to keep the same pinion saves you all the pinion depth set up work, just be very careful to document all of that during disassembly.
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