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Primary drive shaft questions.

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Lets just say a dumbass slighty messed up the threads on the primary drive shaft while attempting the primary nut fix. What die would be required? I know left-hand but from what could measure it looks like a 16mm. Not sure of the thread pitch. I'm hoping someone smarter than me (not hard, could be a chimp humping a football) can give me the 411 on the die sizes needed. Thanks and I really mean it!

Edited by wizze

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Lets just say a dumbass slighty messed up the threads on the primary drive shaft while attempting the primary nut fux. What die would be required? I know left-hand but from what could measure it looks like a 16mm. Not sure of the thread pitch. I'm hoping someone smarter than me (not hard, could be a chimp humping a football) can give me the 411 on the die sizes needed. Thanks and I really mean it!

I could guess, but might be wrong..so you’ll need a very cheap thread pitch gauge, from any sears store, tool store, and most auto parts places. Then measure the pitch.

DO NOT USE A DIE unless you cannot find the proper tool.. which is a thread chase.. You want to “straighten” the existing threads, not cut new ones. A die will just cut new threads form the small amount of material there (the damaged threads) this will leave you with not much, and likely a junk primary shaft.

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I have had good luck with a split die.

Same deal, it is designed to CUT threads, and it will do just that.. from the old damaged threads, leaving, less meterial... Damaged threads need to be "fixed" not new threads cut.

To each his own, do what works for you.

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If it's just the first thread or two, I would use a metric thread file. They come with 8 different thread pitches and one of them will match up. Will work on right and left hand threads.

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If it's just the first thread or two, I would use a metric thread file. They come with 8 different thread pitches and one of them will match up. Will work on right and left hand threads.

Good point, a carful hand with a thread file will straighten a bent or distorted thread in most cases. (I don’t normally recommend then do to most not having one, and the ease one can do further damage)

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Are thread chasers left handed or right hand specific? Or are they universal?

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Thread chasers are specific to size, pitch and direction. Looks like we still don't know the dia and pitch. The only crank I have to measure has damaged threads so I don't have that info.

Could you post a better description of what the damage is? and/or a picture?

Sometimes you can make a thread chaser with a nut of the correct size if the threads are not too bad. Buy 2 new nuts, make 1 saw cut thru 1 nut, use it to chase the threads. Use the second nut for a thread gage. And of course use a new nut for assembly.

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Thread chasers are specific to size, pitch and direction. Looks like we still don't know the dia and pitch. The only crank I have to measure has damaged threads so I don't have that info.

Could you post a better description of what the damage is? and/or a picture?

Sometimes you can make a thread chaser with a nut of the correct size if the threads are not too bad. Buy 2 new nuts, make 1 saw cut thru 1 nut, use it to chase the threads. Use the second nut for a thread gage. And of course use a new nut for assembly.

:thumbsup: Yes this, and use a Grade 8 nut. I prefer to use a thin cut off wheel in a dremel.. as it makes the smallest kerf.

I’m honestly having a hard time finding left hand thread chasers, other them very specific ones for a particular application, spindle, lug nut.. ect.

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hmm, i held off- assumed there was some hardness to the shaft. if a file will cut it, man ya. hell of a lot safer to see what is going on than to cross-thread a cutting tool and booger it worse.

files can love lots of different things too, many many times.

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Thread files have the teeth cut straight and are either left or right depending on how the user holds the file. The one I have has four sides on each end, with a different tpi on each side, you choose the thread and file away. Angle the file so the teeth line up with the threads.

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Here are some pics. The 2nd and 3rd thread look a little too friendly. Metric tread gauges are hen's teeth around here. A sears, 2 auto parts stores and a large local hardware store had nothing. But from what I can tell by matching a tap to the good threads, it appears to be 1.50 pitch. The diameter would be 16mm or thereabouts. No shank to measure and the inside diameter of the stripped nut (no threads) was 17mm.

IMG_1285.jpg

IMG_1284.jpg

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Ahh, you removed a left hand thread nut as if it was right hand. I have a crank just like it in my parts stores that someone gave me. My approach was to recut the threads in the lathe and make a new custom under size nut. I got the threads fixed but never made the nut. A further complication was the seal area of the crank was damaged also so I kinda gave up on it.

What I see in the picture is quite bad. The recommendation to use a proper thread chase die is the only hope I can see. You can probably clean the threads up enough with a thread file to get a nut on but I don't know if it will hold the torque. (100 ft lb upgrated from 80). Bummer.

Hot Rods crank time perhaps?

A standard metric bolt of known thread pitch works good for a thread gage.

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Hmm, seen that before.. Air gun, set to CCW rotation on a left hand thread fastener.. Pulls the threads over just like that.

As Noble stated, a hardened, proper thread chaser die is your best option.. If you can find one. Thread file is not going to fix this one.. And as bad as those threads are..... Id be looking to install a new crank.. as Id be concerned the damged / repaired threads with not hold up with the clamp load required.

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Ballpark. What kinda $$$ am I looking at so I know how much blood to sell. :worthy::ride::worthy::thumbsup::worthy::worthy::worthy:

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Ballpark. What kinda $$$ am I looking at so I know how much blood to sell. :worthy::ride::worthy::thumbsup::worthy::worthy::worthy:

Call Eddie at SSW.. He often has good used cranks…. It’s about $95 shipping to CO.. so that plus the crank and labor, and anything else you want done while it’s in his hands.

Couple of hundred Id guess.. but you need to call or email him to be sure.

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I figured out the shaft is a 18mm x 1.5 threads. I found a die and was able to chase the threads without much material removed. The die spun on and hit some drag 1/3 of the way in and spun freely the rest of the way. Since the nut holds past this I was happy. Lots of red loctite and torqued the nut to 103 lbs. I was going to get the nut welded at a lower torque but with it holding the right torque should I still?

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I figured out the shaft is a 18mm x 1.5 threads. I found a die and was able to chase the threads without much material removed. The die spun on and hit some drag 1/3 of the way in and spun freely the rest of the way. Since the nut holds past this I was happy. Lots of red loctite and torqued the nut to 103 lbs. I was going to get the nut welded at a lower torque but with it holding the right torque should I still?

I would not weld, but I would remove that nut, clean and degrease, then use a drop of Loctite 270

http://www.google.com/url?q=http://tds.loctite.com/tds5/docs/270%2520NEW-EN.PDF&sa=U&ei=pYCtTpinNM_3sgbPxK3KDw&ved=0CBAQFjAA&usg=AFQjCNER0h_qQwEfJIOymnPWJCwtzbyUkQ

:busted:

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