EDM broken diff pin bolt - The 1947 - Present Chevrolet & GMC Truck Message Board Network

demian5 · 01-04-2018, 12:47 PM

So in an OG 93k 12 bolt rear diff, the bolt broke off at near the bottom of the threads. Drilling was unsuccessful, going to take to a broken tap guy to EDM out. I thought i'd start a post as I am sure this is a normal thing that happens.

**LockDoc** · 01-04-2018, 01:18 PM

Quote:

Originally Posted by demian5

So in an OG 93k 12 bolt rear diff, the bolt broke off at near the bottom of the threads. Drilling was unsuccessful, going to take to a broken tap guy to EDM out. I thought i'd start a post as I am sure this is a normal thing that happens.

Did you buy the drill kit or just wing it? I bought the kit and have had really good luck with it. I didn't buy it from here but this is the type I bought....

http://www.freedomracing.com/dpk-01-...SABEgLnpfD_BwE

LockDoc

demian5 · 01-04-2018, 03:04 PM

Quote:

Originally Posted by LockDoc

Did you buy the drill kit or just wing it? I bought the kit and have had really good luck with it. I didn't buy it from here but this is the type I bought....

http://www.freedomracing.com/dpk-01-...SABEgLnpfD_BwE

LockDoc

I could make one on my lathe, but no I didn't try it. Whats the thread pitch?

**Ol Blue K20** · 01-04-2018, 03:19 PM

I've had pretty good luck by just using left-handed drill bits. It usually catches and spins them out.

Killer Bee · 01-04-2018, 03:28 PM

some related discussion here recently, some methods may be useful..

broke bolt in end of crank

I have some experience hiring EDM work.. all larger benchtop machines, have not seen a portable in action personally..

most memorable; had a tech break a bolt in an expensive german hydrostat pump housing belonging to a local offshore platform.. not only expensive, extremely long lead times and customer would not have been happy.. $75 [20 years ago] local machine shop blasted it out of the housing, clean as a whistle, saved out butts!

toolboxchev · 01-04-2018, 04:30 PM

Quote:

Originally Posted by Ol Blue K20

I've had pretty good luck by just using left-handed drill bits. It usually catches and spins them out.

I am putting that one in my tool box!

**LockDoc** · 01-04-2018, 05:18 PM

Quote:

Originally Posted by demian5

I could make one on my lathe, but no I didn't try it. Whats the thread pitch?

Thread pitch of what?

LockDoc

demian5 · 01-04-2018, 06:50 PM

Quote:

Originally Posted by LockDoc

Thread pitch of what?

LockDoc

Of the bolt that goes into the diff. The one that broke.

**Ol Blue K20** · 01-04-2018, 08:24 PM

Quote:

Originally Posted by toolboxchev

I am putting that one in my tool box!

Good idea, I have a left-handed drill index up to 1/2 inch by 64ths. It comes in handy quite often.

**LockDoc** · 01-04-2018, 09:18 PM

Quote:

Originally Posted by demian5

Of the bolt that goes into the diff. The one that broke.

I think it is 5/16-18.

Don't you have the one that you took out?

LockDoc

**jerry moss** · 01-04-2018, 11:07 PM

the kit Loc Doc mentions is the best thing to use. it comes with a guide so you can drill it perfectly in the center, along with a super long drill bit so your drill is away from the carrier and the proper size e-z out. i've used mine many times at work and never had a problem getting the broken piece out.

01-04-2018, 12:47 PM	#1
demian5 Registered User Join Date: Aug 2016 Location: Lake Forest, CA Posts: 2,177	EDM broken diff pin bolt So in an OG 93k 12 bolt rear diff, the bolt broke off at near the bottom of the threads. Drilling was unsuccessful, going to take to a broken tap guy to EDM out. I thought i'd start a post as I am sure this is a normal thing that happens. __________________ "Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC

01-04-2018, 03:19 PM	#4
Ol Blue K20 Proprietor of Dale's Corner Join Date: Nov 2012 Location: Vacaville , CA Posts: 16,245	Re: EDM broken diff pin bolt I've had pretty good luck by just using left-handed drill bits. It usually catches and spins them out. __________________ "Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man R.I.P. FleetsidePaul

01-04-2018, 03:28 PM	#5
Killer Bee Registered User Join Date: Jan 2016 Location: Barber City, CA Posts: 4,809	Re: EDM broken diff pin bolt some related discussion here recently, some methods may be useful.. broke bolt in end of crank I have some experience hiring EDM work.. all larger benchtop machines, have not seen a portable in action personally.. most memorable; had a tech break a bolt in an expensive german hydrostat pump housing belonging to a local offshore platform.. not only expensive, extremely long lead times and customer would not have been happy.. $75 [20 years ago] local machine shop blasted it out of the housing, clean as a whistle, saved out butts! __________________ *I started out with nothing - and I still have most of it*

01-04-2018, 11:07 PM	#11
jerry moss Born Psycho Join Date: Feb 2001 Location: brentwood,cal,usa Posts: 4,936	Re: EDM broken diff pin bolt the kit Loc Doc mentions is the best thing to use. it comes with a guide so you can drill it perfectly in the center, along with a super long drill bit so your drill is away from the carrier and the proper size e-z out. i've used mine many times at work and never had a problem getting the broken piece out. __________________ jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA

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