Rebuilding my C3 differential which the ring bolts backed out of and destroyed the case. I bought a rebuildable core with a good case. Reading past threads has given me most of my answers and I noted that because of poor quality control in the day that some bolts would bottom out in the ring before fully securing the ring to the carriage. I ordered a new set of ARP 230-3001 bolts. I measured the thickness of the carriage where each bolt goes thru and came up with 0.35. I cleaned and blew out each bolt hole in the ring gear, ran each bolt down till it bottomed out and then measured the bolt from the ring gear to the bottom of the bolt head...I get 0.33-0.34. This only leaves me 1-2 hundreths before the bolt bottoms out once the carriage is figured in. Since I only need 10 bolts out of the pack of 12, I wondered if I could grind the bolt down a bit without screwing up the threads which I found out was easily done and I closed the gap to 0.30 on one bolt....which once the carriage figures in will give me 5/100ths before the bolt bottoms out. I feel better with the extra room but would like to get opinions as to if I should do this to all the bolts? will be securing with locktite and torquing to 55ft/lbs. Any input appreciated.

 

I had the same issue on mine with the ARP bolts.
My GM 336 ring gear was not drilled very deep.
I had to measure each bolt hole carefully, and grind each bolt shorter, to fit.
Every hole wound up being a little bit different.


My original short GM bolt on left.
Original but too long ARP bolt on right.
My shortened and tapered ARP bolt in the center.

IIRC I wound up about 1.5-2.0 turns longer than the GM bolt, but I had to grind off 1.5-2.0 turns to get there.
I made sure I had about 1 turn of extra hole depth. The threads do not go all the way to the bottom.

 

New imported gears have deep tapped holes, US Gear had deep holes.

Used GM, were all over the place. The ARP bolts are not the problem, lack of QC at GM going back to 1965 was. I machine fit every ring gear bolt I install. I just did a 66 RG, 6 of the 10 holes were shallow tapped. Not enough to toss the gear but enough I had to fit them and make sure they didn't bottom out in the hole. I use a lathe so I can measure the amount I remove. You can grind a chamfer on the end as Leigh did, but check every hole.

 

Exactly the info I was looking for with a pic to boot!!!. Thank you so much.