Q: How do you stop the lower part of the broken pinion shaft lock bolt in GM or Ford differentials from spinning because there are no threads left on it?

Q: How do you stop the lower part of the broken pinion shaft lock bolt in GM or Ford differentials from spinning because there are no threads left on it?

Posted by Doug Gillis on Dec 4th 2018

A: Using the Deluxe Differential Pinion Lock Bolt Extractor Kit can save you a lot of time in pulling out the broken pinion shaft lock bolt, but it can sometimes be difficult to keep the bolt from spinning. We recommend you use the longer of the two guide bolts so you can apply pressure on the broken pin by tightening the guide bolt. This will allow you to drill into the center of the broken pin without spinning the piece. Keep in mind that you want to drill approximately 3/16" into the broken piece and remove all of the shavings.

On the original differential repair kits that have been put out for years by a competitor, they used a regular strength drill bit. We began making our own version of this differential repair kit in the summer of 2018 and quickly decided to use a better quality of drill bit, so we started using an M42 Cobalt Aircraft 1/8" Drill Bit. By reading feedback about the differential kits on other websites, we decided that the drill bit needed to be much stronger, cut easier and quicker, so we went with the Cobalt.

Keep in mind that the drill bit is a 12" by 1/8" bit and a little finesse needs to be used to keep the bit from flexing. With the proper amount of pressure and steady, low RPM (Approximately 500 RPMs) you should quickly be able to drill into the head of the broken pin. As to the extractor, my personal preference is the spiral type extractor, which is a #2 extractor. However, some mechanics may prefer the #1 square extractor, which is also included in the kit. In our kit the extractors are top quality, made in USA, and can be used with confidence for years to come.

My experience with drilling out any type of broken bolt is to use an oil based lubricant and always apply even, steady force to the bit. As you may know, every broken bolt extraction has it's own unique solution. My explaination for the extraction of the pinion shaft lock bolt is what has worked for me for years and I believe you can be successful by using my information as a guide to a solution to your problem.  This is a system that has been tried and worked for this specific application for many decades.

Deluxe Differential Pinion Shaft Lock Bolt Extractor Kit