Auto Restoration 101

One of the biggest and most frustrating problems that you come across restoring an old car is stripped or damaged threads. One way that might help fix the problem is to “chase” the threads with a thread restoring tap or die. They are different than a thread cutting tap and die. A thread chaser is essentially a slightly undersized tap that will clean threads without removing any metal. Basically what they do is move the threads back into place. For years I always used a regular thread cutting die to clean up threads. Every once in a while there would be a situation where the bolt would easliy strip out after using a thread cutter on existing threads, this was because I was removing thread material and weakening the threads.
I now use the thread restoring taps and dies to repair damaged threads.

The thread chasers actually work very well to clean the threads of parts after they are painted. For example I use them a lot before installing a freshly painted hood. Some of the old car hoods are very heavy and to mess with getting a bolt to start with primer and paint in the holes is a pain. After chasing the threads you can easily screw the bolts in by hand.

Just remember that rethreading taps and dies renew existing threads, they are not for hardened threads or for cutting new threads.

I own this rethreading kit that I purchased from Snap On Tools.

Here is the same kit by Kastar at Amazon.com