Hitch mounting problem.

When mounting hitch I discovered that frame rail captured nuts had rusted so badly that after chasing the threads they would not hold torque causing the nut threads to strip. My plan is to over drill the holes and tap to the next size bolt (from 10x1.25 mm to 7/16x20). I am looking for advice on which type of tap to use. It will be going up from the bottom of the rail. I know a $7 straight flute tap from a big box store will break in two turns but I also don't want to spend hundreds of dollars. Any advice on style and composition would be greatly appreciated. Thanks.

Hi

Same wagon, that you've always had? Sold you the seats for it quite a few ago.

Anyways, Is the frame rail thick enough to tap? I didn't think it was but it may be. I've bought taps from NAPA that worked. Keep the tap lubricated, use slowly, go back and forth, a little at a time and clean off the tap.

Tom

Hi Tom, nice to here from you. Unfortunately the 95 limited was more then I could keep up with and had to part with it. This problem is with my 2005 Camry. Since everyone on this forum deals with older, and sometimes rusty issues I thought this would be the place to post for insightful responses. The hitch is made for this model and the holes line up perfectly with the now stripped captured nuts. And no, I don't believe the somewhat rusted frame rail would hold a threaded hole to 50 lb/ft of torque. Do you know what style tap you have had success with? Thanks.

Have you tried the manufacturer for substitute parts?

Good morning Fred,

Not sure I understand your comment. Can you explain?

Thanks.

The "nuts" are fairly generic, so you should be able to get others that will serve your purpose.

Hi Fred,

I may have misspoken, the nuts are welded inside the fully enclosed box frame rail- no access what so ever. Sorry.

Thanks.

All, I appreciate the help but after doing more research I have decided to order a 7/16"x20 HSS spiral point 3 flute tap. It looks like the best bet I could find.

Thanks again.

Sounds like a plan.

Tom

I'll let you know how it turns out Tom.

Good morning,

Just a heads up, finished the hitch install this morning. Used a 25/64" bit to over drill the 10x1.25mm frame and captive nut followed by a Drill America (made in China, go figure) DWT57195 7/16"x20 3 flute spiral point HSS tap. Worked like a charm. My guess would be somewhere between a 65 and 70 percent thread cut, which worked out to be more than strong enough for the 35 lb.ft. of torque required, not the 50 I wrongly stated above. The only negative, which didn't matter much is the spiral point tap sends chip forward which in my case pushed the into the teeth of the tap. I've enclosed 2 pictures, one of the work in progress in which you might notice a piece of the LT1 secondary air system plumbing I used as a lever on the tap handle and one of the finished product. Hope this might help others.

You must have had a spiral pointed (aka gun tap) as they are made for tapping through holes where the chips can get out. Spiral taps pull the material out of the hole. In some materials and hand tapping it can be necessary to back the tap all the way out and clean of the tap and if you have compressed air, blow out the chips from the hole. Using heavy oil for lubricant can make chip binding worse in may cases as it hold the chips. I like the light oils like Tapmatic and Tapmatic for aluminum. The percent of thread will be determined by the tap H number but can be less if abrasive chips gouge out the thread.

How long was the trailer hitch under water?

The hitch has been exposed to the upstate N Y weather since 2006.