Semi-stripped threads

It has been. That is how this started I guess. If a tap doesn't work, I can always do the rivnut. It is more than just thin plate on the cross member. Seems like there is a nut or something welded behind it.

 

Installing a rivnut into a drilled out nut is not appropriate, unfortunately. The backside of the rivnut won’t be able to expand properly and compressing it into a solid region would only cause it to pull out and compress the internal threads resulting in a jammed thread.

Most rivnuts require no more than around a 1/8” maximum plate thickness (size dependent of course.)

 

Happened to me as well. I was livid. You know they just hit them with an impact. I ran a tap up there and replaced the bolts. Nothing special about the bolt and it worked just fine. That was two years ago and no issues at all

 

Agreed. Using a rivnut would require removing the oem frame nut first.

 

I am expecting the ones who did it to get the their 4Runners on the ramp and report to us. Come on guys!

 

Excellent information folks. These don't appear to be self-tapping bolts and their metal seems very soft. The taper/rounded end at the tip of the bolt doesn't seem to indicate any special threading. I'm not sure why the little notch and the taper are at the tip of the bolts.

If M8-1.25 is the correct tap, I'll buy one to try. We will see if it goes in straight. Bolts were only $1.25 so I ordered a few.

 

The taper is just to help the bolt engage the threads without needing to start it with perfect angles.

The notches are just to help clear out the bolt hole a little bit. I imagine Toyota chose these types of bolts with tips like this because they anticipated the area would get pretty dirty with dirt/road grit.

The notches act like little plows and help clear grit away from the thread. A careful person can use it as a poor/lazy man’s chasing tool. You can clear out the threads by turning the bolt back and forth and back out until the grit clears. This can save the aggravation of having to get out from under the car to get an actual chasing tool, or something to spray in there to clean it out.

They can also be abused by using
a power ratchet or impact gun to zip it into the hole carelessly. The taper makes it easier to get into the nut without having to start it by hand, and then cross thread it. It’s probably what happened to yours.

 

Lowe's has the tap. I'll pick one up this afternoon as I have to pick up some other things, including Scotch 2228 to (I hope) fix the rear garnish paint chip/rust issue. Hope M8-1.25 is correct thread.

 

From what I recall, there is a specific tool for chasing which are a bit “safer” to use, but I’m not an expert.

Taps are really meant for creating new threads in bare unthreaded holes. That said, I’ve only used taps to chase out holes out of convenience (couldn’t find chasing tool). But you just have to be more careful when you are starting the tap into the threads so that you don’t end up making it worse. I’d try to find a few videos to watch on how to do it right.

 

In a pinch you can make a thread chaser from a bolt, just make sure the bolt is a grade or two higher than the material you’re working on else you’ll end up galling threads.

Cut two flutes along the length of the bolt, around 35°-40° to the bolts radial axis and taper the bolts leading edge (think countersink here)


image credit: Phillip Thomas

Use plenty of cutting fluid!

 

A pack of metric thread chases can be purchased online from Amazon.
(

$44 Lang Tools 2584 15-Piece Metric Thread Restorer Set, Black , Gray

Lang Tools 2584 15-Piece Metric Thread Restorer Set, Black , Gray)
I have used both taps and chasers on existing threads. Most non evasive to start is obviously the chaser, if problems occur with that, turn to the tap!

 

FIXED!

Some research and help here in this thread + Kobalt M8 x 1.25 tap from Lowe's for $6.98 + a little motor oil + some patience + new Toyota bolts for $1.25 each = no more problem!
https://www.lowes.com/pd/Kobalt-M8-X-1-25-Metric-Tap-and-Drill-Set/5013366885

The threads on the bolts seem to be almost sacrificial in nature. Both of the ones that I tried in this hole stripped the bolts almost bare immediately. The bolts seem very soft compared to the metal they go into, which would be a good thing.

I got my head directly under the problem hole and inserted the tap straight on, trying not to drop in my face. It is tapered on the end. It didn't start easily. I did about one turn to get it started and then backed it out, cleaned it with a paper towel, oiled it again, and went back in, repeating the process about 3/4 turn at a time. After a few turns, it suddenly freed itself up as though it found its way back into the original threads. I finished running it all the way through a few times with my fingers and fresh oil to clean out the threads completely. Not a whole lot of junk came out of the threads, but there was some metal debris. Looking at the destroyed threads on the bolts, I imagine a fair amount of it was ground up bolt thread material. I put in a new bolt and tightened it "just so" which is all that is required in this application, and it worked just fine.

Now I have a tap in case this happens with any other holes under there. The step bars also are M8 x 1.25, the eight skid plate bolts are M8 x 1.25, and the two bolts for the oil drain plug opening also are M8 x 1.25. I imagine a lot of others are as well.

If you feel like one of your bolts is not going in easily with your fingers, I suggest stopping immediately. The less damage the better. If a new bolt also will not thread in with your fingers, try this approach. I'll keep a spare bolt with the tap.

Thanks folks!

 

Nice job sir!

Gratifying isn’t it?

 

I hadn't ever used a tap before. Interesting process. Now I know how. 400 miles on the odometer. No more worrying about that bolt. Now I can move on to other things. I still only have one step bar in place. Maybe I can put the other one on tomorrow. I finally got the dashboard speakers and grilles all set yesterday. Lots and lots of little things to do.