Twisted off seat anchor point

[Pyral]

My seats were creaking so today I decided to retorque the bolts holding the seat in place. I got my FSM and set my torque wrench to 33 ft/lbs (more on that later). I was still waiting for a click from my wrench when the bolt head sheared off. Simultaneously I also tore a quarter size chunk of metal off from around where the bolt screwed into the floor. That chunk of metal fell into the beam that it was part of.

The FSM said the torque spec for the seat bolts was 27 ft/lbs, for whatever reason I had set mine to 33 ft/lbs. I would expect the seat bolts to have more safety margin than 6 ft/lbs.

I now have a hole in the beam that once fastened the seat in place, and to make it even worse it looks like I have rust around all my seat anchors. How should I fix it?

 

[Brian.]

Instead of continually handing you information, where you don't learn to do for yourself, I'd like to point you to this link:

Alternate Search for T4R - 3rd Gen Section

It's a search for this forum, using Googles cache results (and thus the Google search vs the forum search). Hopefully you can get into the habit of using that search first, then ask questions. At least try to help yourself before asking others to help you... sorta how you could have 100% resolved that squeaky clutch by spending the couple minutes it took you to just take a look at it yourself.


You aren't even Close to the first person to do this (rip apart the seat mounting bolts), many have gone before you. There are 2 common solutions, I'll leave it to you to find out what those 2 common solutions are and decide between them. Heck, I think you'll find it common among all brands of vehicle, especially as they age.

Just as a bit of secondary information, bolts/fasteners tend to have a 10% safety margin for error. So, 27ft/lb would be fine to about 30 or so before beginning their failure. Unless the fastener was Completely rusted, it also wouldn't have gone from fine to failed without indication, which means that you missed the clues it offered you. Usually, when a fastener is about to shear, it suddenly "feels" different through the wrench... I'd describe it as going soft, but thinking about what happens is that as the metal deforms it requires less force to continue to deform so it'd feel like it's getting easier to turn. You can STOP when that happens and sometimes still back it out for replacement, but usually it's too late. Same happens when shearing the sheet metal, like the part that fell into the rail. These are Learned things, so don't let this opportunity pass by without really thinking about what you Felt. Good to learn not to trust torque wrenches too much too, beyond the human error aspect, they can fall out of adjustment and simply fail internally... best solution is to wrench enough that you develop a feel for what should be "about right" so when something goes beyond that you can test it.

I'd also like to point out, this could be totally NOT your fault. Someone else before you could have over-torqued that bolt, just to the point of failure and STOPPED because they felt it failing, leaving you the mess.

 

[Bad Luck]

Google will get you places: https://www.google.com/search?q=site%3Atoyota-4Runner.org%2F3rd-gen-t4rs%2F+seat+bolt+broken&newwindow=1&rlz=1C1QJDB_enUS784US793&sxsrf=AOaemvLwj3lGb4kqLyg2sX0SVfYUn55Vjw%3A1636030495660&ei=H9iDYae-J66qqtsP-_-AMA&oq=site%3Atoyota-4Runner.org%2F3rd-gen-t4rs%2F+seat+bolt+broken&gs_lcp=Cgdnd3Mtd2l6EANKBAhBGAFQqgpYmSdg8ihoAXAAeACAAVOIAYEIkgECMTeYAQCgAQHAAQE&sclient=gws-wiz&ved=0ahUKEwjnyaPE4P7zAhUulWoFHfs_AAYQ4dUDCA8&uact=5 This problem/repair has been covered multiple times.

 

[spartacus]

My seats were creaking so today I decided to retorque the bolts holding the seat in place. I got my FSM and set my torque wrench to 33 ft/lbs (more on that later). I was still waiting for a click from my wrench when the bolt head sheared off. Simultaneously I also tore a quarter size chunk of metal off from around where the bolt screwed into the floor. That chunk of metal fell into the beam that it was part of.

The FSM said the torque spec for the seat bolts was 27 ft/lbs, for whatever reason I had set mine to 33 ft/lbs. I would expect the seat bolts to have more safety margin than 6 ft/lbs.

I now have a hole in the beam that once fastened the seat in place, and to make it even worse it looks like I have rust around all my seat anchors. How should I fix it?

You can use a floatING cage nut or a weld on floating cage nut.

 

[Pyral]

Sorry for the duplicate post, should of checked before I posted.

I am taking it into a body shop to have a patch welded in. They told me that it was good that I didn't wait to have this fixed because driving around with a missing mount fatigues the other 3 bolts and increases the likelihood of needing additional repairs. It feels like I'm sitting on a table that has one leg shorter than the others.

Washers, floating cage nuts, and larger diameter bolts will all work, and thanks to everyone who gave me advice. But this is purely my opinion, all of those should be considered temporary solutions while you find someone to reweld the plate. In places with MOT, having a loose seat anchor or rust within a certain distance of a seat anchor is enough for you to fail a test and be unable to register the vehicle. None of the body shops I talked to would give me a quote without seeing the vehicle because it is considered a safety issue that has risk of legal liability. A seat anchor should not only be stable, it also has to be stationary in a crash. Its the same level of importance as having secure 3 point seat belts or a head rest.

After talking to a few shops I came to the conclusion that rewelding is the only truly safe option that I am confident in if I get in an accident. For anyone in my position, I strongly suggest welding if you drive your 4runner on public roads. That is the end of my little PSA.