Need Options/opinions: Welded Nut Inside Frame Broke Loose Installing

[llebcire]

Installing factory hitch and was removing the 17mm bolts by hand. One pictured (passenger side) snapped the nut loose that's welded into the frame (best guess) as it now just spins.

Looking for options/opinions:

The frame appears to be boxed on all sides so there isn't access spot - it feels like the back is closed off as well but I'd like to hear from someone who knows before I pull the bumper to look.

Is there an access hole that I'm missing so that I could wedge something between the frame and the nut so that I can remove it?

Do I need to have a body shop create an access hole, re-weld the nut, then close the access?

12 bolts in a 6500 lb hitch seems to be a bit of overkill - looks like the 6500 lb limitation is from the vehicle/brakes/etc. and not the hitch. Thoughts on running without this one bolt?

Thanks!

-Eric

[xxstewart]

To get the bolt out, I'd try using a small crowbar. Apply pressure between the frame and bottom of the bolt head to force the nut against the inside frame surface, and use your ratchet to unscrew the bolt. The nut should spin into its previously welded position, fixing it so that it resists turning. The weld may have broken due to rust/corrosion on the bolt threads that created excess resistance when you tried to remove it. Before removing this last bolt, and before reintalling all the bolts, I'd use some WD40 or penetrating oil to lube the threads a bit. Once you have the broken nut's bolt removed, you have the problem of fishing the nut back onto the bolt. (Twelve bolts may seem excessive, but I'd not advise leaving this bolt uninstalled. Its absence will distribute the hitch load among the other bolts, and probably unequally.) Try fishing a bent coat hanger through the adjacent hole and holding the nut in place while getting the bolt threads started. Then use the crowbar again to create pressure to hold the nut stationary. If none of this works, try drilling an access hole nearby the stuck bolt. Start with a small pilot hole (~ 1/8") and enlarge it in stages. A step drill bit works really well for this. Good luck!

[lenore]

I wonder if after removing the bolt, find a self tapping bolt just a little larger than the existing hole....Thread it in and at least provide some support from that point.

[llebcire]

Thanks for the advice!

Someone on CL forums suggested removing the bolt and using a blind threaded insert - looks like they're available (hopefully locally) for high capacity needs such as this.

-Eric

Exhaust hanger did a great job giving me a hand.

[llebcire]

Here's what I ended up getting in a 12mm configuration:

http://avkfasteners....php#pn_standard

-Eric

[lenore]

good job, what kind of store carried those....my bad, just saw your link...Thanks again for the solution to your problem

[llebcire]

good job, what kind of store carried those....my bad, just saw your link...Thanks again for the solution to your problem

Couldn't find anything locally - had to get online and it wasn't easy as these are designed for high volume production line applications.

-Eric

[xxstewart]

This type of blind fastener will hold the bolt in place in this application, but it is not designed for installation in thin wall steel. It's meant for installation in a blind hole -- that is, a hole in a solid material that has no opening at the bottom. This type of fastener works by expansion. The bolt expands the fastener's outside diameter, and in a blind hole causes it to grip the inside hole surface. In a thin wall installation, it will be difficult to prevent the fastener from spinning while the bolt is being turned. Also, bumper hitch bolts and nuts should be grade 8. Since this blind fastener is designed to expand, it is purposefully made from a soft grade steel. I think using this fastener is almost as effective as leaving the bolt uninstalled. A self-tapping bolt installed in thin wall steel will be similarly ineffective. I'd spend a bit more time and ensure the bolt and original nut are used. If this turns out to be impossible, you could try using a snowplow frame mount j-bolt, but you'll have to open up the hole diameter to install it.

[llebcire]

This type of blind fastener will hold the bolt in place in this application, but it is not designed for installation in thin wall steel. It's meant for installation in a blind hole -- that is, a hole in a solid material that has no opening at the bottom. This type of fastener works by expansion. The bolt expands the fastener's outside diameter, and in a blind hole causes it to grip the inside hole surface. In a thin wall installation, it will be difficult to prevent the fastener from spinning while the bolt is being turned. Also, bumper hitch bolts and nuts should be grade 8. Since this blind fastener is designed to expand, it is purposefully made from a soft grade steel. I think using this fastener is almost as effective as leaving the bolt uninstalled. A self-tapping bolt installed in thin wall steel will be similarly ineffective. I'd spend a bit more time and ensure the bolt and original nut are used. If this turns out to be impossible, you could try using a snowplow frame mount j-bolt, but you'll have to open up the hole diameter to install it.

Thanks for your response!

While I agree that this will not have the strength of the original fastener, I disagree that it would be equally effective as not using at all.

The strength difference between a grade 5 and grade 8 is approximately 30%, and while substantial in a one to one comparison, this is one of 8 12mm mounting points (plus 4 additional bolts) and when considering the load this one bolt will be subjected to that 30% difference would be further diminished.

Additionally, this hitch configuration is similar to other hitches that I've installed on full size trucks where the tow rating is 9,000 lbs+ (assuming the GX is limited by the chassis/braking not hitch) thereby further reducing the 30% difference.

As far as difficulty in tightening the bolt without spinning, this will be directly related to the opening I create. If the opening is too larger it will spin and won't work.

The suppliers that I worked with were aware of my specific application (tow hitch rated @ 6,500 lbs) and indicated this insert would satisfy those requirements.

-Eric

[llebcire]

xxstewart :

While I still think the insert would have worked in this applications, your hypothesis regarding the insert spinning in the frame was correct

Thanks for the idea on the snow plow insert and I will try an locate one - good news is that I'm in Iowa so things related to snow shouldn't be too hard to find!

-Eric

[llebcire]

So this insert didn't work - just spun in the hole and as I found by messing with one it takes a tremendous amount of force to get this thing to crush.

Looks like I have a couple of options:

J-bolt - can't find anything in the way of specs

Having a body shop weld a stud into the frame

Create an "access hole" above the opening so I can get a nut into the frame - thinking 3/4" x 1.25" - don't know if it would affect the structural stability of the frame but I can't imagine it would.

-Eric

Let me know if pics don't work - using Picasa as Photobucket seems to be having issues.

[xxstewart]

I think your best option is to try using the original nut. Try to center it over the hole using a fish wire through the other hole. If you can capture a 1/4 turn of threads, you should be able to pull down on the bolt and the nut will seat in the broken weld nibs. You might be able to catch it with bent metal rod through the adjacent hole and keep it from spinning. As long as you keep some pull tension on the bolt, the nut should stay in place while you turn the bolt. Use a wire brush and some WD40 to clean up the bolt threads so it will spin into the nut easily. The J-bolt is a specialty snowplow bolt Meyer P/N 14595 available from www.storkauto.com for $21 (not cheap!). It's a grade 8 3/4" SAE thread, so you'll need a matchin grade 8 nut to go with it. The hole will need to be opened up in an elongated manner, rather than just drilling a large diameter hole. The j-bolt will take much more installation effort than the original nut. Be patient and nimble. Once it's done, you won't need to worry about messing with it again.

[llebcire]

I think your best option is to try using the original nut. Try to center it over the hole using a fish wire through the other hole. If you can capture a 1/4 turn of threads, you should be able to pull down on the bolt and the nut will seat in the broken weld nibs. You might be able to catch it with bent metal rod through the adjacent hole and keep it from spinning. As long as you keep some pull tension on the bolt, the nut should stay in place while you turn the bolt. Use a wire brush and some WD40 to clean up the bolt threads so it will spin into the nut easily. The J-bolt is a specialty snowplow bolt Meyer P/N 14595 available from www.storkauto.com for $21 (not cheap!). It's a grade 8 3/4" SAE thread, so you'll need a matchin grade 8 nut to go with it. The hole will need to be opened up in an elongated manner, rather than just drilling a large diameter hole. The j-bolt will take much more installation effort than the original nut. Be patient and nimble. Once it's done, you won't need to worry about messing with it again.

Thanks!

I was considering this approach as there is an access point on the other side of the frame (toward the top - not close to where the bolt needs to go) where I could insert a new nut - the original is now somewhere inside the frame with the remainder of the original bolt still in it.

Think it'll be a pain to get done but as you mentioned this will be the only time I need to fight with it.

-Eric

[xxstewart]

Here's another idea. There appears to be a hole on the frame channel side above the two hitch mounting holes. If you can open up the diameter of this hole large enough for a 12mm bolt head to fit through, you can fish a bolt down through the mounting hole.. The bolt threads will extend through the mounting hole, and you can use a nut on the outside. Fishing the bolt through the hole isn't that difficult. Get some fine gauge steel wire and feed it through the top hole and then through the bottom hole. Place a star washer on the bolt to help keep it from spinning. Then tightly wrap the wire around the bolt threads. You should be able to pull on the wire and the bolt will go through the upper hole and come down through the mounting hole. Put a small o-ring around the bolt so it doesn't accidentally pop back into the frame channel before you get the nut on it. Make sure the bolt is a grade 8 so you don't have to do this again. You might want to try fishing the broken nut out with a small magnet attached to the wire so it doesn't rattle.

[llebcire]

Here's another idea. There appears to be a hole on the frame channel side above the two hitch mounting holes. If you can open up the diameter of this hole large enough for a 12mm bolt head to fit through, you can fish a bolt down through the mounting hole.. The bolt threads will extend through the mounting hole, and you can use a nut on the outside. Fishing the bolt through the hole isn't that difficult. Get some fine gauge steel wire and feed it through the top hole and then through the bottom hole. Place a star washer on the bolt to help keep it from spinning. Then tightly wrap the wire around the bolt threads. You should be able to pull on the wire and the bolt will go through the upper hole and come down through the mounting hole. Put a small o-ring around the bolt so it doesn't accidentally pop back into the frame channel before you get the nut on it. Make sure the bolt is a grade 8 so you don't have to do this again. You might want to try fishing the broken nut out with a small magnet attached to the wire so it doesn't rattle.

That's so weird - I had this revelation yesterday and was on my way to get the bolt when your post came through. I'm planning on the fishing line, leaving the old bolt in and cutting the new one to length after secured. I will also rust proof everything so it won't stand out.

Hoping to access through existing opening on outside of frame rail where body is mounted to frame.

Thanks!

-Eric

Grade 8 1/2"

[xxstewart]

A final comment -- be sure the grade 8 nut is a standard one, not one that is clinched to be self locking. Although a locking nut would be preferred in this application, installation will be nearly impossible because there's no way to grip the bolt. Your best best is to use a lock washer and a bit of Lock-Tite thread adhesive. This will keep the bolt secure. It's still a good idea to check the bolts once a year.

[llebcire]

Install failed - I couldn't get the bolts on both frame rails to align. When one was aligned the other was off by 1/2" - 3/4".

So - either my vehicle's frame is tweaked or something happened to the vehicle this hitch came from (was her parent's but purchased pre-owned). I didn't see any evidence the entire time I've been under my vehicle that the frame has been massaged back into place.

I was able to get the bolt installed and will leave in place (with nut & lock washer) until I find another hitch.

-Eric

[xxstewart]

Sounds as if you have the wrong hitch -- is the hitch from Lexus or an afermarket item? With a hole offset of only 1/2" - 3/4", adding another hole to the frame is likely to be too close to an existing hole.

[llebcire]

Sounds as if you have the wrong hitch -- is the hitch from Lexus or an afermarket item? With a hole offset of only 1/2" - 3/4", adding another hole to the frame is likely to be too close to an existing hole.

Hitch came from her parents 2006 GX470 before they traded it. Believe it was a factory installed option on that vehicle so the hitch is OEM.

-Eric

[llebcire]

Finally getting back to the hitch - big shout out to KODA4 from the other Lexus Club as it looks like I need a different bracket. There's a post there showing an alternate piece from Toyota/Lexus. Part #08925-35870 center support.

Looks like I need to track this part down!

-Eric

Here's some pics from today when I used the frame bolts without the mounting for the pintle:

[llebcire]

It worked!

All done:

-Eric