Loose subframe mounting point - What do?

I have had a rattle coming from under the NSX for a while and I recently tracked it down to a loos component. The frame that holds the shift linkage in place was missing a 14mm 10x30 bolt. I bought a replacement bolt and tried to install it, only to have the threaded hole rotate with the bolt. Is there a way to fix this?
Frame with missing bolt:


Threaded hole in body:

I would say helicoil is the only way.

It shouldn't be to hard to do.

To be clear, from your description it appears that the retaining nut on the backside of the body extrusion is rotating as opposed to the threads being stripped out? If that is the case, then I don't think a helicoil insert is the answer. If the threads on the retainer nut appear undamaged, I might be inclined to try bonding the nut in place with something like Loctite stud mount (don't ask me how to get the adhesive in place). All it needs is enough adhesion for you to get the bolt started and mostly tightened up. Friction of the nut on the backside should allow for final tightening.

If the bonding agent isn't going to work, then something like a nutsert may provide the solution. However, I don't know whether you can get nutserts in materials or with coatings that are compatible with aluminum. You may have to do some searching to find something suitable. Try your Acura dealership body department or the body service manual. Stripped / damaged threads in the body extrusions had to be a foreseeable issue so there may be an approved repair technique.

As a suggestion, pull the bolt out of the other end of the support and have a look at the nut fitting on that hole. It may give you an idea as to what failed and what might be the best method of repair.

Old Guy said:

To be clear, from your description it appears that the retaining nut on the backside of the body extrusion is rotating as opposed to the threads being stripped out?

Click to expand...

That is the case. I was just unable to articulate it

The threads are fine.

The locktite sounds good, but yeah, I am not sure how to get in in there.

depending on how loose it is, but I would buy a stud in the right size, with an allen key drive.

If you put some Loctite on the thread, then you can loosely thread the stud in as far as you can. You will then be able to put a nut on the stud, and use the allen key to hold the stud whilst you turn the nut

https://www.belmetric.com/8mm-metric-studs-c-9_71/

hkz286 said:

depending on how loose it is, but I would buy a stud in the right size, with an allen key drive.

If you put some Loctite on the thread, then you can loosely thread the stud in as far as you can. You will then be able to put a nut on the stud, and use the allen key to hold the stud whilst you turn the nut

https://www.belmetric.com/8mm-metric-studs-c-9_71/

Click to expand...

That's a really great idea!

Looking at the pictures, there must have been someway Honda put that nut there via inside of the car? Couldn't you just find the top side of the fastener and tack it back into place?

You could also try to mix up some sort of epoxy and squeeze it into the threaded hole so it oozes out like a volcano. The epoxy will run down the sides of the nut inside the frame and cure in place. The idea is to use some sort of squeeze tube that can fit in the hole so the epoxy won't get in the threads. I hope that makes sense


Sent from my iPhone using Tapatalk

I am not keen on the idea of loctite or anything on the threads. This will be a major issue later, if this ever needs to come apart(like when you need a clutch, or trans removed for some reason). You may want to try using a small punch on the edge of the hole to create a dimple to hold the internal nut from turning.

One question, is this on the front beam end, I am thinking not? It is not 100% clear on the pics exactly which part it is.

JMO......

HTH,
LarryB

Larry raises a good point about my bonding the nut to the body suggestion. It might allow you to get a bolt in and retain the bracket. However, if you ever had to remove the bracket and the bond broke the nut would be free to rotate and you would be knackered trying to remove the bolt. You would have to drill it out.

If you had been driving around for a while with the bolt missing on the support bracket, something must have been holding the retaining nut in place. Otherwise road vibration would have caused it to migrate someplace else in the body extrusion. If you can figure out what is keeping that nut located at the hole it might provide a clue as to how to capture the nut.

As a further observation, if the nut is loosely captured at the hole my suggestion about the nutsert will not work. The nutsert needs to replace the existing nut (i.e. you need an empty hole). If the existing nut cannot be moved out of the way the nutsert cannot be inserted into the hole.

Larry Bastanza said:

You may want to try using a small punch on the edge of the hole to create a dimple to hold the internal nut from turning.

LarryB

Click to expand...

If you can do that, then you may want to run a tap through the nut to 'clean up' the threads. Then get a new bolt and apply pressure on the nut (like prying the attaching arm down) while tighting the bolt. Cleaning up the threads and having a new bolt will make tightening easier, then it should loosen if necessary (although it still may spin).

Larry Bastanza said:

I am not keen on the idea of loctite or anything on the threads. This will be a major issue later, if this ever needs to come apart(like when you need a clutch, or trans removed for some reason). You may want to try using a small punch on the edge of the hole to create a dimple to hold the internal nut from turning.

One question, is this on the front beam end, I am thinking not? It is not 100% clear on the pics exactly which part it is.

JMO......

HTH,
LarryB

Click to expand...

The first picture was taken facing the rear of the car. The loose bolt hole is right in front of the gas tank.

I did some digging and found a better pic of the underside. The missing bolt and stripped socket is circled.

If we look at the interior, that hole seems to correspond to this:


There is also this picture with some studs around that same area:


Don't really know if that tells us anything. I suppose I could pull up the carpet in that area and see what I find...

JMChristopher,

I believe you will find a platenut at the location you've identified in the above first photo once you lift your carpet. The platenut will be made of a nut element either crimped or spring clipped into a retainer plate. I suspect someone has either over torqued or used too much upward push force when installing the bolt causing the nut element to dislodge from the retainer. You should be able to re-crimp the retainer around the nut element or if it was spring clip retained then the clip should be captured by your carpet so then just reinstall the clip to retain the nut element.

Those studs are for the seats. Not sure if you knew or not.
Good luck fixing..

I had the same problem with a different type of vehicle & I used a pneumatic wrench or air drill, what ever you call it, and it tighten right up. I dont know what will happen when you try taking it off, I never did with mine yet.