How do you fix stripped nut/Engine crossmember?

[prayers1 153]

I've been keeping an eye on the internal nut for the front crossmember. I assume in the past someone over tighten it and stripped some threads, now I just installed a heavy duty crossmember and I can't seem to get the bolt tight enough. It turns in but gets to a torque point where it jumps threads and spins. I've tried replacement  similar bolts and have the same results. I was thinking of forcing a coarse thread bolt in. I can't find a bolt re-threader big enough to retread it.

What do you all suggest!

Thank you

[RPM 1,190]

When one of mine got buggered up to the point I thought it was toast, I ran a 1/2-13 tap thru it to clean it up. I only use hand tools on these bolts now.

[LoneWolf2U 136]

The retap may work, Or try getting a next size up self tapping bolt to replace it with.

[prayers1 153]

I found a re-threader in my bottom draw hidden, so I'll try to retap it and see if there is enough metal to work with. I did find a spot to get these special bolts that are sold as 1/2-13 tractor wheel bolts. I'll stop at a local tractor dealer and see if I can pick one up. These bolts are specific to the design of the crossmember where it has coned hole to except the coned shoulder of the bolt.

I read that Ford made tractors and used this specific bolt on them so this maybe why it shows up on the Mustang.

[Alan_Mac 48]

My crossmember bolts hold a TCP Rack.  One of my internal threads was bad likely from corrosion.  I tapped both holes 1 size larger and installed grade 8 bolts with a washer and lockwasher.  

[1969_Mach1 333]

If chasing the threads with a tap doesn't work, the next easiest thing to try is a thread repair (heli coil).  There is also, a repair like Alan_Mac did.  Whatever the repair, use anti-seize compound on the threads and do not tighten them with a torque wrench.  With anti-seize compound, if using a torque wrench it's possible to damage threads before reaching the desired torque setting.

Curious, is the new heavy duty cross member designed to reuse the original bolts with a counter sink head?  I've looked at aftermarket cross members but noticed they are not designed to use the original bolts.  The original cross member uses bolts with a counter sink (taper) below the head.  This positively locates the cross member and prevents any relative movement between the frame and the cross member.  

[bigmal 225]

I recently replaced the chassis rail ad didn't notice that the anchor nut on the new rail wasn't installed. Rooky error. I cut a small slot big enough to slide a not in. Once in I positioned it and welded from underneath. A bit of a tidy up with a grinder and it looks good and is quite solid. Possibly not what you need to do but an option.

[prayers1 153]

1969_Mach 1- The holes are tapered. I purchased it from a Guy On VMF, if you mention you are a member he gives a 10% discount. He's also on eBay https://www.ebay.com/itm/1967-1968-1968-1970-Mustang-Cougar-Shelby-Low-Profile-engine-crossmember-/232224703239?fits=Year%3A1969|Model%3AMustang&hash=item3611abc307:g:sp4AAOSwo4pYkVLt&vxp=mtr

I went to the John Deere tractor store and all they had was a 1/2-20. The original is more course 1/2-13.

I picked up a tap at Home Depot 1/2-20 and if possible work on it tomorrow.

[RPM 1,190]

Prayers, why are you going to run a 1/2-20 tap thru a 1/2-13 nut? Seems to me like you're asking for problems. 

[prayers1 153]

 

As Alan_Mac did, I have to leave the crossmember in place while I make the repair, if not it would throw the alignment off. I would need to take it off to tap one size bigger.

I haven't done it yet, but my thinking is that there isn't enough material to run a 1/2-13 tap which is a coarse thread.

If I use a fine thread tap such as a 1/2-20, this will allow more threads to develop.

I've been thinking all morning about it and I'm leaning towards a heli-coil. Downside is that due to the aftermarket heavy duty crossmember design the bolts need to come out everytime I need an alignment.

[1969_Mach1 333]

First try chasing the threads with a 1/2-13 tap to see if it straightens out the threads enough to work.

1)  Rethreading it to a fine thread will not help if there is not enough material for a course thread.

2)  If you rethread to a larger diameter or a fine thread you cannot install the original style bolts with the counter sink that locates and holds in position the cross member.  Doing this eliminates the purpose of the counter sink bolt holes in your new cross member.

3)  IF there is enough material, I would get a thread repair kit for 1/2-13 UNC.  Heli-Coil is a common brand.  NAPA auto parts usually has a good selection of these.  Also, most hardware stores have them as well (not Home Depot or Lowes).  If you go this route, when you install the heli coil put a small amount of red Loc-tite on the outer threads of the heli coil.

I looked at the cross member you purchased.  It's actually the nicest aftermarket cross member I've seen.  But the bolts to the frame do not have to be removed for an alignment.

[prayers1 153]

Yeah, I don't want to wad up the bolt hole and get screwed, I'm kinda leaning your way since I didn't do anything to it yesterday and had more time to think on it. Also, it seems to be the easier way to start, I'd like to have a new bolt with more bite on the threads instead of the old one I have to use after I retap the hole. I feel if I go back to the old one I might be back where I started. I can't seem to find a1/2"-13 lug bolt, I'll keep looking.

FYI- The bolt do need to be removed in order to place shims on the new bolts for the LCA.

PS> Found the bolt as a set on Summit-379068-S

[RPM 1,190]

On 10/21/2017 at 8:28 AM, prayers1 said:

Downside is that due to the aftermarket heavy duty crossmember design the bolts need to come out everytime I need an alignment.

I'm not following you on this.  Which bolts, the lca bolts or the crossmember mounting bolts?

[prayers1 153]

The original LCA bolts with the eccentric washer are removed and new bolts are used with spacers, There are 4 different spacers provided that have 4 different mounting holes used to adjust the LCA for the front end alignment.

Look at my above thread where I show where you can purchase the crossmember and you will see the spacers I'm talking about.

[RPM 1,190]

Ok, I'm familiar with the parts, but got corn fused on the process.