Hidy folks. This is my 2004 XJR and like many others, I was tightening the nuts on the ground studs behind the right side head light and they snapped off. Using 8mm, 1.25 pitch, 1 ½” long bolts, lock washers, star washers, and two nuts per, I was able to replace them.

First, I drilled a pilot hole in the location of where I wanted the new studs. As I could not drill lower due to space restrictions, I had to make them a bit higher. After that, I drilled a 5/16" hole and used a wire brush to clean off the paint around both sides. I put a star washer on the bolt, put it through the hole from the back (had to unbolt the fuse block to gain access), put on a lock washer and a nut. Tightened it down and did not hold the bolt itself in place at first to ensure the star washer bit down into the metal and then tightened them all up. I put the wires on the newly created studs and was even able to use the original 13mm nuts.

Here's a few pics. You can see where the previous studs were. I made one a little higher than the other so I could keep the top and bottom wire sets. I can remove either at any time now though. Hope this helps anyone who is considering it.

 

If you do use a new nut/bolt make sure you purchase an al

like this AL 7075 T6 Hex- Flanged Bolts : Racebolts, High Performance titanium parts at Titanium Performance

Using an alloy bolt will prevent oxidation reoccurring as you wont have dissimilar metals

Also a better way is to Tig the bolt on rather than drill a hole and use a retaining nut.

Most fastener shops will have alloy bolts fairly cheep and you wont have trouble finding someone to Tig it on if you don't have a Tig welder.

Cheers
34by151

 

Excellent point! I had considered getting it welded as I've got friends/neighbors with welders, but I just didn't feel comfortable enough with them welding so close to the head light assy. I'm probably being over cautious, but it makes me nervous. lol Thanks for the input!!!

 

Excellent point, 34by151. The reaction between aluminum and steel is called "galvanic corrosion." I had intended to mention that to Ragman earlier when we were exchanging PMs but I must have forgotten. Sorry, Ragman!

Cheers,

Don

 

You've all got me thinking that I need to "test" this setup with some dielectric grease on the wire loops and the contact points on the bolt along with some Anti-seize on the threads where the nut contacts the bolt. Any thoughts?

 

The main reason to use an alloy bolt (welded or drilled) is corrosion
That's the white stuff for allow (brown is rust on steel)

The reason it goes at the body is the dissimulator metals

So if you have an alloy post it will never corrode at the body again
The worst that can happen is corrosion on the bolt thread but that just a matter of replacing the bolt not repairing the radiator support panel its mounted to as well

Adding some grease or coating will slow it down but the lug will always react with the bolt over time anyway

Id rather replace a bolt than replace a bolt and repair a panel

Think of the bolt as a sacrificial anode (same as on a boat)
Corrosion is going to happen you have to choose as to where it happens on the body or the bolt. Im for the bolt every time

Cheers
34by151

 

Well side! I have them working now and will search for the proper bolts when i have the chance. I don't feel that a week or two will corrode the steel that soon. lol

Respects,
Jason

 

I'm facing this issue with the snapped stud now and trying to drill a hole to put a replacement bolt. How did you achieve enough clearance with the drill bit? I'm struggling with 1. clearance to drill a new hole, and 2. the length of the wires since they only seem to have a few cm of play

 

I think you have to remove the headlight unit

 

You may be able to accomplish the job with a right-angle drill or a flexible drill bit extension, but it's far easier if you remove the headlamp, which also requires removing the grille and disconnecting the bumper cover, which are not difficult at all. Placing your new bolts a little higher like Ragman did will help, if your wiring harnesses will reach.

Please let us know how you get along.

Cheers,

Don

 

We Just did that repair as well (WORKS GREAT! by the way) We did have to pull the headlight to get good access. We used stainless steel bolt and aluminum washers on both sides of the frame. I over sized the hole so the steel wouldn't touch it. Then I used the aluminum washers between the radiator support and the steel bolt. If the washers corrode so be it. I'll replace them. But the washers will be the problem not the frame of the car. Then I painted the whole thing so no water gets in to make it even worse. I have a welder, but the existing aluminum bolt and nut corroded from the factory, so I didn't believe that would work. Since I didn't want to have to do it again in a few years I figured that it's easy enough to replace washers when the time comes.