A bit frustrated right now with my GSL rear end swap I have been working on...

As I was piecing together all of the parts over the last 2 years or so, I noticed that one of the wheel bolt threads on the axle was a bit rough. At the time, it still looked OK so I ran a M12x1.5 tap through it and felt good about how the threads looked. At the time I contemplated having all the holes re-drilled and pressing in studs... but decided not to.

I installed a rebuilt GSL rear diff, GLS-SE LSD/ring and pinion, all new OEM suspension links... complete front and rear caliper rebuild and brake overhaul.

And as I am tightening the rear wheel bolts for the test drive, one just kept turning. I was pissed.

It s stripped out. I figure there are two options.

#1: Drill out and install a stud. I figure I can do this without pulling the axle. I can make a drill guide from a big block of metal and drill it out to pull a stud in with a spare lug nut. ARP stud with 15/32" drill dia.
#2: Heli coil repair, similar to above but re-tap and install a helicoil.

I figure #1 is the best way to go and the lest risk of messing stuff up further.

I found a few threads on this but figured I would post to see what you guys think. Lesson learned, if you have the time, always drill out and convert to studs. Studs are the way to go, strange that VW and BMW still use threaded hubs instead of studs.

 

drill it out for studs. i wouldn't trust helicoils in this application. more torque involved than say a stripped out water pump bolt hole would have.

 

The other option would be to TIG weld the hole all the way and drill/tap.

 

Helicoil would work fine in this application, as long as you have enough thread depth. It’s essentially like sizing up to an m14 bolt.

 

Drill the hole bigger and install studs from behind and you will be set...

https://www.mazdatrix.com/product/st...se-86-92-rear/

 

And I just remembered I have spare OEM -SE studs since I have a set of spare -SE axles stored away for future use. I think I can borrow one to get back on the road.

I will follow up with a post of the install.

Thanks for the link Raven, it made me remember the -SE has studs. And the ARP ones need a chamfer on the other side and might have a knurled length that is too long for our thin axles.

 

I had this happen, I ran a tap through to 1/2-20, then ran a 14x1.5 tap, and used a Volkswagen/Audi lug bolt. All 5 lug VWs had 14x1.5 bolts.

 

Had this happen when I was racing in IT7. I got a used axle from a friend that turned out to have a couple of less than ideal lug holes. So I just drilled out all of the holes and pressed in 12mm ARP lug studs. Super easy fix.

One way to avoid this kind of thing is to install screw in studs and stop using lug bolts. Which is something I did on my race car and never had any issues with the OE lug holes.

 

Oddly, a big issue I am having with my Ford 9" is studs galling. They don't like constant tire changes. This is 100% due to cheapo aftermarket studs, unfortunately the axles were built around Ford Escape studs for some reason, not super common GM studs, which have a smaller knurl.

It's funny, out of six cars I own, my '84 GSL is the only one with studs instead of bolts...

 

Probably not as funny but my RX7 race car is the only car I have ever owned that had lug bolts. Just not something I am used to so I converted to studs.

Weird regarding the size of the knurl in your 9" axles. ARP or Moroso don't have an application for it? I have used studs from both of them and they are harder than the nuts.

I used to have lug nut issues until I started getting them from Track-Studs.com Also used their screw in studs before I went to the press in variety.

 

It's a weird size. Annoying because I have about 40-50 studs scavenged from GM hubs over the years. Had a stud gall, so I knocked it out and went to install one of my saved ones, and it just rattled in the hole. By sheer happenstance, I had a front hub from a '10 Escape in the scrap bin, and the studs are identical.

ARP does not make studs for this application The super annoying part is, ordering auto parts store studs would have a 2-3 week wait, and they're probably the same junk that is failing.

 

Probably you will have to weld shut the holes completely, drill and tap new holes to fit the new studs....

 

There's plenty of material to drill for a different pattern.

What I SHOULD do is just drill and tap for 14x1.5 threads and be done with it. That way I can also drill for 4x100 and be able to swap wheel flavors without having to worry about the studs being in the way.