LR bolt specs?

[Mozambique]

Hi,
Bolt size specs have always been a mystery to me. I am in Canada so we have north American sizing systems and also metric. LR bolts take metric spanners so obvs metric sized bolts, but is there more than one metric system?

I ask because the lower air compressor bolt that holds the plastic cover on snapped when I breathed on it with a spanner. Cover stays attached fine with the existing screws and plastic tabs. However while I have the compressor out I thought I would drill the bolt out and re-tap the hole. What bolt thread type tap to get? I guess I could just purposely drill a slightly larger dia hole and ignore current bolt size as the bracket has enough meat in it and I would just need to drill a larger hole through the plastic cover too.
Any advice gratefully received!

 

[ryanjl]

There is only one metric. A millimeter is a millimeter. But there are different thread pitches.

 

[Mozambique]

Yes, obvs metric is metric.
Its the thread pitch that I guess puzzles me. As an example, I wanted to clean up the threads on the half shafts. Bought a "shark tooth" gauge to determine the thread pitch, but was not very definitive re. Determining what die size to buy.

 

[ryanjl]

The pitch is almost assuredly the same across the board for a given part, so just take one of the other bolts out, go to a hardware store, and figure out what it is.

 

[ftillier]

You might not need to drill it, if you have the bracket out. Spray with some pb blaster and see if it loosens up? My concern with drilling is that the bolt is steel, while the mount is aluminum. If you don't stay centered you could make a mess of things. A screw extractor might work, though. I snapped my compressor mount and the cheap knockoff I got wasn't tapped for the bolt, and the hole was too big so I had to find a larger bolt, I think m10 instead of m8.

 

[Mozambique]

The pitch is almost assuredly the same across the board for a given part, so just take one of the other bolts out, go to a hardware store, and figure out what it is.

Well I am hoping the other three bolt shafts are larger dia as they are holding the weight of the compressor. The single bolt on the underside of the plastic case is not holding much weight. It snapped immediately without much torque. I sprayed the other three bolts holding the bracket with WD40, but have not tried to undo them yet. Fingers crossed not siezed as located within plastic case.

 

[Mozambique]

You might not need to drill it, if you have the bracket out. Spray with some pb blaster and see if it loosens up? My concern with drilling is that the bolt is steel, while the mount is aluminum. If you don't stay centered you could make a mess of things. A screw extractor might work, though. I snapped my compressor mount and the cheap knockoff I got wasn't tapped for the bolt, and the hole was too big so I had to find a larger bolt, I think m10 instead of m8.

Not sure a screw extractor would work as bolt head snapped off. It may loosen as I drill it out.

 

[ftillier]

the screw extractors still require you to drill a hole in the center of the broken off bolt, but it's reverse threaded and tapered so when you tighten it, it eventually works the broken bit out (in theory, at least). You're only drilling within the steel though, and not at the steel/alu interface.