I was picking up parts to do my rear drum brake rebuild today, and the store had two different cylinders listed. One had a US pipe thread, and the other had a metric pipe thread. Anyone know which is the one I need? As you can see below, I have an '86. I looked in the GM shop manual and the Haynes manual and I couldn't find out which one it was.

Some guy at work told me it was probably US, someone in the brakes forum told me it was metric '84-up.

I looked at two different online GM parts dealers, and one said metric was '84-92 and US was '84-88. So now I don't know what the heck to believe. Anyone know?

 

No one?

 

All GM cars, starting in 1984, used metric threads and flares for their brake lines. They're also known as the ISO flare, or "bubble flare".

82-83 is standard (SAE) threads and double flares.

 

Thanks TomP. I figured out an easy way to tell if they are metric or US. See if a metric wrench fits on the fitting. The drum rebuild didn't go so well. I'll post a thread later with the details.

 

Good idea! Let me guess; 11 mm?

 

Actually it was twelve. But the NEW LINE FITTINGS (more to come on that) are 10mm.