[Lightfoot]

My '89 LeSabre needs a new brake pipe for the LF corner. Master cyl to flex hose.

I can't tell if the fitting threads are 7/16-24 or 11mm-1.00 (at the master cyl outlet)
and 3/8-24 or 10mm-1.00 where it threads into the flex hose junction.

Very important because I can't find pre-flared straight line that has the two different end sizes and will need adapter fitting(s).
I'm having a hell of a time finding pre-crimped line that has the 'approximate' thread size plus proper flares. Looking on-line because I'm stranded at home.
Any help is greatly appreciated.


Secondary question:
This OEM also has the 'bubble' flares instead of inverted flares on the ends.
Would NiCopp line be too soft for the bubble flares to hold high braking psi?
It sure would be easier to make the bends to make the installation.

[Lightfoot]

Using open end wrenches as a poor man's outside caliper, I found that the large end is too big for an 11 mm to slide over (threads), but my Snap On 12 mm goes over it with approx 1/32" clearance.

Also, the small end would not allow a 3/8 open end to slide over the threads, but a 10 mm wrench goes over with about the same amount of clearance as the one above.

So now, I think I am dealing with a 12mm-1.00 (upstream) and a 10mm-1.00 (downstream), providing they are truly metric, and not fractional.
I previously eyeballed them against a tape measure, when I estimated them to be 7/16 and 3/8. Still not totally sure though.

The PITCH is still in question. I think it is the same on each end because I could 'mesh' the two threads together, plus I carefully counted the grooves over the same distance, and came up with 8 or 9 on each fitting.
So it's 24 per inch if SAE. Or if it's metric, it could be the more common 1.00, or possibly 1.25.

I appreciate input from anyone who has a good handle on what GM would have commonly used in that era.

[jerry455]

It should all be metric. I have always used the lines at AutoZone and have never had a problem. You could see if anyone makes a line kit for your car.