I wanted to share a learning that may save other rookies (like myself) some headache when working with brake lines. Some of you experts I'm sure can clarify a few things.
On my '51 1/2 ton, rear brakes, I decided to replace the left wheel cyclinder as it was a different diameter than the right WC (15/16" vs 1"). I ordered a new WC from ClassicParts.com. I ruined 2 new brake lines trying to screw them into the WC. I thought I was cross-threading, so I pulled the WC so I could get a better handle on it. I actually had to put it in a vice in order to screw in the brake line. I knew this wasn't good.
I took the WC to O'Reilly, and the guy immediately identified the problem as the new WC taking a brake line with a "balloon flare" (rounded on the end), not a double flare (recessed on the end). The bottom of the hole in the WC was concave or sunken, so it could accept a rounded flare. The bottom of the hole on the old one was slightly convex, so it would fit into a double flare. Also, apparently, the threads on the fittings are different pitch between the two types of flares/lines/fittings.
I had no idea there are different kinds of flares on brake lines (this is the first brake job I've done in my life). So to anybody who may replace a WC, look at the bottom of the hole where you screw in the brake line. If it's concave (sunken), it takes a balloon flare (apparently, the odds are a new WC will be of this type); if it's convex (protruding), it takes a double flare.
Experts, please tell me if I'm spreading garbage here. In any case, there's one indisputable fact: I can't thread a new brake line with a double flare into my new WC, for wahtever reason. I haven't determined whether a ballon flare line will thread in properly, as nobody locally stocks those lines. ODD--new WCs take balloon flares, but nobody stocks balloon flares!!
Last edited by ol_red; 04/06/2008 5:33 PM.
