Hey, i have a question regarding the installation of a wilwood proportioning valve. the outlet for the rear brakes is 3/8-24 whereas the line going to the rear brakes is 9/16-18. How am I supposed to make that connection? The other lines also don't have the correct fittings but I thought I could reflare the lines with the 3/8-24 fittings but the rear line is larger in diameter so the 3/8-24 nut won't fit. any thought?
Apparently Wilwood thinks you need to plumb the rear brake tube using smaller-diameter tubing (which is unreasonable, but somewhat common.) GM products tend to use 1/4" tubing to the hose at the rear axle. The hose tees into a pair of 3/16 tubes to the brakes at each wheel. I worked on a Ford a few weeks ago that had 3/16 tubing all the way back, and I guess Wilwood thinks that's adequate for everything. Any chance Wilwood makes a proportioning valve more suitable to GM applications which might use 7/16-24, 1/2-20, or 9/16-18 thread sizes? Tube nuts suitable for 1/4" tubing are available. http://www.summitracing.com/parts/sum-220115/applications By comparison, 3/16 tube nuts typically come in the same three larger sizes, plus the smaller 3/8-24 thread size. http://www.summitracing.com/parts/sum-220137/applications
Howdy, I had the same issue when I did my front disc brakes. This stuff will make your head spins. There are two typical brake lines sizes used: 3/16" and 1/4". Typically, 1/4" is only seen on the rear lines. Most of the guys doing high performance brake system conversions are going all 3/16" hence the Wilwood proportion valve that is setup and you have already seen. There is much debate about the difference in brake line sizes, but again many have ditched the weird 1/4" stuff and many modern cars are using all 3/16" as well. The stock 1/4" rear line uses a weird giant fitting that no one seems to use any more, which complicates things. There are a few companies that sell some odd inverted flare fitting adapters, but you will be hard pressed to find one in that size. Typically, you will see 3/8-24 fittings for 3/16" lines and 7/16-24 for 1/4" lines. Those are the standard sizes, but there are others to be found. They are not interchangeable between line sizes obviously. This gives you two options. Option A involves removing the old 1/4" line and making your own 3/16" line to the rear. It is not that difficult to bend and make fittings (the proof is the I actually made some brake lines, so I bet you can too!). You would then be able to use the 3/8-24 fitting. You would need to get a different Y fitting for the individual rear wheel lines as well since the old one was for 1/4" line. Option B involves removing the old weird fitting on your 1/4" line, and putting on a more common size that will allow you to use an adapter that goes from 1/4" to 3/16" line. I bet you can find one that goes from 7/16-24 1/4" to 3/8-24 3/16". Google it! Hope this helps, and hit us up with more questions!
One of the things I've done in the past is to slip the 3/16 line into the 1/4 tubing & braze them together. The one's I've done have held up for 20+ yrs. Just another option. Tom T.
