Question about residual pressure valve

[mc1984ss]

The car I'm working on currently has drum rear brakes. It's getting upgraded with wilwood front brakes and a wilwood master cylinder and adjustable proportioning valve. Wilwood told me to install the red residual pressure valve in the rear line and then remove it when I swap to rear discs. My question is it possible to "empty" the residual pressure valve when I don't need it? When I remove the valve it will be such a short area it will be impossible to make a line to fit in the short space. I figure if there was a way I could keep the valve in place but empty or hollow it out so it takes up the same amount of space but is rendered useless? I hope this makes sense. Thank you in advance.

[oleyeller]

Yup, just remove it, take the guts out and reinstall.

[Blown353]

What kind of rear end? C-clip 10/12 bolt, floater, 9" with pressed on bearings?

For cars with c-clip axles and fixed rear calipers leaving a 2# residual valve in is a good idea, otherwise you'll likely have a low pedal from axle movement and pad knockback. If using fixed rear calipers on c-clip axles it's also a good idea to buy an oversize c-clip kit and put in the thickest c-clips in that you can for the least amount of axle endplay possible, again, for pad knockback reasons.

This is a lot more critical on cars with manual brakes and small diameter master cylinders, as a little pad knockback on a manual system can result in a very low pedal on the first application. For a car with power brakes and a large 1 1/8" diameter master, the master moves a lot more fluid volume and the pedal drop won't be nearly as bad.

If you're running manual brakes with fixed calipers I would probably replace your 10# red residual valve with a 2# blue residual pressure valve regardless of what kind of rear axles are in the rear end, same goes for a 2# residual valve for the front brakes. The 2# residual valve doesn't cause any excessive pad drag and helps keep the pedal higher with manual brakes.

[mc1984ss]

Thank you for the very detailed response. The car currently has a 10 bolt with stock drum brakes. I do have a q.p. 9" with Torino "big bearing " ends that will go in the car someday. When it does it will be getting disc brakes, probably explorer disc brake setup