another proportion valve question

[bad86ss]

I have an 86 ss monte carlo and am doing a brake swap. The first step (doing tomorrow) is 12" ls1 rear disc. Ill ride around for a month or so like this. Then, ill swap my front stock disc to 13"c5s.
Can I ride around town without touching my stock valve for the month of stock fronts, ls1 rears?
What about when im completely finished (c5 front, ls1 rear)?
This is my first rodeo with brake swapping....any input is appreciated!

[a67]

The main thing to check for is the rear disc brakes dragging. If they do then the combo valve is going to need some work or to be replaced. Drum brakes typically have a residual pressure check (RPC) valve. If there is one in place that will cause disc brakes to drag. A RPC valve retains about 10 psi in the system to keep the drum brake wheel cylinder seals tight against the bore.

The proportioning will be incorrect, with less braking force in the rear then there should be (drums are self actuating). The metering valve section of the combo valve will cause the rear disc pads to wear faster then the fronts. But neither of these are an issue for a months worth of driving.

Bob.

[bad86ss]

Thanks for the fast and descriptive response!
Some guy online told me once the fronts are on, I need to bypass the factory valve. That would give equal pressure front and rear, is that right?

[a67]

Bypass the factory combo valve and place an adjustable proportioning valve in the rear brake line.

Bob.

[bad86ss]

So nothing on the fronts, adjustable rear?

[a67]

So nothing on the fronts, adjustable rear?

Yes, use an inexpensive adjustable valve in the line going to the rear brakes. Wilwood and Baer both sell the valve, with the Wilwood part number being: 260-8419

Bob.

[bad86ss]

Thank you. I got everything ironed out today as far as the swap goes. Doesnt do too bad with the stock combination valve, surprisingly. Ill do an adjuster rear though

[Skip Fix]

Yes just a simple T on the front or if any drag racing use a Line Lok as the T in front and adjustable prop in the rear.