c2 stingray

Hello, I'm asking for support : My car ( C2 convertible MY65 with 396 - engine ) has the disc brake conversion kit with dual master cylinder, front = 4 piston Caliper and this Proportional Valve from "Corvette America" ; The problem is the distribution of brake power ! too much on rear axle . Does someone know an adjustable "distribution valve" to get more hydraulic pressure to the front axle ? Something instead of this Proportional Valve ?? ; thanks for your advice Alex

jim lockwood

I don't know of such a valve.

In my not always humble opinion, the way to achieve proper proportioning is to fiddle with the sizes of the caliper pistons. In your case, increasing the sizes of the front caliper pistons or reducing the sizes of the rear caliper pistons will move the proportioning in the direction you need to go.

If you install front calipers with larger pistons, you'll have a more responsive pedal feel, although pedal travel will increase.

If you install rear calipers with smaller pistons, pedal will be less responsive but pedal travel will be less.

Another way to change the proportioning would be to install front pads which have higher friction coefficient than the current pads. Any of the aftermarket brake pad suppliers, Hawk, Carbotech, Porterfield, etc..... can help you with this approach.

MelWff

The 65 came with 4 wheel, 4 piston, disc brakes from the factory. The only thing based on your description that is not factory is that you have a dual master. So I think you are looking for this
http://www.ecklerscorvette.com/propo...ht-switch.html

c2 stingray

that is exactly what I'm looking for ; Thanks from Germany

Tampa Jerry

What system do you have? A handful of 65 vettes, maybe 300 to 350 came with drum brakes. The rest of the 65 year came with discs on all four wheels. Do you have an aftermarket system that started out as a stock drum system and was changed to something else? If you have a stock system, there is no proportioning valve required. The front pistons are larger than the rear pistons by design. I converted my 66 to a dual M/C system and did not require a proportioning valve. I think something else is going on here. Jerry

Plasticman

Do you have the original GM 4 piston calipers on both ends, or did someone change to aftermarket calipers?

Plasticman

JohnZ

Your '65 came with disc brakes all around, and never used/doesn't need any sort of proportioning valve - the front/rear proportioning is designed into the system hydraulics via different size caliper pistons in the front and rear, and if the car came with power brakes, it already had a dual master cylinder from the factory. Leave the system alone.

jim lockwood

John makes a good point..... your car almost certainly came from the factory with disc brakes. So what is this conversion kit you mentioned?

MikeM

All that is really known is that he has a '65 Corvette with a 396, disc brakes and a proportioning valve from CA? Nothing there says it's factory.

Based on other posts, many people often confuse a distribution block with a proportioning valve. There are also combination blocks that do both.

Which block are we talking about here?

c2 stingray

the car was originally with small block engine and drum brakes; then engine change to 396 and brake system change to "Corvette America" disc brakes with Delco Calipers ; First I drove without proportional valve, but this results in too much brake power on the rear axle, then I installed the proportional valve : the result now still too much on rear, but better - the disadvantage : need in sum more pedal force for the same retardation;

jim lockwood

I'm looking at a Corvette America disc brake conversion kit, but I'm seeing a single piston front caliper, not a four piston caliper. Also, the kit I've found is just for the front...... use of this kit would mean rears would continue to be drum brakes.

See: CA disc brake kit

So, two questions:

1. What calipers do your brakes use?

2. At the rear, disc or drum?

toddalin

That's the way it works. In your initial post you asked for more pressure to the fronts. But that's not the way it works.

The only way to get more to the fronts with your current set-up is to use different material pads, or cut pressure to the rear and boost the overall pressure (e.g., power brakes), or pedal travel (e.g., smaller M/C cylinder bore).

I have Corvette disks in front and drums in the rear with a Corvette dual 1" manual M/C and even with the proportioning valve and 10# residual valve in the rear line, the brakes sucked. It was always that "last bit of the stop" where the car just didn't want to stop even mashing on the pedal with all your might and you felt like you would tap the bumper of the car infront of you.

But when I replaced the front pads with Andy Porterfield R-4S compound, all that went away and they became a world better.

c2 stingray

disc

MikeM

Possibly your master cylinder is by passing the seals for the front brakes?

LB66383

Correct me if I'm wrong, but the system in your picture looks like a basically stock '67 master cylinder and lines. If so, are you calling the chunk of metal that the master cylinder lines go into a proportioning valve? It is not, it is basically a fancy junction block that does not proportion any of the brake pressure. As John Z and others have noted, all of the proportioning in the C2 and C systems was done by the different sized pistons in the front and rear calipers. If you are not using factory Corvette calipers, then the brake balance is a big unknown. Although you did say they are Delco calipers, so maybe they are the factory-type.

mrtexas

The various hot rod suppliers sell a metering valve that delays the front disc brakes from coming on before the rear drums.

JohnZ

Here's a primer on the various types of brake hydraulic hardware that's out there, when and how it's used, and how each item operates. Unless you have the wrong master cylinder (disc/drum instead of disc/disc), your CA system should work fine - it's identical to the stock '67 system, and DOES NOT need a proportioning valve in the rear line.

http://www.camaros.org/brakevalve.shtml