1966 proportioning valve

[Peter J.]

Why is it only the L-72 option got a brake proporting valve in 1966? And for you guys that drive your Power brake cars, do you use a valve to equalize your brakes? I have seen the small easy to hide valves that appear easy to splice in a brake line out of obvious sight. I am left with the choice to use a correct part on a wrong optioned car or an aftermarket part. Any in put would be appreciated.

[Michael W.]

Re: 1966 proportioning valve

I thought only J56 cars with L72 got the valve. Other combinations didn't need the valve as the inherent front to rear balance was acceptable. Nothing to do with power/non power brakes.

Why do you believe that your car needs a valve?

[Duke W.]

Re: 1966 proportioning valve

That's correct. Only J-56 got a proportioning valve and J-56 was only available with L-72.

Duke

[Joe L.]

Re: 1966 proportioning valve

Pete-----

As Mike and Duke mentioned, the adjustable proportioning valve was only used with J-56-equipped cars. As a matter of fact, only 1966-68 with J-56 had the valve. 1969-75 with J-56 used no valve.

In a 1965-82 Corvette disc brake system, brake system "proportioning" is accomplished by the different size pistons used for the front and rear calipers. The 1-7/8" pistons used for the front and 1-3/8" pistons used for the rear provide the front-to-rear proportioning required for most of the 65-82 Corvettes.

Also, the widely misinformed notion that the brake system distribution block and pressure differential sensing switch used on 1967+ Corvettes is just that----a widely misinformed notion. For 1967 through 1977, this component had NO proportioning function, whatsoever.

In 1978, the weight of the Corvette began to exceed the inherent proportioning of the brake caliper piston sizes. Rather than change the piston sizes, GM went to a FIXED RATE proportioning valve which also included the brake distribution and pressure differential sensing functions. The unit then became a COMBINATION VALVE. This continued through the 1982 model year.

[Peter J.]

Thanks Joe, That is what I was looking for. *NM*

[Peter J.]

Thanks, Mike & Duke *NM*