Has anyone ever installed a disc brake conversion on a 70-72 Skylark? If so, were there any issues? I purchased a disc brake conversion kits from Jegs. The mechanic who is installing it as been having all sorts of trouble with the installation. He tells that when he installed the kit that the pedal will go all the way to the floor. However, if he pinches off the brake lines going to the rear brakes , then he will get pressure in the front brakes. He also states that the proportioning valve that came with the kit has a 1/4 inch inlet, whereas the brake lines are 3/16th's. In a nutshell, the mechanic is saying that there are issues with the proportioning valve. Has anybody else ever ran into issues like this installing a disc brake conversion kit on a Skylark? Any ideas for possible solutions?
Can be made to work I believe (Re: Disc Brake Conversion Issues) Dear 1970Skylark350 and V-8 Buick brake experts, I'm definitely no expert but my local shop installed a SSBC front disc brake kit in my 1965 Buick Special. I believe the kit was this version (or an earlier version of it: ) http://ssbrakes.com/i-10092579-disc...n-with-11in-rotor-power-2in-drop-spindle.html It has a proportioning valve that it fit as advertised and works properly. My only compliant is that there is a slight tendency to pull to the left while braking that has never been worked out. I'm hoping this matter can be resolved when the car gets her assertive JW masterpiece engine. You might get better feedback if you can post which disc brake conversion kit you purchased. Clearly different kits may be easier or harder to install. Cheers, Edouard :beer
I answered your post on BuickForums.com also, but here is my answer. The proportioning valve you are using is actually a combination valve. It combines a hold off valve, proportioning valve, and warning light connection. The purpose of the hold off valve is to hold off the front brakes until pressure is built in the rear. This is because disc brakes inherently apply instantaneously whereas drum brakes have clearance between the shoe and drum, and must overcome spring pressure to apply. On stock 70 disc brakes, the hold off valve is separate, and is mounted up near the master cylinder, but in later years, OEM used a combination valve. Being you have a conversion kit, you probably have a combination valve. For the stock system, the service manual instructs that when you bleed a disc brake system, you must depress a pin in the combination valve (hold off valve pin). It is located under a rubber boot on the stock valve, but I don't know what you have. Also, it is very important that you bench bleed a new master cylinder before installation. You did get a new master cylinder, right? A disc brake master cylinder is different than a drum brake master. __________________
