Date: Tue, 17 Apr 2001
Greetings. I have been having a difficult time with a disk brake conversion on my 66 1800S. I used the four wheel disk system from a later 1800e, seemed like a simple switch at the time. Now that it is all replumbed with new lines, pads, turned rotors, and new double master cylinder, I cannot get the confident braking I was hoping for. The wheels seem to lock up at different times when I brake hard (quite exciting in traffic). I have bled the lines through a few gallons of brake fluid and always get the same result. Do you have any suggestions? Thanks in advance.
Erik
66 1800s, 65 pv544
Erik - I am not familiar with the later model brake systems, but I have heard that they use a pressure equalizing valve located near the middle of the car (underneath). If you didn't install this valve, or if it is the wrong valve, or if it is gummed up, it might cause lockup problems. It would be best to study the original equipment on the donor car or one like it, and try to duplicate the setup on your car.
On the other hand, this could be a "normal" type of brake problem -- leaking fluid, stuck calipers, contaminated or ill-fitting pads. If it's the equalizing valve, then either the front or the rear brakes will lock up fairly consistently. If it's a normal brake problem, then the chances are that only one wheel will lock up. You can tell if it's one wheel, because the car will jerk to one side. Check the brakes carefully all the way around for any symptoms of poor operation. Look at your skid marks or get a friend to stand by the side of the street to help you determine which wheels are locking up.
Lockups can also be caused by deteriorated rubber hoses. Old rubber brake lines are susceptible to swelling inside when they are unused for any length of time. When they get this way, fluid can be forced through them with the brake pedal, but then it takes longer than usual for the fluid to drain back from the calipers. The only remedy for this is new hoses.
For more information about your particular setup, you might try asking on the Brickboard (http://www.brickboard.com) or the 1800 e-mail list (http://groups.yahoo.com/group/1800list). -Glenn.