Post by Volktales on Sept 30, 2016 21:03:26 GMT -8
Soooo, if you are like me and spend a bit of time on the Samba, you will see constant references to the above. It seems many people would like to see all single circuit master cylinders as found on all 1966 and earlier Volkswagens, replaced with the dual circuit type as found on 1967 and later models. Why would you do this? For safety reasons. 1967 was the year that dual circuit cylinders were mandatory by government decree in both the US and Canada. The reason for a dual circuit system, is that if one half of the system fails, you would still have the other half functioning. For the air-cooled era, this means that if the rear brakes hydraulically failed, the fronts would still operate. If the fronts failed, the rears would still operate and stop you safely. This was seen as a more safe option then the old single circuit system. If hydraulic failure occurs in the single system, you have no working brakes at all! The dual systems always contained a warning light as well to tell you that a failure had occurred. This is the mysterious "B" button/light on the dash that few understand...
So you would think converting from the early single system to the later dual system would be a no brainer, right? Well... If you do the conversion you do have to make some changes to the brake lines, you need a different dual reservoir and mounting bracket, and associated reservoir pipes to the master cylinder. The wiring will need to be modified for the dual brake switches, and probably no one would ever install the warning light. Is it worth the extra effort???
That depends on one thing. Which circuit is most likely to fail in a dual system? I have personal experience with this, as it happened to me in my 1970 VW Beetle. While coming to a major intersection in Victoria, my right front flex hose decided to fail! This meant a complete loss of front brakes, yet the rears worked just fine. Except they were useless as the rear wheels simply locked up and the car still ended up skidding into the middle of the intersection! Luckily it was late at night, and few cars were nearby. This is just a matter of physics and your front brakes do way more work to actually stop your car then the rears do. This is why the front brakes are always bigger then the rear, and why many cars use better disc brakes in the front, and drums in the rear.
Anyway if you lose your rear braking system, the car will stop fairly well on the front brakes only. So is a dual system superior? Only if the rears fail. This is actually a very common problem on pickup trucks with rusty brake lines, and usually the owner is successful in stopping. If the fronts fail instead? You ain't gonna stop in time...
So you would think converting from the early single system to the later dual system would be a no brainer, right? Well... If you do the conversion you do have to make some changes to the brake lines, you need a different dual reservoir and mounting bracket, and associated reservoir pipes to the master cylinder. The wiring will need to be modified for the dual brake switches, and probably no one would ever install the warning light. Is it worth the extra effort???
That depends on one thing. Which circuit is most likely to fail in a dual system? I have personal experience with this, as it happened to me in my 1970 VW Beetle. While coming to a major intersection in Victoria, my right front flex hose decided to fail! This meant a complete loss of front brakes, yet the rears worked just fine. Except they were useless as the rear wheels simply locked up and the car still ended up skidding into the middle of the intersection! Luckily it was late at night, and few cars were nearby. This is just a matter of physics and your front brakes do way more work to actually stop your car then the rears do. This is why the front brakes are always bigger then the rear, and why many cars use better disc brakes in the front, and drums in the rear.
Anyway if you lose your rear braking system, the car will stop fairly well on the front brakes only. So is a dual system superior? Only if the rears fail. This is actually a very common problem on pickup trucks with rusty brake lines, and usually the owner is successful in stopping. If the fronts fail instead? You ain't gonna stop in time...
) 