by m1dadio Mon Nov 01, 2010 9:07 pmI have come across another idea to fix up the low brake pedal problem when on Disc brakes. Without changing the pedal ratio or master location.
Somebody is going to have to take the chance and spend the coin to see if it works.
In 1980 GM came up with a new caliper design called "low drag" calipers. The seal slot in the casting was machined to a 30* angle instead of a 15* angle like older calipers. This made the caliper piston retrack twice as much from the rotor to reduce drag for better fuel economy.
Some of us may have this design of caliper on our rear disc brakes which would surely cause for a low brake pedal.
To compensate for this extra volume of fluid needed on brake application GM developed the "Quick take up" master cylinder. These master cylinders have a two stage bore with two different piston sizes in one. They have a very large dia bore that moves a large volume of fluid at first until preasure begins to build then internal valving switches up to the smaller bore that increases preasure rapidly with much less pedal movement.
I think one of these quick take up masters will seriously reduce pedal travel on our disc brake set ups.
The costly part will be expirementing to find the one that works best.
They are all duel circuit, some with two and some with four outlet ports of the same line and thread sizes as the current 68 corvette master.
They come in 1" bore and 1.125" bore with the quick take up bore sizes from 1.4" to 1.5" dia bore.
Here are some examples:
Napa # 39571 bore is .944" and 1.41" (1985 blazer T10 4wd)
http://www.napaonline.com/Search/Detail.aspx?R=UBP39571_0236103985
or Napa # 390259 bore 1.125" and 1.5" (1995 blazer T10 4wd)
http://www.napaonline.com/Search/Detail.aspx?R=UBP390259_0192051904
These are only two. The same master can be had in new or reman or without the reseviour and other applications are different bore sizes.
These masters would fit into our vans better if we used a remote brake resiviour mounted up in the dog house for easier access. Purchased as an aftermarket kit. Also if the resiviour was mounted up in the dog house, being much higher then the callipers, the disc brake system would not need the two lb residual check valve. (the drum brakes would still need the ten lb valve installed).
Whos game to start playing with this idea???
M1D
Somebody is going to have to take the chance and spend the coin to see if it works.
In 1980 GM came up with a new caliper design called "low drag" calipers. The seal slot in the casting was machined to a 30* angle instead of a 15* angle like older calipers. This made the caliper piston retrack twice as much from the rotor to reduce drag for better fuel economy.
Some of us may have this design of caliper on our rear disc brakes which would surely cause for a low brake pedal.
To compensate for this extra volume of fluid needed on brake application GM developed the "Quick take up" master cylinder. These master cylinders have a two stage bore with two different piston sizes in one. They have a very large dia bore that moves a large volume of fluid at first until preasure begins to build then internal valving switches up to the smaller bore that increases preasure rapidly with much less pedal movement.
I think one of these quick take up masters will seriously reduce pedal travel on our disc brake set ups.
The costly part will be expirementing to find the one that works best.
They are all duel circuit, some with two and some with four outlet ports of the same line and thread sizes as the current 68 corvette master.
They come in 1" bore and 1.125" bore with the quick take up bore sizes from 1.4" to 1.5" dia bore.
Here are some examples:
Napa # 39571 bore is .944" and 1.41" (1985 blazer T10 4wd)
http://www.napaonline.com/Search/Detail.aspx?R=UBP39571_0236103985
or Napa # 390259 bore 1.125" and 1.5" (1995 blazer T10 4wd)
http://www.napaonline.com/Search/Detail.aspx?R=UBP390259_0192051904
These are only two. The same master can be had in new or reman or without the reseviour and other applications are different bore sizes.
These masters would fit into our vans better if we used a remote brake resiviour mounted up in the dog house for easier access. Purchased as an aftermarket kit. Also if the resiviour was mounted up in the dog house, being much higher then the callipers, the disc brake system would not need the two lb residual check valve. (the drum brakes would still need the ten lb valve installed).
Whos game to start playing with this idea???
M1D
