Quote
JimmieD
There's been some incorrect info circulating for many years that clutch & brake master are identical.

The 200 truck brake and clutch master are the same bore and casting

This could be a serious problem if it's the clutch master offered for both masters, which would change fluid volume per stroke to the brakes.

There is already different fluid volume to the brakes, depending on the truck size, since the brake masters changed from model to model. The larger the bore, the less pressure in the system for a given force applied to the system, but the greater the volume of fluid moved per inch of stroke.

If it's the brake master offered then it can over-pressure the clutch hydraulics.

It will not "over-pressure" the system. The pressure is dependant on how hard u push on the pedal. Normal operators will only push as hard as needed to release the clutch. Additionally, as long as the slave piston is free to travel, pressure will not increase above that which is needed to overcome the springs in the pressure plate. The only way for the system to "over-pressure" is if the slave piston is restrained and the operator continues to apply increasing force to the pedal

I believe the port drillings may be at different depths also, effecting at what point in stroke the master refills.

Port drillings do not effect the point at which the master refills, as the piston cup does NOT travel past the port

If a guy buys a truck and doesn't know what's installed then it can be years of grief simply because it has the same master for both applications, installed back when NAPA & others said they were the same. Having the correct bore specs straight from the FSM can answer the question once & for all.

Bore specs do NOT cause any problem with operation. It is the "residual pressure valve" in a brake master that will cause grief if it is in the clutch system. This valve is what bleeds the fluid pressure off the brake system slowly to control lurching and other braking control difficulties. If a brake master is installed in the clutch system, this valve will cause massive slipping of the clutch as the fluid will return to the master way too slowly.

Without doubt the Town Wagon & Town Panel use a different bore for clutch & brake masters, but using the same braking system & same clutch system as other Sweptline trucks.

Thats because they are 1/2 tons, using 1" brake masters and 1 1/8" is the clutch master bore. 200 model swepts are the same bore for each.

That makes me think that all Sweptlines specify a different bore between the two as well.

Nope, not all.

We've been over this same subject in the past, in detail. The residual pressure valve was discussed in detail back then. Have u forgotten it, or did u not grasp it, or what? Here u are harping yet again on your same, tired old erroneous theories about what is different between the operation of the 2 different masters. Your post also shows that u still lack a complete understanding of basic hydraulics, hydraulic system design and operation. Please give it a rest.