Disk brake booster different than drum booster?

[THX 138]

Since drums take less pressure than disks, and mine was converted from 4 wheel drums to front disks. Maybe my lack of brake pedal travel is from the booster not being changed?

 

[70vert]

Need more volume/bore in MC for discs?

Since drums take less pressure than disks, and mine was converted from 4 wheel drums to front disks. Maybe my lack of brake pedal travel is from the booster not being changed?

hmm, I'm about to go from manual 4 wheel drum to manual Baer disc/drum. Bill at Street or Track said the manual pedal would be just fine with the Baer master cylinder.

My understanding is that it's not the pressure, it's the volume - discs need more volume, i.e. a larger bore. That might make sense that since you didn't change the m/c, it's not giving you the volume you need.

at least I think that's how it works. <prepares to put foot in mouth>

Are the brakes working fine w/o much pedal travel? What's the problem, then?

 

[THX 138]

hmm, I'm about to go from manual 4 wheel drum to manual Baer disc/drum. Bill at Street or Track said the manual pedal would be just fine with the Baer master cylinder.

My understanding is that it's not the pressure, it's the volume - discs need more volume, i.e. a larger bore. That might make sense that since you didn't change the m/c, it's not giving you the volume you need.

at least I think that's how it works. <prepares to put foot in mouth>

Are the brakes working fine w/o much pedal travel? What's the problem, then?

well, they have half the travel of any other car I've driven. The pedal is almost to the floor when the car is stopped and in most cars you still have the extra zone of the "more firm" pedal feel beyond the level of where you can make the car stop. I know the 3 previous owners of the car before me and I was talking to the one that owned it two people before me and he said he did the conversion himself. He'd NOT a very mechanical guy so either he did it and didn't cover all the bases or someone did it for him and didn't cover all the bases.

as for the pressure and volume, pressure = force x area, area is the area of the plunger I would imagine so volume is a cylinder= circular area x distance... yada yada they're all related

 

[70vert]

well, they have half the travel of any other car I've driven. The pedal is almost to the floor when the car is stopped and in most cars you still have the extra zone of the "more firm" pedal feel beyond the level of where you can make the car stop.

as for the pressure and volume, pressure = force x area, area is the area of the plunger I would imagine so volume is a cylinder= circular area x distance... yada yada they're all related

ah, when you said "lack of brake pedal travel" I thought that meant your brake pedal didn't move much until it engaged. I guess by "travel" you mean "an arc in which there is steadily increasing pedal pressure and stopping power."

I would think that with not enough volume you'd have almost nothing then FIRM near the bottom. Or maybe you're just not getting enough total volume to take full advantage of the brakes, so you never get to the full stopping power of the brakes.

I still say check the m/c bore if no one else chimes in. <bump> This is a brake thread guys, come on! safety before speed.

 

[wild70stang]

I too have heard that disk brake cars need a bigger volume in the master cylinder. And about that foot to the floor thing, the brake lever litterally hits the floor when I occasionally drive my moms 97 (piece of sh**) chevy 3500 to pick up parts.