master cylinder for 4 wheel disc brakes

[SHX669]

Is there a MC for 4 wheel disc brakes that'll work without a power booster? I don't want to go to Hydroboost or even a power booster but the only MCs I've seen say they take more effort to depress the pedal and recommend going with the booster.

 

[Broncobowsher]

Simple fact. The larger the master cylinder bore, the less travel and more effort it will have. A smaller master cylinder will have more travel but less effort. Providing the rest of the brake system is the same.

Stock bore is 1". Might want to go looking for a 15/16" bore master cylinder.

 

[RPM289]

Look in Summit or JEGS they have master cyl that bolt up think they are for mopar drag racers use them on ford setups.

 

[toddz69]

Second Broncobowsher's recommendation on a 15/16" bore master. You may also want to try a 7/8" bore. That's what a lot of folks with manual brakes can run.

Todd Z.

 

[Apogee]

The MC is just one part of the brake system. Ultimately, the calipers don't care how you supply pressure to them to work, so long as you supply enough of it. In the 1" bore size range, a 1/16" difference in MC bore size equates to about an 11% difference in output pressure for a given input force, and a corresponding increase in pedal travel of 11% as well.

That said, the bore size of your MC should be related to the caliper piston areas of your calipers, pedal ratio and brake pad coefficient of friction. I generally try to set up manual brake systems such than they achieve lockup at less than 90 pounds of pedal force, but how you get there is up to you. Since the pedal ratio is one of the more difficult things to change without doing a bunch of fabrication under the dash, that leaves MC bore size and pad CoF. While the bore size is an easy way to gain 11-23%, you typically make larger differences with the pad compounds.

Most pads with be tagged with a hot/cold friction CoF range in the manufacturer numbers, indicating a CoF range for the pad at a certain temp. It's a letter code where E=.25 to .34, F=.35 to .44, G=.45 to .54, etc, so you'll typically see an "EE", "FF" or "GG", however some will be "EF", "FG", etc, although they usually try to keep them the same since that gives the appearance of a more linear CoF, whether it is or isn't. I prefer to run a "GG" friction rated pad in a manual installation, something like the Hawk HP Plus, EBC Yellowstuff, Carbotech AX6, etc.

 

[jw0747]

The MC is just one part of the brake system. Ultimately, the calipers don't care how you supply pressure to them to work, so long as you supply enough of it. In the 1" bore size range, a 1/16" difference in MC bore size equates to about an 11% difference in output pressure for a given input force, and a corresponding increase in pedal travel of 11% as well.

That said, the bore size of your MC should be related to the caliper piston areas of your calipers, pedal ratio and brake pad coefficient of friction. I generally try to set up manual brake systems such than they achieve lockup at less than 90 pounds of pedal force, but how you get there is up to you. Since the pedal ratio is one of the more difficult things to change without doing a bunch of fabrication under the dash, that leaves MC bore size and pad CoF. While the bore size is an easy way to gain 11-23%, you typically make larger differences with the pad compounds.

Most pads with be tagged with a hot/cold friction CoF range in the manufacturer numbers, indicating a CoF range for the pad at a certain temp. It's a letter code where E=.25 to .34, F=.35 to .44, G=.45 to .54, etc, so you'll typically see an "EE", "FF" or "GG", however some will be "EF", "FG", etc, although they usually try to keep them the same since that gives the appearance of a more linear CoF, whether it is or isn't. I prefer to run a "GG" friction rated pad in a manual installation, something like the Hawk HP Plus, EBC Yellowstuff, Carbotech AX6, etc.

Wow, I didn't know this but does anyone have a specfic MC recommendation with a part #?

 

[SHX669]

Thanx for the info - gives me places/directions to look . I put disc brakes on the front 4- 5 years ago and have had no problem with braking but I just installed a rear disc conversion { TBPs and WHs sells em } so I'm looking for a MC with the big reservoirs front and rear for 4 wheel disc. I don't really want to go with power brakes unless i have to { already lots of stuff under the hood } . I've found one at Summit with a 1" bore and it says disc/disc /non power and I see Wildwood also has a 1" bore disc/disc { a little spendy }. With either of these I don't know if i can reuse my existing pushrod or if I have to find one that will work. I haven't located a disc/disc 15/16 bore yet but will keep looking.

 

[spap]

My last bronco was. 76 and I added rear disk brakes from a older Lincoln.
It was not power brakes and I never switched the MC at all and it worked really well. The front brakes would lock first which is what you want anyways.
Try what you have and go from there and see
I'm sure different different calipers react differently and the rear 9 inch Lincoln calipers were probably equal in size the stock bronco fronts.

One thing I have learned having a few Broncos, what works on one, the same set up might not work on another

 

[68ford]

From experience I recommend even smaller bore with manual brakes, I have a dual master set up and run a 3/4 bore front and 7/8 bore rear and it works very well. Brake effort is compatible to my Chevy avalanche. Very easy to stop. I do have big calipers as well though. You will notice increased pedal travel though.

 

[Apogee]

Wilwood does now offer 15/16" versions of their die-cast aluminum master cylinders if you're interested in spending ~$200 for a master cylinder (260-13375).

Otherwise, if you're not opposed to slotting the mounting holes, CPP offers a 15/16" version of their C3 Corvette master cylinder for $59, and there are several OE applications that used 15/16" [24mm] units as well. I've always thought that the aluminum S10 units from the late 80's with the quick take-up piston design could work well, but haven't ever gone through the motions to get one mounted in an EB.

Assuming GM D52 front disc brakes and D154 rears, that would mean 2-15/16" front pistons (~6.7 square inches piston area) and 2-1/32 pistons in the rear if you have the parking brake calipers (3.23 sq in area), so most applications running this combo would use a 1" bore MC in a manual installation with a 6:1 pedal ratio.

 

[Apogee]

From experience I recommend even smaller bore with manual brakes, I have a dual master set up and run a 3/4 bore front and 7/8 bore rear and it works very well. Brake effort is compatible to my Chevy avalanche. Very easy to stop. I do have big calipers as well though. You will notice increased pedal travel though.

Dual master cylinders with a balance beam are different since the MC's are in parallel rather than having the pistons in series like in a conventional tandem disc/disc master cylinder, so it's not really comparing apples to apples. The dual setup divides the pedal force between the two master cylinders, whereas the tandem setup does not, since the pressure from the primary piston is applied to the secondary piston. For example, the output force on (2) 1" bore MC's in parallel will be half that as a conventional 1" bore MC for the same pedal ratio and input force.

While there are definitely benefits to running a dual master cylinder setup with a balance beam, most of those benefits are specific to racing applications in my experience.

 

[68ford]

Dual master cylinders with a balance beam are different since the MC's are in parallel rather than having the pistons in series like in a conventional tandem disc/disc master cylinder, so it's not really comparing apples to apples. The dual setup divides the pedal force between the two master cylinders, whereas the tandem setup does not, since the pressure from the primary piston is applied to the secondary piston. For example, the output force on (2) 1" bore MC's in parallel will be half that as a conventional 1" bore MC for the same pedal ratio and input force.

While there are definitely benefits to running a dual master cylinder setup with a balance beam, most of those benefits are specific to racing applications in my experience.

I find this impossible, when I initially switched to the dual master set up I went with 2 1in bore masters and no other brake changes. My pedal ratio increase leverage by around 10% I believe, but that would have been my only increase. So by what you saying is I should have had to press harder to stop my truck. At this same time I added about 800plus pounds to the truck. All said an done, it stopped easier, less pedal effort and slightly more pedal travel as expected from leverage increase. So please explain that to me.

 

[5001craig]

I'm running a WH master cylinder with non-assisted (for now) discs front and rear. If memory serves me correctly, WH recommended this MC for discs front and rear now and will work when I go with hydroboost.

Maybe Paul will chime in on this.