Home Page › Forums › Discussion Topics – Ask the Experts › 62 Cutlass Spindle conversion
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joe_padavano.
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July 18, 2017 at 4:27 pm #12933joe_padavanoParticipant
[quote quote=12890]
I used a 1980 Ford Fairmont MC at 7/8″ bore, fits nice but I am not happy with the “long” pedal.[/quote]You can trade M/C bore and/or pedal ratio for stroke, at the expense of pedal force. The M/C for a mid-70s AMC Hornet has RH ports and is about the same overall size as the Fairmont M/C. These are available in both 1″ and 1 1/16″ bore. This will reduce travel, but increase required pedal force.
July 19, 2017 at 11:15 am #12934
62cutlassconvertParticipantYes,thanks Joe, saw those in the Scarebird/Skylark Forum discussion. Gotta go back on there and ask how they worked out. I looked up application on Dorman and although most of the applications are drum/drum there is a manual disc/drum app for a 1976 CJ7. Talked to Dorman tech but they couldn’t add anything to it other than it does not have a residual valve, which is kinda funny since it has a drum drum and disc/drum application. Could always put one in line for the rear brakes I guess.
July 22, 2017 at 1:03 pm #12941joe_padavanoParticipantThe reality is that you can use a drum brake MC for front discs so long as 1) it has the correct bore for the application, 2) you remove the residual pressure valve that is in the outlet port to the front brakes, and 3) you understand that the smaller reservoir for the front brakes will require more frequent checking of the fluid level.
There is nothing magic about a master cylinder for disc brakes. The calipers neither know nor care what it looks like. All they care about is the piston bore and stroke.
July 23, 2017 at 5:50 pm #12944
captiannapalmParticipantThat does not make sense that the front reservoir is smaller seeing as the front bakes account for the majority of the stopping power.
August 13, 2017 at 12:44 am #12991captiannapalmParticipantsharp looking car….notice the headliner is white….what color is the rest of your interior.? just looking to get ideas.
August 13, 2017 at 12:47 am #12992captiannapalmParticipant[quote quote=12941]The reality is that you can use a drum brake MC for front discs so long as 1) it has the correct bore for the application, 2) you remove the residual pressure valve that is in the outlet port to the front brakes, and 3) you understand that the smaller reservoir for the front brakes will require more frequent checking of the fluid level.
There is nothing magic about a master cylinder for disc brakes. The calipers neither know nor care what it looks like. All they care about is the piston bore and stroke.
[/quote]
Now why is a dual m/c needed? I know ford has a single m/c for power disc/drum. just asking if GM had one.
August 20, 2017 at 6:10 pm #13012joe_padavanoParticipant[quote quote=12992]Now why is a dual m/c needed? I know ford has a single m/c for power disc/drum. just asking if GM had one.[/quote]
In fact, there have been cars built with a single circuit M/C and disk/drum brakes. Personally, I prefer a dual system just for the added safety, but there is nothing that mandates it for disks. GM did not offer disk brakes until the 1967 model year, and the Feds required the dual circuit brake system at that same time, so no GM cars came with the single circuit M/C and disk brakes.
August 22, 2017 at 10:56 am #1301562cutlassconvertParticipantDon’t ask me why but the Disk/Drum MC pictures you see earlier in this thread use the larger reservoir at the rear for the front disc brakes. The reason the disc reservoir is larger is that as disc brake calipers work, the pistons move out and stay out creating a larger and larger cavity in the caliper cylinder resulting in a “permanent” use of the fluid. The larger reservoir holds more fluid so frequent checking for fluid levels in not necessary as the pads wear and the pistons move out. Drum brakes return most of the fluid to the reservoir when the pedal is released since the shoes mechanically adjust out toward the drums and the springs pull the shoes back in resulting in the slave wheel cylinder pistons returning to their at rest position. As has been stated you would just need to check a non-disk/drum MC more often and remove the residual valve if fitted for the disk application. In our case where space is at a premium it’s one of the options.
August 22, 2017 at 1:16 pm #13016joe_padavanoParticipantThe orientation of which end of the dual M/C feeds which end of the car depends on the source of the M/C. GM typically (but not always) fed the front brakes from the front of the dual M/C. so GM disk/drum M/Cs tend to have the larger reservoir in the front. Ford and Chrysler typically fed the front brakes from the back of the M/C, so the Fairmont M/C has the larger reservoir in the back. So long as the system is plumbed correctly, the brakes don’t care which of these M/C configurations is used. Interestingly, the M/C used on the Vega/Monza cars are disk/drum but have the same size reservoirs.
August 23, 2017 at 8:36 pm #13021captiannapalmParticipanthas anyone used the abs power brake conv. kits?
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