OldDad67 Posted March 6, 2012 Report Posted March 6, 2012 Here's another disc brake question, what's the best and cheapest master cylinder conversion for a disc brake set-up? I see some use the 74 75 Mustang ll set-up, is there something as good or better? I would think a 15/16 bore would give more pressure than the larger bore cylinders. Thanks in advance. Quote
Robert Horne Posted March 7, 2012 Report Posted March 7, 2012 I used a Mustang II on my 48 Dodge, about $20 at Advance Auto. I used an aluminum 1986 Dodge type on my 38 Coupe. It was free. I have another aluminum Dodge type from a Dodge Van. I see these in the Speedway catalog also. Can not remember what the cost is..... Quote
Robert Horne Posted March 7, 2012 Report Posted March 7, 2012 Advance Auto has the Dodge Van master cylinder rebuilt for $24. Has a 1.125 bore... Quote
55 Fargo Posted March 7, 2012 Report Posted March 7, 2012 Advance Auto has the Dodge Van master cylinder rebuilt for $24.Has a 1.125 bore... Hey Bob, have you any pics of how you fabbed and installed these MCs:confused:, was it firewall mounted or OEM.... Quote
Daliant. Posted March 7, 2012 Report Posted March 7, 2012 The old cast iron master cyls always seem to get rusty around the rim where the cover seal is and the fluid leaks out as it sloshes around in the resevoirs. Personally I like the aluminum master cyls just because they dont leak around the caps. Both styles do the same thing though, its just a matter of which bore size to use. I have a 1 1/16 bore aluminum master from an 80's Dodge pickup in my 46 coupe w/disk front brakes (Chevy calipers) and it stops fine, the pedal has about the same feel as the original drums w/stock master cyl. If you buy an aluminum master cyl from a part store just make sure the resevoir is included, sometimes they sell the resevoir seperately. Quote
Robert Horne Posted March 7, 2012 Report Posted March 7, 2012 Hey Bob, have you any pics of how you fabbed and installed these MCs:confused:, was it firewall mounted or OEM.... ON my 48, I bolted up the Mustang II MC to the original MC. I made a rod about 8 & 3/4 long to go through the original MC. Has been working pretty good. Quote
OldDad67 Posted March 7, 2012 Author Report Posted March 7, 2012 ON my 48, I bolted up the Mustang II MC to the original MC.I made a rod about 8 & 3/4 long to go through the original MC. Has been working pretty good. That looks great are the port sizes the same for both front and rear brake lines? Quote
Robert Horne Posted March 7, 2012 Report Posted March 7, 2012 Hey Bob, have you any pics of how you fabbed and installed these MCs:confused:, was it firewall mounted or OEM.... Here is the Dodge MC on my 38, using the original clutch/brake pedals. Quote
Robert Horne Posted March 7, 2012 Report Posted March 7, 2012 That looks great are the port sizes the same for both front and rear brake lines? The first outlet has larger threads, but I used 3/16 lines on both outlets.. This is a photo of an old Mustang II MC I used for a test fit. Quote
Robert Horne Posted March 9, 2012 Report Posted March 9, 2012 Here is the Dodge MC on my 38, using the original clutch/brake pedals. This Dodge MC came from a 1986 small Dodge. The piston is about 13/16. I cut the bolt on section and redrilled so I could use my original pedals on the 38 Coupe. This set up has worked good the past 10 years... The other Dodge MC I have came from a 95 Dodge Van, has a bigger piston. Quote
chopt50wgn Posted March 9, 2012 Report Posted March 9, 2012 With any change from drums to discs, it's not the pressure you need ,it's volume. So getting a M/C with a bore of 1" or more is what you want. Quote
Don Coatney Posted March 9, 2012 Report Posted March 9, 2012 With any change from drums to discs, it's not the pressure you need ,it's volume. So getting a M/C with a bore of 1" or more is what you want. I think that is not correct. I was told by the vendor I used that it would require a lot of leg pressure to push any master cylinder with a bore over 1". Follow this link for more details. http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=22469 Quote
OldDad67 Posted March 10, 2012 Author Report Posted March 10, 2012 (edited) I think that is not correct. I was told by the vendor I used that it would require a lot of leg pressure to push any master cylinder with a bore over 1". Follow this link for more details.http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=22469 The smaller the bore in the master the more pressure it produces. Less leg needed. However the trade off is more travel of the brake pedal is required. That's one reason I liked Robert's use of the 75 Mustang ll 15/16 bore size. Should be about right. Edited March 10, 2012 by OldDad67 Quote
Robert Horne Posted March 10, 2012 Report Posted March 10, 2012 You will notice that small weight vehicles have small bore MCs and small brake disc or drums. Heavier weight vehicles have bigger more MCs, and bigger disc or drums. A small or large bore MC takes little force to push fluid, the only resistance is the inner springs. When you bench bleed a MC, little force is needed to do so. I have been using a 13/16 bore MC in my Coupe for 10 years. Brakes work good, and little leg force is needed to stop the car easy. My old van is 1000lbs heavier, manual MC, larger bore. Van has always stopped easy, little leg pressure needed, even when towing a small load. When in snow or wet roads, i have always had better control for slowing or stopping my vehicle, than in vehicles I have owned, that had power brakes.... Quote
Don Coatney Posted March 10, 2012 Report Posted March 10, 2012 The smaller the bore in the master the more pressure it produces. Less leg needed. However the trade off is more travel of the brake pedal is required. That's one reason I liked Robert's use of the 75 Mustang ll 15/16 bore size. Should be about right. I agree completly. With my setup I get full resistance at about half peddle. Chevy disc calipers on the front and Dodge Charger drum cylinders on the rear. Quote
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