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Manual brakes master cylinder bore sizes #375818 07/15/09 12:30 AM 07/15/09 12:30 AM
Joined: Oct 2005 Posts: 8,872 Ontario, Canada S Stanton OP Don't question me!
Stanton OP Don't question me! S Joined: Oct 2005 Posts: 8,872 Ontario, Canada	"Mancini Racing's new duel inline master cylinder kits are ideal for sportsman classes or hot street machines requiring four wheel braking, assuming the rear wheels are equipped with 4 piston calipers. The 1.032" bore master cylinder should be used is 2 piston calipers are used for the front two wheels. The 1.125" bore master cylinder will allow optimum volume and pressure for vehicles using 4 piston calipers for the front two wheels" So, which m/c do you use if you have drums on the rear and converted to single piston calipers on the front ??? Also, how do you get the rod out of the piston ???

Re: Manual brakes master cylinder bore sizes [Re: Stanton] #375819 07/15/09 08:55 AM 07/15/09 08:55 AM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: So, which m/c do you use if you have drums on the rear and converted to single piston calipers on the front ??? Also, how do you get the rod out of the piston ??? The smaller one but I would contact Dr Diff here on Moparts as he may have a better selection for you. Clamp the old M/C in your vise & pull the rod out. live every 24 hour block of time like it's your last day on earth

Re: Manual brakes master cylinder bore sizes [Re: RapidRobert] #375820 07/15/09 09:38 AM 07/15/09 09:38 AM
Joined: Oct 2005 Posts: 8,872 Ontario, Canada S Stanton OP Don't question me!
Stanton OP Don't question me! S Joined: Oct 2005 Posts: 8,872 Ontario, Canada	One more question ... how do you get the front piston out ??

Re: Manual brakes master cylinder bore sizes [Re: Stanton] #375821 07/15/09 10:05 AM 07/15/09 10:05 AM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: One more question ... how do you get the front piston out ?? Air Fastest 300

Re: Manual brakes master cylinder bore sizes [Re: Stanton] #375822 07/16/09 04:12 PM 07/16/09 04:12 PM
Joined: Oct 2005 Posts: 8,872 Ontario, Canada S Stanton OP Don't question me!
Stanton OP Don't question me! S Joined: Oct 2005 Posts: 8,872 Ontario, Canada	Ok, got everything apart except for the rod - it won't come out of the piston !!! Don't want to start hammering anything ... any suggestions ?? When doing the conversions, are folks using the original firewall plate or does that get put aside in favor of the 2 to 4 bolt adapter ???

Re: Manual brakes master cylinder bore sizes [Re: Stanton] #375823 07/16/09 04:18 PM 07/16/09 04:18 PM
Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O 70Cuda383 Too Many Posts
70Cuda383 Too Many Posts Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O	the optimum size master will depend not only on how many pistons you have, but what their diameters are. I measured the single piston sliding calipers on my Dakota, and did some math taking into account the leverage advantage I have with my pedal, and decided that I needed a 7/8" master cylinder to achieve the 1200 psi for disc brakes using only 50 lbs of leg pressure. I then let the "experts" at master power sell me a 1" bore master, saying that I absolutely needed the larger bore for the disc brakes, and that anything smaller was just plain unsafe. after I had it all put together and running, I had a really hard pedal! I then found out that the original POWER master cylinder was only a 15/16" bore, so much for needing the 1" for discs! I could have gotten away with the 7/8" that I originally calculated that I needed. oh well. I'll keep what I have for now because I plan on upgrading my 98 dakota front brakes to an 03/04 Dakota set up, the discs are a inch larger, and the calipers went to a dual piston sliding caliper, and it's all a simple bolt on deal, just swap out the whole spindle at the ball joints! Photobucket sucks

Re: Manual brakes master cylinder bore sizes [Re: 70Cuda383] #375824 07/16/09 09:23 PM 07/16/09 09:23 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: I measured the single piston sliding calipers and did some math taking into account the leverage advantage I have with my pedal, and decided that I needed a 7/8" master cylinder to achieve the 1200 psi for disc brakes using only 50 lbs of leg pressure. I shoulda set next to you in school live every 24 hour block of time like it's your last day on earth

Re: Manual brakes master cylinder bore sizes [Re: 70Cuda383] #375825 07/16/09 10:38 PM 07/16/09 10:38 PM
Joined: Jan 2003 Posts: 9,982 Ansonia, CT C CJK440 master
CJK440 master C Joined: Jan 2003 Posts: 9,982 Ansonia, CT	Quote: I then found out that the original POWER master cylinder was only a 15/16" bore, so much for needing the 1" for discs! I never understood why mopar put large bore masters on manual brakes and small bore on power setups. Seems like it should be opposite. 2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"

Re: Manual brakes master cylinder bore sizes [Re: CJK440] #375826 07/16/09 11:05 PM 07/16/09 11:05 PM
Joined: Oct 2005 Posts: 8,872 Ontario, Canada S Stanton OP Don't question me!
Stanton OP Don't question me! S Joined: Oct 2005 Posts: 8,872 Ontario, Canada	I'm guessing that if the power brakes failed you'd never stop the car with a large bore m/c - its tough as it is if the engine stalls or whatever and you have to stop a p/b equipped car. Also, looking at some of the diagrams, the p/b unit is leveraged so (for example) for every 1/4" of travel at the rod mounting point on the pedal the m/c rod/piston travels double. Hence the need for the smaller bore. On the manual brake systems there is no leverage - the m/c rod attaches directly to the pedal. A smaller bore would mean less effort BUT more travel.

Re: Manual brakes master cylinder bore sizes [Re: Stanton] #375827 07/16/09 11:15 PM 07/16/09 11:15 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: Also, looking at some of the diagrams, the p/b unit is leveraged so (for example) for every 1/4" of travel at the rod mounting point on the pedal the m/c rod/piston travels double. Hence the need for the smaller bore. On the manual brake systems there is no leverage - the m/c rod attaches directly to the pedal. A smaller bore would mean less effort BUT more travel. That answers something that I had (until this point) never understood and that is why not a large bore on a PB setup. I'd think that'd be the best of both worlds, less travel and the booster taking care of the increased effort from less leverage. So what happens when you use a 1&1/8 M/C on a PB setup? live every 24 hour block of time like it's your last day on earth

Re: Manual brakes master cylinder bore sizes [Re: Stanton] #375828 07/16/09 11:16 PM 07/16/09 11:16 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	Quote: Ok, got everything apart except for the rod - it won't come out of the piston !!! Don't want to start hammering anything ... any suggestions ?? I've read of plenty of methods on Moparts, back in the 70's was the last time I did one & I did it the hard way... The best suggestion I've read is to pull the saddle off your floor jack, slide the rod throught the open hole with the piston sittng on top of the plate now pass a heavy rod through the hole in the rod then just jack the thing apart..

Re: Manual brakes master cylinder bore sizes [Re: 1_WILD_RT] #375829 07/17/09 09:06 AM 07/17/09 09:06 AM
Joined: Oct 2005 Posts: 8,872 Ontario, Canada S Stanton OP Don't question me!
Stanton OP Don't question me! S Joined: Oct 2005 Posts: 8,872 Ontario, Canada	Quote: The best suggestion I've read is to pull the saddle off your floor jack, slide the rod throught the open hole with the piston sittng on top of the plate now pass a heavy rod through the hole in the rod then just jack the thing apart Well, I didn't do it exactly like that but a very similar way. Now I need to fing a new doohickey that holds the rod in the piston 'cause pulling it apart ruined it !! Quote: So what happens when you use a 1&1/8 M/C on a PB setup? You go through the windshield if you so much as touch the brake pedal !!! All joking aside I would imagine the brakes would be just too touchy - more like an on/off switch.

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