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Author
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Topic: Disc brake conversion question
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Tom G
Gearhead Posts: 1069
From: Bethlehem, Pa USA
Registered: Nov 2001
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posted 01-24-2006 08:20 PM
 
I want to go to front discs and will probably go to manual discs. My question is about a master cylinder. Will a disc/drum master cylinder work(power type) or are they different from manual?------------------
67 Mustang F/B 302 GT-40X FMS engine RPM Air Gap 650 Holley DP Crane 1.7 roller rockers, Edelbrock Performer Nitrous, Dynomax ceramic headers WCZ rated-T5, cable clutch Flows X Pipe 3.89 9". Clearwater Aqua GT Clone Vintage wheel works 40 series 16X8 225 front 255/50 rear drag radials 308 RWHP@5800rpm 300 tq NA 385rwhp 380 w 75 shot 13.11 @111mph
92 VERT triple black 5 speed, 88 GT (FiveOfastback's ride)GT 40 X Track Heat, BBK headers X pipe 5 spd Red and Silver
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427Fastback
Gearhead Posts: 530
From: N.Vancouver.B.C
Registered: Jan 2005
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posted 01-24-2006 09:59 PM
I have done the conversion counless times and always used the stock disc-brake master cyl...Just remember...use the power brake pedal on power brakes and use the manual brake pedal on manual brakes.The pedal ratio's are completely different between the two. Cory ------------------
68 Fastback 427MR 4 spd.Deluxe interior,8000 tach,140 speedo,am/fm,tilt.
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BLstangin
Gearhead Posts: 856
From: St. James, MN
Registered: Apr 2002
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posted 01-24-2006 10:22 PM
Well, I haven't got it together yet, but I'm gonna do it on my 70 and have all the parts. I used a stock proportioning valve off a 70, although I might just get an adjustable one, and will go with manual disc/drum setup. I was told to use a master cylinder from a 74 maverick with manaul disc brakes, because you could get them with manual disc/drum setup from the factory. Like I said haven't put it on yet, but it should work since they're bascially the same setup as the mustang. Supposed to bolt right onto the firewall and looks pretty much like it will.------------------
1970 coupe restored with the help of my dad. currently engineless, soon to be 418w stroker, lakewood bellhousing, 4-speed toploader, and 3.50 9" locker rear.
1986 f-150, 5.0, factory towing package with original c-6 trans
http://www.supermotors.org/registry/vehicles/detail.php?id=7794
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mikel3891
Gearhead Posts: 111
From: philippines
Registered: Sep 2005
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posted 01-25-2006 04:08 AM
what happens if you interchange the manual brake pedal and power brake pedal
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427Fastback
Gearhead Posts: 530
From: N.Vancouver.B.C
Registered: Jan 2005
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posted 01-25-2006 04:55 AM
The power brake has very little pedal ratio as the booster does all the work..The manual pedal has lots of ratio as you do all the work.. The Mustang Master cyl is 1 inch bore and the Maverick master cyl is 15/16.Smaller cylinder gives you an increase in pedal stroke but more effective pressure applied.Have not done the math so I dont know how much 1/16 bore difference would make..
HP Books.."How to make your car handle" is loaded with all the mathmatics of brake systems and suspension systems.Its a great book....but you have to read it 10 times to take it all in..
Cory ------------------
68 Fastback 427MR 4 spd.Deluxe interior,8000 tach,140 speedo,am/fm,tilt.
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Tom G
Gearhead Posts: 1069
From: Bethlehem, Pa USA
Registered: Nov 2001
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posted 01-25-2006 07:40 AM
quote:
Originally posted by 427Fastback:
The power brake has very little pedal ratio as the booster does all the work..The manual pedal has lots of ratio as you do all the work.. The Mustang Master cyl is 1 inch bore and the Maverick master cyl is 15/16.Smaller cylinder gives you an increase in pedal stroke but more effective pressure applied.Have not done the math so I dont know how much 1/16 bore difference would make..
HP Books.."How to make your car handle" is loaded with all the mathmatics of brake systems and suspension systems.Its a great book....but you have to read it 10 times to take it all in..
Cory
Thanks Cory!
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sigtauenus
Gearhead Posts: 3969
From: Va Beach
Registered: Jun 2000
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posted 01-25-2006 10:34 AM
quote:
Originally posted by 427Fastback:
The Mustang Master cyl is 1 inch bore and the Maverick master cyl is 15/16.Smaller cylinder gives you an increase in pedal stroke but more effective pressure applied.
I don't quite think that's accurate Cory, or perhaps I misunderstand what you are saying in regard to more effective pressure applied. The smaller diameter piston will apply less pressure than the larger piston given the same foot pressure and the same pedal displacement. I think we agree on that. With the smaller piston you would need longer pedal displacement to get the same application of force at the brake cylinder, and due to the reduced piston size you would have more pedal effort to get the same braking action. Bottom line: I don't consider a longer pedal stroke with more effort to be more effective.
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68 S-code GT
Gearhead Posts: 3835
From: Sayreville, NJ, US
Registered: Mar 2000
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posted 01-25-2006 11:30 AM
I found this while searching around on here.If you went with nonpower assist manual discs then a 74 Maverick manual disc brake MC will work. '83 Ranger non-power m/c is a direct bolt-in for a non-power application; identical pushrod depth so there's no need to buy another one. W/core exchange (any core will do), I think I paid $30 at a local parts house. And, it's aluminum
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427Fastback
Gearhead Posts: 530
From: N.Vancouver.B.C
Registered: Jan 2005
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posted 01-25-2006 12:34 PM
Sig...I think we are both trying to say the same thing ..The smaller M/C would require you to push the pedal farther to displace the same amount of fluid as the larger one... The effective line pressure of the smaller one should be greater tho.. Cory ------------------
68 Fastback 427MR 4 spd.Deluxe interior,8000 tach,140 speedo,am/fm,tilt.
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Tom G
Gearhead Posts: 1069
From: Bethlehem, Pa USA
Registered: Nov 2001
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posted 01-25-2006 05:56 PM
quote:
Originally posted by sigtauenus:
I don't quite think that's accurate Cory, or perhaps I misunderstand what you are saying in regard to more effective pressure applied. The smaller diameter piston will apply less pressure than the larger piston given the same foot pressure and the same pedal displacement. I think we agree on that. With the smaller piston you would need longer pedal displacement to get the same application of force at the brake cylinder, and due to the reduced piston size you would have more pedal effort to get the same braking action. Bottom line: I don't consider a longer pedal stroke with more effort to be more effective.
Leave it to a Marine Corp Aviator to figure it out! 
How ya been SAM?
Tom Goodwin------------------
67 Mustang F/B 302 GT-40X FMS engine RPM Air Gap 650 Holley DP Crane 1.7 roller rockers, Edelbrock Performer Nitrous, Dynomax ceramic headers WCZ rated-T5, cable clutch Flows X Pipe 3.89 9". Clearwater Aqua GT Clone Vintage wheel works 40 series 16X8 225 front 255/50 rear drag radials 308 RWHP@5800rpm 300 tq NA 385rwhp 380 w 75 shot 13.11 @111mph
92 VERT triple black 5 speed, 88 GT (FiveOfastback's ride)GT 40 X Track Heat, BBK headers X pipe 5 spd Red and Silver
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