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Author
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Topic: '66 disc brake master cylinder
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rockafellz
Gearhead Posts: 833
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 05-29-2002 10:17 AM
  
Hey Guys,I installed the SSBC disc brake kit on my '66 Mustang a few weeks ago and I ended up using a '67 dual master cylinder for disc brakes. Well I'm about to return the master cylinder because I think it's defective. I can't seem to get rid of the spungyness of the 1st inch of brake pedal travel. What master cylinder do you guys recommend I get? What year/make/model car master cylinder would work better? This is all manual brakes by the way. Thanks in advance. Erik ------------------
1966 Ford Mustang / 289 / C4
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mellowyellow
Gearhead Posts: 5469
From: So. Fl.
Registered: Aug 2000
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posted 05-29-2002 12:22 PM
When I talked to someone on thir tech line, where you get short answers! they reccommended the single chamber which has better pedal action. The guy told me the dual chamber had a soft pedal. I have the single chamber. For an antiquated design, they work well. I know eveyone will say dual chamber which DOES make sense.
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rockafellz
Gearhead Posts: 833
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 05-29-2002 01:12 PM
The thing that i'm worried about with the single chamber master cylinder is if it fails, I lose ALL brakes. In a dual MC situation, I believe you'll lose one or the other but not both (front & rear) brakes.I called their tech line an hour ago and he said their kits come with '67 Mustang disc brake master cylinders and the 1" of brake pedal "play" is normal because the pads don't have pressure applied. Is that correct?!? Here's what i've got in my head now. Exchange this particular '67 Dual MC for another '67 Dual MC. If it feels the same, i'll return it and buy a Power Brake Booster Conversion kit ($300.00).  I don't get why disc brakes have 1" of play and require MORE pedal pressure than my previous DRUM brakes. Erik
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V8 Thumper
Gearhead Posts: 2830
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 05-29-2002 10:39 PM
Hey Erik... you did purchase/use the adjustable length pushrod (Mustangs Plus), correct? The dual stage m/c's have a different stroke than the (hurt-me) single stagers... I'm retrofitting my '65 with the same m/c out of a '67. My car isn't driving yet, so I can't confirm the 'feel' of the pedal.
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Pierre
Gearhead Posts: 349
From: France
Registered: Apr 2002
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posted 05-30-2002 11:23 AM
I had manual dual MC on my 67 with disk. It had some play (may be an inch or less)in it. And pedal pressure was very very very high for a normal stop light Your play (and mine) was probably related to some air in the system added to normal fluid displacement in the calipers when the piston presses on the pads.I then moved to Power brake, and it is a breeze ! It does still feel spungy but brakes a lot better Just my input 
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Pierre
Gearhead Posts: 349
From: France
Registered: Apr 2002
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posted 05-30-2002 11:29 AM
Forgot to add that I also had 4 corner drum before and remember being very disappointed when I had disk installed because it felt harder and did not brake much better ! (this is why I went to power)
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rockafellz
Gearhead Posts: 833
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 05-30-2002 12:03 PM
V8 Thumper,Well, I thought of the adjustable pushrod, but figured, if it is spongy at this height, it'll just be spongy at a different height. Make sense? Pierre, Well, at least your symptoms are very similar to mine. I'll be swapping my MC for a new one today and I'll post what happens. I've also been contemplating the power booster conversion option. But it's ~$300-350. Also, when you say that pedal pressure was "very very high" do you mean you had to really apply more foot pressure to stop the car? Erik p.s. the 4 wheel manual drums on my dad's '66 coupe stop just as good (and straight!) as ALL of the new cars!!
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rockafellz
Gearhead Posts: 833
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 05-30-2002 12:05 PM
We've also never pulled the rear drums, so we'll be doing that today as well. Maybe the shoes are bad or the wheel cylinders are $h!tErik
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Pierre
Gearhead Posts: 349
From: France
Registered: Apr 2002
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posted 05-30-2002 03:11 PM
It seemed like I had to apply as much foot pressure as with the front drums. But again, the car was in the shop for a week and drove a modern car in between so my judgement could have been altered. I remember being worried to break my seat, that's how hard I had to press to stop it 
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Fastback68
Gearhead Posts: 1280
From: Sucat, Paranaque, Philippines
Registered: Jul 99
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posted 05-31-2002 04:40 PM
quote:
I called their tech line an hour ago and he said their kits come with '67 Mustang disc brake master cylinders and the 1" of brake pedal "play" is normal because the pads don't have pressure applied. Is that correct?!?
I'm no techie, but I think this needs to be addressed. I don't think 1 inch of brake play is normal at all. Over the years I've driven Lord knows how many cars with all-around drums and not experienced this. I currently have a full-sized Ford MC (from an LTD or something) and all-around drums. I have zero brake play.EDIT: I've been thinking about this all day! Is it possible that when you guys talk about "play", you mean "travel"? An inch of travel will be quite normal before the brakes really bite. But by "play" I think of the mechanism taking up slack -- and there should be no slack in the system. [This message has been edited by Fastback68 (edited 06-01-2002).]
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rockafellz
Gearhead Posts: 833
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 06-03-2002 09:48 AM
Fastback68,Yes, I am referring to 1 inch of brake pedal travel before actually biting. On Saturday, I took the master cylinder back and exchanged it for another one ('67 dual master cylinder for disc brakes). The master cylinder is supposed to be for a power brake booster, but in this case, it's used manually without a booster. Anyways, same problem. Before I actually buy a power brake booster conversion kit, I think i'm actually going to replace the rear rubber hose. That is the only original rubber line left in the car. That rubber line may be flexing when I press the brake pedal. Also, can someone explain exactly what the rear adjustable proportioning valve should be doing? When I screw the knob in, I am increasing pressure, when I screw it out, i'm decreasing pressure. That shouldn't have any effect in brake pedal feel right?!? Also, I've been really thinking about this, but what will happen if I use a '67 Dual master cylinder for Manual Drum brakes? Since the one I have now is for a brake booster. How is everyone else's disc brake conversion setup?? Thanks again. Erik ------------------
1966 Ford Mustang 2+2
Mine - Restomod in Progress 1966 Ford Mustang Coupe
Dad's - Original Unrestored [This message has been edited by rockafellz (edited 06-03-2002).] [This message has been edited by rockafellz (edited 06-03-2002).]
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Pierre
Gearhead Posts: 349
From: France
Registered: Apr 2002
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posted 06-03-2002 04:10 PM
Rubber hoses do expend, changing it with aircraft quality type will reduce pedal travel some. Do not know how much thoughMy take is that as you open the valve, you allow more PSI accross to the rear side and I observed that this increase my brake pedal travel. Now, you want to adjust this not according to pedal travel but according to braking balance on all 4 corners. Having your rear wheel lock-up before the front ones could be scary ! Disk & Drum master cylinders ARE NOT interchangeable. The drum one have a rubber valve inside their port that will be incompatible with disk brakes. It would not allow the pistons to go back in place, they would grab onto the disk.
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Moneymaker
Administrator Posts: 18280
From: Lyons, IL, USA
Registered: May 99
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posted 06-03-2002 04:36 PM
The proportioning valve is to adjust the front to rear brake biased, or how soon the rear applies after the front. I had a single large reservoir M/C on MM forever with fantastic feel and pressure. I did not swap to another (dual) until I went to aftermarket Willwood racing brakes. I would try and return the dual master you got with the kit and use a different one like from a Ranger or an aluminum one from early 80's Fox body. I have much better luck with those that the one supplied from SSB. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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rockafellz
Gearhead Posts: 833
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 06-03-2002 04:54 PM
Hey Alex,What year ranger MC do you think would work? Erik
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SteveLaRiviere
Administrator Posts: 30261
From: Saco, Maine
Registered: May 99
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posted 06-03-2002 07:21 PM
Wait a minute!Spongyness in the first inch of travel?  Spongyness is only felt at the end of the pedal travel, because is only at that point that you are compressing the air bubbles in the fluid, which is what you are feeling. I believe what you are feeling in that first inch of travel is the taking up of slack at the calipers and rear brakes. Before I changed the master cylinder, I'd check/replace the rear brakes and wheel cylinders and make sure the rear brakes are adjusted right. That can give you excessive travel if not adjusted properly. I bet there's nothing wrong with your mc. ------------------
'70 Mustang Mach 1 ~ '72 Mustang Sprint ~ '94 F-150
MCA Member # 47773 "Doubt is not a pleasant condition, but certainty is absurd."
- Voltaire
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TomP
Gearhead Posts: 4585
From: Delta BC Canada
Registered: Dec 99
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posted 06-04-2002 12:09 AM
Agree with Steve , also if you are using a power brake master cylinder the pedal will be harder, the bore size is different.Any 83-up Ranger m/c will work, the earlier ones look more old fashioned though. Many are manual disc.
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Moneymaker
Administrator Posts: 18280
From: Lyons, IL, USA
Registered: May 99
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posted 06-04-2002 12:21 AM
There is free play travel and then there is sponge travel? I am assuming that we are talking about sponge travel where you would get fluid from the bleeder. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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