Rear disc m/c
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Senior User
Joined: Dec 2005
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From: Southern Delaware
Rear disc m/c
I was curious if the master cylinder for a 77 Lincoln would fit the booster on my 78 f150. The lincolns had rear disc brakes but also worked on a hydroboost system. I have converted the rear of my truck to disc but I have to pump the brakes a couple times to get the rear calipers to grab. I have bled them to no tomorrow and was thinking I need more volume. The master for the lincolns are designed for the added volume requirements of disc brakes. but I was wondering if it would fit my truck w/o changing the booster. ALso the lines are on the same side of the m/c, therefore I would not have to modify the lines. I looked at the pictures from autozones website and they look close, but I would have to order it and it wont be here for another couple of days. WHat are the bore diameters on but m/cs? And how would it effect my front brakes? ANy info would help, thanks.
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Senior User
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From: Southern Delaware
I just looked at the M/C for the lincoln last night. It looks like it will bolt in place, it has the fittings on the same side as my truck, the rear brake resevoir is considerably larger than the one on the truck, and the bore diameter is a little larger. Im gonna put it on the truck probably tomorrow, and ill let yall how it works out...
Elder User
Joined: Feb 2005
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From: Spokane, WA
If you are having to pump the pedal to get rear brakes it is not the master cylinders problem (well for the most part), you need a residual pressure valve plumbed into the rear brakes. Maybe 4 wheel disc masters have this embedded in them, I don't know, but you can purchase a small residual pressure valve and put it inline to the rear brakes. This holds slight pressure in the lines so the pistons don't retract into the bore so far each time youl let off the brake.
Had this issue on my stock car with Chevy front calipers and small lincoln (granda body) rotors.
Kenny
Had this issue on my stock car with Chevy front calipers and small lincoln (granda body) rotors.
Kenny
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From: Southern Delaware
Well, I was informed that drum brakes have a 10lb residual valve built into the m/c and disc brakes generally have 2lb. Drums require more pressure, and disc need less. When I pump the brakes, the fluid level drops dramatically, suggesting insufficient volume, not pressure. Drums need the pressure to keep the shoes in slight contact with the drum. Im gonna try the lincoln master designed for disc brakes and see how well it will performs.(as long as it bolts up ok.)
Elder User
Joined: Feb 2005
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From: Spokane, WA
Maybe I am mistaken but I think you have the 2 and 10 crossed. Also with self adjusters the shoes are always in contact with the drum, it needs not real pressure to do that. Since you are dropping so much in the master upon application, it truely sounds like the pistions are pulling back in the bores (as I said, I have been down this road before) and thus needing a lot of fluid to get them back to the point of application.
The big Lincoln master might work, but the 70's Lincoln Versailes (sp?/Granda/Monarch) with 4 wheel disk option, would be the one you want. Don't go nuts on the bore size, you will hate the response (again, been down that road).
Kenny
The big Lincoln master might work, but the 70's Lincoln Versailes (sp?/Granda/Monarch) with 4 wheel disk option, would be the one you want. Don't go nuts on the bore size, you will hate the response (again, been down that road).
Kenny
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Joined: Jun 2002
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From: Atlanta GA
> Drums require more pressure
Yes, one reason is probably because they fight the springs.
What you might try is the master from an Explorer with rear discs. You will find most Ford master cyl are interchangable bolt/rod wise.
You could go to a junk yard and try hunting down a later model F-350 2x4 with rear discs and grabbing the master/booster for the core. Then buying the master/combo reman for $120 at Advance Auto.
Yes, one reason is probably because they fight the springs.
What you might try is the master from an Explorer with rear discs. You will find most Ford master cyl are interchangable bolt/rod wise.
You could go to a junk yard and try hunting down a later model F-350 2x4 with rear discs and grabbing the master/booster for the core. Then buying the master/combo reman for $120 at Advance Auto.
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From: Southern Delaware
I just put it on and it feels alot better. It was basically a bolt on, just had to find some adapters for the lines. The stopping performace seems better. It stops alot better. The next step is to install the lincoln calipers up front, but I have to find some fittings to adapt the hose. Also, I want to change the booster and braket to the longer pushrod, to get better pedal height. Its getting there.
And I just checked tsmmfg.com and found some info on the site about the residual valves. Drums do have a 10lb valve in the m/c and can be removed for rear disc conversions.
And I just checked tsmmfg.com and found some info on the site about the residual valves. Drums do have a 10lb valve in the m/c and can be removed for rear disc conversions.
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