Aluminum Master with rear drums

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chrgdrt

chrgdrt

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For guys that have swapped out your cast iron master cylinder for the lightweight aluminum, did you have to add a residual valve inline for the rear drum brakes? (front disc's/rear drum)
Gary
 
I used one from a 87 pickup went right in and no issues.
 
bolted mine on and went.. stops great

Buy the correct one. Most of those cars had front disc rear drums so no problem. Stay away from the master cyl from the 4cyl cars.
 
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my understanding is that the newer car have a different type of rear wheel cyl. that does not require a residual valve so i was wondering what everyone has done and how it worked out.
 
if you car was factory disk/drum then you have the correct proportioning valve
if your car was factory drum/drum you do not and you need to fix the proportioning 1 of several ways. In-line adjuster spliced into the rear hard line, correct proportioning valve (they remake them new), adjustable proportioning block
 
chrgdrt said:
my understanding is that the newer car have a different type of rear wheel cyl. that does not require a residual valve so i was wondering what everyone has done and how it worked out.
Click to expand...
Correct, but "newer" means c.a. 1970's. The change was that the springs in the wheel cylinders have either a cup or a tightly wound spring to form a cup. That keeps the lips of the rubber piston seal tight against the bore. Before that, the "residual valve" locked up ~10 psi to keep the piston seals tight so they wouldn't leak. No need for a residual valve in the MC since. The only people who use them now are hot rodders who install the MC below the floor.

Most people here use an 80's Dodge truck MC, and that is what Dr Diff sells w/ his adapter plate. But many MC's would work as long as they have the bore you want and two female dbl-flare ports. I use one for a 95-99 "cloud car" (Breeze, etc) w/ ABS (2 ports) w/ 7/8"D bore. Around 2000, many manufacturers changed to bubble-flare fittings, which you might want to avoid.
 
Ok, thanks Bill. Where I am confused is my '73 service manual show residuals valves in the master. I guess just a carryover.
I recently installed a Wilwood master on a friend's '70 chevelle and the instructions stated 10 psi rv required for drums and 2psi/disc and 10 psi for drums if the mater was located lower than the wheel cyl.
When i get ready to do the swap I'll try it w/o the RV using DD's master & plate.

Thanks,
Gary
 
Car is originally power disc/drum so proportioning valve is there. just going from power to manual.

Thanks.
 
chrgdrt said:
my understanding is that the newer car have a different type of rear wheel cyl. that does not require a residual valve so i was wondering what everyone has done and how it worked out.
Click to expand...
Your understanding is correct, and it is easy enough to check the wheel cylinders on Your car, pop the drums and push the pistons in w/a blunt screwdriver. If they want to
push back out as soon as you let up, Your good, if not and/or went in really tight....it's time for new ones anyway. As far as cirrus/stratus/breeze inline jobs, forget snagging
used ones, most of the time the nuts pull the threads taking them apart. And they're old by now, and have sprung leaks only 5yrs. old, I would consider new ones only.
Do not fear the bubble flare!Lol! They are easy to form, seal fine, & the correct line nuts are readily available. I have a couple FSM's stating that all dual tandem masters
on passenger cars/light trucks except some 1ton models have no RCV's and expanders in the WC's on Chrysler products, but I would give the RamMan or like person a call
to verify this to be fact.
 
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