Hi guys Merry Christmas!
I was wondering if any one has tried to use a newer style aftermarket mastercylinder on a 69 b body with drum brakes.The reason I ask is I have one I purchased from Rick R.
on ebay a while back and forgot.
The cast iron style one with bolt on top leaks to much for my likeing.
Any reason not to use the aftermarket master with plastic tank.?
Not sure what the bore size is.
Thanks Cj

Sounds like you are working with 4 wheel drums. Correct? Leaking MC's are a PITA. I have had to touch up the paint on my inner fender more than once as a result of leaks.

The AL MC should have plenty of fluid volume for drums since discs take more volume vs drums. As far as the rest, is it compatible with your setup in terms of pushrod length (manual or power... it matters!)? Does it need an adapter plate and do you have the right one? Bore size does matter, especially if you don't have power assist. Larger bore size can result in excess pedal effort. If you can check these areas, worth a try.

Personally, I'd probably ask Eherenberg for advice on your particular application first.

the only issue you could possibly have is if the bore size is too large & gives you an exorbitantly hard pedal & others have had to deal with that tho I had a 1&1/8 dualie on a 65 dart with 76 (2.75) discs/10" drums with OE drum splitter & it worked flawless with no excessive pad wear (aftermarket ceramic? pads). I would measure the bore dia of it right now just for a reference if there IS an issue. the other thing is the 4 to 2 bolt adapter & the 2 bolt MC will possibly have a deeper piston recess both of which will lower the pedal & there are several lengths of OE pushrods and there's the MP adjustable one. Short version: install it/another pushrod as needed to get the needed pedal height/bench bleed the MC/bleed the corners/take it for a spin/holler how it turns out

Drum brake masters have a check valve in the line to keep all of the fluid from bleeding back into the reservoir. You at have a low pedal.

Almost forgot, if these are manual brakes (& I'm thinking they are) then the master cyl must have the shallow circular recess in the rear of the MC piston "thimble" about halfway down for the neoprene retainer to lock into. Just look in the back of yours & if it is a smooth taper then it is a PB unit & will not work for manual brakes

All drum brakes have to have residual valves, I think 10 pounds to keep the brakes energized, springs in the brakes will pull the shoes back away from the drum if not used. Most brake company's have these to install in lines. Check your mc they might have them in the front already, drum-disc car.

Thanks yes it is a 69 bee with 11 inch drums ,
I have the adapter plate. And manual pushrod .
Imwill check the bore size on Saturday.
Not sure about this residual valve or how to tell ?

stick a drill bit into the brass inverted flare cone seat deep into each of the MC ports & you'll feel the RPV if it has one as it is just a piece of neoprene on a spring (a crude 1 way valve). reportedly wheel cyls mfr'd after ~1975 had a flat ~quarter sized thin metal disc on the outside of the rubber cups which helped keep them sealed to the bore wall for instant take up to accomplish the same thing. Just me I think you might be fine either way

Residual valve, if there, it's behind the brass flare in the ports. Use a small spray can tube or anything that will slide into the fitting, nothing that will cut, if you can feel something a short way in, got one, if tube goes in quite a way feeling nothing, not there. Front port would be 50-50 on having one. Not sure how many of these ms came with drums front and back, but majority where disc-drum. In-line residual valves can be bought from any of the brake manufactures, it's about 2 inches long with ports on each end, easy to install, can't run drums without them, as the shoe wears these keep the slack out(full pedal). Hope I helped

Yes, duly noted on using a thin red straw from a spray can rather than a drill bit