0k quick question here for all who know, drums all round on my a model, about a dual master cylinder i bought from so called brake specialists, what they sold me has 1 inch bore and is ford/chrysler (aussie models) and no booster, now these clowns know im running 4 wheel drums as they are the ones whom relined my shoes to suit the 40 ford brakes at the front, from the model on this cylinder i have worked out it is for disk on the front and not drums all round, hence my questioning here , what id like to know is do you think im at a point with this where i have to run a 10psi residual valve to the front brakes im just building my a at the moment and are close to setting up my lines which is why im investigating this a bit more , and yes i know i shouldnt trust what so called specialist say
10psi is usually for discs, on drums I use 2 psi residual valves. It's what I have read is correct. But I've not tried 10 psi valves on drums, they may or may not cause the brakes to drag. EDIT: Wrong, I was tired when I posted that, I have no excuse for getting it backwards. If your master cylinder and resivoir are under the floor, you might need more pressure, or not. 40 Ford in the front? What's in the back? Are they actual vintage components, replicas, or perhaps you have shoehorned newer components in there (double leading shoe? C-mon, fess up ).
genuine 1940 ford front drums backingplates,shoes kit and caboodle , rear is ford diff ststock drums out of late 60s falcon (xy) ,its under floor master cylinder adapted to 40 ford pedal assembly Erik are you sure 10 pounds is for disk and 2psi for drums , im not an expert which is why i asked but i thought i read it around the other way now ive fessed up eric haha i have no secrets, how many residuals u have and where are they????
I am running 10lb on my A, frame mount master but still have to pump um up to stop. I assume the arrow faces away from the master? When I bleed the brakes I get some bubbles but do not see a leak anywhere. Damn air....
Yeah, that's my fault, I was tired when I posted that, it is 10 for drums, 2 for discs. I'll throw an edit in my previous post. I tend to use discs on anything with fenders (tends to be a heavier car, and you can't usually see them) so I try to have at least the resivoir mounted above the pedals, which reduces (eliminates) the need for residuals (for discs all they do is keep the fluid from draining back to the resivoir).
I just, a couple of days ago, installed the residual valve on my brake system. What a difference it made. No more bleed down to the master cylinder. No more long pedal travel after the car sets for a couple of days. My master cylinder is at least 6" lower than the calipers and brake cylinders. By the way, 2lbs for disc, and 10lbs for the drums. Lee
thanks all ive decide ill get one for fronts , theres definitely one in the rear of cylinder in the mc, easy to get right im thinking, my master has front and rear stamped on it, and i checked it was in there with a small drill bit (but end,not sharp end, for all who are wandering and did it very softly and not forcing anything, it went deeper in to the front hole ,alot deeper) now heres something to start debate about now ive established what im doing here with that and happy i am as its cheap easy and i dont have to get another master, is it a bad idea to run 2 of em or is it a gd idea, the way i see it 2 heads are better then one can anyone see a bad side to doing this, just in theory thanks again all for ur advice
I have a similar set up on my A. Is it a PBR type m/cyl with a cast in reservoir and tin lid? Mine is Ford Chrysler type m/cyl and I use a 10lb valv to the front drums, and a adjustable proportioning valve to the rear drums, and it works well. Hope this is of some help.
yes thats the same mc tin lid ,cast body, jimbo can u tell me more bout ur proportioning valve please, i dont know a great deal about em, keen to learn more , thanks
If your master cylinder is under the floor you run 10lb valves for drums front & rear, The residuals should be fitted as close to the master cylinder as possible to work correctly.
Exactumando Have 2lb on the discs on my front and no long pedal travel and stops great... its the way to go..
I thought the main diff. between master cylinder for disc/drum and drum/drum was that disc/drum had two diff. size resevoirs and possibly bore/stroke size to make up the diff. in the fluid cap. of a wheel cylinder vs. disc. fluid cap.? If running 4 drums, I would think it would be best to run a drum/drum mc with matching resevoirs..and as for a prop. valve on drum/drum, I also thought props. were only for disc/disc/ and disc/drum...I run under floor drum/drum mc with 4 drums, and 10lb. residuals, no problems... but I am just a life-long learner..........
Well something to remember in master cyl size... larger the bore the more fluid you move but less pressure... smaller bore, less fluid, more pressure... I say 3/4 or 7/8" bore generally for drums and 7/8" to 1" bore for disc drum combos, and 1-1/8" for disc disc. I have 7/8" on my disc- drum rides and its perfect combo.. And your right 4 drums with 10lb residuals is right... Hell in the old days it was single circuit master cyl for everything... I still run that way these days on my personal stuff mostly. Going to change to 2 circuit for saftey purposes probably this year though.
I am using the chev. or Gmc master with the clutch slave built in, mounted on the firewall of my modified. I'm running F 100 drums on the front with 40 drums on the rear. My dad and I have bled these drums and we still can't get a hard pedal, goes almost to the floor. Could there be a residual valve in that master that I don't need, if so how do I remove it?
here in australia we have to run dual masters for rego, i had a 40 ford single til i found that out, hence my can of worms haha, from what i read residuals help retain pressure in your braking system as well as stopping bubbling back (as i just named it) into the master, great invention from what i can tell and cheap to get
How about cars with the M/C under the floor but a remote resevoir on the firewall. Does it still need the residual valves? Does it hurt to run them if not needed?
good question and by all means im no expert, however id say yes, purely on the fact ur reservoir is only filling the cylinder, your lines are still coming from the master to the wheel cylinders or caliper piston, the pressure comes from master to these and with drums i believe that the vac pressure from return spring on shoes is what causes the issue, they say with disk/caliper setups if your master is below the height of wheel cylinders or caliper pistons then you need em, so in your case id say yes, correct me if im wrong here anyone, and as we established 2psi residual for disk and 10 psi for drums as i said im no expert
Mine is a Wilwood adjustable proportioning valve. It is mounted on the chassis just after the master cylinder and feeds the rear brakes. The idea is that it can reduce or increase pressure to the rear brakes to create an ideal bias between front and rear and prevent the rears locking up before the fronts, resulting in a possible skid. At least that's my understanding and it certainly seems to work. Check out the Wilwood site for more info.
cheers jimbo i may just do that, are they pricey????? havent plumbed anything just yet so im going to look a bit more into it, i imagine is not hard to tune these things a twist here ,a turn there till it works in a perfect manner, the way im looking at it though in my situation my 40 drums are near on twice the size of my rears (well maybe not double ,but my rears are def smaller) so my fronts should pull up harder than my rears im thinking, but yes jimbo i know what your saying mate, and its not like it can make my situation worse just better, cheers
Theoretically you shouldn't need them but in practise i've found them needed, they don't do any harm.
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