So I put all new shit on my 33 pu. Bench bled the master, 10# rdv front and back. (4 wheel drums with 40 model up front, all new modern 8-3/4 mopar drums in back) 3/16 line in the back . 1/4 line in front. Damn thing is soft. When you pump it for a while, around 5 times its hard and feels like it should. Let off and it goes to the floor. The master is a speedway item (non boosted) for 4 wheel disk, or drum. Ive jacked with this thing most of the day and still dont know whats up. Ive run almost 2 qts of dot 3 fluid through it and there is no air anywhere. Help me please. Is it that the front lines need to be 3/16 or what. Thanks for any help. Bishop
Are the residual valves in backwards? I've never seen a master cylinder that works both 4wdisc AND 4wdrum. May be a problem there as well.........
There in there the right way. I wonder if the little plastic thingy inside the rdv is touching the fitting. If so does this have any affect on the performance of the rdv. I wouldnt think it would mess with how it works seeing the valve part is in the center of the thing. As far as the master goes, I used to run a 1975 corvette master for disc up front and drum in the rear, switched to 4 wheel disc and it was great both ways. I would think the master I have now would be fine.
Is your Booster[or pedal] to master cylinder "pushrod" adjusted properly? too loose and it will be as described-too tight and it holds the M/Cyl's piston so it will notreturn far enough to uncover the hole that allows fluid into the bore from reservoir above M/C bore....... OR..... is the ratio of the brake pedal correct?
Good point, I went back to the shop and moved the adjustment out and it didnt help. Even with the pedal uncomfortably close to the driver it still had the same effect. Pump to get pressure.
I know this sounds stupid...... But, Have you checked ythe adjustment on the brakes themselves ? When i finished my sport coupe i thought i had the brakes adjusted fine, 4 wheel Lincoln drum & '40 ford master cyl. Felt good so i took it around the block and when i got back you had to pump the pedal to get pressure. They just needed to be re~adjusted, Now they are fine
Thats what I did last night, I pulled the rear drums off and adjusted those. The fronts (40 ford) well they dont have adjustment. Or is there a trick I need to know.
The front '40 brakes do have an adjustment.....it's the 2 anchor pins at the bottom.....they move the pivot point of the shoe.....
The 40 brakes have four adjustment points per wheel. (if you really have 48 brakes there are only two per wheel) The bottom pins have a small dot on the end, which is the high point of the accentric. Start with them inward and slowly turn them up and outward while you spin the wheel. Stop when they just touch the drum, then back off a very little. Then move up to the side adjusters and do the same: a little at a time until they just touch, then back a little bit. I forget if it is up or down to adjust, but it will be very obvious once you give it a try. You may need to re-adjust the bottoms, then the side again after you are close. When all done adjusting and testing the pedal, make sure to check your fluid level. 40 brakes are very touchy in their adjustments, and will need much attention as the shoes wear into the drums.
It sounds to me like it is an internal master cly. leak. But take a look at your front brakes and see if you can adjust them. (see pic)
I had a master cylinder do the same thing to me. It was slightly lower than the calipers and wheel cylinders and when you would let off the residual valve would suck air past the seal on the rear piston of the master cylinder. It took longer to draw enough air to cause a problem though (usually a couple of heat cycles). The cylinder was bad from new (and yes it was new not reman). But I would check the front adjustment first, as that would do the same if you have them adjusted all the way loose (in, small, short ??).
hey bishop hope you get the brakes sorted out,the fronts do have the eccentrics like was noted before,once you adjust the shoes up you should be ok with the brakes,have you got any pics yet? wayne
I got the brakes worked out, and they work nice. Thanks everyone for the advice, all was taken in consideration. It turned out it was adjusment in the fronts. I feel like Im a master at the 40 stuff now. I didnt know jack about'm before, so thanks, and the picks will be up when I get the doors finished. Wont be long before it hits the road.
and yet you looked anyway.... Bishop- shoot us some pics! that's no joke about really monitoring the brakes, either- throw an extra wrench in the car, and leave it there. Long trips will make the adjusters back off a bit.
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