disc brake conversion

[Hawkrod]

As far as the booster is concerned that makes perfect sense.

Went to refresh my knowledge on drums and saw this:
"The residual valve holds ten pounds on a drum brake system when the brakes release to keep the spring on the shoes from collapsing the wheel cylinders."

If the wheel cylinders don't collapse all the way, the shoes don't retract all the way correct ?

No, you are misunderstanding it and that description is wrong. The shoes retract all of the way and seat on the large round pin at the top of the backing plate so there is no way the springs can collapse the wheel cylinders. The pistons can actually travel even farther in but only go as far as the shoes push them when they are seated. The issue is the piston seals which are small round rubber cups and a lack of pressure will allow them to pull away from the cylinder wall and leak. There are other cylinders that do not use cups but use a ring style seal so that is not an issue with those but they still use a residual pressure valve so that reaction in the cylinder is immediate. You can easily check this, go pull a drum off and note that the shoes are seated on the stops. Now take a screwdriver and push in on the piston in the wheel cylinder. Combined, they will travel in about another 3/4 inch or so (depending on application)! Hawkrod

[Rusty67]

Ah ha ! I see. Thanks for the brake down on brakes =)

[Hawkrod]

oops double response

[onetuford]

ok....so i talked to some dude at some outfit that sells conversion kits today (mpbrakes.com). He talked about shallow well and deep well masters. Its obvious that through that outfit than when you buy a power conversion they sell you a booster that comes with two rods. One is for the '67 only short rod. I saw pictures of it. I was as at twoocations today and physicallyb saw two trucks that had dics with no power booster. One was indeed a suspected 1979, the other was for sure a 1973 f100 with disc and no power booster. I stopped to try to buy the thing and the guy claims he got a Torino from his cousin when he died and the truck has a 428..........I'll research casting numbers......Just prove to me there is no such thing as disc, no power with-i don't know-proof that I can read. My brother has dealt with these old trucks forever, even though everything he's touched is 4 wheel drive and seems to remeber trucks with discs and no power. Maybe today i was not in the right mind and that old POS 1973 I saw was not what I though. I've called 6 junkyards today in Wi to find a P/S A/T steering coulmn and all say they scrapped anything older than 1985 or so.............

[Hawkrod]

ok....so i talked to some dude at some outfit that sells conversion kits today (mpbrakes.com). He talked about shallow well and deep well masters. Its obvious that through that outfit than when you buy a power conversion they sell you a booster that comes with two rods. One is for the '67 only short rod. I saw pictures of it. I was as at twoocations today and physicallyb saw two trucks that had dics with no power booster. One was indeed a suspected 1979, the other was for sure a 1973 f100 with disc and no power booster. I stopped to try to buy the thing and the guy claims he got a Torino from his cousin when he died and the truck has a 428..........I'll research casting numbers......Just prove to me there is no such thing as disc, no power with-i don't know-proof that I can read. My brother has dealt with these old trucks forever, even though everything he's touched is 4 wheel drive and seems to remeber trucks with discs and no power. Maybe today i was not in the right mind and that old POS 1973 I saw was not what I though. I've called 6 junkyards today in Wi to find a P/S A/T steering coulmn and all say they scrapped anything older than 1985 or so.............

Actually, I was wrong, I am sorry about that. There were some really stripped F100's and F150's with manual disc brakes. I always forget about them becuase I only Have F250's and F350's. There were no F250's or F250's with disc brakes that were manual. The F100 and F150 was light enough that they were offered that way but I have never seen one around here (actually, it is pretty rare to even see a 73-79 F100 around here. Almost all the trucks I see are F250's). Hawkrod

[onetuford]

Well Hawkrod, in searching of posts you seem to be a very reputable source of info. I was confused for a bit there. I do appreciate your help.

[Hawkrod]

Well Hawkrod, in searching of posts you seem to be a very reputable source of info. I was confused for a bit there. I do appreciate your help.

Well thank you for that but I will tell you that I try and only answer questions that I already know the answer to. It makes it easier to be right. The upside is I have no issue admitting when I am actually wrong! Unfortunately it happens a bit more often that I would like though! LOL Hawkrod