Master Cylinder Fittings

[Madsen1970F100]

Hi,

OK, some problems with fitting sizes, etc, etc. The distribution block has a 1/4 and 3/16 inch female fittings for brake lines to attach to. I just bought a new master cylinder at AdvancedAuto. Its fittings appear to be 3/8 and it came with an adapter to create a 5/16 female fitting. But it only came with one adapter. So to make this work? ...... it would appear I need another 3/8 to 5/16 adapted for MC. Use 5/16 lines, then install another adapter for the rears? to go from 5/16 to 1/4 so it will attach to the distribution block. Then I need two adapters to go from 5/16 to 1/4 and then to 3/16 so it could attach to front brakes on the distribution block. Yes?? or no??

I have some concerns. Does the actual size of the brake lines play a critical role in the performance or operation of the brakes? If I install adapters in the middle of a line (so not all crowded at distribution block) wil that be ok to go from 5/16 line to 1/4 line? Does it sound right to have to use all these adapters? Anyone run into this situation before? Am I even making sense? Is it possible I have the wrong MC? MY original one was suspect in that PO may have installed a 67 or some other one. It worked fine but its fittings on it were not 1/4 and 3/16 to match the distribution block, yet the lines did not use adapaters. Can one put a 3/16 male fitting on a 5/16 line? I can't see that working right.

I am confused and tired of trying to figure it out. Can someone advise what might the issue or do I just need a boatload of adapters and all will work fine? Thanks!

[fordman]

is the distribution block stock from your truck? this is a drum brake truck still right? is this a F100 or F250?

[Madsen1970F100]

is the distribution block stock from your truck? this is a drum brake truck still right? is this a F100 or F250?

Hi Fordman....As far as I know it is stock, its what took out. It has 1/4 female fitting going back to the rear and 1/4 female fitting to go to MC. The front brakes are 3/16" female fittings. It is all drums and is a 1970 F100. 302 engine, if that matters.....

[fordman]

did you save the fittings off of the old master? if so use them. they should work. are am guessing your old lines are still on there? if not use them or copies of them.

[Madsen1970F100]

Yes and no. Saved one fitting but lost the other. They are both mangled some as I had no intention to reuse when I took off and stripped them somewhat. They appear to have been on a 3/16 line. Can you have a 3/8 male fitting on a 3/16 line? The brake lines I took off were in pretty bad shape and are not usable anymore. My initial inquiry was whether I could or if I should use a series of adapters to make them fit? Is there a local type of place one can have brake lines made?

I bought two- 5/16" lines that are 6 feet in length. I figured I would bend my own and use adapters so I can leave the factory created flarings in tact. OR can I cut the line and change fitting to 3/16 and 1/4 and flare my own ends?

Sorry for the repeated questions.....

[thorn1968]

seems confusing...The lines to my master are 3/16th. The fittings were both 1/2 inch. My master had 1/2 and 9/16 ports. My new master had 1/2 and 7/16 ports. I ended up cutting one line and putting on a 3/8th fitting, re-flaring, and using a 3/8 to 7/16 adapter.

The only line around that area that I can think of that's 1/4 or 5/16 would be the fuel line??

Which master did you get?

[Madsen1970F100]

OK everuyone, thank you for your help. For some reason this issue was blocked in my brain. I went to NAPA and poured through all their adapters and after about 1/2 hour got the fittings I needed. The Master Cylinder is OEM. I got it from Advanced Auto and I suspect the reason it had 3/8 fittings is to allow it to fit multiple types of vehicles/trucks. I was able to get a 3/8 to 3/16 master cylinder adapter fittings so I can use 3/16 lines. Returned those 5/16 lines too (bastketcase). THat never felt right. I also got a 3/16 to 1/4 adapter to insure the rear lines will fit to the distribution block. So tomorrow night or maybe Saturday will put it all together and test the system for leaks and function, etc. before I continue bolting more things up! Sometimes I am convinced I am getting early alzheimers as this issue should not be as complicated as I made it to be. But I think I have it sorted out......for now.

[basketcase0302]

Eric,
I feel the same way at times! Glad you found the fittings!
Remember that teflon tape or paste, (I prefer the tape) is you friend on all your fittings.
When I put my last MC on I could not get any pressure to bleed at the wheels, (this was after multiple attempts to bench bleed the MC, and a couple of hours of trying to bleed at the wheels). I had one fitting that was not quite tight enough, (at the MC) that was not allowing the pressure to build up to bleed. Brakes should be so simple, yet can be a PIA!