Master Cylinder replacement - Couple of Ques.

[Jcos]

Replacing the MC & front calipers on my '86 FJ60.
The first question that came up is...what the heck is that cast iron piece that the two brake lines coming from the MC go into before continuing on to the wheels? It is bolted on to the bottom two MC mounting bolts & it has the front & rear lines in from the MC and two lines out that continue on to the wheels. It is a separate casting from the MC & there is no picture or mention of this component in the FSM! The system was "subjected" to some Dexron ATF a couple of years ago & I want to make sure I flush everything thoroughly. (OK, the story goes... Dad says, "make sure you top off the PS fluid before you drive it". Son, dutifully reporting upon coming back into house, "added some, but it really wasn't very low!" to which I replied )

Second... the gasket that goes between the MC & power brake booster was not included with the A1 Cardone MC. I made one from some sheet material on hand which is Rubber-Fiber that's 1/32" thick & I think it was the thinnest that Advance Auto stocks IIRC. This is probably 2 or 3 times thicker than the original plain paper gasket that I found remnants of. Will the extra clearance pose a problem? Probably over-thinking this one, but a little affirmation is always nice!

Thanks, John

 

[Jan-78FJ40]

Replacing the MC & front calipers on my '86 FJ60.
The first question that came up is...what the heck is that cast iron piece that the two brake lines coming from the MC go into before continuing on to the wheels? It is bolted on to the bottom two MC mounting bolts & it has the front & rear lines in from the MC and two lines out that continue on to the wheels. It is a separate casting from the MC & there is no picture or mention of this component in the FSM! The system was "subjected" to some Dexron ATF a couple of years ago & I want to make sure I flush everything thoroughly. (OK, the story goes... Dad says, "make sure you top off the PS fluid before you drive it". Son, dutifully reporting upon coming back into house, "added some, but it really wasn't very low!" to which I replied )

Second... the gasket that goes between the MC & power brake booster was not included with the A1 Cardone MC. I made one from some sheet material on hand which is Rubber-Fiber that's 1/32" thick & I think it was the thinnest that Advance Auto stocks IIRC. This is probably 2 or 3 times thicker than the original plain paper gasket that I found remnants of. Will the extra clearance pose a problem? Probably over-thinking this one, but a little affirmation is always nice!

Thanks, John

1) Does the piece have a bleeder valve? If so, it is a proportioner and needs to be bled. If not, it is just a junction.

2) Yes, this ill affect your brakes. The rod that comes out of the booster has to be in an exact position to the piston in the master. You just increase that distance. Since it was just a tiny increase, it is probably fine. However, not all masters are exact the same, so one should check this distance as per FSM.

cheers,
J

 

[Jcos]

1.)JUNCTION! That's the word I couldn't think of when I wrote the post. No bleeder, but it does have a large bolt head at one end (towards engine), will try to remove to be sure I've gotten all old fluid(s) out!

2.) Yeah, this concerns me enough (realized after I had written the post!) that I went to NAPA this time & got 1/64" fiber gasket, no problem. Funny how just seeing what you're thinking about "written out" clarifies things. My trouble is I try to use what's on hand & I get carried away sometimes (OK, ALL the time!)

 

[DrivingMissRosey]

I haven't done this job yet on mine, but will be shortly, so everything I say comes with that caveat.

1) I dont think mine has a bleeder on it but am not sure so I'll be doublechecking it.

2) The Gasket you are talking about is 2 bucks at your local Yota dealership. I'm no OEM Nazi, but in this case it might be worth it. I dont think you have to have the exact right thickness because there is an adjustment nut on the end of the rod coming out of the brake booster that you more than likely will have to adjust anyway as Jan-78FJ40 stated as each MC is slightly different anyway.

Jcos do you have the FSM for your 60? There is a pdf floating around on mud that has a link. Search under thread tools tools to find it.

 

[scrowley]

1. prop. valve
2. The little bit of thickness in the gasket shouldnt make a diff. I recently replaced mine. I measured the distances on the stroke in to make the rear brake part of the cylinder work. I would say you have up to 1/8" at least before it would make a huge differnce.....as in improper engagement of rear brakes.

 

[ted0]

I've just finished having a go with the brakes on my old 82 FJ60 (and learning a heap), so hopefully this will help..

1. As said, it's a load proportioning valve. There's a bit about it (plus some pics) in this thread: https://forum.ih8mud.com/diesel-tech-24-volts-systems/136159-bj60-brake-lines.html
My FSM didn't have any info about it; seems to be a bit of an old school system. None of the local auto shops could help me out with it, and I ended up going through a bunch of FJ and HJ60s at a few of the local wreckers before I could find a replacement.

If you just bleed out your brakes normally it'll empty out this bit.

2. No idea about gaskets .. my MC just bolted directly onto the brake booster.

Anyhow hope that helps..

 

[ambulancechser]

yes,there's a gasket between the master and booster.i was barely able to reuse my old one with a little smear of rtv.

don't forget to bench bleed the master...i went to napa and bought 2 short brake lines that fit (can't remember the size) and bent them around to stick into the resivoir...just mount the master gently in a vice and push the piston in with a screw driver.add fluid until the bubbles stop.if you forget this step,your brake bleeding process will drive you nuts.

one more thing...a vacum bleeder is your friend.i'll never try to bleed brakes without one ever again.