ToolBoy

Brake Booster Rebuild Help

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    Hello to all, 

    It seems I have shot myself in the foot needlessly again. The expression goes "If it aint broke, don't fix it"   Well, I really fixed it. Bought the rebuild kit for 7 inch brake booster, bead blasted and cleaned it up, pulled it apart and got down to the "valve operating rod assembly"  There is a cylindrical rubber boot in the rebuild kit so I proceeded to rip off the existing rubber part, trusting that I would figure out how to disassemble and remove the springs etc to install the new one. Now I'm thinking the parts are permanently crimped on and not designed to be removed. I either need to find a way to dissassemble this part or order a replacement valve operating rod assy.or buy an entirely new booster if that is the only option. Can't figure out why that part is included in the kit if one can't remove the old one?  Any input is welcome. . . Thanks  Andy.IMG_7972.jpeg

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    Thanks Patcon,  I read thru all the posts and comments on your Brake Booster topic but there doesn't doesn't seem to be any information that addresses my problem. 

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    Post #3/4 of the way down Page 3?  No good?

    image.png

     

    Edited by Zed Head

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    Yes. actually very good. I didn't look at the following pages at first. Didn't realize the post was so deep. I'll pop the unit apart tomorrow. Thanks.

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    Hello to all,  I understand that this topic was created a year and a half ago but I didn't acquire my Z till december and my booster is ripped apart now. Patcon  was super helpful by directing me to this conversation and I've poured through the discussion and the photos repeatedly. I am suspicious of the booster as it came on the car and I'm thinking it wasn't done right the last time.  I'm now doing my best to match up the new rebuild kit parts with what I have and preparing to reassemble after some final paint work I still need to do. This morning I put the poppet assembly back together and re-punched the 3 divets thanks to the input and courage you all provided. I have included a photo of how I'm thinking the unit will be reassembled with a few questions.  If anyone would take a look, I'd be real appreciative.

    Questions. . . I didn't notice when I took it apart but I'm wondering if the key that holds the poppet assembly needs to be facing up so as not to fall out ever.

    Also I'm thinking bearing/seal part "P" is to replace soft seal "L" . The new part is a really tight fit but once lubricated, I think it'll go in. Also thinking the metal ring side goes in first and installer pushes on the hard plastic side? And then it's followed by the serrated ring?

    "I" is the old dust boot which I like better than the replacement and it's still pretty supple. 

    The poppet assembly is also a super tight fit but with silicone grease it should go.

    If anyone wants to chime in with comments I'm all ears. 

    Thanks to all and stay well and prosperous,

    Andy

    7InchBooster.jpg

     

     

    Dec2019.jpg

    Jig01.jpg

    Jig02.jpg

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    I am unsure on the seals. I did a lot of guessing there and just working through it by looking at the seal edges

    The retaining key can probably go in any orientation because the rubber diaphragm will go in that slot and keep it in place. If I remember correctly...

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    Thanks Patcon,      After I posted I started doing a preliminary assembly and I'm much more confident than I was. And you're right about the key. . . the big rubber diaphram holds it in. I had a hard time stuffing the bell shaped rubber piece on the central rod but it finally went in. Looking forward to getting it to close up in the end. That should be fun to figure out. Thought about modifying an oil filter wrench to make it the right diameter. Thanks for the feedback. . . 

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    @ToolBoy I’m hoping you can remember the assembly process.  I removed my booster and something doesn’t seem right with mine.  Regarding the parts you identified as D and N, those are the only two parts that come out of the assembly.  Does N slide onto D and then fit into C?  If so, does N get affixed to C with something like RTV?  Any help is appreciated.

    i also started a thread with pics. The thread is titled “Brake Booster Questions - Please Look” in the subject.

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    Hey Happy Z,  It's been a while but I haven't put the booster back in the car yet so I was able to remove the parts as shown. The push rod "D" is only stuck to the reaction disk "E" with the silicone grease and it's kept from falling out when the master cylinder is bolted in.  That push rod "D"seems to be centered with disk "N" that's pressed into the front of  "A". I was thinking that Disk "N" needs to seal against "D" but I'm hoping that vacuum will be sealed on the other side after the master cylinder is bolted on. Mine is holding vacuum when tested but I can't really test in the real braking world as I won't have the car running for some time. I've attached a photo of the front pulled apart to Illustrate. I wish I could say I have it assembled correctly but at some point I was winging it as I didn't take as many photos as I should have. Good Luck. . . Andy

    Booster Frt.jpg

    BoosterFrt2.jpg

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    Not sure if that disk gets glued in, mine's just sealed with grease but might be a good idea.

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    Ah. . . here. See page from FSM that lists parts that get silicone grease. . . calling it "plate and seal". Part can also be seen in second photo first column.

    Booster assemble.jpg

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    Just occurred to me when thinking of your initial question. The rubber reaction disk "E" that sits against the pushrod can fall inside the housing when the pushrod is removed if one isn't careful.  

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    I read the FSM, but couldn’t figure it out.  You pick really helped.
     

    last question @ToolBoy ... will the booster hold vacuum without plate and seal installed with pushrod?

    thank you...thank you

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    Hey HappyZ,   Glad to help out a little as most of the time I'm confused and terrified.  After I had mine torn apart I went to the local Z mechanic to find out how the poppett assembly came apart. He said he didn't know as he had never done it and always "sent them out". The guys on this site saved me on that one. When you tear apart the entire unit and study it you see that the vacuum is held inside the front shell between that shell and the big rubber diaphram that is included of the rebuild kit. There are only a couple places vacuum can escape but one is to the front around the plate and seal and thru the pushrod. My suspicion is that if you don't have a perfect seal at the plate and seal, the installation of the master cylinder stops the vacuum after it has been fitted. I think I checked vacuum only after bolting that on.  ( I think ).

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    10 hours ago, HappyZ said:

    will the booster hold vacuum without plate and seal installed with pushrod?

    No, it will not hold vacuum without that front seal. If that seal is not in place, it's a direct link from the vacuum port to that hole.

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    9 hours ago, ToolBoy said:

    My suspicion is that if you don't have a perfect seal at the plate and seal, the installation of the master cylinder stops the vacuum after it has been fitted. I think I checked vacuum only after bolting that on.

    In reality, you don't ever want to draw a vacuum against the back of the master cylinder. In fact, on the original system, I there's a hole to prevent just that.

    You shouldn't block that hole (like with a gasket or something). and because there IS a hole there, the bolting of the master cylinder to the booster will do nothing to retain vacuum.

     

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    I wasn't sure and knew if it wasn't right I would hear about it. Thanks for that. I'll look for that hole too. 

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    I believe there is a small dimple on the lower part of the hole the master cylinder bolts into on the booster. I believe it is designed to allow brake fluid to drain out instead of into the booster

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    ToolBoy, You can see the vent passage in one of the pics you previously posted:
    vent hole.jpg

    I thought there was slot in the master cylinder or adapter as well. I looked for pics, but unfortunately don't have any that would help there.

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    Perfect, I never noticed that passage before. I'm hoping I can get plate/seal/rod to seal well enough.

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    21 hours ago, ToolBoy said:

    Just occurred to me when thinking of your initial question. The rubber reaction disk "E" that sits against the pushrod can fall inside the housing when the pushrod is removed if one isn't careful.  

    I ALWAYS crazy glue the reaction disk to the piston when I take these things apart. No way I’m ever losing that thing again...

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    7 hours ago, ToolBoy said:

    Perfect, I never noticed that passage before. I'm hoping I can get plate/seal/rod to seal well enough.

    If the surface of the rod isn't all pitted with rust, it should seal pretty well. In the area where it matters, yours looks pretty good.

    So about the vent passage... Are you sure the gasket you put on there isn't compressed into the vent and blocking it off? I'm beginning to think that there is NOT another passageway on the adapter plate or the back of the master cylinder. That slot may be the only vent?

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    Thanks for the follow-up. The rod does look good although it might have a few tiny chips in it and I don't remember if I used the plate and seal from the kit or the one that came with the car. The first time I checked vacuum it held and the second time it dropped a little. I cut the gasket myself but given the new info I'll leave it off when I reassemble. You're in Philly?  My mom's brother lived in Philly for 30 years and my mom is from Beaver Falls. I'm originally from Lancaster. 

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    I've seen a couple other owners use rods with some small imperfections in them (what it sounds like yours has), and they were OK. Mine had been bathing in brake fluid for a couple years and was not OK. Haha!

    And small world... I lived in Lancaster for a year, and my brother lived in Venice for maybe 10? I also lived in Pittsburgh for a couple years.  We have probably run into eachother in the past!     LOL

    Edited by Captain Obvious

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