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Brake Booster replaced: Reaction Disk missing?

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So Im fairly new to this but Ive done a good deal of searching, and will continue to after this post.


72 240z, no brake mods


First, I started having really tough braking combined with a hissing noise and idle speed jump. Searched and everyone says brake booster is the culprit. Prior to this issue, the brakes felt very normal ie. had progressively more pedal pressure depending on how hard you wanted to stop (like every other car).


So I hunted for a reman'd 240z found one and ordered it. I got excited and put it in following instructions found online. Hopped in and took it for a slow test ride. Discovered very little brake feel until the very end of the throw then it was really grabby. Fiddled with the plunger rod and ended up having to swap tips (the old booster had a much longer tip), but still didn't solve the problem.


Searched again and found that the "reaction disk" missing had very similar symptoms. The obvious solution was to grab the reaction disk from the old booster and put it on the new one. Low and behold, there's no reaction disk on the old booster..... go to check the new one and its missing too. Common?


So now Im stumped because the old booster didn't have a reaction disk and brakes felt fine until the booster started leaking. 


Im thinking of going to the JY and trying to find a reaction disk.

Any ideas on what to do now? 

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The reaction disc is likely in the booster, They can fall out of the hole they reside in and bounce around the booster.


I recently had to replace my booster as well. The replacement booster (used) had the reaction disc floating around the booster.


I tried for several minutes to bounce it around and hoped it would get to a spot near the place it should be to manipulate it it into position. Best I could do was get it to fly past the small opening.


I ended up stuff a rag into the booster, on one side and was then able to get the reaction disc to then land on the rag and retrieve it.

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Imaginary internet points for you! It was a little bit of a pain to pull the booster off again, but you were right. Here I thought I was doing something wrong with the adjustment of the plunger rod.


The reaction disk was the problem. 


Im amazed what a little piece of rubber does.

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