Jump to content

IGNORED

New booster, now sticky brakes


Recommended Posts

I installed a new brake booster and now I have LOTS of brakes! Anything more than minimal pressure and the brakes are on hard.

i was careful to measure the lengths of the brake rods and the master cylinder rod, so the new booster is set up exactly the same. They don’t seem to be hanging up; none of the wheels show excessive heat after a short drive. The brakes worked ok before the booster swap; the old booster just had an air leak. 

any suggestions?

Edited by Trimpe.bob@gmail.com
Link to post
Share on other sites

Must be nobody looking because this is - first! - a classic sign of a missing reaction disc.  A rubber disc between the rod and the booster surface that sometimes falls out and ends up in the bottom of the booster.

Search "reaction disc" and you'll find a bunch.

Link to post
Share on other sites

I agree with Zed Head, Reaction disc. Happens a lot and had to tell if you are not looking out for it. 

Most gue them back on to the push rod piece. The manual says to use grease, but I didn't think that would hold as well. spacer.pngspacer.pngspacer.png

disc.jpg

IMG_3455.jpg

IMG_3453.jpg

 

Edited by Terrapin Z
Double pic's
Link to post
Share on other sites

Yes #18 it sits in the pocket normally but when pulled out even just enough it can fall off and ends up in the bottom of the booster. 

Hard to get out with the booster still mounted in the car. Usually have to pull the booster and shake it around until you can grab the little sucker. 

Link to post
Share on other sites

In the 240Z booster there would be a lock washer type plate as seen in the pic here, down in the plunger hole. (not shown in book diagram) 

Then the three pieces in my first picture above a disc with the rubber seal (#1), the plunger itself (#2) and the reaction disc (#18)

I found all this out a while ago when I bought a rebuilt booster from MSA. I don't know when the disc was lost, but it was not where it was supposed to be. 

I had brake problems as you describe. With the reaction disc out of place you would had to have readjusted the plunger rod to get any brakes as you would be missing a quarter inch of set up. 

 

booster1.jpg

Link to post
Share on other sites

Amazing what that little rubber disc does. I am very surprised that no one makes a replacement disc so you wouldn’t have to pull the booster, but I’ve never seen one offered. I super glued mine on to keep it from falling off on installation.

Link to post
Share on other sites

That does look strange, Where did you get the Booster? 

Was there a lock washer and seal disc in there? It looks like scrape marks where the lock washer was pulled out. 

It almost looks like the spring is in backwards. If you look at my third picture above the spring gets larger toward the back.

Yours looks to me like it gets smaller in the back thus blocking the plunger.

The rod should be attached to the plunger piece and the reaction disc is on the back side of that. They usually come right out with no interference from the spring.

Did you send your old booster in for a core? If not maybe compare the two.

Link to post
Share on other sites

The booster is from Autozone. I sorely regret turning in the core. The was a lock washer and seal in the unit. I took them out.

 

since I have it out, and it came with a warranty, I may see about getting a replacement, just because. 

Edited by Trimpe.bob@gmail.com
  • Like 1
Link to post
Share on other sites
2 minutes ago, Trimpe.bob@gmail.com said:

The booster is from Autozone. I sorely regret turning in the core. The was a lock washer and seal in the unit. I took them out.

If you bought it recently maybe they still have it in with their cores, They usually don't get picked up until they have a good amount to make the load haul worthwhile. It would be worth a shot to ask.

If it is gone I would at least try and get it swapped out for another one. Explain the issue with the brakes and content you think it was rebuilt incorrectly. 

If the spring is on backwards it will not push against the diaphragm correctly and will not function as intended. Auto Zone  should get you another one. Those stores often get bad rebuilds with core product (reman's)

  • Like 1
Link to post
Share on other sites
15 hours ago, Trimpe.bob@gmail.com said:

I wish we had Napa in our area.

I'm not a snob about these things, as I sometimes use Autozone, but I agree that Rockauto would offer more options and quality levels of parts if you don't have NAPA around.

Link to post
Share on other sites
19 hours ago, Trimpe.bob@gmail.com said:

The booster is from Autozone. I sorely regret turning in the core. The was a lock washer and seal in the unit. I took them out.

since I have it out, and it came with a warranty, I may see about getting a replacement, just because. 

The auto parts stores are all used to accepting returned reman parts.  Just take it back and ask if you can look at the other units that they have in stock.  You'll probably find one that looks right and they'll just swap it, no problem.  Defective reman parts is normal.

Link to post
Share on other sites

Once you get the replacement, I suggest you confirm the reaction disc is in there and glue it on if it is not already. 

I hope this all works out well for you. I think it is safe to say we have all encountered similar problems with these cars and have worked through them to fruition.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.