1972 240 brake problem Help Needed

[Strongback]

Hello Hybrid Z, Long time reader, first time posting. I need some help with my new to me 72 240. Ill be as quick as possible. Here's my problem..... My brake petal goes nearly to the floor before breaking. Once its there I have a some squish/pressure and the brakes work like a champ. When I say like a champ I mean its stops full stopping power. There is no gradual braking at all. Anyway thanks in advance if anyone has any ideas. 

[Miles]

1. What, if any, modifications have been made to the brake system? Be specific.

 

2. Have you removed the master cylinder?  yes / no

 

3. Have you replaced the booster? yes / no

 

4. Have you inspected the brake pads/shoes for wear?  yes / no

 

5. Have you adjusted the the rear shoes? yes / no

 

5. Do you ever have to pump the brakes?  yes / no

 

7. Is it like you have no brakes at all and then the pedal goes low and then the brakes grab really hard?  yes / no

 

8. Do you know what a reaction disk is?  yes / no

 

9. Do you know about the rod adjustment between the booster and the master cylinder?  yes/ / no

 

10. Have you downloaded a copy of the Factory Service Manual (FSM)? Available on-line or in the forum marked "downloads here on HybridZ.  You will need it.

 

Answer all of the questions  yes or no.

[Strongback]

Hi, Thank you very much for taking the time to write all of that out. Its appreciated.

 

1. What, if any, modifications have been made to the brake system? Be specific. The car is new to me by roughly 24 hours ago. Their are no upgrade type mods.

 

2. Have you removed the master cylinder?  yes / no ...No

 

3. Have you replaced the booster? yes / no ...No

 

4. Have you inspected the brake pads/shoes for wear?  yes / no ....Yes pads,,,,, no shoes

 

5. Have you adjusted the the rear shoes? yes / no .... No

 

5. Do you ever have to pump the brakes?  yes / no... No, it does not make a difference they will not build pressure above the bottom end of the stroke.

 

7. Is it like you have no brakes at all and then the pedal goes low and then the brakes grab really hard?  yes / no ....Holy crap yes. Exactly

 

8. Do you know what a reaction disk is?  yes / no .... I have heard of the part as of today and am at a loss. Thanks for bringing it up.

 

9. Do you know about the rod adjustment between the booster and the master cylinder?  yes/ / no ... Yes

[Miles]

Before proceeding, check that your rear shoes are not worn out and or not adjusted.

 

Per question 7, it is possible that the reaction disk has fallen out. It is a  rubber disk about the size of a quarter and 1/4 inch thick and goes between the booster and the MC push rod. They typically fall out when people change the MC , try to adjust the push rod, pull the push rod too far out of the booster such that the reaction disk is pulled out of a pocket it sits in and falls to the bottom of the booster.  Symptom: pedal travels almost to the floor and then the brakes grab really hard.

 

Recommend that you search HybridZ. There is a post by a member that details this problem.  It may be in the FAQ bake section or in the brake forum.

 

Do your research and  before doing the next step.

 

You will need to visually confirm that the disk has fallen out.

 

1. You do not have to remove the MC for this.

2. Remove the nuts that hold the MC to the booster.

3. Do not remove the brake lines from the MC. Just pull it away from the booster and push it aside.

4. Remove the spacer that goes between the MC and the booster.

5. With a flashlight, look inside the booster where the  push rod is. You will see a star shaped "keeper" that holds the push rod seal in place.

6. Carefully remove the keeper so you don't bend it. You may have to reshape it when reinstalling it.

7. After the keeper is removed pull on the push rod until it comes out. The seal will come out with it.

8 With a flashlight look at the pocket in the booster where the push rod sits. You should see a black rubber disk. If all  you see is shiny metal pocket,  then the disk has fallen out.

 

Now you have a choice:

1. Remove the booster and shake it around until the disk falls out or

2. Buy a new booster as it will have a disk installed.  Note if you pull the push rod out too far while adjusting the length per the FSM then the new disk will fall out.

 

Recommend that you glue (JB Weld) the disk to the push rod, even on new units.  Just  orient the booster in a vise with the push rod pointed up vertically. Dig out the disk ,  glue it to the push rod and then replace the push rod, seal and keeper in the booster.  This will save your mental heath when adjusting the push rod length.

 

Your Z is over 40 years old. In the interest of safety, I always completely rebuild the brake system on old cars before putting them on the road.

 

 

 

 

Edited May 6, 2018 by Miles

[Miles]

 

Edited May 6, 2018 by Miles
add pictures

[Strongback]

Miles, I am going to take your advice. I plan on tracking this car and instead of replacing a few needed parts I am going to replace it all and start new. I owe you one and appreciate the time you gave to helping my problem. Great advice! Thanks again

[Miles]

Nice clean Z you have.

[JSM]

8 hours ago, Strongback said:

Miles, I am going to take your advice. I plan on tracking this car and instead of replacing a few needed parts I am going to replace it all and start new. I owe you one and appreciate the time you gave to helping my problem. Great advice! Thanks again

 

Nice. This was on eBay in Cape Coral  not long ago. Did he end the auction for you?

 

[Strongback]

Thanks Miles. Ive been riding in them since I was 8 years old. 41 now and I have had a few over the years. My son is 12 and I took him for his first ride in a 240 Friday night..... Its truly my all time favorite car. I am excited to get this one up and going after the past 10 owners did not own a manual or bother to ask questions. For example I adjusted the SU's yesterday and discovered it was at best 50% throttle at WOT. LOL the battery was grounded to the battery tray and the tail lights were wired to have the recepticals be hot all the time when we know they are supposed to be grounded.... Ughhhhh...... Overall its a great car but it needs some sorting out.... My plans are to auto cross it sometime this summer once she has been gone through and expose my son to more than spectating races. Again thanks for your help today. Ill look for you on here and if you ever need anything just shoot me a message. Quinton

[Strongback]

2 minutes ago, JSM said:

 

Nice. This was on eBay in Cape Coral  not long ago. Did he end the auction for you?

 

Thanks JSM, Yes I was the lucky guy.  His name is Vinny. I live about a hour down the road. It was a solid deal, hes happy, I'm happy. Rare!

[JSM]

That is great. Congrats. 

 

[jhm]

Looks like a really nice old 240.  You are already WAY ahead where most of us usually are when starting with a newly-acquired Z. 

Have fun with it, and welcome to HybridZ.