master cylinder leaks

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rjpohl

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I recently replaced the front disc brakes (pads/calibers/rubber lines).  I use DOT 3 fluid to refill/bleed.  Is this the correct fluid?  I now have a leak between master cylinder and booster, also i have fluid inside booster.  It leaks just sitting still.  Brakes work fine when reservoir is full.  

I'm leaning toward replacing the master cylinder.  Is there a seal on booster that needs replacing too.

thanks

Bob

 

Hemikiller

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Definitely want to replace that ASAP. Brake fluid is no good for the booster and will ruin it.

DOT 3 is the correct fluid.

 

rjpohl

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Definitely want to replace that ASAP. Brake fluid is no good for the booster and will ruin it.

DOT 3 is the correct fluid.
can booster be drained without removing from car.  I stuck a wire down in the vacuum line hole and it showed fluid.

 
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More than likely from bleeding the brakes it damaged the plunger. Rust gets in the cylinder and then when you bleed the brakes, the plunger travels further down the cylinder and hits where the rust forms. This can damage the plunger and makes it leak. It’s easier to replace the master cylinder than to try to fix the existing one. This same thing happened to me last year.

 
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The brake fluid will kill the booster. Go to the WCCC West Coast Cougar Classic web site they have a video on the boosters. They go to the old Booster Dewey shop now Booster Steve I think. 

The brake fluid eats paint off the booster and will destroy your rag joint on the steering shaft. 

To get the fluid out of the booster you have to take apart. I built a fixture to hold the can while reversing the crimps around the outside. Inside there is not much. Diaphragm, rod with a seal, Bakelite part that diaphragm fits on and big cone spring. The check valve on the booster can be checked by blowing into it. See on the video on WCCC. 

I have not found a supplier for new replacement parts for the booster.

You can get a replacement cartridge for the master cylinder. There is a allen button head screw in the bottom you take out and remove the snap ring and scrape the rust out of the bore. Put air pressure on front port and it should blow the piston out. You can get a brake hone and clear the rust.

The parts house masters are not exact in shape as Ford if you want original keep yours. It should be 15/16" dia. and drum was 1" dia. The setting of the rod length is critical on install in the booster see the Ford manual has to be set correct to work correct.

 
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As luck would have it I found a supplier for the brake booster rebuilds. So I will probably beef up my fixture some and see how it goes. Need some new molasses to clean the rust off also. 

The cost they gave to me is diaphragm $25.00, seal between master and booster, $6.00, Firewall seal $5.00 and the rod boot is $6.00. Check valve an seal is also around $5.00.

Probably going to order enough to do 4 tomorrow. I need two for me and will see how it goes might start rebuilding them. I need another project, lol.

 

rjpohl

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As luck would have it I found a supplier for the brake booster rebuilds. So I will probably beef up my fixture some and see how it goes. Need some new molasses to clean the rust off also. 

The cost they gave to me is diaphragm $25.00, seal between master and booster, $6.00, Firewall seal $5.00 and the rod boot is $6.00. Check valve an seal is also around $5.00.

Probably going to order enough to do 4 tomorrow. I need two for me and will see how it goes might start rebuilding them. I need another project, lol.
Thanks for the info, let me know how your rebuild goes.

Bob

 

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I need the 2 wire plug for the brake pressure switch.  I can't find any vendor who has it, did found the switch.

Bob
I got lots of those.

 

rjpohl

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Found the booster seal thanks to the help from Carolina. Now I need the 2 lines that run from the proportioning valve to the master cylinder. I want the type that are bent into a circle. I ordered a set from CJpony only to find they were out of stock. I contacted them and was told they would be in on 5/20/20. Yesterday I got a email saying now they won't be in till 6/5/20. They offered to sell me a complete set because the lines were in it, they were not willing to pull the parts from the big kit.

If you know here I can find them please let me know. I've looked a NPD and Summit but didn't see them.

 

Bill73Ragtop

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former owner (25 yrs) of 1973 Convertible, 351c, A/C, RA
You could try Classic Tube and see if they can help. https://classictube.com/

However, sometimes they take their time to produce 'custom lines' and ship them so no guarantees they will be able to speed things up for you.

 

rjpohl

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Your washer looks the same as mine but mine has the washer on the back side. The lady at power brakes said to make sure I kept washer because the seal didn't come with it.

 
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rjpohl

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Got lines from proportioning valve to MC today. These are the lines I ordered back in May from CJPony and they're still on BO. I ordered a set from Shafer Classic in Florida Wednesday and got them this morning! Great people, fast shipping.

Now My problem is making sure I connect the lines correctly. Based on the fitting sizes it looks like the large bowl is going to rear wheels and the smaller to the front. l

Please let me know it this looks right.

thanks

Bob



 

rjpohl

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The large reservoir is for the disk brakes.
Thanks Don, I was pretty sure it was.   I found the fitting I needed yesterday at NAPA and started bleeding process.  Had hard time getting one fitting onn proportioning valve to seal but I think it's good now.  Thanks again for all your help.

Bob

 
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