72 240z rear brakes leaking

[bowl of seeds]

So I recently removed my brake master cylinder to bench bleed it, now that its installed i went to take the car out for a sping and the brakes fail me.. also i noticed the rear brakes are leaking? i removed the drum to see the cylinder is dripping brake fluid.. any ideas as to why?

[Miles]

Three things come to mind:

 

1.You may not have removed all of the air from the MC and brake lines after you bench bled it. Could be too the old MC just gave up the ghost.

 

2. Your rear wheel cylinder will need to be replaced. Given the history of your car you should replace both left and right side wheel cylinders.

 

3. You may (?) have dropped the reaction disk down inside booster in which case the pedal will go to the floor which will make the brakes suddenly grab. See the Brake Forum for the Reaction Disk explanation.

 

 

Brake parts should be replaced in pairs for right and left sides of the car. Such as wheel cylinders, shoes, pads, calipers etc.

 

While you are at it you might as well inspect the brake lines, shoes, pads, rotors and calipers and repalce any defective parts before you hit the road again. Motor Sports Auto (MSA), Black Dragon, Autozone, Kragen, Carquest etc all sell some or all 240Z brake replacment parts.

 

On both of my 240Zs the first thing I did was to replace all of the old leaking and wore out brake parts.

 

Always take your parts with you for comparison when buying from a parts store. Kknow the month and year your 240Z was manufactured as there are differences that matter. Info is on driver's door jam.

 

 

If you aren't sure about what to do ask lots of questions and/or get a person experienced with brake repairs to help you or take it to a brake shop.

 

In addition to the service manual, Haines manual etc. also pick a copy of "How to Restore Your Datsun Z-Car by Wick Humble. It is available from MSA.

[Zinpieces]

You just got this car and it has been sitting right? Well you probably have a buildup of rust in the wheel cylinder and when you stepped on the brake, the rubber cup ran over the rust. Presto-Leako!

In the old days we would hone the wheel cylinder replace the cups and spring and have a nice day, today you will probably have to buy new wheel cylinders.

You should inspect all the lines and hoses and at the very least flush fresh fluid through the system.

[Leon]

Why is the brake cylinder leaking? It will leak if the seal doesn't seal anymore, as the above post mentions. You don't have to get new wheel cylinders as rebuild kits are available. Just make sure to clean up the bore of the cylinder. Rockauto is good for replacement parts.

[bowl of seeds]

Thanks for all the info guys! Well I'm going by what was mentioned and taking it that the cylinder seals are just old. I'm going with the rebuild kit from Autozone but I was wondering If they were any good? I'm going to go ahead and buy the brake shoes and all necessary hardware and replace it all since I just got some money that was owed to me. The drums don't seem to show any signs of wear.. should I replace them also??

[Miles]

Thanks for all the info guys! Well I'm going by what was mentioned and taking it that the cylinder seals are just old. I'm going with the rebuild kit from Autozone but I was wondering If they were any good? I'm going to go ahead and buy the brake shoes and all necessary hardware and replace it all since I just got some money that was owed to me. The drums don't seem to show any signs of wear.. should I replace them also??

 

 

There is no way to tell if the drums are still in spec without measuring them.They could have been turned in the past. You could take your drums to a machine shop and have them measured to see if they are still in spec. Or you could buy new drums then you will know for sure they are ok. I bought a couple of sets from Autozone.