Master Cylinder Question

I have been tinkering on the '74 CJ5 I picked up last week. There were some definite issues (standing on the brake to slow down just didn't feel right) with the braking and I have now checked and noticed that the front reservoir of the MC is bone dry. This feeds the rear brakes if my tracing was accurate.

I checked as best I can the lines and was not able to find any indication of a leak. My current plan is to fill the reservoir and watch for any leaks to see if this helps my issues. What do I need to be aware of when refilling this line? Do I need to have someone help me bleed the lines? Do I just fill it and then place a shop towel over the open MC and pump the brakes to fluid back through the line?

I am really a noob when it comes to this garage stuff, but I am willing to make the mistakes necessary to learn. Thanks for the input. I still need to get some pictures on here.

 

The best way is to start at the RR wheel. Fill the master cyl & put the cap on. Open the bleeder on the RR wheel cyl. Slowly push the brake bown almost all the way and hold it. Have your bud close the bleeder. Let the peddle up and repeat untill brake fluid comes out. Then do the LR. This should get the air out of the lines. Recheck the master cyl. after a few so you don't run it dry again. If you do, you will have to start all over. Once all the air is out, then you can check for leaks. Good luck

 

Thanks guys. This is going to do a lot for my confidence while doing this project over the weekend.

Switching gears for a second: What is the best way to free a rust locked bolt? Where is the best place to find replacement hardware while working on my Jeep? I was going to replace the V-belt last night, but wasn't able to get the lower bolt loose to allow the alternator to swing towards the fan. I am going to give it another try tonight. TIA for all recommendations.

 

The problem with pumping the brakes, is that if you have a air bubble in the line it gets broking into alot of small air bubbles. This makes it harder and longer to get all the air out.It will work but it takes longer.

 

Soak it in PB blaster, give it a little while and then give it alotta manual power And you can find most replacement bolts and nuts at any local harware store.

 

Don't pump the brakes rapidly when bleeding! Pump them slowly with even strokes. If you pump them too fast it will do just what KDX250 said. As long as you go slow and sure it works fine.

 

I've managed to gravity bleed my brakes from a dry system three times now. It takes a couple minutes longer, but so far it hasn't given me any problems.

 

Repeatedly soaking the frozen bolt in PB blaster is the a great way to get those old rusty bolts loose. Get some today from your FLAPS and start repeatedly soaking the bolt over the next coupe of days.
There are other secondary methods that should be used with discretion. Such as gently heating it with a torch, cussing at the bolt loudly, hitting the bolt with a hammer to help the oil penetrate.

After you've mastered some of these techniques you can move on to advanced bolt removal techniques; such as spraying the bolt with oil, then lighting it on fire with the torch, and cussing. R)

 

Thanks for all your suggestions on the rust lock problem. I did happen to pick up some PB Blaster last night and it did the trick about an hour after spraying, plus two beers! The knuckles were spared on this one, but their collective future is looking bleak. I got the belt replaced and drove the Jeep to work after lunch today.

I will apply all of the suggestions that have been made when I bleed the brakes tomorrow. Here are a couple of pictures that my wife took. I will get some better ones later.

 

As a follow up to this original post, I wanted to state that I have narrowed the brake fluid loss to the left rear. While bleeding the right rear, I noticed that there was brake fluid running down the inside bottom of the left rear tire.

After further inspection, I was able to determine that it was not the sending or return lines. The leak was coming from inside the brake itself. My initial thought is that there is a busted Wheel Cylinder to blame.

Since I was moving into unknown territory, I put everything on hold. After removing the wheel, how do I proceed dismantling the brakes? According to the TSM, the WC seems simple enough to replace. Are there any gotchas with this procedure? Would it be a good idea to replace both the rear left and rear right even though it looks like the culprit is the left? Thanks again for your help on this.

 

Hi mate,

Im new to the forum but i have done when your talking about before. I find taking digital pictures during disassembly helps when im trying to remember how to put things back together! I can only think of a few things to note.

Your drum may be full of potentially dangerous dust, depending on the age of your brake shoe linings they may contain asbestos, not nice if you get it in your lungs. Also make sure you've got a few cans of brake cleaner on hand to clean parts etc. Also if you have to remove any springs, watch out for them... spronging' (?) you dont wanna cop one in the face.

Good luck,

Disclaimer, im just an electrician, i know nothing about everything mechanical LOL

-Ads

 

Oh, and just my personal preference, but i would be replacing both. If one has failed, the other may not be far behind!

-Ads

 

Thanks for the input. I figured if I was going to be spending the time replacing one, then I might as well spend the extra $20 and replace the other.

According to the TSM, I will need brake cylinder clamps to retain the pistons in the WC while I remove the shoes. Once the shoes are removed, I assume that the WC can be disconnected from the brake line and replaced. Then repeat the process in reverse to reassemble the brake. Outside of a brake spring tool and the brake cylinder clamps, are there any other special tools that I will need to perform this maintenance?

Thanks again for all the instruction.

 

You don't need clamps to hold the wc pistons in place. They will not come out unless you apply pressure to the brakes. Start spraying up the brake line going into the wc. Removing the brake line from the wc can be a pain in the butt. If your lucky, it won't strip or brake. Good luck.

 

I was able to get the job done on both. I did run into a funny issue which you can see in the picture. There was no adjusting hardware to be found. I went out and picked up the hardware at my FLAPS, which then allowed for everything to get replaced. Unfortunately I didn't get a picture after I replaced all the hardware.

I ended up replacing the shoes and hardware for the entire brake. The drums were in good shape so I decided to reuse them. Thanks for all your help here, I was able to get this repair job done in an afternoon!

 

The bottom spring looks like it is up side down. it should clear the star. Just turn the angle of the spring is up. After looking at it close it is the wrong spring. It in the wrong hole in the left shoe.