Brakes?

Brakes?
BBCJ5

BBCJ5

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Location
Texas
Vehicle(s)
1980 CJ5; AMC 304; dana 30 Transfer case; T176 Transmission; edelbrock carb
Diving into the brakes on the CJ5 today. Most of my mechanical experience is with lawn mowers and appliances so I'm a bit lost when it comes to brakes. The master cylinder was dry, so I put a little brake fluid in to see if I could find a leak. Pumped the brake a few times and no leak. Pedal dropped to floor though. Compressed the caliper piston with a c clamp and it stayed bottomed out wheb clamp removed. Pumped brake a couple more times and got a little resistance and the calipers compressed. The back brakes seem to be locked up though. Would simply bleeding the brakes free them up?
 
What's the status of the brakes? Have they been working? Has the vehicle been sitting up for along period of time?
 
The pads look pretty good still, but I'm sure it has been sitting for some time. Haven't pulled the rear drums yet so I don't know the condition of the back brakes. The hoses don't look too bad, but the E brake cable is broken at the connection to the ebrake assembly
 
I'd check out the wheel cylinders first. If they look ok. I'd start trying to bleed them, while having a helper add fresh DOT4 brake fluid to the master cylinder. Be careful because brake fluid is excellent paint remover.:mad:
 
If the rear brakes are stuck in the applied position will I be able to remove the drums, or should I try to bleed them first?
 
Also, what is the difference in DOT 3 and DOT 4. I had some DOT 3 at the house, so that is what I put in today. Will that cause any issues? didnt put much, just filled the MC about 1/3 -1/2 full...
 
Dot 3 fluid is fine. Frozen drums can be an <-BAD WORD-> ache to get free, You should start by getting a brake tool into the adjustment slot on the backing plate, and backing the tensioner off to see If it will break loose. If not, you can remove the rear tires and try pounding the drums with a dead blow hammer, which should do the trick. Brakes are a sealed system, and should not leak down for any reason, unless something is wrong. I recommend you do a good inspection and repair the faulty component. There should be pretty clear evedence of fluid where it's been leaking out, so check carefully.
 
When you get the brakes free, and are ready to bleed do yourself a favor and pick up a set of speed bleeders they are like $10 for 2 at autozone, so get 2 packs, also pick up some tube to put on the bleeder screws and some vaccum caps to cover the bleeders once finished.

All you do is crack it open mash the brake a couple times and close the screw it's that easy. But be sure to watch the brake fluid level as you bleed.
 
This morning I rolled under the proportioning valve and noticed that there was some brake fluid on the rear brake line hidden by the skid plate. I guess Ill go ahead and replace the brake lines, then use the speed bleed. I am thinking i should go ahead and flush everything out too. It would probably make sense to do that before I get the new clean brake lines on. Should i remove the old and flush just MC and P-valve seperately, or should disconnect the lines from the wheel cylinders and calipers, flush it all, then put the new lines on?
 
If you are changing the lines anywy, I would just do that and the little bit of contaminated fluid left will be purged during the bleeding process. Remember the pleeding route. Right rear, left rear, right front, left front. (furthest to the nearest) and never "pump" the pedal, just a slow easy press and hold, then a slow return to the up position. Pumpling the pedal will only aerate the fluid and you'll pay the devil getting them bled out after that!
 
Actually I've heard to bleed the front first to ensure the proportioning valve is seated or working or some shiz. Remember reading it some place. One of those CJ things.
 
Not farmilliar with that. I have herd that an ABS system is diferent though. Maybe I have been doing it wrong for all these years!:eek:
 
I thought the same thing when I read it, I'll have to locate the reference.
Might have been the in FSM.

Found a link about someone mentioning it but can't locate the reference.
"bled the front brakes first, then the back as usual, then the fronts again. the pedal is solid as a rock and the CJ stops better than ever"

Of course there is also the debate on if you have to use a tool on the proportioning valve to hold it open/closed what ever.
Someone with the service manual could clear this up.
 
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they say you should use the tool, I always use a power bleeder and have never needed the tool. I've always heard you should start with the one farthest from the mc first.
This is a great tool to have Motive Products 0252 - Motive Products Power Bleeder Kits
at least I think that is the one I have.
 
on my 79 CJ5 it will not bleed right unless i have the tool on the proportioning valve. just in case you run into that. spent hours trying to bleed them without it. put it on and got a vacuum bleeder from harbor freight $20. now it is a breese to bleed them.
 
What does the tool do? I bleed the brakes on my 79 with nothing more than speed bleeders.
 
I used to just pop a hose onto the bleeder and stick the other end into a jar/ can with some fluid in it. Break the bleeder open and push the pedal a few times, go back under and tighten it up, them move to the next. Some time back, I bought a Mity Vac, so now I bleed the system from underneath. I push the fluid through the bleeder and move the air in It's natural upward path to the master. Easier, and I use less fluid.
 
I havent been able to find the brake line that goes from the P-Valve to splitter for the back brakes. All the brake line kits I find are for the individual wheels. Any suggestions on where to get one? I went ahead and replaced the wheel cylinders today while I was changing the shoes on the rear, and I hope once I find that line I can install bleed and go.
 
i bent my own line when i replaced it. but i have a cool bender that can bend up to 90 degrees.
 
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