Birty Dastards Jeep Club
Tech Forum => Workshop => Topic started by: IrishKenCJ7 on August 07, 2012, 08:23:02 PM
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My brakes are usually soft, but I noticed yesterday the brakes were very hard on my 1978 cj7. Then at the end of the drive they got very soft, had to go whole way down to get it to stop. Today at lunch while driving I had to go down further to get Jeep to stop until I finaly got home and they totally went just outside my house.(Lucky)
There is no signs of leeks near each of the wheel so I said I'd open the master cylinder under the hood. When I was openin it slowly, the rubber seal seemed to expand out until It looked like the rubber seal thing is actually 50% bigger that it should be. May be off another auto. The bigger cylinder looks low on fluid and smaller cyclinder is half way. Where can I order a proper seal and do I just top up with brake fluid here. Looking at my Chiltons manual I see that the master cylinder is off a 82-83 Cj. I dont have power brakes.
Aplogies I am non auto-techincal but trying to learn on CJs.
Any help appreciated,
Cheers
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Hi, check with other replies, as brakes are safety related I do not want to get you to do anything you are not used to.
Check all your brakes have material left on and are working and not leaking, and still in the right place!
Without a booster , brakes should be firm/hard, if soft maybe air in system or hoses expanding.
If they go soft, then air or water in system and need bleeding.
If the pedal goes to the floor, either a LOT of air in system, or there is an external leak. If all looks OK, and all pistons are pushing out and returning, then, suspect a faulty master cylinder.
Seals oversizing can be caused by incorrect brake fluid in system, and this will affect ALL the seals.
Fluid levels again are affected by external leaks, or just the normal drop as the brake pads and shoes wear, the pistons take in more fluid. Depends on the period of time it took for the fluid to drop and how much wear the pads/ shoes have.
I am sure other points will follow.......
Will.
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The larger part of the reservoir is for the front discs, you must have a leak, try and find that first, before you go any further.
As you have a 78 it's likely you have the big brakes which are notoriously difficult to bleed, and not an easy job for the non technical minded. Its likely as the fluid level is low the master cylinder has air in it and will need bleeding first, before you try bleeding the brakes themselves.
The brake system has a proportionating valve with a button on it which needs to be held in to enable any bleeding work to be done. Conventional bleeding procedures don't seem to work so well with these cjs, will need to either gravity bleed or use a mityvac to get anywhere, getting the air out of the front calipers is right pain.
Hoe this helps, suggest you get some help or you could spend a lot of time trying to get a firm pedal!
Brakes Arnt the place to start learning your skills, safety first
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its just a simple brake system as found in alot of motors of the era, dont think its complicated cos its a CJ
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when you opened the master cylinder was the level low ?
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If your not sure what your looking at, get someone who does know. Its your brakes after all, you need to know they are right :icon_winkle:
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If your not sure what your looking at, get someone who does know. Its your brakes after all, you need to know they are right :icon_winkle:
:iagree: :iagree:
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Ya low on the small cylinder and very low on the large cylinder, I coould see the fluid outlet almost being exposed so I presume air is now in there. I'll have to bleed them, I've just been youtub-ing it so I think I can tackle this. I presume Dot-3 fluid will be fine so long as its not dot-5 thats in i already (I doubt it)
Then I'll just grab a buddy at the weekend and see what we can achieve. I should really google how to check the pads before the weekend, but I believe pads was changed 2000 miles ago before I bought it last year but who ever listened to a PO.
As its the Breaks I just want to get the jeep to the other side of the city to my garage. The local Suziki dealer would change me 170+VAT for a job like this but my own garage are into vintage stuff.
Any pointers on checking the pads on cj7.
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add fluid and rebleed the whole system starting from the furthes point away from the master cylinder.
DOT3 DOT4 no real difference.
just take a wheel off and look at the caliper, you will see the pads and how much material is left, if they were changed 2000 miles ago then there should be plenty left.
a local independant garage should be cheaper than a suzuki dealer.
the cj should be a simple process of bleeding as there is no abs to take into account. pressure bleed the system or vacuum bleed the calipers using a mittyvac or large syringe
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Thanks for the replies,
Would you know where I could get a new master cylinder seal/diaphram ordered online.
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USA is easy but you might have to wait a week.
UK sorry no apart from lighthouse jeep ??????
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usa atomotive or ultimate spares america