CJ-5 Master Cylinder Piston Travel

Hey everyone, so here is my problem, the Jeep is tagged and almost all wired up (got the basics, lights, ignition, etc) but I haven't got the brakes completed yet. All new components such as wheel cylinders, lines, mc, etc however I can't seem to get the brakes to fully engage. I have driven plenty of single res non-powered brake vehicles so i am familiar with the stiff pedal and so on. My question is, what is the approximate pedal travel I should have? the brakes will keep the jeep from rolling but they do little to slow it or stop. no leaks, its all been bled. the piston only seems to want to travel and inch or less, I seem to remember another jeep I had having a lot more piston travel. Thanks for any help and sorry as I'm sure that this question has been answered many times before but I couldn't find the thread(s).

 

Is this the under the floor master, did you bench bleed it, can you pump the pedel and get it better? Was the master new or rebuilt?

 

Sounds almost as if some of your wheel cylinders are frozen.

 

The MS piston travel is relative to the brake shoe adjustment. On my 66 I adjust the wheel adjuster up tight and then back it off 5 clicks. Do this on each wheel. My piston travel at this point is approx 3/8 of an inch. Now if I want more peddle travel then I would adjust the wheel adjuster to 7 or 8 clicks.

 

Thanks for the replies, its the original under the floor board design, bench bled, new wheel cylinders, etc. the travel question was while bleeding the wheel cylinders so there shouldn't be any resistance on the pedal and the pedal should have full travel of the piston in the MC. Pumping doesn't help and upon removing one of the drums i saw that there is very little travel of the shoes themselves. all 4 corners have new wheel cylinders as well as a new, not rebuilt, mc and new lines and hoses, etc. I've had problems with 4-way drums and frozen wheel cylinders where the functioning ones would lock up the functioning wheels due to the extra volume of fluid, pull to one side, or any of the other number of 'fun' things that happen in older vehicles lol. no leaks anywhere and the system was def bled with clean bubbleless fluid coming out for a few cycles before I considered each wheel 'done.' I believe its a problem with the mc so just looking for a total travel of piston under no resistance so i don't take it out and rip it down for nothing lol. thanks again for the help so far!

Oh yeah, as far as the adjustments, it has the old style eccentric bolts so i have them adjusted out to contact with the drum then backed off about 1/8th of a turn at each corner and all the springs and hold down hardware is brand new.

 

Hello Andy,
Any chance you could send me a photo(s) of your front end brake plumbing?
From the Mastr Cyl forward I'm trying to piece together metal tubing and rubber hoses without a map.
Nothing was there when I picked this CJ up... so I'm in the dark w/clips, connectors, etc.
Any help would be appreciated, the rear end is all set.
Thanks,
Joe in Jersey

 

Another thought - is the master cylinder push rod adjusted correctly?? Are you getting a full stroke?

It needs to be able to fully return, with just a tiny bit of free play when the brake pedal is all the way up.

 

I'd be interested in where you purchased all of your parts for the brake rebuild. I need to pretty much do a full rebuild and to get all new USA made parts.
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I'll try to get a pic but there is a difference it seems in brake parts in the 60s model CJ5s (and MB 38s). some require a wheel cylinder with a 60 degree and others are straight in. if the top of the hole that the WC mounts into is the same height as the bolt holes you don't need the 60 degree wc (found that out the hard way and had to dust off my grinder haha). Having done that modification my application is pretty custom as well as using longer flex hoses so I probably don't have the best plan to go off of. I believe I had done a google search and found some plans if I come across any i'll let you know.

 

Davistroy - I got a bunch of stuff from different places...lol Planetautoparts on ebay (http://myworld.ebay.com/planetautoparts&ssPageName=STRK:MEFSX:SELLERID this is the link for his store) has a great selection of of the wheel cylinders and master cylinders. He has the best prices i found and will combine shipping. if you don't see an active auction for what you need send him an email and he'll probably get it for you. I got all NEW not rebuilt raybestos parts from him FAST. for the additional hardware (hold down springs, etc) I went through Kaiserwillys.com The owner, Mike, was very helpful through phone and email and I'm not sure if you need it but he sells the complete wiring harnesses for about $250 for the cj5 which is more then 1/2 what painless wants for them (they include the turn signal harness), granted he uses electrical tape for most of the harness instead of split looms and the directions are a little difficult to get through if you haven't ever wired a vehicle before but i'm sure he'll help you out if you get stuck. I also ordered a brake hose from JC whitney as I had a coupon but be careful I believe they sent me a VW brake hose so i had to go to an auto parts store to get a metric to standard fitting...not fun lol quadratec.com is a decent place too but recently they have gotten away from older cj parts it seems. Good luck and let me know if you find any cheap places as well as money is getting tight and I might need to go back to iraq or afghanistan to earn some more money for the jeep lol!

 

Pete - It had a little play in it but the pedal would only want to go at most half way to the floor while bleeding and didn't want to return completely. almost seems like the spring inside is messed up or it may have a burr on the wall inside. all jokes aside it seems as if its short stroking...being a new mc i would be a little surprised to find that out but there is no quality in so much stuff made now. I've had the misfortune of driving a vehicle on an interstate with 4-way drum single circuit and know that the pedal goes ALL THE WAY to the floor when you blow a line i am thinking the same is true with this one but don't know the piston travel.

 

If you had the short travel problem while bleeding, then I guess it's not frozen wheel cylinders

If it's not returning fully, then you are indeed only getting a short stroke. Maybe it is bottoming out and only returning halfway? But in that case if the pedal is not going all the way down, the the pushrod would be way overextended and would not have any freeplay when the pedal is up. Is the push rod centered and at full depth into the MC piston?

Otherwise, as you describe it, at this point I'd say maybe pull the Master cylinder, remove the innards, and check it out.

Amazing how often the "good" new part is the problem.