Front Brakes Will Not Bleed!

Hey guys I’m new to the forum. I would like to get a little bit of advice regarding my front brakes on a 1969 Jeep CJ5.

Info on the Jeep: 1969 CJ5, closed knuckle front axle, manual brakes, master cylinder mounted on the inside of the frame rail.

I just finished up converting the front drums to discs and now they won’t bleed. I’m getting fluid to the T- junction on the frame rail from the master cylinder when I loosen the line that comes from the MC but I can’t seem to get any fluid from the calipers.

This is my first Jeep and I’ve never dealt with this sort of brake setup where the master cylinder is mounted underneath the floor. Is there some sort of trick that needs to be done in order to get these things to bleed properly? The rear brakes bleed just fine.

Thanks y’all!

 

Welcome to the club!

Were you using a vacuum bleeder? I had that same problem using a vacuum bleeder hooked to my air compressor. I finally gave up and had my wife pump the pedal old school style, and it worked fine. Don't ask me why, I have no idea.

 

The first time I tried it I had someone push the pedal and it would kind of “spit” a little bit of fluid out (On the drivers side) but it would never flow past that. The passenger side nothing will come out besides alittle bit of air and I did this probably 12-15 times and it never changed. I also got similar results using the vacuum pump.

 

dual master cylinder or stock single cylinder? If dual, did you bench bleed the master cylinder? On my '68, I installed 4 wheel disc and found it useful to put teflon tape on the bleeder threads, keeps from sucking through the threads when using a vacuum. I'd guess there's not a pressure differential switch in the system? hey, it's a start Welcome!! I'm dne'

and hey, where's the pictures

 

Hey DNE
It is a dual master cylinder and I haven’t bench bled it yet bc I didn’t feel like it had air in it before and I never took it off the vehicle but that sounds like it is probably the next step just to make sure I will also try the Teflon tape on the threads as well.

I will also try and get a few picture of it lol

-Thanks, Hunter

 

I am sold on the SpeedyBleeders, brand name may vary, they look the same as a standard bleeder but they have a one-way check valve, so you just loosen it, pump it a few times, the air and eventually the fluid can go out but the air can not go back in. Close it, do the next one. Way handy, no special tools, and you do not need a helper.

 

Welcome aboard from Ga.

 

Use extreme care with teflon tape - you don't want any fragments floating around in your system. It is verboten in some applications, for this reason.

 

Brain is a little foggy but if your master is for a drum/drum setup the residual valve needs removed for the disk circuit. There may also be a volume issue. You will also most definitely need a proportioning valve to keep the fronts from locking up first.

 

I'd have thought it was the other way round. Why would drums need a residual valve?

 

I had this problem a while back. Someone told me to take the calipers off and place a piece of wood between the pads. Then hold the calipers as high as you can while bleeding the brakes.
Worked for me

 

I keep this bookmarked
Brake Valve Overview

 

FinoCJ- Yes I do have the pads installed into the calipers and have the caliper mounted.

Rich- Yeah I was curious about whether the proportioning valve was needed as I’ve seen some conversions where it wasn’t used but I always thought it was necessary for sending the proper amounts of fluid to the fronts discs opposed to the rear drums. I believe the residual check valve has already been removed but I need to check for myself since the PO had already mixed up the front/rear brake lines on the master cylinder.

Pete- I believe the residual check valve is needed on the drums bc of the spring pressure pulling the shoes off of the drums and thus causing a bit of a soft pedal where as on discs the residual pressure would cause the brakes to lock up. I could be mixed up on that though.

Thanks for all the responses guys! I really appreciate the help and ideas

 

JZeber- Thanks I’ll give that a try and see if maybe that’ll get whatever air pocket is in there out!

 

Make sure the lines from the MC are plumbed correctly. Port towards the back goes to the front brakes. Also make sure you are using organic pads.

 

To be precise, the residual pressure valve is used on drum brake systems with low mount master cylinders to always keep some positive pressure on the lip seals in the wheel cylinders.

The adjusters are what keep the shoes near the drums for pedal travel/feel.

Residual Check Valve Function: Drum Brake System

 

So... does the OEM underfloor CJ5 master cylinder have an internal residual valve built in?

This is my understanding, despite what one reads on the intertoobs.

I also read that "many [drum brake] vehicles do not require residual valves."

 

I have them plumbed correctly now and the pads came with the kit so I have no idea if they are organic or semi metallic but I guess I’ll find out if I can’t get them to wear in, thank you!

 

Yes, it’s usually in the port where the brake line goes underneath a seat According to the manual