Brake system rebuild questions

[hollasboy]

Have had nothing but problems with my braking system ('79 CJ5 Renegade ) since I bought it last year - very hard pedal, long time to stop, parking brake doesn't hold anything, rear drums cracked, etc. So I decided to get all new parts and rebuild the whole system from ground up and with all new parts. I'm 75% done with that, but have a few general questions about the brake system as I near completion.

1. Low brake indicator light. I bought one of those wiring diagrams as recommended on here, and it shows a "Low Brake" warning light coming from the proportioning valve. My old P-valve has a female wire pin on it with more than 1 wire (can't remember if it's 2 or 3 wires total) going up into the engine bay, and the replacement part has the same pin to connect wiring. However, during my dash rebuild and wire clean up, I never came across any such indicator light or wiring. Was this standard? Should there be a brake warning light somewhere?

2. Parking brake indicator light. Is there supposed to be one? The parking brake pedal assembly that I took out did not have any kind of electrical components/contacts/switches/wires, but the new replacement came with a copper contact which I presume goes to the indicator light. Should there be one of these indicator lights somewhere?

3. Proportioning valve port thread size - the new P-valve I bought matches the old one exactly, EXCEPT the female threads going to the rear drum brake line are much larger size than the old or new rear brake line. Can I just put a brass adapter fitting on it to reduce the thread size so the brake line will fit, or will that have repercussions on the braking system?

4. In a couple places on the driver side chassis, the rear brake line was secured with a loop bracket, along with 2 other rigid lines (bundle of 3). What do those lines do/go to?

5. Adjusting parking brake - since I replaced the rear drums, springs, wheel cylinders, pads, etc. AND the parking brake cables and foot pedal, should I wait to adjust the parking brake tightness until after I've bled and activated the brake system? Not sure if I tighten it to just the right amount now, then later stomp on the pedal, pushing out the pins in those wheel cylinders for the first time, if it will get too tight in there and mess something up.

6. Bleeding entirely new system - I've seen lots of comments about having to hold in the pin on the P-valve when bleeding a system, but not enough detail in any comment to guide me on how to do it. I've also seen some comments saying don't worry about the pin and just do the bleed in Front-Back-Front order and it will work. What is the final answer on this issue?

7. P-valve adjustment - I am pretty certain that the P-valve comes from the auto parts store pre-calibrated - is it necessary to adjust it? If so, how is that done?

Thanks!

 

[jp360cj]

Have had nothing but problems with my braking system ('79 CJ5 Renegade ) since I bought it last year - very hard pedal, long time to stop, parking brake doesn't hold anything, rear drums cracked, etc. So I decided to get all new parts and rebuild the whole system from ground up and with all new parts. I'm 75% done with that, but have a few general questions about the brake system as I near completion.

1. Low brake indicator light. I bought one of those wiring diagrams as recommended on here, and it shows a "Low Brake" warning light coming from the proportioning valve. My old P-valve has a female wire pin on it with more than 1 wire (can't remember if it's 2 or 3 wires total) going up into the engine bay, and the replacement part has the same pin to connect wiring. However, during my dash rebuild and wire clean up, I never came across any such indicator light or wiring. Was this standard? Should there be a brake warning light somewhere?

2. Parking brake indicator light. Is there supposed to be one? The parking brake pedal assembly that I took out did not have any kind of electrical components/contacts/switches/wires, but the new replacement came with a copper contact which I presume goes to the indicator light. Should there be one of these indicator lights somewhere?

3. Proportioning valve port thread size - the new P-valve I bought matches the old one exactly, EXCEPT the female threads going to the rear drum brake line are much larger size than the old or new rear brake line. Can I just put a brass adapter fitting on it to reduce the thread size so the brake line will fit, or will that have repercussions on the braking system?

4. In a couple places on the driver side chassis, the rear brake line was secured with a loop bracket, along with 2 other rigid lines (bundle of 3). What do those lines do/go to?

5. Adjusting parking brake - since I replaced the rear drums, springs, wheel cylinders, pads, etc. AND the parking brake cables and foot pedal, should I wait to adjust the parking brake tightness until after I've bled and activated the brake system? Not sure if I tighten it to just the right amount now, then later stomp on the pedal, pushing out the pins in those wheel cylinders for the first time, if it will get too tight in there and mess something up.

6. Bleeding entirely new system - I've seen lots of comments about having to hold in the pin on the P-valve when bleeding a system, but not enough detail in any comment to guide me on how to do it. I've also seen some comments saying don't worry about the pin and just do the bleed in Front-Back-Front order and it will work. What is the final answer on this issue?

7. P-valve adjustment - I am pretty certain that the P-valve comes from the auto parts store pre-calibrated - is it necessary to adjust it? If so, how is that done?

Thanks!

1 & 2 (low brake level and parking brake) both use the same indicator light. It's in the speedometer cluster (around 3 o'clock IIRC).

3 - Yes, you can use an adapter. And from what I've seen in the aftermarket, all of the prop valves listed for a CJ use an adapter for the rear output.

4 - Depending on the engine, I would guess some combination of fuel to engine, fuel return, & fuel vent to charcoal canister. Trace them out and see where they go.

5 - Not sure if it matters or not, but I would adjust the parking brake after the brakes are bled.

6 - I've never personally never held the pin in on the p-valve and never had an issue. But I've also never replaced the whole system at once. But absolutely bench bleed the master.

7 - Unless you bought an adjustable p-valve, I wouldn't touch it.

 

[cglax6]

Hopefully I can answer a lot of your questions. I did a complete overhaul of my brake system this past year and converted front brakes to disc.

1. There should be an indicator light in your speedo (not 100% if it should be there or not, but if you have one, it'll be on your speedo)

2. Same as #1. I didn't hook up my warning lights.

3. Avoid adding additional adaptors to brake lines. There's a ton of pressure that goes through there and adding an adaptor just adds another potential point of failure. When I did my brakes, I replaced all brake lines. It's a PITA, but inexpensive and your local parts store can rent you bending/flange tools. Call the folks that you bought the pro-valve from an ask them what fitting you need. I may have some left over from my project, so I'll check when I get home, and I can tell you what size. You can get the fittings from your local parts store.

4. Careful with those...those are fuel lines!

5. You can adjust that parking brake whenever you want. It has nothing to do with the wheel cylinder.

6. If you replaced the MC, then be sure to bench bleed before you install, or you'll never get the air out of your system. You shouldn't have to fiddle with the metering valve when you bleed....only if you're not getting fluid to one of the cylinders. Start with the wheel that has the longest brake line and work your way to shortest...should be right rear, left rear, right front, left front. This is the process I follow:

a. fill MC and put cap back on.
b. attach bleeder bottle to bleeder on brake.
c. crack bleeder, have your bestest friend slowly depress brake pedal to the floor.
d. close bleeder valve.
e. have your bestest friend let go of the brake pedal.
f. repeat until you stop seeing bubbles in the bleeder bottle line.

Also, be sure to keep that MC topped off...if you empty a reservior, you'll have to take it out and bench bleed.

7. You shouldn't have to adjust it.

When you're done installing and bleeding your system, you'll have to adjust the tension on those drum brakes. Before installing the drum over the brake shoes, back out the adjustment nut to a point to where it doesn't require any effort to put the drum on. Put your wheel on and tighten the lug nuts to a point where it's on there snug...no need to torque just yet (keep that axle jacked up. Spin the tire fast enough to where it's free-wheeling. Get behind the dist cover with a flathead screwdriver and tighten the spindle nut to where you just start to hear contact of the shoe on the drum (there is a slit near the bottom of the dust cover and there's usually a rubber plug that you'll have to remove. Repeat for the other side and adjust to where there's about equal contact on both sides of the vehicle. If one side is a lot tighter than the other, you'll veer off to one side when you brake and end up in a ditch or a head-on collision...especially during a panic brake situation. this final adjustment may take a few iterations after some test drives. Do some normal braking and some panic braking to get your system set up how you want it.

Let us know how it goes.

 

[hollasboy]

Hopefully I can answer a lot of your questions. I did a complete overhaul of my brake system this past year and converted front brakes to disc.

1. There should be an indicator light in your speedo (not 100% if it should be there or not, but if you have one, it'll be on your speedo)

2. Same as #1. I didn't hook up my warning lights.

3. Avoid adding additional adaptors to brake lines. There's a ton of pressure that goes through there and adding an adaptor just adds another potential point of failure. When I did my brakes, I replaced all brake lines. It's a PITA, but inexpensive and your local parts store can rent you bending/flange tools. Call the folks that you bought the pro-valve from an ask them what fitting you need. I may have some left over from my project, so I'll check when I get home, and I can tell you what size. You can get the fittings from your local parts store.

4. Careful with those...those are fuel lines!

5. You can adjust that parking brake whenever you want. It has nothing to do with the wheel cylinder.

6. If you replaced the MC, then be sure to bench bleed before you install, or you'll never get the air out of your system. You shouldn't have to fiddle with the metering valve when you bleed....only if you're not getting fluid to one of the cylinders. Start with the wheel that has the longest brake line and work your way to shortest...should be right rear, left rear, right front, left front. This is the process I follow:

a. fill MC and put cap back on.
b. attach bleeder bottle to bleeder on brake.
c. crack bleeder, have your bestest friend slowly depress brake pedal to the floor.
d. close bleeder valve.
e. have your bestest friend let go of the brake pedal.
f. repeat until you stop seeing bubbles in the bleeder bottle line.

Also, be sure to keep that MC topped off...if you empty a reservior, you'll have to take it out and bench bleed.

7. You shouldn't have to adjust it.

When you're done installing and bleeding your system, you'll have to adjust the tension on those drum brakes. Before installing the drum over the brake shoes, back out the adjustment nut to a point to where it doesn't require any effort to put the drum on. Put your wheel on and tighten the lug nuts to a point where it's on there snug...no need to torque just yet (keep that axle jacked up. Spin the tire fast enough to where it's free-wheeling. Get behind the dist cover with a flathead screwdriver and tighten the spindle nut to where you just start to hear contact of the shoe on the drum (there is a slit near the bottom of the dust cover and there's usually a rubber plug that you'll have to remove. Repeat for the other side and adjust to where there's about equal contact on both sides of the vehicle. If one side is a lot tighter than the other, you'll veer off to one side when you brake and end up in a ditch or a head-on collision...especially during a panic brake situation. this final adjustment may take a few iterations after some test drives. Do some normal braking and some panic braking to get your system set up how you want it.

Let us know how it goes.

Thanks! I actually bought pre-formed lines, and other than this one connection at the P-valve, all of the nut thread sizes match all the other connections. I think it's because it's a generic P-valve, my original Jeep brake line has the same smaller nut size.

Thanks for the tips on bleeding the new system!

 

[hollasboy]

1 & 2 (low brake level and parking brake) both use the same indicator light. It's in the speedometer cluster (around 3 o'clock IIRC).

3 - Yes, you can use an adapter. And from what I've seen in the aftermarket, all of the prop valves listed for a CJ use an adapter for the rear output.

4 - Depending on the engine, I would guess some combination of fuel to engine, fuel return, & fuel vent to charcoal canister. Trace them out and see where they go.

5 - Not sure if it matters or not, but I would adjust the parking brake after the brakes are bled.

6 - I've never personally never held the pin in on the p-valve and never had an issue. But I've also never replaced the whole system at once. But absolutely bench bleed the master.

7 - Unless you bought an adjustable p-valve, I wouldn't touch it.

Thanks! I will have to go look at my old speedometer and see if there is a light there. I used all of the "always on" lights as instrument lights, I guess if my brake system had an error I would have misdiagnosed that light as an "always on" instrument light instead of a dedicated brake light. The new speedo I bought does not match the old perfectly, apparently you can't get a new speedo for '79 (I was told on this forum).

I'll have to find a video on Youtube for how to bench bleed a master cylinder - hoping that's easy.

 

[cglax6]

I'll have to find a video on Youtube for how to bench bleed a master cylinder - hoping that's easy.

It's a pretty easy process. There are kits that you can buy, but I've always used clear tubing and extra brake line and fittings. Key is to use tubing that you can see through to see if you have all the bubbles out. Don't get discouraged if it takes a while. YouTube has a ton of videos.

Don't pump the fluid fast...it'll turn big bubbles into smaller ones and then it'll take forever.

Sent via Google translate using braille through Tapatalk

 

[phaques]

I am doing the same thing on my '74 CJ6 and have some related questions....

1) You found pre-formed lines??? Where? too late for me, but still interested.

2) (way more important) Master cylinder/prop valve. Having trouble finding a master cylinder with the deep cylinder for the longer push-rod that comes off my brake pedal - any suggestions?

3)Also, moving my prop valve to mount it right underneath the MC instead of on the frame rail. So, I appear to need an MC with deep cylinder AND ports on the left side of the MC. This is hard to find - again, any suggestions? I think another solution is to have a local shop make up some of the lines that run from MC to P-valve, and I'll bend them myself to fit. Thoughts?

Thanks!

 

[jdcxyz]

I just restored my "79, and literally finished the brakes yesterday! Looks like most of your questions have been answered, but a couple of things. I had the same issue with the fitting size on the new prop valve. I cut my new rear brake lines, put on the correct size fitting and re-flared the lines. I didn't want to use an adapter. Before you bleed, there is a small tool you can buy that screws into the same port where that warning indicator switch goes on the prop valve. It holds the center piton in place. Here's a link to summit: https://www.summitracing.com/parts/...MIwerkrraA5QIVEYiGCh2cOwpoEAQYAiABEgLDtvD_BwE

good luck! Mine seems to stop ok!