Removed residual pressure valve now peddle goes to the floor

Timmy390 · Aug 19, 2012

I’ve read several threads on the topic of M/C’s and what to do when doing a disk conversion and it’s not working for me. I’m in the last stage of a total Dana 44 rebuild and Ford disk conversion using 79 bronco parts. I'm back on teh road if I can get this sorted out.

I removed the residual pressure valve or what I think is the residual pressure valve (rubber stopper and spring no ball found) from the rear reservoir on my drum/drum M/C and now the peddle goes to the floor. There are no leaks in the system. I’m doing this in my shop and there is noting on the floor and all fitting are dry.

Steps in the process
I took the drum/drum M/C off, removed the RPV and bench bleed the M/C. Install M/C back on the truck, gravity bleed the new front calipers then moved to the rear and pressure bleed them both. Then came back to the front and pressure bleed them (thanks to the wife for pumping the peddle all afternoon). Result, was no peddle. Re-bleed the system again starting at right rear, then left rear, right front, left front, still peddle goes to the floor.

Had a buddy come over to try and sort this out and we found you can pump the living hell out of the brakes and you will get peddle and it will hold. Jacked up the front and verified the calipers are moving and that once pumped up, the wheels can’t be turned.

When you even lightly let off the peddle after pumping it up, fluid gushes back to the M/C (due to the removal of residual pressure valve ?).

I know it sounds like air in the system but I’ve bleed brakes many many times and have never had this problem.

I was thinking about buying a new M/C but I need the line connections on the drive side and after reading several posts, I’m still confused as to which one to get. What's the deal with the camper special M/C? Is that my golden ticket?

Suggestions please

Tim

broncnaz · Aug 19, 2012

I'd say bad MC many times while bleeding the seals can get dinged up and fluid bypasses so you get no pedal. Not sure on what all MC's have the driversside outlet

Timmy390 · Aug 20, 2012

broncnaz said:
I'd say bad MC

You might be right. After thinking about it last night (all night while I couldn't sleep) I've decided it's a bad M/C.

All of the fluid is gushing back into the rear reservoir with little to none returning to the front reservoir. When I say gushes I'm talking aobut a geyser when you let off the peddle.

Guess I'll go buy a new drum/drum M/C and remove the residual pressure valve and see what happens.

Tim

surfer-b · Aug 20, 2012

Are the bleeders on the calipers at the top, its easy to get them reversed.

Timmy390 · Aug 20, 2012

surfer-b said:
Are the bleeders on the calipers at the top, its easy to get them reversed.

Good call. Yeah, I read that in a post when searching for answers last night. Had that Oh Sh!t moment and had to go look. They were on top. Kind of wish they hadn't been so the problem would be fixed.

I have a new drum/drum M/C ready for me to pick up after work. Going to pull the RPV and see if it acts the same way as the one I have now. If it don't work, I'll try the 76-77 disk/drum and just replumb it. Probably should just go with the disk/drum and be done with it but I have custom hardlines to the M/C and don't want to fab new ones.

Why in the heck did they move the ports on the M/C from driver to pass side when for those two years? Ford is sometimes cray IMO.

Tim

broncnaz · Aug 20, 2012

because when they went with power brakes the MC was angled away and the inner fenderwell is there. so installing them on the driver side takes some creative bending and routing basically doesnt look all that great.

bronconut73 · Aug 20, 2012

Timmy390 said:
I’ve read several threads on the topic of M/C’s and what to do when doing a disk conversion and it’s not working for me. I’m in the last stage of a total Dana 44 rebuild and Ford disk conversion using 79 bronco parts. I'm back on teh road if I can get this sorted out.

I removed the residual pressure valve or what I think is the residual pressure valve (rubber stopper and spring no ball found) from the rear reservoir on my drum/drum M/C and now the peddle goes to the floor. There are no leaks in the system. I’m doing this in my shop and there is noting on the floor and all fitting are dry.

Steps in the process
I took the drum/drum M/C off, removed the RPV and bench bleed the M/C. Install M/C back on the truck, gravity bleed the new front calipers then moved to the rear and pressure bleed them both. Then came back to the front and pressure bleed them (thanks to the wife for pumping the peddle all afternoon). Result, was no peddle. Re-bleed the system again starting at right rear, then left rear, right front, left front, still peddle goes to the floPR.

Had a buddy come over to try and sort this out and we found you can pump the living hell out of the brakes and you will get peddle and it will hold. Jacked up the front and verified the calipers are moving and that once pumped up, the wheels can’t be turned.

When you even lightly let off the peddle after pumping it up, fluid gushes back to the M/C (due to the removal of residual pressure valve ?).

I know it sounds like air in the system but I’ve bleed brakes many many times and have never had this problem.

I was thinking about buying a new M/C but I need the line connections on the drive side and after reading several posts, I’m still confused as to which one to get. What's the deal with the camper special M/C? Is that my golden ticket?

Suggestions please

Tim

Just went through this. I won't bore you with the details.
I ended up getting a '73 F-250 master cylinder for manual "dual piston“ caliper brakes.
This thing has a 1.25" bore. The biggest one I could find. Best of all....the line hook up is on the drivers side.
Autozone had it for $17.99. Yup! Cheap and much better than the stock disc mc.

Timmy390 · Aug 21, 2012

surfer-b said:
Are the bleeders on the calipers at the top, its easy to get them reversed.

If I would just listen to what I'm told and think about what I've read things would be so much easier. By on top you mean on TOP TOP and by reversed you mean left/right. No wonder I had issues with the hoses fitting the calipers. I think I have them reversed too.

I installed the new M/C and bench bleed it, hooked everything up and still had the same problem. So I'm laying there under the bronco banging my head and telling my buddy how I know what I'm doing and how I've never seen anything like this problem before and how I've been bleeding brakes for 20 plus years and it hit me like a BFH. BLEEDERS ON TOP. I jacked the rear up and bleed the front left and bubble bubble bubble. The calipers are full of trapped air.

I have the damn calipers on backwards, left on right and right on left.

Thanks for the help guys. Next time I'll think about what I'm told and what I read.

On a side note, the new M/C didn't have a RPV to remove in either port.

Thanks for advising me to pull my head out of my ASS.

Tim

jim3326 · Aug 21, 2012

I'm not sure on the front (can't recall%)) but on the rear you can just move the bleeder from the bottom to the top, there is a plug that you swap for the bleeder, might check that out before you tear it apart.

Jim W.

DirtDonk · Aug 23, 2012

Noticing that a lot of new and rebuilt MC's are not coming with the RPV's lately.
Not sure if it's an oversight, or they just finally decided that it's not really as necessary as they once thought.
After all, even with the 10psi or so valve in there, the springs on a drum brake are still going to pull those suckers back down to their stops. Which is why keeping the rear drums adjusted up fairly tight contributes a huge amount to how solid your brake pedal feels.

Did reversing them fix the problem? Sounds like it did (happy typing sounds) but wanted to be sure.
If so, glad you got it fixed!

Paul

Timmy390 · Aug 23, 2012

DirtDonk said:
Did reversing them fix the problem? Sounds like it did (happy typing sounds) but wanted to be sure.
If so, glad you got it fixed!
Paul

Just got them reversed last night(8/22/2012). My daughter had soft games and had some after hours "work" to do so just getting to it.

I haven't bleed them yet (had to help daughter with homework) but things sure look much nicer. I'm also out of brake fluid because of all the bleeding and cracking the system open. Putting the calipers on corrcetly solved the brake hose issue I was having as well. Now the hoses fit much better and are up out of the way of the lower shock mount.

Was going to bleed them tonight but daughter has softball again so it will be Friday night before I get them bleed.

I'll post once it's done

Tim

bknbronco · Aug 23, 2012

Let us know what happens in the end. I been following all your threads on your axles and brakes and steering.

So you ended up with 79 all ford disk conversion?

Stock drum drum MC?

Stock drum drum H-block?

Timmy390 · Aug 24, 2012

After work, a trip to the parts store, a hair cut and pizza, I got the brakes bleed.

As talked about above, the calipers on wrong (rigth on left left on right) was the issue. Everything bleed out nice and easy this time however I didn't like the peddle.

Not sure if it's the new M/C or the addition of the disk brakes but the peddle was junk. It had pressure but still went near the floor with a gap of 2 inches or less and the feel is different than before the teardown. In a word, it felt soft.

I rememberd I had an adjustable brake pushrod so I screwed it out to get more peddle travel and that really helped. It's now 3 inches off the floor and hard but it's still a touch different than what's it's been.

My current configuration is 79 bronco knuckles, spindles, hub/rotor, caliper brackets and calipers. I used 76 F100 2WD brake hoses and my original 74 lockout hubs. Drum/Drum M/C with no RVP in front or rear line ports (it came that way from the parts store) and stock 74 H-block.

Havn't been on the road yet (fired it up and the carb was leaking gas all over the place) but hope to test drive it tomorrow.

Tim

shamu · Aug 24, 2012

Tim I think you are under bored on the master cylinder. I have done the F 150 swap and I am still using a 1976 bronco M/C. Which is Disc/drum.
Believe it or not a 1/16 of an inch bigger on the bore of a M/C is huge.
On the 4 wheel disc broncos that I wheel I use the M/C from Wild Horses.
http://www.wildhorses4x4.com/product/Hydroboost_Master_Cylinder/Bronco_Power_Brakes

Timmy390 · Aug 25, 2012

shamu said:
Tim I think you are under bored on the master cylinder. I have done the F 150 swap and I am still using a 1976 bronco M/C. Which is Disc/drum.
Believe it or not a 1/16 of an inch bigger on the bore of a M/C is huge.
On the 4 wheel disc broncos that I wheel I use the M/C from Wild Horses.
http://www.wildhorses4x4.com/product/Hydroboost_Master_Cylinder/Bronco_Power_Brakes

WOW, now that's a M/C.........I like the double caps and hold downs. Every M/C I've ever had on my bronco leak from the lid.

Got the carb to stop leaking gas so went out for a quick test drive.

The new brakes are GREAT, WOW, and WOW again. Nice and smooth and easy. No pulling, grabbing or locking up. I was worried about the peddle travel while bleeding but you don't have to use much peddle to stop the rig so my fears amy have been for not. To recap Manual drums = ok, Power drums = better, Power Disk/drum = WOW

I was so focused on the brakes I ddin't notice how nice it was driving. NO MORE bump steer (I changed all steering releated parts on this project). It was just a quick run down the road and back. I need to do another check to make sure everything is tight before putting through it's paces.

Tim

shamu · Aug 25, 2012

Timmy390 said:
WOW, now that's a M/C.........I like the double caps and hold downs. Every M/C I've ever had on my bronco leak from the lid.

Got the carb to stop leaking gas so went out for a quick test drive.

The new brakes are GREAT, WOW, and WOW again. Nice and smooth and easy. No pulling, grabbing or locking up. I was worried about the peddle travel while bleeding but you don't have to use much peddle to stop the rig so my fears amy have been for not. To recap Manual drums = ok, Power drums = better, Power Disk/drum = WOW

I was so focused on the brakes I ddin't notice how nice it was driving. NO MORE bump steer (I changed all steering releated parts on this project). It was just a quick run down the road and back. I need to do another check to make sure everything is tight before putting through it's paces.

Tim

I bet you will sleep great tonight. And are you going the OCBR gig?

Timmy390 · Aug 25, 2012

To be honest, I'm not going to know what to do with my time as this project has been going all summer long and has been intensive. I think I'll get that bench seat recovered and installed next.

Sept = bad month for me. My oldest daughter is getting married and we have a ton of things to do.

Superlift is a nice place. Maybe next year I'll have my ducks in a row.......

Tim

half cab · Aug 27, 2014

Hate to starting a new thread so I thought i would hi-Jack this one .

I have bleedind my rear brakes and am still getting air bubbles?

MC is about 3 yrs old and no leaks in the lines anywhere . I have pulled a quart or more of fluid through and still got bubbles n sponge brakes?

chuzie · Aug 27, 2014

Usually folks say "hate to hijack a thread so I will start a new one."

made me laugh.

I have seen air get sucked in through the bleeder threads and then go out the bleeder tube. Hylomar is great for this.

R u sure it is coming from upline in the system. It is certainly possible but if you don't have any leaks it is hard to introduce air.

You may be chasing a ghost.

half cab · Aug 27, 2014

I been usin a pump bleeder n it might be pulling it through the threads like you said?

My wife's home now n will see if the old fashion way will do better?

Removed residual pressure valve now peddle goes to the floor

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