Why - only one caliper works

[Shugalou]

Guys I have fluid going to the rear and have bled out the bubbles.

Am I correct with the assumption that if the valve was closed off I wouldn't have fluid coming down.

[Shugalou]

Guys I have fluid going to the rear and have bled out the bubbles.

Am I correct with the assumption that if the valve was closed off I wouldn't have fluid coming down.

[KQQL IT]

Mine had fluid dripping, but no pressure

[wilkin250r]

At this point, I wouldn't trust too many "assumptions". I'm not 100% sure how the proportioning valve works, but I know a thing or two about troubleshooting. You've gone through all the likely scenarios, it's time to start testing unlikely ones.

A fautly proportioning valve does indeed seem like the logical culprit. You have essentially eliminated blocked lines and frozen calipers, and you have replaced the master cylinder. The prop valve is now the only place left I can think that would allow pressure to build in one circuit of your brakes, but not the other.

[Shugalou]

Thanks Wilkin,

Yes it is possible that it could be the prop valve, but it is brand new from CPP.

Before I go that route though I'm really thinking if it's the rear brakes are so far out of adjustment...? I backed off the e brake and retightened but not sure if it's enough so here's what I plan on doing to make sure rear brakes are adjusted to see if I can get pedal.

I found a good pointer on how to adjust the rears while on a stand emulating the truck going in reverse.

http://lugnutz65chevystepside.weebly...ake-shoes.html

After I get to this than I'll make sure the ebrake is correct by tightening it
right up till I can't turn the wheels then back off a bit.

Any suggestions are always welcomed and I appreciate everyone's feedback...when people say brakes are a PITA now I know why.

[hatzie]

Try bleeding with a pressure pot and a soda bottle catch can.
Motive Products 105 pressure bleeder. http://www.amazon.com/Motive-Products-105-System-B...
$61 for the complete Motive unit includes the darn nice $38 Aluminum 1105 master cylinder adapter. I built one 10 years ago for around $40 in parts. Factoring in your time and inflation on parts... you can't build it cheaper than they are selling it anymore. The coathanger, soda bottle and, 1/4" ID clear tubing catch can is worth looking at tho. http://www.ibmwr.org/ktech/pressure-.../bleeder.shtml

[nonstop]

Originally Posted by Shugalou

Thanks Wilkin,

Yes it is possible that it could be the prop valve, but it is brand new fromCPP.

CPP had a bad batch of proportioning valves for a run. Went through it on a 1950 Chevy project. I googled it and learned about the run. It has since been fixed, but you could have one of the older ones.

[Shugalou]

Shoot I hope that I don't have a bad one, I will look into replacing it after I rule out a couple of things rear brake adjustment and air in lines.

hatzie, I was thinking something along those lines as I think there might be air trapped. But since I'm north of the border that price doubles.

I was looking at this and if it doesn't work it will be easy for me to return.
http://www.princessauto.com/en/detai...it/A-p8050832e

[Shugalou]

And for anyone following along

This is a good reference to troubleshooting problems

http://www.classicperform.com/TechBo...oubleshoot.htm

[hatzie]

Originally Posted by Shugalou

Shoot I hope that I don't have a bad one, I will look into replacing it after I rule out a couple of things rear brake adjustment and air in lines.

hatzie, I was thinking something along those lines as I think there might be air trapped. But since I'm north of the border that price doubles.

I was looking at this and if it doesn't work it will be easy for me to return.
http://www.princessauto.com/en/detai...it/A-p8050832e

Missed that. Just checked Amazon.ca $110 for just the pressure pot and no adapters OWCH!!!

I've used a Mityvac for bleeding and was not impressed. The bleeder threads leak air... If you sacrifice a rear and a front bleeder by drilling all the way through it'll work. But then you need a replacement for each modified bleeder.

Check on component prices for the DIY weed sprayer unit. Canadian Tire has Chapin weed sprayers for $20 and bottom and rear threaded pressure gauges are $10... clear tubing and the other assorted bits are likely not that expensive.

You can make a reasonable facsimile of the Motive 1105 MC adapter with brass pipe, AL or steel plate, threaded rod, & a chunk of rubber inner tube.

[Shugalou]

Thanks for all the info Hatzie,

I'm really hoping I don't have to go that route of fabbing up some tool I don't fully understand how it works.

I thought you just hook up to bleeders and pull vacuum. Not sure what the purpose of creating a lid for the master is for - to create a perfect seal?

I haven't gotten around to adjusting the rear brakes yet, I'm hoping tomorrow works well.

I'll also be lowering the front off the jackstands and keeping the rear in the air - hoping for luck drawing air back further to the rear.

Thanks for the suggestions guys

[hatzie]

The weed sprayer bleeder is a pressure pot that pushes the fluid down from the top. Hence the need for a sealed cover on the MC.
I own both a pressure bleeder and a Mityvac. I'll never go back to vacuum bleeding brakes.

Building a weed sprayer pressure bleeder

Building Yet another weed sprayer pressure bleeder

Using a pressure bleeder

View of the results at the caliper catch can on...

[Keith Seymore]

Originally Posted by hatzie

The weed sprayer bleeder is a pressure pot that pushes the fluid down from the top. Hence the need for a sealed cover on the MC.

Nice!

I'm thinking about making something like that to push anti-freeze through my outside pipes after shutting the water off/draining, to prevent freezing.

K

[Shugalou]

Hatzie you contribution is appreciated! Thanks.

I'll keep these in mind should I still be at a dead end after my troubleshooting...which I haven't had a chance to make any progress on yet.

[swissarmychainsaw]

Originally Posted by Shugalou

<snip..>

I can get pedal pressure - but not firm.

Everything is new other than rotors and pads there was plenty of material on them. (New booster, master, lines, prop valve, stainless lines, calipers, wheel cylinders spring kit)

Front right caliper will grab and hold the rotor.
Front left no resistance (nothing on the rears either). I have checked for leaks, bled and re bled and re bled - no bubbles just clear fluid.

I have a new CPP prop valve but there are no leaks.
<snip..>

(what vehicle are you talking about here?)
My first question is, why did you replace all the parts in the first place?
Were they not working or did you just decided that newer parts would be better than the old stuff?

My understanding is: The Master Cylinder should have two reservoirs, one for front and one for rear. (safety, if you lose a line on front, you still have rears).

The proportioning valve essentially splits the pressure left and right for the front brakes.

I do not believe that there is a rear proportioning valve, that the rear is fed by one line and is split at the rear differential.

If you have the old Proportioning valve, have you tried putting that on?

Did you bench bleed the new Master Cylinder?

FYI, the rears are "self adjusting" when you either drive backwards or apply the parking brake the rear pads 'ratchet' themselves out.
I adjust mine by hand so that the drum is *just snug* when going back on; then let them self adjust.

[Shugalou]

Hey Swiss


It's a 78 GMC shortbox 2WD

I replaced everything because it was all screwed...Booster failed, lines were siezed on master and prop valve. The calipers and wheel cylinders had rust all inside of them so I figured while I'm in there replace most of the parts and do it right the first time - which has turned into.... an experience.

Yes Master was bench bled twice

You are correct with both the master and prop valve functions.

I really need to try to get the adjusters dialed in - hoping today. I'm going to try rolling the wheel back in jackstands while having someone apply the brakes to see if I can hear the adjuster working.

I feel like I'm close...just gotta keep trouble shooting it.

[swissarmychainsaw]

Yes, I agree you are close! Keep after it and take breaks when you get too frustrated.

I read your stuff about finding you Dad's truck, good stuff!
Post more pics of Your truck! It looks good and will be worth all the effort!

--Nick

[KQQL IT]

We tried vacuum bleeding from the bottom, pressure bleeding from the top.

Finally had to force the proportioning valve to center. It was stuck.

[Shugalou]

Swiss, when it get it out of the garage I might have to hire 10 topless models to celebrate the achievement - perfect time for photos

I'm really thinking it might be pressure bleeding time.

The front brakes only grab once the brakes are pumped up. I tried spinning the rear tires backwards with the brakes pressed - before and after pump up and nothing. Does that sounds like air in the lines still? I didn't hear the adjusters clicking at all

[swissarmychainsaw]

Originally Posted by Shugalou

Swiss, when it get it out of the garage I might have to hire 10 topless models to celebrate the achievement - perfect time for photos

Call me, Ontario is NOT THAT FAR!

Originally Posted by Shugalou

I'm really thinking it might be pressure bleeding time.

The front brakes only grab once the brakes are pumped up.

That means you very likely have air trapped in the front lines.

Originally Posted by Shugalou

I tried spinning the rear tires backwards with the brakes pressed - before and after pump up and nothing. Does that sounds like air in the lines still? I didn't hear the adjusters clicking at all

I would ignore the auto-adjusters until you get the air out.
Yes, I think you have air in the lines.
Do you have a mity-vac?

It sounds like you ARE getting pressure in the front though? that's progress, right?

[Shugalou]

I'll do one better when I win the 64 mill tonight I'll fly you up ha.

I don't have a mighty vac yet, I've been doing this solo with a club holding the pedal down while I crack the lines.

I noticed the the front was more in the air than the rear so I will be lowering and having my wife pump the brakes. Told her she needs to wear high heels to ensure proper function.

Yes fronts grabbing is progress I'm trying to hold dropping 100 bucks or more on a tool I'll only use once. It will be a last resort though.

I'll keep you guys posted gonna try and work on it over the weekend.
Posted via Mobile Device

[swissarmychainsaw]

I recommend you get a MityVac. I bit the bullet YEARS ago and have not regretted it. I'm sure I paid more than $50 and have gotten MORE than 15 years of service out of it. Well worth it.

But then again, having your wife help in the high heels could be priceless!

This one is a mere $40 'Merican!

Amazon.com: Mityvac MV8000 Automotive Test and...
And if you want the ULTRA DELUXE for a mere $62, you get full metal WITH A CASE!

Mityvac MITMV8500 Silverline Elite Automotive Vacuum Pump Kit
Amazon.com: Mityvac MITMV8500 Silverline Elite...
OR if you want, just wait for that winning lottery ticket, and when you fly me up I'll just bring mine. Actually I have an Extra on (garage sale!) and I'll just GIVE IT TO YOU! :-)
--Nick

[hatzie]

Once you use a pressure bleeder you'll never want to go back to any other method. I flush my brakes every couple years when the DOT4 hydrometer shows more than 2% H20... The testers are fluid type specific one for DOT3 & one for DOT4. They are around $25

Vacuum bleeders will work fine as long as you can seal the bleeder threads to keep from sucking air through them.

My solution was to drill all the way through a caliper bleeder and a wheel cylinder bleeder so they could be tightened up against the tapered seats and not leak air. This, of course, requires that you buy replacement bleeders for the ones you mutilate into tools.

[Shugalou]

Ok guys, I have been wondering if the vacuum or pressure bleed will solve my problem and you have my convinced it's worth the investment.

I will first rule out the high heel method in the name of research before moving onto the pressure method.

hatzie that's a good tip with the bleeders I do have some extra's as I bought calipers and wheel cylinders that had the bleeders with them already.

[mrolds88]

Shug, here's a video to give you a good idea. https://www.youtube.com/watch?v=GAE6i1Sd2S0 and double check your prop valve to make sure its centered.