47-55.1 Please critique my brake line plumbing......

[paintman]

Hey guys! Some of you may have seen my 46 build thread over on the pre forum but i figured I would post here for more response. I have had to take my truck back off the road because of brake trouble. I just can't seem to get a good pedal and i am thinking it's how I routed my lines.

First pic shows my prop valve. Can I have it mounted in this position or does this trap air up by the brake light switch?


Second and third pics show how I seperated my rear brake lines and ran them through the frame with thru frame fittings. Can this be done or am I tying to move to much fluid having 2 seperate lines running to the drums? Furthermore, If it is in fact ok to run my lines like this, do I still need the rear rsidual vale since the lines come thru the frame above the wheel cylinders?

[Jemezcrusher]

This looks horrible! I suggest you come over to my house and try it again to see if you can get it right

[_Ogre]

ogre has no problem posting your thread here, as few builds in the pre-47 section i think they should make it pre-59
i feel your pain. truk had brake problems that kept it in the barn half the summer
i ended up rebuilding/modifying the whole rear brake system to get decent pedal

overall your plumbing looks good, nice bends and routing, did you ever have good brakes?
as for the split: hydraulics don't care what the path is to function, mine split similar to your and worked fine right out of the gate
from the residual valves i'll assume you have rear drum, front disc.
both front and rear appear to be 3/16" line. 1/4" lines are recommended for drum brakes, 3/16" for disc
3/16" brake line slow the flow to drum brakes, makes them apply slow, drums need the 1/4" line
did you bench bleed the mc? some mc can be trouble to bleed on the vehicle
is the mc disc/drum?

[joedoh]

prop valves usually trap air and it takes vigorous bleeding (tapping on the valve with a hammer) to get the air out. since you have it installed at an angle that makes it possible to get stuck up higher than the lines in the area of the switch, you may have to bleed the valve itself by pumping up the pedal and holding it to the floor and then "cracking" the switch body. I had to do that on a mazda years ago that just WOULD NOT build pressure, we eventually tried cracking all the lines on the combination valve and sure enough, the switch fitting (pointing up on that valve too) bllloorped out an almost black set of bubbles and suddenly the brakes worked.

hydraulic pressure doesnt care about line length (at least within the lengths of even the longest car/truck). the in-compressible fluid with an input of 1/2 inch will move 1/2 inch. so there isnt a "pushing too much fluid" problem. but like ogre says, the rear lines for the drums should be 1/4".

I have only had a bad master cylinder once. every other time and even after many bleedings it was air in the lines. when I need to bleed something aggressively I use the tried and true method, a clear line from the bleeder into a jar of fluid and STOMPING on the brake pedal. the only problem I see with your setup is like you said, the switch is above the lines and like ogre said the rear lines look to be 3/16. otherwise it looks well thought out and well executed.

[dsraven]

the reason drum brakes need residual valves is partly because air can get past the cups in the wheel cylinders without a positive pressure inside the cylinder. it is very important to also have properly working auto adjusters and a park brake and keep the park brake adjusted properly. auto adjusters keep one end of the shoes adjusted to the drum diameter, and the park brake keeps the other, wheel cylinder, end properly adjusted. without a park brake mechanism the wheel cylinders are returned all the way back into the cylinder when the brakes are released. that means next time the brakes are applied the first part of the brake application is used up just bringing the cylinders out far enough for the brake shoes to contact the drum again. some worn out stuff even needs the pedal to be "pumped up" because the shoes are worn out and the park brake isn't adjusted.
make sense?
check this link also
I agree with others in that the adjustable prop valve should sit level with the exit lines at the topmost position, that way any air stuck in the valve has nowhere to go but out the top, which is where it collects anyway. sometimes leaving a tough bleeding system over night will bring the bubbles to the topmost spot and then the line cab be cracked there when bleeding.

https://techtalk.mpbrakes.com/how-to...t-brake-valves

[dsraven]

another related link

http://www.yogisinc.com/index.cfm/pa...at/cat1911.htm

[dsraven]

and another maybe interesting for those just learning about brake systems

https://www.freeasestudyguides.com/r...eck-valve.html

[hogfarm]

Good Morning
I had a problem just like yours,could not remember what was wrong,but will help from people from the forum got it figured outgo back and look at an old post of mine "brake Problems"But it ended up the brake booster and master cylinder were not a total match.it just needed a little sleeve between the booster and M/C

[paintman]

Hey thanks for all the help guys!!!! I didn't know that drums require a 1/4" line. If that is in fact true, why would Wilwood sell a prop valve with a 3/16th inlet and outlet ports to the rears. Wouldn't that defeat the purpose of running a 1/4" line? Seems to me your just putting a blockage in the line restricitng the movement of the fluid. Do they sell one specifically for drum/ disc set up with a 1/4" outlet port to the rear?

Also I have been reading that some guys have trouble with thru frame fittings. This is because you are going from a small inlet hole to a large chamber thru the frame back down to a small outlet port to the wheel cylinders. I have found that Art Morrison supposedly makes a special thru frame fitting that eliminates the bleeding problem. what the difference is, I have know idea, except perhaps it has a 3/16 hole all the way thru the bore.

Any thoughts??????

[paintman]

Just to respond to Ogre question............... When I first got the truck on the road I had probaly 85% good pedal with the engine off. I had the 85% pedal through it's full range of motion. However, when I turned the motor on I lost all pedal for the first 3-4" of travel ABSOLUTELY NO PEDAL just flop. After pressing the pedal down about 3" I got my 85% pedal back and the truck stopped pretty good.

I was able to drive the truck,it just wasn't comfortable if you know what I mean. When I was young and dumb I used to race dirt cars and liked a real "quick" pedal if that makes any sense.

[Softpatch]

In one word
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.....................................NICE.!
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[oldman3]

Paintman, after looking at your first pic, and then checking Willwood prop valve. You have yours plumbed wrong. The two top line, #1 is FI or front inlet #2 is RI or rear inlet. The bottom 3 are 1 & 2 FO or front outlet (one for left side and one for right side) and 3 is RO or rear outlet. You do not have anything in #3 at bottom, it's empty. The valve controls the fluid in #3, can't see the size but it apprears to be larger. On the pic I saw from Wilwood each outlet was marked. Hope this helps...Jim

[mick53]

Originally Posted by oldman3

Paintman, after looking at your first pic, and then checking Willwood prop valve. You have yours plumbed wrong. The two top line, #1 is FI or front inlet #2 is RI or rear inlet. The bottom 3 are 1 & 2 FO or front outlet (one for left side and one for right side) and 3 is RO or rear outlet. You do not have anything in #3 at bottom, it's empty. The valve controls the fluid in #3, can't see the size but it apprears to be larger. On the pic I saw from Wilwood each outlet was marked. Hope this helps...Jim

I have one in my hand I just polished. It's true the 2 you have hooked up are front the other is rear. The front has 2 outlets so you can split the front lines or in my case put a gauge sending unit for brake pressure so I can see how much line lock pressure I'm holding. This will allow me to vary my launch because I don't have 3 feet. Mine is disk/disk so they are all the same size. I noticed Wilwood doesn't make one with bigger rear line probably because they sell disk brakes but other vendors do. Check 4 wheel drive.

[mr48chev]

Everything looks spot on except maybe the angle of the proportioning valve as they mentioned. I don't know if pressure bleeding rather than just pumping the pedal would get around that or not.

I'm not sure I'd get too excited over the size of the rear brake lines as a lot of newer drum brake cars had 3/16 rear brake lines on disk/drum setups. Usually the later brakes have much smaller rear wheel cylinders and you don't have to move the volume of fluid like you did with the original setup.

Nice tidy work there all the way around.

[paintman]

Originally Posted by oldman3

Paintman, after looking at your first pic, and then checking Willwood prop valve. You have yours plumbed wrong. The two top line, #1 is FI or front inlet #2 is RI or rear inlet. The bottom 3 are 1 & 2 FO or front outlet (one for left side and one for right side) and 3 is RO or rear outlet. You do not have anything in #3 at bottom, it's empty. The valve controls the fluid in #3, can't see the size but it apprears to be larger. On the pic I saw from Wilwood each outlet was marked. Hope this helps...Jim

You are looking at the prop valve before the plumbing was complete. All the lines are installed in the proper ports!

[mick53]

Originally Posted by paintman

You are looking at the prop valve before the plumbing was complete. All the lines are installed in the proper ports!

You do beautiful work. I really like the cleanness of the rear brake lines coming out of the frame. I think I will steal that idea.

[dsraven]

I admire your nice clean work area and tidy build with attention to detail. one thing I would mention, and I assume it is just not completed yet, is the fuel line support above the rear axle. it may be chaffing on the frame there over time without some sort of clamp to hold it tight.

by "good pedal" what do you mean, exactly.

-pedal has a lot of movement/travel before any resistance is felt
-pedal slowly goes to the floor with a light pressure applied
-pedal movement seems normal to feel some resistance, like the master cylinder is being pushed, but then still goes to the floor with little or no brake application and no real change in pedal effort. drums and rotors can still be rotated by hand by a helper while brakes are applied
-pedal feels spongy
-pedal doesn't get hard on the first application but will get better with a second or third "pump" of the pedal

not sure if the pics are the most recent, showing everything connected, but I don't see any park brake cables. without them the rear brakes will take considerably more fluid to push the wheel cylinders out far enough to take up the slack where the park brake mechanisms hold the brake shoes away from their anchor posts. could this be part of the issue?

things to check, assuming the lines are all in place correctly on the prop valve:

-check to ensure the master cylinder is for your application, disc front drum rear I assume. if the master was originally for a drum/drum set up it may have residual valves in both ports. if it was originally for a disc/drum set up it may have a residual valve in the rear brake port. if disc/disc there should be no residual valves in the master cyl outlet ports. these res valves would hold up to 10 lbs in the lines of the drum brake applications and may mess up a disc/drum set up, especially with the master mounted low on the frame. a paper clip sized wire can be used, inserted into the port where the brake lines connect to the master cyl, to see if a residual valve is installed in the master cyl. if there is one, a spring pressure will be felt on the wire when pushed into the port. just don't push the wire in too far. a paper clip works well because it is not sharp on the end like a cut off piece of tie wire would be

-check the brake pedal pivots and linkage points for any slack that may be gobbling up pedal travel. also ensure there is a pedal return spring of some sort to bring the pedal all the way back up. sometimes this step gets lost when there is no cab in place and guys are mocking up. with the pedal at the top of it's travel there should be some play at the booster/master cylinder input end of the linkage. I assume you have the pedal and master cylinder attached to the frame but that would also be some good info for us to know. frame mounted boosters may need a different residual valve set up

-check the movement and adjustment at the master cylinder to booster, especially if the master and the booster were not a matched pair. sometimes the push rod on the booster is not long enough or is out of adjustment so pedal travel is used up before the master cyl piston is actually contacted or the push rod is too long/out of adjustment so the master cylinder doesn't get to return fully and so the system becomes hard/impossible to bleed correctly. below is a link explaining that in detail and shows a handy little tool for the job. I think a lot of the frame mounted boosters are a copy of the system he is demonstrating the adjustment on. a quick check of this canbe done by having some one step on the pedal while you look into the reservoir. when the pedal is initially activated a small fountain of fluid should be seen in the reservoir. this is because the piston sits behind the fluid holes in the bore and then as the piston is pushed down the bore some fluid is displaced and comes back up the holes. this is normal. it allows fluid to be "topped up" in the bore of the master cylinder as the brakes wear and require a bit more fluid in the wheel cylinders or calipers plus it allows excess fluid to return to the reservoir when the brakes heat up and the fluid expands. a booster with a push rod that is too long or a pedal/linkage system that doesn't allow the pushrod to return fully will not allow the piston to "uncover" these holes and can cause lots of issues

https://www.youtube.com/watch?v=qc6MgNNMQts


-check to ensure the drum brakes are assembled and adjusted correctly. below is a quick link to POL's diagram. it is important to have the park brake set up as well, after the basic drum brake adjustment, because that is what "adjusts" the wheel cylinder end of the shoes out to fit the drum and allows the shoes to center themselves at the anchor end of the shoe. there should be a flat bar that fits between the shoes and it has a stepped slot on one end that can sometimes give trouble if it is tight fit between the bar and the shoe/park brake actuator lever. also, if you are using a second hand set up, check the backing plates for wear in the area where the shoes contact the backing plate. I have seen grooves worn there that cause the shoes to "hang up" and not center or return correctly because the shoe drops into the groove and can't be returned by the shoe return spring tension. this can make it harder to adjust the brakes. better to replace the backing plates now than later
to recap, adjust the park brake to have lots of slack, then adjust the star wheel adjusters, then adjust the park brake

https://www.performanceonline.com/19...ET-OF-4-18537/

What works for me is to install a couple of nuts/washers to hold the drums up tight on the axle flanges. this eliminates a drum being a little off and causing some drag that wouldn't normally be there. then loosen off the park brake to ensure there is no drag from that end of the brake shoe. then adjust the shoes up right tight with the star wheels. this will center the shoes against the drums. then back the star wheels off until the drums can be turned. you need a long skinny tool to hold the star wheel "ratchet" mechanism away from the wheel so it can be turned backwards to slack the brakes off some. do the same number of "clicks" on the star adjuster wheel for each side. this is adjusting the bottom end of the brake shoes to fit the drum. then apply the brakes a few times and go back to check again to ensure nothing is dragging. then adjust the park brake. this will adjust the anchor/wheel cylinder end of the shoes to fit the drum. a lot of guys don't do the park brake adjustment or simply leave the park brakes disconnected because they "never use it anyway". these are usually the guys that have a low pedal because the wheel cylinder pistons are returned fully into the cylinders and require a bunch more fluid to be displaced in order to bring that end of the brake shoes out against the drums.

-bleed the brakes, start with the wheel that has the longest run from the master cylinder, bleed that one first, then go to the next longest run and so on. usually the right rear first, then left rear then right front and finally left front. when you bleed the brakes, if using a one man bleeder or a vacuum system, ensure you don't open the bleeder screw too far because it can draw air in from around the threads of the bleeder screw and fool you into thinking the system is still full of air bubbles. the same goes for the rubber fitting or tubing used to fit over the bleeder screw. just make sure to have the best fit you can so you are not drawing air in around the connection. if bleeding the system using the buddy method, where someone steps on the pedal while a buddy opens and closes the bleeder screw, just ensure the pedal man holds the pedal all the way down and keeps it there until the bleeder screw is tightened back up. make sure to check the master cylinder fluid level often as well.

-try the pedal again to see if you have a good pedal now. don't rule out the possibility that a new part may be defective

here is a link to show a backyard cutaway of how a brake booster works

https://www.youtube.com/watch?v=I4Ka4__ws1E

here is a link to show the master cylinder residual valve in the port, also an explanation of how it works

http://www.underhoodservice.com/diag...der-diagnosis/


sorry for the long winded response, hopefully you get it sorted out.
post up some more pics, nice looking build you have there.

[oldman3]

Originally Posted by paintman

You are looking at the prop valve before the plumbing was complete. All the lines are installed in the proper ports!

OK, sorry but that's all I got. Hope you figure in out...Jim

[Gippetto]

Brake lines are nicely done.
What did you use for your gas tank?

[paintman]

dsraven, I think you may have hit on part of my problem. Neither of my backing plates or drums have access holes in them to get to the star wheels. The only way I can snug my shoes up is to pull the drums, tighten up on the stars a couple of clics and then try to force the drums back on. From what I was told the rear is a 12 bolt out of early-mid 70's truck. However, all the brake components are new s I bought a complete kit from Early Cassic Enterprises.

Perhaps I should just go a punch a hole in the backing plates for access. Has anybody ever had to do this????????

[dsraven]

yep, it was a pretty common occurrence back in the day to drill the backing plates for access to the star wheels. grab a rubber plug first so you know what size the hole needs to be. I think 1/4 drill but oblong hole.

[dsraven]

if you check the plate it may have an indent where the hole should be, might even knock out if it was sort of 1/2 punched. otherwise drill it out and carry on.