Factory Brake Job

[Jeff Balazs]

Dave that is a very good point. If the cab were to shift or settle some on the mounts this adjustment would almost certainly be affected.

This possibility could be easily overlooked......when in fact it is probably a fairly common occurrence.

You should get an award for one of the best tips of the month!!!

Jeff

[HanksB3B]

Well with all the help, tips and tricks it should be a piece of cake. The MC is back in the truck and there is slop betewwn the push rod and the MC. For a minute I was thinking my cab may have been restricting the proper clearance, but from under the truck there's plenty of room for adjustment. Now it's just a matter of dialing in the 1" of freeplay, bleeding the brakes and taking a test drive. If all goes well, the new MC I just got from VPW will be a back-up unit.

 

Hank 

[HanksB3B]

RodFru2U (Rod) came over this morning and we spent the better part of the day on the brakes. We got the pedal freeplay adjusted to 1" (and with the spring off I could feel where the push rod touched the aluminum cone) I read about "bench bleeding the master cylinder in documentation received today included with the VPW master cylinder. It was not possible to do this with the MC mounted in the truck and I didn't want to go backwards. We tried to attach a bleeder hose to the port that supplys the brake lines but due to clearance issues with the steering column, were not able to do that. Instead we improvised and bled the master cylinder at the "T" junction where the swirly brake line plugs into the T. I was able to tell the difference between squirts of brake fluid mixed with air and just plain fluid only.  Next bled the passenger rear driver rear (top cyl. first then bottom cyl.) then passenger front, driver front. Got pedal pressure now, running the Roberts MC installed a couple of years ago (which seemed to be in fine shape) Hoping the proper push rod adjustment and pedal freeplay does the trick and the brakes no longer lock up.

 

Thanks Guys,

 

Hank   

 

P.S. Todd, a mechanic at VPW said it is best practice to have a power flush done. Rather than take it to a shop I want to make fittings that will enable me to use the power bleeder I bought for my BMW.

Edited March 11, 2014 by HanksB3B

[HanksB3B]

Things seem good, breaking in the shoes brakes seem good pedal is hard (but I think the stroke could be shorter). I may still have some air in the system but the truck comes to a fairly ever stop. I'm not ready for the stomp on it in the rain test (that's when I really know things are good)

 

Hank

 

P.S. It was the length of the master cylinder pushrod causing the lock-up problem.  

Edited March 11, 2014 by HanksB3B

[Don Coatney]

 

 

P.S. It was the length of the master cylinder causing the lock-up problem.  

So how did you change the length of the master cylinder?

[HanksB3B]

So how did you change the length of the master cylinder?

 

Oh I meant the master cylinder pushrod...but you knew that didn't you..What I would like is an explanation of how the MC works especially how the pushrod and the relation to the two vents or passages.

 

Tahnks,

 

Hank 

[Don Coatney]

This might or might not help.

 

http://www.onallcylinders.com/2012/07/17/video-how-master-cylinder-brakes-work/

[Jeff Balazs]

So I was on the right track. Glad that got it fixed.

Jeff

[HanksB3B]

Hank;

I don't know for a fact if the stock master cylinder can behave in this way.......but on some M/C's if the piston does not fully return then you can pump and pump and never make the fluid flow. It has to do with the position of the seals in relation to the inlet orifice. I don't have a stock M/C to check so I really don't know if this is the case with one of these. It seems to me if your M/C was functioning properly before you started this project then there is a good chance it still is. Especially one with low wear on it.

 

I do know that if the pedal adjustment is not correct it can easily prevent the piston from making it all the way back. I have run into this condition with my Cherokee M/C modification and it causes the system to retain a bit of pressure and make the brakes drag.

 

It is worth checking......might just solve the situation.......and it only takes a few minutes to readjust. All you will need is a 5/8" and a 7/8" open end wrench and a light.

 

As far as bleeding the system you should not need any special equipment. A lot of folks like these "new fangled" auto fillers but I have never found them necessary. Just one more thing to break or malfunction. Simply find a helper.....they do not need to possess any particular skills.... except to have a right leg and follow your directions. If the components in your system are all functional and leak free ...... bleeding it shouldn't take more than about 10 or 15 minutes from start to finish. I like to start at the wheel cylinder farthest away from the M/C......but on a simple system like these trucks either direction should work. Go all the way around (from bleeder to bleeder) 2 or 3 times and all should be good.

 

Hope this helps. Jeff

 

You hit the nail on the head back in post #37.

 

and I personally thank you,

 

Hank 

 

Oh and P.S., most of the new paint is off the MC so you were right about that too. (wonder if it'll remove my blue engine paint and I can hand paint my engine silver? Maybe you can find a machine that cuts louvers through steel and hush mat at the same time...just kidding. Alternately riding around with the hood off does/does not cause the "hot start" "vaporlock syndrome" 

[Jeff Balazs]

Hank;

Glad to be of help. Sometimes it is the simple little things we all look at ....but don't really see.

It will take the blue paint off but good luck getting the silver to stick!!! Brake fluid is insidious stuff.

 

On that other topic......with the hoods up and the engine idling  it takes forever to warm up.......and pretty much everything except the exhaust manifold and the block stays much cooler. Cool down time is a one heck of a lot quicker too........so I figure venting the hood would have a similar effect. Just got to find the right vent scoops. If I am right about this it should make a huge difference.

Jeff

[HanksB3B]

Hank;

Glad to be of help. Sometimes it is the simple little things we all look at ....but don't really see.

 

Here's a good example: RodFru2U asked me if there was a difference between the pilot bearing of a three speed floor shift and a three speed column shift transmission. So I emailed him this picture in an email titled "I found it"

 

 

Never even saw it,

 

Hank 

[Dave72dt]

The two holes in the master need to be open when the brakes are at rest. The rear hole (push rod end) is always open or supposed to be. It's the feed hole. The front hole when the piston is all the way back is open. It's the return from the wheel cylinders which have to retract to release the shoes. As soon as you start to apply the brakes, the piston is moved forward and covers that hole so fluid is pushed into the brake lines. If the piston does not fully return or the pushrod length adjustment prevents it from doing so, the hole remains covered and the brakes remain applied. Dirty fluid or a partially plugged hole can cause the return of fluid to slow and cause the brakes to grab and release over time. Because of the design of the piston, piston rubber, more fluid can be introduced into the brake lines faster than it can return which allow you to 'pump up" the brakes. That's the simple version.

[HanksB3B]

Thanks Dave that simplifies it and now I understand why my brakes were locking up. The piston was not retracting enough to clear the front hole (fluid return port) so the brakes were in essence still applied or "locked up".

 

Thanks to everyone,

 

Hank 

[HanksB3B]

Test Drive Fail

 

The brakes locked up on yesterday's drive and showed me I'm not out of the woods yet. I set the pedal so that I had 1" of pedal freeplay but the length of the MC pushrod ended up looking like the same distance I started with in the top picture.

 

Following Dave's post #62 above I will back off the adjustment about 1/4" and see if that makes a difference. I have a new Master Cylinder but am not convinced that there is anything wrong with the one now installed (less than 500 miles on it). All the fluid that was bled indicated that the system is clean so I don't think the return hole is partially plugged.

 

PM Update: Test drive results; Still locking up. The pedal feels strong so I'm thinking it has to do with the shoes & drum interface again.

 

This is taking longer to sort out than I expected,

 

Hank 

Edited March 13, 2014 by HanksB3B

[Dave72dt]

If you had free play before, shortening the rod will only increase the amount of free play. That's assuming the master is correctly assembled and working properly.   Describe the "lockup".  Have they ever worked correctly or is this a new development?  Is it one wheel or two or four.   Front axle or rear?  Is it more of a grab when brakes are applied and do they release when you let off the brakes or is it a consistent drag.?  Does the lockup get more prominent the farther your drive or every time you apply the brakes?  Have you mixed types of brake  fluid?  Have the hoses been replaced?  Any grease, oil or fluids of any type get on the shoes?

[Robert Thornton]

I had a wheel locking on me once. It took me a long time to figure out that the rubber line had collapsed inside, it would let fluid in, but slow to let it out. causing brake to stick. you may have already checked this out.
 

[Jeff Balazs]

Hank;

You could try this to determine if it still a hydraulic problem. Jack up one of the offending wheels. Open the bleeder and see if the binding free's up. If not then it is probably a problem with clearance between the shoes and the drum.

 

Hope this helps; Jeff

[HanksB3B]

I had a wheel locking on me once. It took me a long time to figure out that the rubber line had collapsed inside, it would let fluid in, but slow to let it out. causing brake to stick. you may have already checked this out.

 

Robert, if I had to describe the actual feeling, that would be it. As if someone was pinching a house. Are you referring to the actual rubber brake hose being defective somehow.

 

Hank;

You could try this to determine if it still a hydraulic problem. Jack up one of the offending wheels. Open the bleeder and see if the binding free's up. If not then it is probably a problem with clearance between the shoes and the drum.

 

Hope this helps; Jeff

Jeff jacking the drivers front wheel (the one that locks up) is next. I will try what you suggest. I guess determining if the lock up is hydraulic or mechanical might give me some direction.

 

Thanks guys,

 

Hank

[Jeff Balazs]

You just put new hard lines in a while back right? Surely the hoses are not that old.

Just a guess but if it is a not hydraulic problem.....then having the linings arc'd to fit the new drums is probably going to be the next step.

 

Jeff

[HanksB3B]

Jeff,

 

Thanks for helping. Even though in an effort to ease the lock-up condition I did taper the drivers front wheel brake linings, the shoes on my B3B are not supposed to be tapered. Today I plan to first jack up the wheel, step on the brake to try to make it jam then as you suggest crack the bleed valve to release pressure in an effort to determine if the malfunction is hydraulic or mechanical. I'll also just for the heck of it (I'm an expert now and can probably swap the shoes out in 15 minutes) going to fetch my box of brake shoes and just try another set, adjust them and give it a go.

 

• I no longer think it's the master cylinder itself or the MC pushrod length.
• The hard lines and hoses were replaced during the frame up restoration and can't have 500 miles on them.
• It couldn't hurt to take forum member "deathbound" up on his offer to borrow the Ammco 1750   

  

x

Edited March 14, 2014 by HanksB3B

[Robert Thornton]

yes that is what I was talking about I just had to replace the one at rear axle on my b3b this week I would not let me bleed rear brakes. they can look just like new but collapsed inside.  just take it off and blow through it you will know then if ok         good luck rwt

Edited March 14, 2014 by Robert Thornton

[HanksB3B]

Thanks guys,

 

Robert, It's not to say that it's not a possibility, but the brake hoses were replaced along with the MC, wheel cylinderss and new steel line.

 

I tried Jeff's suggestion, spun the left front wheel up to speed then stepped hard on the brake, got out and the wheel spun free. This points to  the hydraulics are not the problem (which is a good thing).

 

Mechanically here's what appears to be happening:

 

 

Both the leading and training shoe have a dark shiny contact patch near the lower pin.

 

but before I replace the shoes with the best set of used ones I have (just to see if that makes a difference) I'll re-adjust the driver side front brake for one more test drave.

 

Feel like I'm getting close (but then I've thought that before)

 

Hank 

Edited March 14, 2014 by HanksB3B

[Don Coatney]

 

Mechanically here's what appears to be happening:

 

 

 

From this picture it appears your shoes are not adjusted correctly or the shoes need the arc treatment to make them match the drum. Pictured below is a problem I had with incorrectly adjusted shoes.

 

[HanksB3B]

Don I always appreciate your input. I hope you are going to Tim's BBQ and I get a chance to meet you.

 

Guys,

 

Here's what I did today.   

 

(previously stated): "I tried Jeff's suggestion, spun the left front wheel up to speed then stepped hard on the brake, got out and the wheel spun free. This points to  the hydraulics are not the problem (which is a good thing)."

 

Well making the statement; "This points to  the hydraulics are not the problem." is not necessarily true.

• It could be the wheel cylinder sticking on return.
• It could be the hose aren't holding up

I took a run (not with the truck) to NAPA and they do not have a p/n. (I'd like to get one locally and I do have some cores and Rotex (local commercial component rebuilder) might rebuild a pair (probably cheaper from VPW, Roberts or Bernbaum but that's a week away on the west coast)

 

I then drove to an old shop and looked for someone old but no luck EXCEPT they suggested ch topping (CHT has been mentioned previously and it seems their reputation goes unsurpassed for brakes on old vehicles)

 

Was I surprised to speak to one of the guys that told me the following: The shoe with the longer (and thicker) lining should be towards the rear. I've never read or seen any specifications of how thick and how long the shoe is supposed to be relined. (Has anyone heard of this or does anyone have documentation 

 

took a look at the as-found

 

 

here are the shoes flipped as-is

 

 

 

I was real happy about the phone support CH Topping was willing to provide it made me feel like they are a good place to do business with. Another possible reason for brake lock up (and it makes perfect sense) is that both the right and left should brake in sync with equal pressure being applied from the cylinder to the shoe to the drum

 

I have a tub full of cores and am thinking of having the drums turned and have CH Topping re-line a pair.

 

 

Judging by all the differences in brake shoe lining material, length and configuration, I'm not so sure my truck didn't fall victim to crumby brake repair at random gas station garages, but from what I see in the picture below it looks as if the lining runs the length of the shoe. 

 

   

 

Hank 

 

P.S. flipping the shoes around did "something" it made the lock-up seem less severe. I'll get back to it Monday and with both wheels free will try to get the brake action consistant left & right. Thanks for looking.  

Edited March 15, 2014 by HanksB3B

[Dodgeb4ya]

No front primary short lining shoe or rear secondary long shoes are used on our B series trucks like what the man was talking about.

The linings on the B3 P/U's should be the same length for front and rear brakes.

 

Do you know the oversize of each drum?

I think your shoes need to be properly arced to each of the drums to get the shoes to work and wear in properly.Your shoes are way out of adjustment -only the heel is contacting the drum. Always arching the shoes if you can saves a lot of time and frustration.

 

Well for a quickie test I think I'd try putting the lower anchor bolt arrows back to stock position pointing to each other , readjust the cams so the shoes lightly drag against the drums and do a good road test. They might work a heck of a lot better-hopefully! Re check the wear pattern location after the road test too.

Bob