Technical Weird Brake Problem - Can anyone recommend a good dual drum/drum master cylinder?

To go with what @Kerrynzl said above, check the shoe pads on the backing plates to make sure the shoes aren’t getting hung up on them not allowing them to return, I too highly doubt it’s the master cylinder

 

OK...

I broke out my huk'T On fONics - WeRX 4 mee remedial reading text and found the passage ...

That is their opinion. My opinion is that you do not compound them and make changes that are completely unnecessary and possibly unsafe.

If you are designing/building a braking system and can't cipher if the MC has/doesn't have an internal RPV(s), you need to do more research.

Another factor is that most plumbing is now CHI-COM and they will not (or cannot) tell you if it has an internal RPV. You ask one of the so-called counter people and they go brain dead.

FORD got away from RPV's around 1970/ . The vendor might say it is a direct replacement for an earlier model but you need to check it.

 

I've always sourced out a Wagner master for whatever application I'm using and stuck with res valves from SSBC.

 

Not seen any mention here that confirms the presence of a brake pedal return spring. Just mentioning that for the sake of completeness.

Also, unclear from the info provided as to whether the brakes have ever worked properly. For all we know its a new build with the master being on the shelf for 4 years. I'm unfamiliar with the Rodsters truck, as best I can recall, so apologies if this is common knowledge.

Chris

 

I have always used whatever M/C would follow the recommended factory fitting for a vehicle the same weight and brake configuration. Drum brake M/C's should have factory residual valves perfectly capable of keeping the correct pressure. Brake systems need to be as simple as possible.

 

The brake pedal return spring is within the MC itself. That is taking into consideration the pedal linkages and bushings are correct and sound.

 

If it is residual valves it seems odd that it effects both front and back open the lines and check how much fluid comes out of each. I am inclined to think the piston is sticking.

 

I may be wrong (again), but it seems that relying on that spring only will result in a zero clearance between the pushrod and piston. That is a condition that is not ideal. An dedicated pedal return will provide clearance if the pushrod is properly adjusted. And that assures that the piston returns to the end of its stroke everytime.

 

Proper push-rod clearance is obtained with correct push-rod adjustment. A helper spring needing to be used points to something out of adjustment and/or hiding a mechanical defect. If the push-rod length is too long, a helper spring (to return brake pedal to full release - and that points to another problem with the linkage) will not give the clearance needed as the push-rod will still be pressing against the MC piston regardless (push-rod length). A brake pedal that does not return fully after release (due to linkages/bushings) and merely rests on the push-rod will not put enough pressure on the piston to apply the brakes if the push-rod is adjusted correctly.

Another factor is the push-rod style. Does it seat properly within/against the piston or rides high at the piston?

If the brakes are dragging due to residual line pressure from the MC after brake release, it will cause the brakes (drum in this example) to drag causing excess heat. That heat will be absorbed by the wheel cylinders and cause the brake fluid to overheat and expand, making the situation worse after driving for awhile. The drums will expand from the constant heat source and make braking even more difficult due to needed shoe travel.

Same scenario for disc.

Now all of this is taking into consideration the MC and foundation brakes are installed correctly, fully functional and of good quality. No J.C WHITNEY here. You use only quality parts from a reputable manufacturer/vendor. If you have a need to shop by price only without taking quality into consideration you are taking a gamble.

Is this vehicle manual or power drum?

SIMILAR REFERRING URL - https://www.jalopyjournal.com/forum/threads/need-some-help-with-brake-issue.1272098/

 

The pedal, fully retracted by a return spring, should not be riding on the master. The first movement of the pedal in use will take up that clearance, and then the piston will begin to move. The weight of the pedal can cause dragging problems, which is why the clearance is required, along with the spring.

Using a spring on the pedal doesn't mean there's bind somewhere, and of course there shouldn't be any.

Chris

 

Where are these helper retracting springs everyone here keeps talking about? I have never come across one. Illustration please.

If the weight of a pedal/linkage rests against the MC piston, and the rod to piston clearance is correct, there will not be enough pressure generated to initiate piston movement to apply any hydraulic pressure. Now this setup is not desirable but everyone keeps mentioning this helper spring. If there is that much slop in the linkage(s), the system is not setup correctly.

I a$$-u-me you are describing a fabricated under floorboard setup. If the MC internal spring(s) does not return the pedal correctly, the system is either ill-designed or has a mechanical defect somewhere in the system

 

Kult, since the OP said his vehicle is a 41 Ford pickup we are assuming it has under floor pedals. And, every old Ford with under floor pedals must have been defective from the factory because they all had a spring attached to the pedal to bring it back up to the underside of the floor.

It's actually a good idea as then the master doesn't need to try to push the pedal's weight with its small internal spring. And, it ensures the clearance between push rod and master we are all talking about.

 

OK, I will give you that. All of this was way before my time. I never had interest in much pre-1957. But a hydraulic brake system operates the same throughout designs.

Now let me ask you something. When you bench bleed a MC, how much pressure has to be applied to move that piston, especially once it fills with fluid? Do you think just the weight of linkage(s) will be able to move that piston? The spring was most likely designed to keep the pedal at a certain height with the correct adjustment of the MC push-rod.

The obvious problem with the vehicle is push-rod adj (or incorrect geometry) as there is a preload pressure on the MC piston. That push-rod either needs to be adjusted correctly or a correct adjustable rod used,

 

Interesting point, makes total sense and I can't dispute it. However, a search on the auction site (brake pedal spring) delivers thousands of results. Admittedly substantially older models, but plenty of later models too. Possibly not much call for replacements on later models for vendors to be bothered listing?

Maybe the spring is there as an aid in achieving correct adjustment in the first place, as it is a feel thing rather than an actual measurement? Irrespective, I'm keeping my return spring and suggest others do likewise!

Chris

 

I never bench bleed masters. And I just install a return spring strong enough to keep the pedal up against the bottom of the floor. Nothing more. And then I adjust the push rod so there is a sixteenth of an inch of play before it hits the cylinder. I like to keep things simple, and I go with proven methods.

 

I never said delete a spring if designed that way.

What I am trying to get across is that the spring is most likely a pedal height assist and the linkages will not put enough pressure on the MC piston if the spring failed (unless the donor setup was off a B-61 MACK). That can only be done with foot application or incorrect adjustment.

I have no experience on these early models but have searched through ILL's and see no assist spring on a built system. I remember as a young varmint riding in these things as the pedal vibrating between gear changes and some pedals riding low.

 

... I would ask but I don't want to know ...

 

I used one of these when I converted my 58 AMC to a dual master setup and it's been twenty years with no issues.

 

I'm currently completing the installation of suspended pedals in my 56 Dodge pu. Using a factory setup from a 60 Dodge. All bolts in, after making the correct hole in the firewall, along with the reinforcement plate. The factory setup include returns for brake and clutch. The pedals weigh at least 3 lbs each. With the leverage that exists in the design I'd bet that without the springs the pedal 'bounce' on rough roads could build up enough pressure over time to drag the front disks. Not sure about extending the rear shoes against the retraction springs, but maybe.

 

Now if a guy wanted to do some reading, I found these 5 pages a quick read to give the reader an overview of the system. That said, and with a factory FORD Chassis Parts and Accessories Catalogue for reference, I'm not seeing a return spring on the brake pedal. Clutch pedal, but not the brake.

It's what's in my library for reference.

 

https://www.dennis-carpenter.com/cars/transmission/clutch/99a-7523-clutch-pedal-retracting-spring

For brake pedal and clutch pedals

 

I wouldn't put a lot of faith in that ad. These vendors use partial FORD PN's to sell product as using the actual FORD PN without license infringes copyright laws. How would you know what it is claimed to be if not marked NOS or FORD APPROVED REPRO?

The FORD BASIC PN for the spring is 7523 which puts in the MAN TRANS PARTS GROUP. What is being done there is their offering the spring for service replacement or fabrication (for either application). The spring advertised is an anti-rattle spring for the clutch linkage.

The problem with the brakes dragging is pressure is being applied by some means (defective MC/wheel cyl/caliper - improper adj - or incorrect fabrication/service) causing the brakes to drag. The only certain way to diagnose it (other than the obvious - cracking the bleeder or output line @ MC) is with gauges.

The .020" clearance between the push-rod and MC piston dictates proper mechanical clearance(s) before any application, not any perceived weight of the linkages against it. If that actually happened, the MC would be defective (weak/failed internal spring(s).

You guys are beating yourselves to death.

 

I’m just trying to help a guy fix his old Ford, letting him know what works for me. If a guy with questions about his 57 Chevy asks, I’ll keep quiet.

 

From the "Green Bible"; nuf said...

 

Again, those are anti-rattle springs. They have no bearing on either MC PISTON or CLUTCH RETURN (performed by clutch pressure plate).

 

Brother, that's all I am trying to do here. No disrespect to you is intended. That teensy-weensy spring is not going to over ride a MC piston return spring(s).

And seeing as how it is not connected directly to the MC PISTON, there is no way it could pull it back regardless.

 

Anti-rattle springs???? Ford calls them "brake pedal retracting" springs. Installed to ensure that the brake pedal fully retracts and holds the rod away from the piston... to ensure that the MC piston return spring can do it's job. And the correct one is not a teensy-weensy spring.

Besides this was intended to offset the Ford Service Bulletin that did not mention a pedal return spring...

 

Here's a public service announcement to all the 57 Chevy guys reading this: old Fords have actual bump stops under the floor board for the brake and clutch pedals to rest against (at least in the hydraulic era). They have springs to hold the pedals up there. Henry Ford designed them this way. It removes all the pedal weight and leverage from the systems when they are not in use.

I really hope the OP is able to find a nugget of good in all this sh!t that we did to his thread.

 

This thing is $300 but it is pretty slick. I installed it under the floor of my roadster and it has been trouble free. It has built in brake switch port (hydraulic), built in proportioning valve, weighs 5 pounds (aluminum), 1" bore, can handle disk/drum or drum/drum, power or manual (I run the former without booster), it is dual ported on the bottom so it can run out the left, right or down for ease of fabrication/installation all that and chrome plated too!

 

On the clutch side the spring also serves to keep the throwout bearing alive. Without the spring the bearing would be constantly turning and be very shortlived!