Hello Everyone,

I've been down the soft brake pedal road for a while now and I wanted to provide an update and look for any new suggestions. I did a lot of brake work at once (dumb idea). I went from a nice solid brake pedal to a soft pedal after the following work was done:

• Replaced Rear brake pads
• Replaced all Rear brake hardware (including wheel cylinders)
• Replaced emergency brake cables (Both sides)
• Replaced Front Passenger brake caliper

Somewhere among that list, I lost my firm brake pedal. Below is a list of things I've done since then to try and resolve this issue.

• Full system bleed (RR, LR, RABS, RF, LF) Performed after every attempt below.
• Rear wheel adjustments (No Change)
• New Master Cylinder (Bench Bled - No Change) Rebled a few times
• New Reman Brake Booster (No Change)
• Disconnected Emergency cables (No Change) Engaging Ebrake does not change pedal feel.
• Remounted all old brake hardware (No Change)
• Measured Booster rod length for adjustment (Correct length and contact point)

Normally I'd be fine with the pedal travel. The truck does come to a complete stop and stops efficiently. However, the soft pedal is causing my brake light switch to only activate when I'm coming to a complete stop. This has caused some close rear ends and some people yelling at me.

My next thought would the Front brake caliper being bad somehow. I feel like the "Engaging Ebrake does not change pedal feel" supports that theory. I'm pretty novice at this stuff so that theory might make 0 sense

 

Hello again. You could have continued with the original thread by the way.
The fact that engaging the parking brake makes no difference suggests the shoes are adjusted about right (slight drag). I guess the driver side caliper (the one you did not replace, right?) could cause the soft pedal, but unlikely.

Is the brake light switch at the pedal or the master?

 

Hey Steve, Thanks again for all of your help. I'm new to forums and was having trouble finding my other post.

The drivers side brake caliper was replaced prior to all of this work and had a nice hard pedal after it was replaced. The Passenger side was replaced between the hard pedal and the soft pedal issue. I really wish I would have done one item at a time :/

The brake light switch is at the pedal. The soft part of the pedal travel does not seem to have enough force against the brake light switch to activate it.

 

I thought the way they were set up is that the pin on the brake pedal arm is sloppy in the hole in the brake booster rod. That's how it works. The switch fits snug on the pedal arm pin, and the switch surrounds the booster rod. The booster actuator rod hole is way larger than the pin on the pedal arm. So when you push on the brake pedal, the pin and the switch move forward in the sloppy booster rod hole, and the spring part of the switch ends up hitting the outside edge of the booster rod, and it actuates the switch. After that, all the slop is taken up in the hole, so continued pressure starts applying the brakes.

So this all should happen in the first 1/4 inch of pedal travel regardless of how soft the pedal is as you press harder.

 

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Re the vid...I doubt your new master is plugged.
But it does bring up the question:
How did you bench bleed the master cylinder?

 

Steve: that is exactly how the brake switch works, however there is not enough pressure for the booster rod to press the spring until about half way down the travel. With the truck off and the pedal pumped up hard, it will activate within the first 1/4th inch. I've since replaced the switch with a new one just in case.

master cylinder was bench bled with the hoses and caps provided by the new cylinder. I also bought a new set of hoses/caps in case it really made a difference. The master cylinder has been bled a few times. Basically the same method as this:

https://m.youtube.com/watch?v=kEPXgDGU6_0

 

Hi,

YOUR WELCOME!

 

Called my parts store and it sounds like they are willing to warranty out my caliper just incase it's causing the problem. I'll be able to take a shot at that this weekend.

Gonna give Seagiants idea a shot and lift the rear of the truck and tap the MC while applying. I remember bench bleeding at multiple angles but you never know! I appreciate the fresh ideas!

 

Since the MC went dry, I have the suspicion that the RABS module might still have some air in it but it's not coming out through the bleeder. I've tried the "Slam on the brakes" method that I know is not necessary with RABS, but I don't feel like anything actuated when it should have.

The RABS module would have gone dry just like all the other components. I saw a post on here about removing the spring in the RABS to "bypass". Anyone done this?

 

The master went dry? You new one? How? During a bleeding effort?

 

The Master went dry at the very beginning, when I replaced the rear wheel cylinders. I didn't have a good way to stop the flow before it was empty.

New one has not gone dry. Bench bled and all. Full of fluid the whole time!

 

After reading all this, it seems like the trouble all started after the rear brakes were replaced. Have you adjusted them until the wheel locks up, pushed on the pedal to center things, then backed off until they drag a bit?

Seems unlikely that air is in the system from what you have posted, but just curious what method did you use to bench bleed the master? I like using the two clear hoses re-circulation method because you can see when the air is gone. The rear seems to take longer.

 

And another thing...

Used to be in times past, that when you bought brake shoes, you'd drop off your drums at NAPA or where ever, and they either had a small shop in the back or worked with someone nearby who did. They would skim a few thou off the drums to put a fresh face on them and then they would measure the ID of the drum and using that measurement, they'd "arc the linings" which in effect would re-shape the new linings to fit the ID of the drums precisely.

Nowadays, we just buy linings anywhere online or at some clue-less Autozone, clean up the drums with some emery cloth, and call it a day. Then, when you adjust the shoes to get that mythical "light drag" its usually only the top and bottom inch or two of the linings that make contact; the middle part isn't even touching until they wear themselves in.

If you were to pull your drums I'd bet you see a shiny wear pattern on the top and bottom of the shoes and not in the middle. If the drums have been turned a number of times, then that spot would be in the center. So, with all the work you've done, I think the trouble lies in the rear adjustment. You may have to adjust them a little on the tight side to wear them in. It's either that or find a local auto-machine shop that can arc shoes, then pull it apart and try that.

 

Steve, I wanted to give you an update. It's been a while but I finally worked out my issue.

I ended up taking it to our family mechanic for a look and he confirmed that the Brakes themselves were mounted/bled properly and that they were fully functional. He did note that the brake lights were coming on too late to safely drive around.

He added a shim to the brake light that helped slightly but ultimately didn't fix anything. I did some searching on other forums and found that my brake switch spring (Although new) could be too stiff. It was a long shot but I purchased a switch that was designed for an F350. According to some folks, it had a lighter spring that activated much easier. I was skeptical, but when I compared them by hand the difference was obvious.

Hooked up the new switch and now the lights come on with even the lightest tap.

I really appreciate your patience helping me though all of this. It's been quite the strain on my brain since it all started. Really cant thank you enough!