Soft Brake pedal

At first I thought of Wheatland, now I see how far you're out in Groveland!

You're right about Premium Parts, and I would add, especially about Rear Drum Brakes:

CHANGE EVERYTHING!!! Shoes, Hardware Kit, Cylinders, Wheel Seals, and any Suspect Bearing. It is just Too Much Work to take off four wheels and dismantle those full floating axles and bearings! Too Much to have to do it Again!

Thought I'd check in with an update.

I re-read your post Ron and looks like I need to adjust the brakes one more time. I did as you said and it helped but I didn't readjust after a hard pump. Things are better but not 100%. The reason I can tell is I back down my steep driveway to access the tank dump and used to do it easily enough with the parking brake on, as it would keep me from sliding. It isn't the same now.

The other thing is I didn't have the shoes arched. Thought they would settle in soon enough. I have 400 miles on the new shoes and still am down some stopping power.

One quick note: If anyone is going to do this get high quality replacement parts. Both the wheel cylinders I got from AutoZone were defective. One had a cut dust boot and the other had a stripped bleeder. I didn't notice the bleeder until it was time to bleed so it was a real pain to take it out, get a good one and replace it.

Any problem you have be it air in the system or drums in need of adjustment will become much more apparent once the boost is running. I would highly advise doing what Ron said and then bleed again at all four corners if it's still soft. If all that doesn't work you may be looking at a master cylinder. When they fail they don't always fail hard and trip the light (been there done that).

If you pump the brake pedal with the engine off, the pedal should get hard. If you have a power booster when you start the engine, the pedal should drop. That is normal with a power booster system.

Bob

Thanks again- Living in a small town the parts house didn't have my master cylinder and I should get it tomorrow.

The adjusters looks to be working well. I cleaned everything with brake clean and rags because if there is a new leak I want to be able to see it.

When I put the new shoes on I had to adjust them so the drums would even go on. I adjusted just enough and when it was all back together I backed up about 8 times, hitting the brakes rather hard to hopefully engage the adjusters.

The odd thing with this, and hopefully the telling clue, is I can pump the brakes up easily but when I start the engine the pedal drops. It stops the RV but something is obviously wrong.

I'll check back after I put the new master cylinder on tomorrow.

carringb,

You are so right.

I do many brake jobs at a charity auto shop. Around here in the Chicago area where salted streets is as common as salted McDonald French fries, drum brakes get all messed up and the first thing to go are the self adjusters. Down south and especially in desert regions, I would think and hope self adjusters would be more reliable.

ron.dittmer wrote:
I agree will all said. Adding only that in my experience, if your rig has rear drum brakes and the brake shoes are not adjusted properly, braking response will be noticeably less. I think that translates to a softer brake pedal.

Except in that case it would be soft with the engine off too.

It is a good point though. If the hardware was not all replaced with the shoes, the self adjusters may no longer be working. And.... they only work in reverse, and need some decently hard stops to make a "click". If you back up cautiously, it'll never move the shoes enough to make the adjuster wheel "click".

I agree will all said. Adding only that in my experience, if your rig has rear drum brakes and the brake shoes are not adjusted properly, braking response will be noticeably less. I think that translates to a softer brake pedal.

It's been a long time ago, but with my first motor home with rear drum brakes, the rig didn't have good braking power for over 3 years after a rear axle swap. That is until I adjusted the rear drum brakes which yielded remarkable responsive & stopping results.

To adjust rear drums, you need to jack up the rear axle so all rear tires are in the air, just enough to clear the ground. Use heavy duty jack stands. Have a helper spin the rear tires while you adjust. When there is a slight drag, have your helper pump the brake pedal hard one time, and repeat. This cycle of events will center the shoes inside the drum and place them right close so they respond quickly. When there is a slight drag "After" the pedal pump, that brake is complete. A slight drag is good. It will quickly settle into a better position after a little driving time.

Thanks guys. After reading the process to bleed the ABS I didn't want to get involved. Master cylinder I can do. My understanding is fluid just leaks within the system and isn't visible from outside.

I'll let you know how things turned out.

If the pedal only goes the floor when the engine is running, and you are sure you don't have any fluid leaks, I strongly suspect the culprit is the master cylinder.

Doing brake work at the brakes should not introduce air into the ABS module, and once that light is on, ABS is no longer doing anything except coming along for the ride.