Soft/spongy brake pedal

[SUBURBAN5]

Keeps us posted

 

[Schurkey]

I came to a stop from about ~30MPH, I noticed three things:
1 - my rear right brake drum was smokin'
2 - my brake pedal was a bit soft
3 - the parking brake light came on, which after reading some of the threads on here I learned it has two functions: to inform you the parking brake is set; and to inform you of uneven brake pressure in the system.

After I picked up some speed, my brakes cooled off and the pedal got a bit better - not much though. The brake light was still on as I was driving to Joplin - and conveniently went off once I got to my destination. Once I got my new project, the truck and trailer drove just fine back to my house - about 70 miles.

The following day I looked at my drums and noticed that the right side wheel cylinder blew apart - so I replaced both sides and bled the rear brakes.

Nothing changed. Brake pedal is still soft.


Also, now my parking brake doesn't work. It will apply, but WAY to soft and won't hold the truck.

(EDIT)
This is on my 1997 C1500

1. You have the ****** leading/trailing shoe rear brakes.
2. They don't adjust worth a crap unless you use the park brake regularly.
3. The wheel cylinder CANNOT "blow apart" unless the shoe travel is excessive; and that generally means the shoes aren't adjusting properly.
4. If the shoes are wildly out of adjustment, the park brake is going to be weak or non-existant.


In one place, you say the pedal is "soft". In another you say it's low, but firm.

my pedal will also go down 3/4 of it's travel and stop about 3 inches from the floor - BUT once it stops, it's firm enough to stop the truck at a gradual pace. Also, if I pump the brakes a few times, AND hold the the pedal, it's firm, but once I let go and put my foot back on it, the pedal sinks back down..

That's another classic symptom of the rear brakes not being adjusted properly.





So, yes, maybe you need to fix the ABS; but the real problem seems to be rear brake adjustment, and potentially the park brake cable--you can't use the park brake until the shoes are adjusted, and you can't adjust the shoes normally without using the park brake.

FOR NOW, pull the rear drums off, and adjust the rear shoes. See if the pedal height gets corrected, and see if the park brake starts working properly.

The real "fix" is to scrap the rear axle in favor of a "light-duty" 3/4 ton axle of the same gear ratio--which also gets rid of the whole "****** leading-trailing shoe" brakes in favor of the good "Duo-Servo" rear brakes (which also happen to be larger, more-powerful.)

 

[SUBURBAN5]

I felt like when I redid my shoes and adjusted the brake. It did make my pedal a little bit stiffer.

 

[CKVortec]

What Schurkey said, in order to have good pedal and stopping power you need good clean dry brake shoes, properly adjusted parking brake cable and properly bled lines. any one of those is wrong and your brakes don't function like they should.

Also, I have had issues with rear brakes over adjusting themselves and warping drums because the parking brake was tightened before the shoes were adjusted properly, so loosen the parking brake cable, adjust the star wheel until you get just the slightest drag on the drum and then adjust the parking brake cable until you feel it getting tight at a little before 1/2 travel on the pedal.
if you still have a spongy pedal after that there is air in the lines.

 

[Schurkey]

Good point about adjusting the service brakes first, then adjusting the park brake cable(s).

 

[HotWheelsBurban]

Another fix for the crappy light duty pickup brakes is a Suburban rear end or at least the rear brake swap. C1500 Burbs got the 11 5/32"( bigger )rear drums and shoes. And these are the duo servo style that adjusts when braking in reverse, which works a lot better! And those stop my Burb well. We can't always find a pull through parking space, so we back up enough to keep them adjusted. Not sure about the Tahoe/Yukon etc. because I've never had one apart. But Burbs got the better brakes since they're heavier than the pickups. That built in camper top ya know LOL. IIRC the universal brake shoe # on these shoes is #473. GM started using these on the Heavy Half pickups in the late 70s, and also on the Burbs.
Edit: if you go this route, get the whole Burb brake setup : the calipers have a bigger piston and the pads might be different. The master cylinder is different, maybe the brake booster is too. The rear drums have slightly larger wheel cylinders too. It's a bit of work, but you'll get much better brakes out of the deal. There's several threads that deal with variations on this swap.

 

[SUBURBAN5]

Amen to that lol. I always try to back up. And I love my drums. They stop good and last a long time. I still wanna beef them up though. And swap my front calipers to the 2500 style

 

[HotWheelsBurban]

Amen to that lol. I always try to back up. And I love my drums. They stop good and last a long time. I still wanna beef them up though. And swap my front calipers to the 2500 style

Where we used to live had a carport behind the apartment. The only way to be able to get out was to back the Burb in. Especially if there was another car or truck in the space ( it would fit 2 full size vehicles in it but that was tight). So those back drums stayed well adjusted! Here at the trailer park, we have to back up and maneuver a bit to park near the trailer and not be in the street.
When I replaced the front calipers and hoses, I got a pressure bleeder from HF. Made it MUCH easier to do the job myself. My mechanic friend with the crusty winch truck recommended the unit I got, very well spent $32. Only thing I didn't like was it doesn't have an adapter for the GM plastic reservoir master cylinder. But I made a holder from baling wire and it worked well. Redneck engineering at its finest LOL.

 

[SUBURBAN5]

Stay away from parking in the street. I always see vehicle rear ended and some hit and run.. I'm glad mine in a garage , but it is tight. Even my neighbors wonder how I fit it in lol. Sucks washing clothes though

 

[HotWheelsBurban]

Stay away from parking in the street. I always see vehicle rear ended and some hit and run.. I'm glad mine in a garage , but it is tight. Even my neighbors wonder how I fit it in lol. Sucks washing clothes though

Yes that cost me a taillight and almost got the mirror when a lawn trailer hit the truck when we lived at my cousin's in Katy last year. His street was one of the few that went between Westgreen and Mason, and there was always traffic. I could only park the Burb in their driveway when I had to work on it. Did the water pump twice and before that, the lower hose. Everyone has dogs in the neighborhood so I had to be careful with any coolant spills. But he loaned me some of his tools and gave me advice. With the split shroud it doesn't take too long if you have the right tools.