NBS master cylinder Swap

[SUBURBAN5]

without booster assistanc, I mean none, unexpectedly coming up to a stop sign, pedal goes to the floor, you **** your pants, but the truck will slowly stop, however your fear of the outcome and stomp stomp stomp on it. I blew a line at the same time and went through the stop sign of a major road, with 4 ways on, no one coming, phew. clean the **** out of my pants. discover an empty master for the front brakes. pinch the line with vice grips, fill the master up, test and proceed. I had my entire family in the truck. after every stop I pulled over and topped the MC back up because vice grips wont actually close the line off completely.

Iv been over the brake lines many times but for some reason I never traced the front passanger line and it was rotten sitting on top of the front frame hidden above the plastic splash guard shroud. this spot is terrible for a visual inspection but that plate comes off very easily. I re-routed this line slightly so it didnt sit right on that frame and took a slightly different route to the caliper.

so with a failed booster you will still have brakes but it seems to come at the end of the peddle travel.

I was lucky that I'm not the kind of person to fly up on a stop sign or lights and smash the brakes at the last second. I'm more of the annoying kind who let's of the gas way before and let's the engine brake slow the truck down before activating the brakes.

Al

You could of ace Ventura it and drifted to a stop lol

 

[thegawd]

that's almost what happened.... i went around the corner on the shoulder until it stopped....

 

[SUBURBAN5]

that's almost what happened.... i went around the corner on the shoulder until it stopped....

Good reflexes. I always told myself knock on wood slide it in to neutral and press down the parking brake. Pick the softest area to hit

 

[thegawd]

my choices were terrible, ditches large enough to consume a Burb or a massive transformer... I went with the shoulder and around the corner.

 

[thegawd]

leaving it in drive would slow you down faster than neutral.... if its life or death.... try 1st?

 

[SUBURBAN5]

leaving it in drive would slow you down faster than neutral.... if its life or death.... try 1st?

If I had enough time sure. I would try 3rd 2nd 1st. Not sure if say going 50mph would hurt the tranny if you shifted right away to 1st? Good point though

 

[df2x4]

Speaking from experience, you probably won't have enough time to shift gears anyway during this type of failure. Especially if you're in traffic.

Step one, hit regular brake pedal. Step two, soil pants. Step three, if your brain isn't completely in panic mode then smash the parking brake.

 

[Pinger]

so with a failed booster you will still have brakes but it seems to come at the end of the peddle travel.

Not on mine!
Shunting on the driveway (very briefly as no cooling) without the serp belt I thought my difficulties holding it back were a combination of high(ish) idle speed and lack of drag (water pump, alternator, PAS pump) and maybe a bit of corrosion on the rotors. Only later did I learn about Hydroboost. Pedal was at the top of its travel at all times and rock solid.

 

[stutaeng]

Ok, so I did have this happen to me. I was taking about 3,000 lbs of busted concrete to the landfill on my '00 CCLB K3500 SRW. When I left my house I heard a little unusual whine, but didn't think much about it. I took off and about 1 mile on the stop light the brake pedal went to the floor. I took off and a few hundred feet later I felt the steering wheel hard. I kept going another mile and made a left turn (then realized both steering and braking where gone) and got out to check under the hood, but didn't see anything broken.

Without brakes or steering wheel assist, I contemplated calling someone and getting truck towed. Luckily, it was about time for schools to get out (20 MPH zone I had just passed,) so I decided to limp back home. I got back on the main road and was on a slight decline, so I rode on the brakes and used the ebrake at the stoplight. I didn't think about downshifting, but was going about 25-30 MPH. That probably would of helped me. I finally did make it home, but it was a little scary.

So what happened is the steering pump shaft had broken and the pulley was just spinning there. I think I read on a different forum that this has happened before, can't remember if common or not.

 

[thegawd]

you know I had vacume leak symptoms prior to this failure but I had no idea. it wasnt until I watched a really good video from a mechanic in Alaska where he went through the entire failed brake booster troubleshooting and replacement before I realized.

generally when a vacume booster fails, the diaphram around the plunger tares or disintegrates in some way and the you can hear a massive vacume leak in the cab or none at all because it's a very small leak.

prior to this massive audible leak it was all ready leaking I just had no clue. the symptoms were related to rich fuel trims. I'd reset the code and it wouldnt return for a day or so.

so the guy in Alaska puts a scammer on the truck and loads up the short term and long term fuel trims. he presses and holds the brakes down. if you have a failed booster one of those fuel trims will rise all the way up to 100% if you hold it long enough. then when he let off the brakes and gave it fuel the truck almost died, it fell on its face.

so prior to hearing a vacume leak that's is how you can troubleshoot a failed vacume booster.

here is that video...

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up until this happened I was collecting the parts to do the MC "upgrade." I had the line adapters, still do, and free access to a 2005 Tahoe, hahaha I also still do. but I wanted to know more about the hydraulic systems, how they work, and I truly believed that the individual parts from each brake system has to be rpo specific, (I only order pads/drums/discs/wheel cylinders/brake calipers by RPO code, a lesson learned by only having one vehicle, getting the wrong parts but not realizing it until I had it all torn apart!) so I reached out for an explanation and I got a very detailed explanation. And since I all ready agreed with the explanation that closed the books on the mc swap on my Burb indefinitely. It has JB7 brakes and so I replaced only what was broken, a booster and the line entirely for the front right passanger as it was the last one on my truck that wasnt replaced by me back when I first got the truck. what I could see if that line was perfect, it was what was hidden along the frame under the plastic shroud that was rotten, I dont even know how it hadn't ruptured prior during emergency stops. prior to the failed booster I had no complaints about my Burbs brakes. they worked flawlessly and so does the abs system which I regularly exercise for fun.

I have more brake parts for the burb, all new all 4 corners when though it dosent really need it, it's been years since I replaced what needed to be back when I got it other than a few sets of pads.

Now my Sierra has the JB5 brake system............... but it was replaces entirely absolutely everything except the MC/Booster because they were not broken.... my buddy owned this truck and he fixed a tonne of ****, the right way.

Al