Bad brakes spongy tried everything 1997 K1500 Z71

[Lightning Performance]

Reading your first post the 100k on the drums sounds about right. My little d21 Nissan still has the original shoes/drums at 120k. But still shouldn’t be spongy. Heck we had the opposite problem with our 90s chevys (s10/cavaliers) if we did aftermarket shoes on them they would grab like crazy at low speeds. Only the rear grabbed though. Didn’t bother us enough to change them though lol.


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Proportion valve was wrong and they sucked on my 83 s10 to. Changed it to over to 1978 Monte carlo proportion valve, problem solved. Worked well up to 130 mph. No more scaring people while city driving with rear wheel lock ups. Stock brakes handled nice. The Inline four cylinder automatic was swapped to a 350/7004R or R4 the second time. It was fast and stopped, well. It need to. The first beast engine swap was a nasty lil 327/350 500+hp 3500 stall. It was just too much for the street without wheel tubs and tires. Blow the tires of at sixty in second gear on a hot sticky night. No contest on cold roads and triple digits, the tires lost that battle. It was cool for for two weeks like that on race gas 11.8-1 compression ratio. The brakes always worked better with that update even with power brakes and that no vacuum signal motor. It idled @ 9 psi vac lol. Had a big Holley to. Guys did it to other small trucks. It just worked.

Road test time with rear brake pinched off at the hose. Maybe get some good feedback, I hope. *f-wording hate daily driver vehicles

 

[Lightning Performance]

No real change in stopping power. They still suck and feel like mush. Must be at the master cylinder or a hung valve in the ABS.

No one seems to have a true fluid diagram of the ABS pump valve body on my truck. I looked on the web. Most listed I found were wrong to my truck but listed as they fit that year. Might just be three different pumps.

 

[rjames]

Sounds Awesome. The best one of these brake systems I ever drove was an late nineties Avalanche. It had high end hardware and double braided hoses. We used to have Gary's son make them hoses. 11,000 burst 4,000 working pressure. Had them on all my snow plows with relief at 800 psi. Bought them for many many toys. Dashitz! Good kind

What is the difference here?
Is this update a bore size diameter change of the master cylinder piston, longer piston stroke or added residual valves?

Not an update, just a better design. Smaller piston, much more line pressure from less pedal travel. The avalanche you drove had the same master as the one I pictured.
You can do all the other junk that's recommended, and I'm not going to say that it's wrong or it won't help, but if you swap out that garbage stock master for the newer one, you'll think you have a different truck.
I've been down all those other roads with the abs bleed, tried a brand new stock master, etc, etc. Night and day difference with the nbs master cylinder.
Wish I would have known about the swap long before I wasted countless hours chasing my tail. My dad has a stock '98, and I drive it once in awhile and it reminds me of how crappy my truck used to stop.

 

[Lightning Performance]

Not an update, just a better design. Smaller piston, much more line pressure from less pedal travel. The avalanche you drove had the same master as the one I pictured.
You can do all the other junk that's recommended, and I'm not going to say that it's wrong or it won't help, but if you swap out that garbage stock master for the newer one, you'll think you have a different truck.
I've been down all those other roads with the abs bleed, tried a brand new stock master, etc, etc. Night and day difference with the nbs master cylinder.
Wish I would have known about the swap long before I wasted countless hours chasing my tail. My dad has a stock '98, and I drive it once in awhile and it reminds me of how crappy my truck used to stop.

.
Going to be plugging the rear feed to be sure. Next location is the front frame connection to the vertical line at the firewall. My new line connects right there at a union. One frame clamp and then straight up to the ABS. I don't like those vertical hoops coming off the master cylinder. Just don't get why they did that.

I consider my moms 95' Tahoe K1500 a death trap when it comes to braking or handling. She likes it. My dads 95' Silverado pu with a cap and *s-word in it ain't much better. They all suck at stopping caused by poor rear pressure apparently. I test drove enough customers suvs and pu's at a guys body shop to know it ain't just mine.

 

[rjames]

Holy hell. Good luck, I'm out.

 

[Lightning Performance]

Holy hell. Good luck, I'm out.

Your fix is my best option. Thanks.

 

[Dub11]

Your fix is my best option. Thanks.

You are going with the new style master cylinder?

 

[Lightning Performance]

You are going with the new style master cylinder?

Yes. Hope to get one soon.


Looks like he got pretty pissed at me goofing off. Shame, got nothing else to do but laugh and enjoy when something goes my way.Was just blabbing out loud with the talk to text on while eating. Wish I had time to keep up here with the threads.

Thanks y'all for the help! Now enjoy your train