NBS master cylinder Swap

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scott_williams2

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So I know this maybe an old topic but I hope this will help people who haven’t heard of the swap. Anyways, for those who haven’t, DO IT. It’s literally night and day. I used to have to push the old spongy brakes to the floor and it took forever to stop. Now it is a lot more firm and brakes with half as much travel. The swap is fairly straightforward. All you need is a 99-06 master cylinder( I used a 01) a AGS BLF 26C brakeline adaptor, and a bench bleed brake kit( my MC came with one). It takes maybe 30 minutes and 2 people. Best bang for you buck you can get on these old trucks. The whole swap cost me maybe $120 at the most
 

scott_williams2

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These are some pics of the parts needed
 

kennythewelder

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There are a ton of threads about this already on here. I did mine years ago, and yes it is a good swap, if you have JB5 brake setup, and most 1/2 trucks do.
 

kennythewelder

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Just type in the search bar, master cylinder swap, and threads will pop up
 

L31MaxExpress

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DON'T DO IT!!! It is NOT a good swap. Without changing the booster you will LOSE stopping power in a panic stop. Tried it years ago and in a panic stop I ended up putting both feet on the pedal and was standing on it, all 275 lbs of me at the time up on the pedal and braking power was still not nearly as good as the stock master. Was not good at all. Swapped to hydroboost and a 1-ton master with the hydroboost brake pedal arm. Way better setup. Swapping the NBS master onto the stock booster is a great way to rear-end another vehicle in a true emergency stop from speed.
 

kennythewelder

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There are people here that will agree with L31Max. I will say this. It has dine nothing but help my truck. In no way have I lost any stopping power at any braking. It firmed up my p brake peddle and gave the truck better stopping power at all peddle pressures. The only thing I changed was the MC. Like I said before, I have JB5 brakes. Maybe this swap is not as effective on other brake systems, but it did help my JB5 system a lot. I do drive fast and hard, and brake the same way a lot. If you dont like the swap, you can always go back to what you had. As for me, I am happy with the swap.
 

L31MaxExpress

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There are people here that will agree with L31Max. I will say this. It has dine nothing but help my truck. In no way have I lost any stopping power at any braking. It firmed up my p brake peddle and gave the truck better stopping power at all peddle pressures. The only thing I changed was the MC. Like I said before, I have JB5 brakes. Maybe this swap is not as effective on other brake systems, but it did help my JB5 system a lot. I do drive fast and hard, and brake the same way a lot. If you dont like the swap, you can always go back to what you had. As for me, I am happy with the swap.
Probably doesn't help that my Express conversion van is probably a good 1,200 lbs heavier than your truck and had the same braking system. I also drive fast. Never done it in a truck but in the Van it was terrible. The hydroboost was also a very simple bolt-in swap and was night and day difference in both pedal feel and stopping power. Kicked the ABS in on a dry road at 70 mph after swapping to hydroboost with only moderate pedal pressure practically planting my face into the steering wheel. Swapped to hydroboost and 1 ton master. Had already swapped the front calipers out for single rear wheel 8800 GVW 1 ton calipers like GM put on the Police Tahoes and Tahoe Limiteds. The hydroboost swap can be done fairly inexpensively. Hardest part to find and swap is the brake pedal arm. Weirdest thing to get normal in your mind with the hydroboost is with the power steering fluid operating the booster, it feels and sounds like you are stepping on a garden hose that is at full blast when you put your foot on the brakes. Same feeling gets transmitted into the pedal. Another good thing about hydroboost is it really changes what cam you can run. Can run a cam with 12 in/hg vacuum and still have great brake assist. Drove my 383 for nearly a year with a choppy idle Lunati Bootlegger 232/244 @ 0.050 cam cut on a 108 LSA and zero change in brake assist.
 
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kennythewelder

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Probably doesn't help that my Express conversion van is probably a good 1,200 lbs heavier than your truck and had the same braking system. I also drive fast. Never done it in a truck but in the Van it was terrible. The hydroboost was also a very simple bolt-in swap and was night and day difference in both pedal feel and stopping power. Kicked the ABS in on a dry road at 70 mph after swapping to hydroboost with only moderate pedal pressure practically planting my face into the steering wheel. Swapped to hydroboost and 1 ton master. Had already swapped the front calipers out for single rear wheel 8800 GVW 1 ton calipers like GM put on the Police Tahoes and Tahoe Limiteds. The hydroboost swap can be done fairly inexpensively. Hardest part to find and swap is the brake pedal arm.
Oh, I dont disagree, with a hydroboost swap. And like you said, your van is heavier than my truck. For a 1/2 ton truck, with JB5 brakes, the NBS MC swap is an improvement over the OE MC. Thats all Im saying. There are a ton of things that can be done to improve stopping power. A 4 piston caliper swap is a huge improvement. Bigger rotors a big help as well. But you know all of this already.
 

L31MaxExpress

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Oh, I dont disagree, with a hydroboost swap. And like you said, your van is heavier than my truck. For a 1/2 ton truck, with JB5 brakes, the NBS MC swap is an improvement over the OE MC. Thats all Im saying. There are a ton of things that can be done to improve stopping power. A 4 piston caliper swap is a huge improvement. Bigger rotors a big help as well. But you know all of this already.
Yes sir I do. Did the bigger brake swap when I swapped to the 1-ton running gear. Really wish I had taken the time to find an 03+ rear end for it with factory discs though. The GMT400 C3500HD had hydroboost and a large piston master cylinder for 4 wheel discs that uses a factory adapter between the booster and master. As it sits currently I have DRW 3500 front calipers, 01-02 G3500 front rotors that are 39.1mm thick, and 1-ton rear drums with hydroboost and the 01-02 Express 3500 master cylinder. Stops way better especially towing.
 

jjester6000

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So I know this maybe an old topic but I hope this will help people who haven’t heard of the swap. Anyways, for those who haven’t, DO IT. It’s literally night and day. I used to have to push the old spongy brakes to the floor and it took forever to stop. Now it is a lot more firm and brakes with half as much travel. The swap is fairly straightforward. All you need is a 99-06 master cylinder( I used a 01) a AGS BLF 26C brakeline adaptor, and a bench bleed brake kit( my MC came with one). It takes maybe 30 minutes and 2 people. Best bang for you buck you can get on these old trucks. The whole swap cost me maybe $120 at the most

$120?

You can do it much cheaper than that.

Try $12.

I went to my local junkyard and got a used master cylinder for $8 (every wednesday is 1/2 off) and picked up the adapter fitting for around $3. I already had brake fluid so it was all good.

I also cut the lines when I removed the cylinder, so I was able to use them to bench bleed it in the truck.

It's a night and day difference, and everyone should do it.

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