OBS to NBS MC upgrade questions

[Conspiracy]

I got ambitious today and decided to finally “upgrade” the OBS to NBS MC.

Thing I didn’t think about: I have a hydro boost 2500 and I’m pretty sure I stole the MC from a hydro boost 1500. When I tried to put things back together I realized the NBS MC would not fit.

Before putting the old MC back in, is there anything I can do to continue w the swap or should I just reinstall.

Did I just earn myself bleeding/air headaches for no reason?

 

[Alteca]

You needed an “upgrade” from hydroboost? It does need bled after you put it back together. Take the chance to bench bleed the master and flush all the old fluid while bleeding.

 

[Conspiracy]

You needed an “upgrade” from hydroboost? It does need bled after you put it back together. Take the chance to bench bleed the master and flush all the old fluid while bleeding.

Ya, the brakes aren’t great but I don’t have a lot to compare against. This is my first 2500 OBS. I’m doing new lines, rotors, shoes in the coming weeks and had this NBS MC sitting here so figured I’d swap it while doing power steering lines.

So it’s with emptying the old MC and refilling while doing bench bleed even though I’ll be doing front and rear brakes soon?

 

[Alteca]

If your old master hasn’t been drained then you won’t need to bench bleed but you will most likely still be adding some new fluid while bleeding even if you don’t completely flush the system. Flushing could wait until you do brakes. are you able to do everything at once? I would imagine if your pedal didn’t feel good it was due to air in the lines.

 

[Schurkey]

WHAT VEHICLE???

What is wrong with the brakes that you're hoping to "fix" with the "NBS" master cylinder?

The "NBS" master cylinder is a dogshit "upgrade" to begin with. Either folks are replacing a step-bore 3-chamber Quick Take-Up master with a two-chamber non-Quick Take-Up master having larger diameter primary and secondary pistons, or they're replacing a two-chamber master with another two chamber master having larger primary and secondary pistons.

Either way, pedal effort goes up, goes WAY up if the booster fails--enough to be a safety hazard. And WAY, WAY up if they replaced a Quick Take-Up master.

In short, there's nothing to be gained with the "NBS" master cylinder except headaches and heartaches. AT BEST, it covers-up other faults in the brake system. At worst, it gets people killed when the pedal effort goes way up and they can't push the pedal hard enough for an emergency stop.

FIX WHATEVER IS REALLY WRONG WITH YOUR BRAKES instead of cramming an incorrect master cylinder into place.

At minimum, you'll need to bench-bleed the master cylinder you end-up using--the original, or a PROPER replacement. And then you're going to need to flush the brake fluid including the ABS--which will require a scan tool.

 

[Conspiracy]

WHAT VEHICLE???

What is wrong with the brakes that you're hoping to "fix" with the "NBS" master cylinder?

The "NBS" master cylinder is a dogshit "upgrade" to begin with. Either folks are replacing a step-bore 3-chamber Quick Take-Up master with a two-chamber non-Quick Take-Up master having larger diameter primary and secondary pistons, or they're replacing a two-chamber master with another two chamber master having larger primary and secondary pistons.

Either way, pedal effort goes up, goes WAY up if the booster fails--enough to be a safety hazard. And WAY, WAY up if they replaced a Quick Take-Up master.

In short, there's nothing to be gained with the "NBS" master cylinder except headaches and heartaches. AT BEST, it covers-up other faults in the brake system. At worst, it gets people killed when the pedal effort goes way up and they can't push the pedal hard enough for an emergency stop.

FIX WHATEVER IS REALLY WRONG WITH YOUR BRAKES instead of cramming an incorrect master cylinder into place.

At minimum, you'll need to bench-bleed the master cylinder you end-up using--the original, or a PROPER replacement. And then you're going to need to flush the brake fluid including the ABS--which will require a scan tool.

99 Suburban 2500 2wd

Again, I don’t have anything to compare against but it seemed the brakes could be better. Yes, I know it’s a big heavy vehicle and mostly I use it when towing so it’s going to feel a lot different than my Prius…I guess I was looking for an easy upgrade. Turns out maybe it’s not that great (usually the case with “east” upgrades)

Would I need the scan tool even if I hadn’t removed the MC? I have someone coming to replace pads/rotors and shoes soon but don’t have a scan tool, not sure if they do but I’m guessing maybe no

Buying new parts is tricky because it seems there are SO MANY ways to go about it. Searching “99 suburban 2500 brakes” yields an entire internet of info.

I ended up buying the slightly larger wheel cylinders, the 13x3.5 shoes, and a raybestos element 3 kit for the front. Not sure if I need to buy new drums

Rotors 370H56263E3
Cylinders WC37337
Pads EHT370H
Shoes 452PG

 

[1998_K1500_Sub]

99 Suburban 2500 2wd

What brakes are on that 2500, JB7? Those are about as good as it gets, esp. with hydroboost.

The guys with the JB5/JB6 brakes often suffer, for a variety of reasons.

 

[Conspiracy]

What brakes are on that 2500, JB7? Those are about as good as it gets, esp. with hydroboost.

The guys with the JB5/JB6 brakes often suffer, for a variety of reasons.

Code in the glovebox says JD7

 

[Caman96]

Was there any issue before you messed with your JD7 brakes?

 

[1998_K1500_Sub]

Code in the glovebox says JD7

Yes, JD7 is basically JB7 with hydroboost added.

Yup, that p/n for the wheel cylinders is for the 1.1875" ones, the "big" ones.

You might want to confirm someone hasn't put the wrong calipers on the front, the piston diameter should measure ~3.15" or greater, and be the same on both sides.

If the piston diameter is 3" or under, the wrong calipers are installed... and yes, it'll brake poorly for multiple reasons.

I'm not saying it's likely, but it could happen.

You bought the "370" pads, and those would be an awkward fit on the smaller calipers, if they fit at all, so that would be a telltale.