First hand experience with changing to the NBS master cylinder WOW!

[speedygonzales]

Was tired of the mushy brake pedal. Wife won't even drive it (could be a good thing) it's so bad. Had mentioned that Jeg's has the SSBC 2 piston drop-in calipers on sale. One response was to change the Master Cylinder to the New Body Style.

So I got curious and started researching the change over. Well let's just say it's miraculous. What a difference. I found a post on another website dated July 2012 that got me going and I added some information to what they put together. I would like to throw out this information for anyone out there that is interested in getting rid of the mushy pedal on the cheap. Hopefully they will find it if they are google searching.

The Old Body Style (1988-1999) Chevy/GMC trucks have the most awful brake pedal feel (and grip) of just about anything I've driven. But over the many years I've had it, I got used to it. Killed me when I drove my wife's cars over the years. Being used to this crap and go to stop in her vehicles nearly puts me through the windshield for the first few stops.

Got bored yesterday and found and installed the new MC. This is also referred to as the GMT400 to GMT800 MC swap. The vacuum booster remains behind.

There are 2 things you need. The replacement MC and one brake line adapter. Fluid of course.

The new master cylinder part number is as follows if you don't get one from a junk yard. The guy I copied used a 2002 Tahoe for search purposes. I added a few manufacturers to the list.

NBS Master Cylinder numbers:
GM 19209249
Durastop 18M1159 made by AC Delco
AC Delco 174-1003
NAPA NMC M3432
Cardone 13-2881
Dorman M630031
Fenco NM3089

The lines on the vehicle are 2 different sizes. It has a 9/16-18 at the port located nearest the radiator and 1/2-20 at the rear port closest to the firewall. The new MC is the same 1/2-20 at both ports. So an adapter is needed to allow the 9/16 flared fitting on the vehicle fit the 1/2-20 port on the front of the new MC.
I found the AGS #BLF-26C adapter easier than the others which are also the Edelman #258306 or the Weatherhead #7912

Now here's the new thing I learned about bench bleeding. Over the years we have all encountered some MC's that needed bench bleeding and some that did not. Some would even warn not to bench bleed it. Referring to the method of connecting hoses to the ports and looping them around to the reservoir and the ends are in the fluid. Pumping the piston until the bobbles were gone.

With the Cardone unit I purchased, it did NOT have the bleeder kit and the instructions said to simply fill it up and let it sit until the ports start to drip fluid. The instructions said any MC (I assumed they meant that they sell) that does not have the bleeder kit with it, to do it this way.

So I throw out there that bench bleeding is not always looping the fluid back to the reservoir with tubing. Keep that in mind.

So I connected the tubing to the new MC then bolted it to the booster since the lines are in a different location then the new MC ports. Bled it and viola what a difference.

Bleeding can be very easy if you use a clear catch bottle and be sure the tubing attached to the bleeder is submerged into the drain fluid while you have the bleeder loose. Just wait for the new (clear) fluid to appear and your done with that wheel. I have used the one man vacuum attachment to draw fluid and it stinks cause it always draws air from around the bleeder screw.

Incidentally most brake manufacturers state the best way to bleed them is just let it ooze out the bleeder on it's own. But I'm in a hurry and just get someone to pump it till the clear fluid appears in the catch bottle. Of course if bubbles are there, we keep going till they're gone.

One thing I think I feel is while the brakes grab when the pedal is depressed a much shorter distance than before. They still seem to require the same amount of hard pressure. I'll have to see what happens in the next few days. I hope this information helps anyone searching on google etc... for one method of making our cheesy brakes better.