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.

[jb1016]

Good info as always Speedy. Thanks, this definitely makes me want to try this! I've gotten used to it, but if I let somebody else drive my truck, they always remark on how weak the brakes feel.

[speedygonzales]

Best $75 I ever spent on this truck. I went from researching the swap at 11 am to done by 3 pm and had to go to 2 different stores to get the MC at one and the adapter at the other.

I highly rec this change. I want the wife to try it and see what she thinks.

I don't recommend the junk yard for this purchase. The new ones are cheap enough. Next for me is slotted rotors and 2 piston calipers. AND the proper bedding procedure. That to me is paramount.

[TennesseeZ]

Thanks Speedy, for writing the definitive guide on this swap. I just checked Rock auto and got a couple questions. I looked up a MC for a 2000 GMC Yukon, 5.7. They don't show the same Cardone part number you have, and they list 2 different Cardone MC's, one for the Police Package, one without. What would you suggest ordering? I first tried a sitewide search for the Cardone # you posted, it came back "no matches found." Do you think the police package one would fit and be a good choice? Here's a link

[Tom]

Police package is most likely a hydroboost unit

[jb1016]

TNZ: If a 2000 Yukon had a 5.7, it would have been old body style. There were still some built that year, I think. (Although I think they would have all been Denalis; I think only Tahoes got the Z56 police pkg.) Bottom line: Anything in the new body style would be 4.8 or 5.3.

[TennesseeZ]

Thanks guys, I didn't think of that. I'll check for a 2002 or something. Thanks again!

[speedygonzales]

I neglected to say that this change is for non-hydroboosted vehicles. Any old body styles will benefit from the numbers I provided.

The pickups were old body combined with new body style in 99 (made both body styles). The SUVs went on later after that. But as stated above, anything with the old Vortec 5.7L were old body style.

When looking for NBS, stick with the 2002 Tahoe or later.

[Keith Seymore]

Thanks for posting; I've hated the brake pedal feel in my '97 Suburban ever since I got it.

I'll take a shot at this as soon as I get home from vacation.

Subscribing -

K

[James Hart]

Thanks for the part numbers... I have this planned on my 93 later this year.

[speedygonzales]

Just wanted to clarify for those not sure what we are referring to.

If you have one of these:
crappy master cylinder
replace it with one listed above that looks like this
good replacement

[Mr_Rich]

Judging by the pics you've posted on #11 it looks to me like the NBS master cyl. is a larger diameter which will push more fluid. My braking is already improved by a rear disk conversion, but this NBS master cyl. may improve on that.

[Tom]

Originally Posted by Mr_Rich

Judging by the pics you've posted on #11 it looks to me like the NBS master cyl. is a larger diameter which will push more fluid.

Exactly the opposite. NBS is smaller piston. Nothing from GM was bigger then the OBS master.

[Dobok]

My buddys 93 has this one already so I don't get it. Maybe somebody changed it before he got it !!!

[OrangeAnimal]

Hum, I may try this out cause I am tired of the crappy pedal feel. Even after replacing just about everything I never thought of trying this.

Thanks for organizing the info in one place Speedy.

[speedygonzales]

I guarantee there is no way to get a better pedal feeling than this $75 job. Front calipers, rear caliper change over, none of them will beat this simple change.

Incidentally, Advance Auto gives you a discount if you place the order on line and pick up the part at the store. I got $10 off the Cardone MC that was in stock at my local store.

My wife hated driving it, said it scared her if she had to do a panic stop. Not any more. She loves it.

[Keith Seymore]

Just popping back in to say I did the brake cylinder swap - and I love it.

Took about 4 minutes to do, once I had everything on hand and ready to go. Bench bleed the m/c via gravity bleed, as recommended here and by the supplier. Slammed it on the truck and bled the system and took if for a drive. Night and day difference.

My truck needed friction material front and rear, so I replaced that and adjusted the rears up while I was at it. Should be good for a long time now.

What I would like to attack next is the steering on my truck (over boosted, poor on center feel, no returnability). I'll be starting a separate thread for that, looking for a similar amount of success. Be on the lookout for that new thread if you are interested or have suggestions.

K

[95 Silv]

I did this today! Had uneven front pad wear due to a bad front, left caliper and was the perfect chance to do this while I was at it. Thanks Speedy for the write up process with part #'s. Made finding the right parts so much easier. Definitely feel the pedal difference but like you still have to press hard. Might bleed again just to be sure but really impressed with this mod.

[95 S_Trucker]

Does anybody know what master cyl. to use on a hydroboost truck? I would love to do something like this on my 99.

[Tom]

Originally Posted by 95 S_Trucker

Does anybody know what master cyl. to use on a hydroboost truck? I would love to do something like this on my 99.

If you have hydroboost then there is nothing to be done, you already have as firm a brake pedal as you can get. If people do this MC swap and still don't like the feel then hydroboost is the last option to try, and your already there.

[speedygonzales]

couldn't resist. These were bought on a steal from Summit. I couldn't resist. With the slotted rotors. Hot damn.

[burkey05]

found this on the summit website

looks like SSBC might read this forum too. lol

http://www.summitracing.com/parts/ss...mc/model/c1500

[Keith Seymore]

Originally Posted by burkey05

found this on the summit website

looks like SSBC might read this forum too. lol

http://www.summitracing.com/parts/ss...mc/model/c1500

$223? Ouch!

I think I paid around $70 for mine.

K

[speedygonzales]

Screw SSBC for $220 I got mine at Advance for $75. Don't forget, if you pay online then pick up the item at the store, you save. I saved $10 on my MC.

[t_graham11]

I did some searching and the new cylinder is 1.8" and the original is 1.6" so you'll have to bore out the .2" on hydro boosted trucks. Some guys have said they did it them selfs but I'm going to buy a new hydro boost and get the machine ship to bore it out for me.

I ha a leaky slave cylinder and my pedal went dead changed it and then just yesterday I had zero pedal again and was standing on the brakes when I pulled into my house, luckily I just rubbed the wheel against the retaining wall rather than through my carport. My brake fluid is really dirty, I heard that was because the MC seals were rotten. I'm pretty excited to have a firm pedal again
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