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

[speedygonzales]

Change out the MC
Bleed as required
Start a new thread

[Kudzupatch]

FYI Tried this on a 1993 Suburban with the large 4 wheel anti-lock module and it would require pretty serious line bending. I think it would ended up crimping the line. I think it would be simpler to just make new lines between the proportioning valve and the MC.

My MC gave up and I had to replace it so I can go a trip. So I went back with a replacement unit. Will look at this latter when I have time.

[JTWard]

Originally Posted by Kudzupatch

FYI Tried this on a 1993 Suburban with the large 4 wheel anti-lock module and it would require pretty serious line bending. I think it would ended up crimping the line. I think it would be simpler to just make new lines between the proportioning valve and the MC.

My MC gave up and I had to replace it so I can go a trip. So I went back with a replacement unit. Will look at this latter when I have time.

Thank you, Prior experience is exactly what I need !

[green_grenade]

I am doing the NBS MC swap this weekend. It looks fairly easy. I am hoping it looks as easy as everyone says it is. Can't wait to see if this actually helps on this truck.

How do I find out for sure if I have the light duty 3/4 ton? Mine is a 89 and has the 2500 side moldings, but when I run the codes in the glove box I don't have a F44. Mine is a 6 lug also.

[Tom]

Look at the GVW on the door plate.

[BigRed76]

Originally Posted by green_grenade

I am doing the NBS MC swap this weekend. It looks fairly easy. I am hoping it looks as easy as everyone says it is. Can't wait to see if this actually helps on this truck.

How do I find out for sure if I have the light duty 3/4 ton? Mine is a 89 and has the 2500 side moldings, but when I run the codes in the glove box I don't have a F44. Mine is a 6 lug also.

Light duty 3/4 ton will have a 7200 GVW.

[green_grenade]

Originally Posted by BigRed76

Light duty 3/4 ton will have a 7200 GVW.

Thank you very much. That is exactly what mine says 7200 GVW.

[cmcolfax]

Bumping this thread for reference as my 96 K1500 Burb is going under the knife for significant brake, steering and suspension upgrades in a coupla weeks.

Looks like I am gonna pick up a NBS MC...

[VentureRick]

WOW, I just did the swap on my 95 K1500 Suburban and this thing has never had brake's this good, I can't believe the difference.

[54 jimmy]

night and day difference. now towing trailer will be a lot more safe.

[ScoobyJD]

Originally Posted by Red88

I am following everything you said in this post, however I have a question. Can I just run the lines in a 90 degree bend to ports closest to each other? Only reason I ask is I couldnt get my lines to stretch without messing them up. The only thing I dont know is if the front and rear port of the master put out the same pressure and volume.

[OutlawDrifter]

speedy, did you ever swap lines to see if it made any difference?

[speedygonzales]

No I completely forgot. Man I don't know if I want to have to bleed the thing all over again. I'll post up if I do it.

[OutlawDrifter]

no worries, i've got to put some new wheel cylinders on my pickup, so i'm going to do the mc at the same time. just thought i would see if you ever tried it!

[z71se]

Hey guys I just got done with the GMT800 MC swap and I also took the opportunity to install 02 knuckles and rotors/ calipers (to fit under my stock 16" Alcoa wheels). New drums, shoes, and stock replacement wheel cylinders out back. The dead spot does seem reduced, but I'm not 100% sure the braking significantly improved. As others have stated, the GMT800 MC has a smaller bore size so you have to push harder on the pedal even though the pedal is firmer. Anyways, I'm still not satisfied with the brakes even after all this work (reaming the GMT800 knuckles was kinda a pita). Am I correct that converting to hydroboost is my last option? I wish there was a GMT800 master cylinder that had a slightly larger bore size. My truck is a 2000 Z71 Tahoe (old body style).

[Chris95GT]

I've done this swap on my GMT400 99 3/4 ton, it was simple and I noticed an improved pedal feel and quite a bit better panic stop feeling. Houston traffic sucks. Before, during a panic stop I felt like the pedal was darn near bottomed out and I wasn't going to stop in time, the few panic stops I've done since the swap felt much much safer. I'm very happy with the GMT800 Master so far, my only regret is not doing it sooner. (I had it sitting around for 2+ years before finally doing it)

Next step for me is GMT800 Front and rear disk swap with stock GMT800 calipers, disks, and pads, but I still need to get and modify GMT800 knuckles to fit my truck, and get new tires for my 6 lug wheels (I'll be going from 8 lug to 6 lug)

[z71se]

Originally Posted by Chris95GT

I've done this swap on my GMT400 99 3/4 ton, it was simple and I noticed an improved pedal feel and quite a bit better panic stop feeling. Houston traffic sucks. Before, during a panic stop I felt like the pedal was darn near bottomed out and I wasn't going to stop in time, the few panic stops I've done since the swap felt much much safer. I'm very happy with the GMT800 Master so far, my only regret is not doing it sooner. (I had it sitting around for 2+ years before finally doing it)

Next step for me is GMT800 Front and rear disk swap with stock GMT800 calipers, disks, and pads, but I still need to get and modify GMT800 knuckles to fit my truck, and get new tires for my 6 lug wheels (I'll be going from 8 lug to 6 lug)

You'll want to convert to hydroboost at that point... I would not have converted to the GMT800 fronts had I known they would feel this way (I installed the GMT800 mc at the same time). Yes, the dead spot is gone but the pedal effort required to stop the truck is 25% greater (due to the larger bore size of the GMT800 master) so braking confidence is not significantly improved, if at all. I will be converting to GMT400 hydroboost shortly.

[z71se]

Also - reaming out the GMT800 knuckles is a huge PITA! If you would like to use my tool (I only used once), let me know and you can borrow it! I also have some tips on how to make the reaming easiest... you'll want to use an air ratchet with the knuckle mounted in a vice. Get an old or new GMT400 upper and lower balljoint handy to test fit as you go along. Both the upper and lower balljoint holes will need reaming. The reaming tool in a socket in conjunction with the air ratchet was definitely the best method I found...

[Brandon_Lutz]

Sorry to drag this thread back up, so please forgive me. I've searched many threads on many forums about this swap and I'm still getting kind of confused on which MC I should be looking at.

I have a 95 K2500 with the 5.7. I'd like to do this swap on my truck but I'm not sure with NBS Master Cylinder should I be looking at to to replace it. I'm not looking to go to hydro-boost and I plan on keeping the setup as it currently is, vacuum assisted.

I've found conflicting issues in various places on whether I should get a 1500 4x4 Master Cylinder from an NBS as the 3/4 ton trucks and up were hydro boost on some models. Or I should look into a 2500 master cylinder. Can anyone tell me definitively which one I should look into getting?

[Chris95GT]

Originally Posted by Brandon_Lutz

Sorry to drag this thread back up, so please forgive me. I've searched many threads on many forums about this swap and I'm still getting kind of confused on which MC I should be looking at.

I have a 95 K2500 with the 5.7. I'd like to do this swap on my truck but I'm not sure with NBS Master Cylinder should I be looking at to to replace it. I'm not looking to go to hydro-boost and I plan on keeping the setup as it currently is, vacuum assisted.

I've found conflicting issues in various places on whether I should get a 1500 4x4 Master Cylinder from an NBS as the 3/4 ton trucks and up were hydro boost on some models. Or I should look into a 2500 master cylinder. Can anyone tell me definitively which one I should look into getting?

My truck is a true 3/4 ton 8600GVW 99 GMT400 truck. I went with the MC from a 2003 K1500 Avalanche (Just because it's what I had from another project). It's worked great for me so far. I don't know if there was a difference between the 1/2 ton and 3/4 ton vacuum master cylinders in the GMT800 platform, but I'm using a half ton unit on my 3/4 ton and love it.

[z71se]

Originally Posted by Brandon_Lutz

Sorry to drag this thread back up, so please forgive me. I've searched many threads on many forums about this swap and I'm still getting kind of confused on which MC I should be looking at.

I have a 95 K2500 with the 5.7. I'd like to do this swap on my truck but I'm not sure with NBS Master Cylinder should I be looking at to to replace it. I'm not looking to go to hydro-boost and I plan on keeping the setup as it currently is, vacuum assisted.

I've found conflicting issues in various places on whether I should get a 1500 4x4 Master Cylinder from an NBS as the 3/4 ton trucks and up were hydro boost on some models. Or I should look into a 2500 master cylinder. Can anyone tell me definitively which one I should look into getting?

You want the NBS 1500 master cylinder from a 1999-2002 Silverado. Dorman part # M630031.

[speedygonzales]

Originally Posted by Brandon_Lutz

Sorry to drag this thread back up, so please forgive me. I've searched many threads on many forums about this swap and I'm still getting kind of confused on which MC I should be looking at.

I have a 95 K2500 with the 5.7. I'd like to do this swap on my truck but I'm not sure with NBS Master Cylinder should I be looking at to to replace it. I'm not looking to go to hydro-boost and I plan on keeping the setup as it currently is, vacuum assisted.

I've found conflicting issues in various places on whether I should get a 1500 4x4 Master Cylinder from an NBS as the 3/4 ton trucks and up were hydro boost on some models. Or I should look into a 2500 master cylinder. Can anyone tell me definitively which one I should look into getting?

See this

Originally Posted by 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

Originally Posted by speedygonzales

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

Go back to the first page for instructions because the lines are different sizes

[Brandon_Lutz]

Thank you all who responded. You guys rock

[jcramsey]

Gotta put this on the to-do list!

[54 jimmy]

I used a 2500 nbc on my 97 1500. no issues. I think the 2500 mc is the better option. I have better pedal feel in normal driving and panic stops. as far as the pressure feel of the pedal it is not hard to get it to stop. my wife loves how the brakes feel because they use to scare her before but now she feels much safer driving the truck. not good for me because now she wants to drive the truck. gotta take the good with the bad .