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

[Geomarq123]

Found this thread as I was swapping the rear discs on my 97 k1500. Then did the master cylinder, and figured I'd change to the right combination valve. Now I'm stuck, can someone help?

How can I plumb the new combination valve into the abs unit? The diagram shows what I have..the combination valve bolts and directly takes fluid in and the abs unit has three valves out...two valves for the front, one rear. The correct disc/disc combination valve has two ports in three out. The old is two in, two out. I've never liked the abs on this truck..should I discard? What's the proper way to disable the Abs?

[speedygonzales]

This issue should have it's own thread. People are going to come here looking for changing the master cylinder information.

Repost it as a new post.

[hatzie]

Originally Posted by speedygonzales

Yep just don't let the reservoir get too low.

Oh and always buy new fluid and if there is any fluid left over in the bottle, toss it. Don't keep it laying around. It draws moisture right through the plastic container sides.

Metal cans won't but try finding brake fluid in metal cans.

Metal cans is the only way I buy it. Who knows how long the plastic bottles have been hanging around at the warehouse... Just say no to brake fluid in plastic bottles. Plastic bottles with foil lined caps and vacuum deposition metallized insides would probably do the job but they are trying to wring the last 1/8th penny of profit from any sales.

Brake Fluid I can buy locally in metal cans...

Pentosin DOT4 I can get both Super DOT4 and low viscosity DOT4 LV locally at Bond Auto Parts. DOT4 LV is a 1-2 day turnaround to order it in Super DOT4 is on the shelf. I believe Pentosin is available on-the-shelf at AutoZone for you folks in the city.


ATE DOT4 Type 200 and SL-6 are not as common to find on the shelf but the local NAPA franchise can and will get me the low viscosity SL-6, that I run in my LS4 Impala and VW, in 2-3 days. I have no problem stocking several metal cans because it keeps. They have several local folks with MGB and other semi-antique British cars that use this stuff too.

[satisfied]

I have a 96 C1500 Burb. Will the switch out using the MC 2002 Siverado with rear disc brakes be compatible with my truck with rear drum brakes?

[speedygonzales]

If it looks like this:


Then yes

Incidentally mine is shot already

[Keith Seymore]

Originally Posted by satisfied

I have a 96 C1500 Burb. Will the switch out using the MC 2002 Siverado with rear disc brakes be compatible with my truck with rear drum brakes?

I would say no.

If you have disc/drum brakes then you need a disc/drum master cylinder. I wouldn't think a disc/disc master would have the right design considerations for your setup.

K

[satisfied]

Speedygonzales,

Is your NBS MS already shot? A 1999 would have drum brakes as well.

[speedygonzales]

fluid leaking past the seals. It's been suggested the lines have to be reversed, will try that this weekend with a replacement unit.

[68C15]

Originally Posted by speedygonzales

fluid leaking past the seals. It's been suggested the lines have to be reversed, will try that this weekend with a replacement unit.

I'll be watching for your update. I don't have a newer truck in the shop otherwise I'd follow the lines and see which is which

[speedygonzales]

I looked for any published indication that the ports were reversed on the GMT800 MC. Could not find any.

The reservoirs both old and new seem to have bigger portions on the front. Even if they don't it makes no difference. I did not reverse the lines.

Still crappy brakes compared to everything else on the road but better then it was when it had the original MC.

[Eman85]

I've read thru this thread as a fix for my Chevy truck. I was a GM tech from the 70's up until these trucks were new. They always had the soft pedal from day.
The original MC had a step bore so it did make a difference how the lines were attached, plus since you had frt. disc only the reservoir for the frt. is larger. the reason for this is that disc brakes are self adjusting in the the piston moves out as the pad wears and the space is taken up by fluid. On a straight bore MC the only difference in ports would be if you had a MC from a frt. disc vehicle. The NBS MC is for a disc/disc vehicle so it doesn't matter how you connect the lines.

[SquareOne]

I did the NBS upgrade this afternoon after the drum brake wheel cylinders failed and I had to replace those and bleed the system anyway.

WOW! Night and Day. If you're on the fence, you're wasting your time. This is one of the easiest and quickest upgrades you can do.

I got lucky and I got the MC from a friend who was doing a hydroboost conversion on his 2001 NBS, so it didn't cost me a thing. I know that there is a piece of mind that comes with buying one new but I never hear about stock MCs failing that often so I decided to err on the side of saving money and we with the used unit.

The pedal feel and response is significantly better than the original equipment. I feel it now brakes just as good if not better than the wife's 2015 sedan.

[SquareOne]

I did the NBS upgrade this afternoon after the drum brake wheel cylinders failed and I had to replace those and bleed the system anyway.

WOW! Night and Day. If you're on the fence, you're wasting your time. This is one of the easiest and quickest upgrades you can do.

I got lucky and I got the MC from a friend who was doing a hydroboost conversion on his 2001 NBS, so it didn't cost me a thing. I know that there is a piece of mind that comes with buying one new but I never hear about stock MCs failing that often so I decided to err on the side of saving money and we with the used unit.

The pedal feel and response is significantly better than the original equipment. I feel it now brakes just as good if not better than the wife's 2015 sedan.

[mountie]

Square One is a perfect example why us truck owners are here....

To make our cool trucks better!

I did the MC upgrade 2 years ago, because I learned it here.

[speedygonzales]

All of this is a waste of time.

Trust me I started this thread. In addition to changing the master cylinder I also changed my front calipers to 2 piston and rotors to slotted type.

None of this works as well as the way the brakes should be from the factory. But I'll tell you what does! I just came in from doing it.

It's called the "automated bleed procedure".

I was poking around a few threads mentioning that nothing works until people did this. Some even said most GM's are this way. Without it you're wasting your time.

But what the hell does bleeding the ABS have to do with the normal brake operation. I"m sure I'm not the only one that said that and did normal brake bleeding procedure. I don't know and was skeptical until I did it.

See my new post for a little more information.

[mountie]

I'll gladly check that out.

[Vintage Windmills]

Getting ready to do this and a couple things are bugging me.

1) Everyone buys a NBS MC with application for a truck with rear disc brakes. All GMT400's had rear drums. Does it not matter?

2) Anyone done this on a truck with rear ABS only (94 down)? There is hardly any length of line between the ABS setup and the MC on the older trucks. The 95 up have the ABS stuff a ways from the MC on the fender so that makes things easier. All pics I've seen are 95 up.

Thanks in advance.

[Tom]

Originally Posted by Vintage Windmills

Getting ready to do this and a couple things are bugging me.

1) Everyone buys a NBS MC with application for a truck with rear disc brakes. All GMT400's had rear drums. Does it not matter?

That's been answered many times in this thread. The vast majority of people doing this are not doing rear disk brake swaps along with it. Its works great.

[arrg]

Originally Posted by Vintage Windmills

Getting ready to do this and a couple things are bugging me.

1) Everyone buys a NBS MC with application for a truck with rear disc brakes. All GMT400's had rear drums. Does it not matter?

2) Anyone done this on a truck with rear ABS only (94 down)? There is hardly any length of line between the ABS setup and the MC on the older trucks. The 95 up have the ABS stuff a ways from the MC on the fender so that makes things easier. All pics I've seen are 95 up.

Thanks in advance.

I did it on my 1988. It was a royal pain to bend the short lines. They didn't turn out very straight and I really had to tighten them down more than I should have to get them to stop leaking. I will likely replace them with some Nicopp line at some point because I don't like how they turned out.

[hb32]

Accomplished this today as well and do not notice a huge difference. Lots of dark fluid on the bleed and reservoir on the old mc was really dirty. Going to wait a week and try another bleed. Thanks to the op for the part numbers and tutorial.

[speedygonzales]

Do the automatic bleed process. Best 3 minutes time spent every time.

[hb32]

Originally Posted by speedygonzales

Do the automatic bleed process. Best 3 minutes time spent every time.

Spent an hour searching for the “ automatic bleed process “ and could not find it.

[hatzie]

Originally Posted by hb32

Spent an hour searching for the “ automatic bleed process “ and could not find it.

http://www.youtube.com/watch?v=XsaJ6lkWu7c

[hb32]

Originally Posted by hatzie

http://www.youtube.com/watch?v=XsaJ6lkWu7c

Thanks for the info. Unfortunately I don’t have a scanner so looking at alternative methods. I just took it for a drive and it is noticeably different then yesterday, after slamming on the brakes to activate the ABS. Will try that a couple more times and bleed again.

[hatzie]

If you want to do an auto bleed that's the way it's done.

A Tech2 clone is $259. I own one. They work.
GM VXDiag is around $110 and it comes with Tech2Win and TIS2000. You need a Windows laptop to go this route and those aren't free. The NAO 33.004 Tech2 BIN file is available on the Tech2 Wiki if it's not shipped with the VXDiag tool.

The Snap On Solus tools can be had used for just under a grand.
AutoEnginuity can do it as well but you need a laptop and the cost is right around $500.
There are probably a handful of other tools in the $500 on up range that can do it on some but not all ABS systems.

The nice thing about the T800 master cylinder is the round three tab cap that takes one of the leak free pressure bleeder adapters...
Motive 1107

SPX Kent Moore J-35589-A