New Master Cylinder - Recomendation

[jeff in co]

89' V1500 Blazer. Called Dealer and they said my replacement part number (18013435) is discontinued. He couldn't find a specific replacement that had the JB5 designation.

RockAuto and Amazon show 19176456 (or 18M217) as a replacement, but when I asked the dealer if it would work, he couldn't specifically verify it.

So Amazon/RockAuto are around $45 shipped, but 12 month warranty (ACDelco).

Napa is also around $47, and local pickup, with lifetime warranty. Napa Ultra Premium (NMC M2424).

Or a Dorman for $24.

All new (not rebuilt).

 

[MEMO43]

I would personally go with the NAPA unit, that way no shipping/waiting involved.
Plus with it being lifetime warranty NAPA being local no need for return labels or having to deal with online vendors..

 

[Wes Harden]

Yeah Napa. Nothing special about jb5
New master is the way to go. I personally avoid Dormant these days if at all possible. Dormant quality and QC is terrible these days

 

[sweetk30]

local store as there mostly all the same .

and just get a new with resivor and be done with it .

also bench bled it with a hose setup NOT the stupid plugs they give you now . i tried my first one with plugs and got no were . 5 min with hoses and she was ready for the truck .

 

[jeff in co]

Cool, thanks for the confirmation. Napa had a 20% off (I believe ending yesterday), so I did buy it online just in case. Will pick up after work tonight. I really do like buying locally if possible, especially if there's a potential for problems. So much easier than Amazon returns/warranties.

I've watched a few YouTubes on bench bleeding.....all I got to say is there is some vastly different approaches. Many of which look like they still left bubbles in there. The only one I really liked was using two clear tubes going back into the reservoir, and SLOWLY cycling the piston. Saw a lot of examples of cycling fast a few times and calling it good. Doesn't look like they did a good job.

I assume even after bench bleeding I still have to bleed then entire system again?

Any reason to replace Proportion valve now too? Or just MC and see how it goes?

 

[sweetk30]

The only one I really liked was using two clear tubes going back into the reservoir, and SLOWLY cycling the piston.

Saw a lot of examples of cycling fast a few times and calling it good. Doesn't look like they did a good job.


Any reason to replace Proportion valve now too? if its not leaking and brakes were good before master went out LEAVE IT ALONE

and yes full system re-bleed will be required when you open the 2 lines up swapping the master over .

 

[jeff in co]

Prop Valve....another $50 so I'll wait and see how it goes.

I did increase the calipers to the larger diameter pistons (c2500 truck), so we'll see how everything goes. I'm hopeful for better stopping power than before.

 

[sweetk30]

prop valve is a TEE for the front 100% flow onlly and just the rear is biased .

so swapping the valve unless the rear has changed would get your specific needs NOTHING .

 

[jeff in co]

prop valve is a TEE for the front 100% flow onlly and just the rear is biased .

so swapping the valve unless the rear has changed would get your specific needs NOTHING .

That makes sense, thanks! The rear is the 14SF axle, drums. I'm trying to improve the front discs. Can't really lock them up if I slam on it (unless it's wet roads). The booster was changed a few years ago, new SS brake lines to calipers, new pads, rotors and calipers. Only thing left is MC.

 

[centexk5]

Locking the rear tires up is scary enough. Locking the fronts would be dangerous. Although I would like to increase the front braking some more with my pig. I can lock the rears up easy after a fluid flush but it feels like the rears are doing all the braking the fronts are doing very little.

 

[diesel4me]

I bolt the master cylinder to the booster and fill it up,use a clothes pin to hold the two bleeder tubes under the fluid,and get in the truck and slowly press the brake pedal down several times,usually that bleeds the master completely
Most of the time if the brakes were bled before you took off the brake lines from the master,you wont have to bleed the brakes--you might need to have someone push on the brake pedal and crack the lines at the master if the pedal feels mooshy to burp the last of the air out..if that fails,then you'll have to bleed all 4 wheels again..