Rebuilding Brake Master Cylinder...Easy Job?

[LeftCoast]

Hi,

My 92 base 5-speed brakes are getting soft. Fluid level was a little low, but it was night and flashlight died so not sure of the level. I refilled it with perhaps 1-2 ounces of fluid...would that be enough to have let air in my lines? I'm assuming not.

So I ordered the rebuild kit for the master cylinder, and it looks pretty straightforward. Any tips or wisdom to impart before i have a go? Does the MC need to be honed out, or am I just looking for trouble...i know one scratch inside and the MC is toast?

Also, bleeding the brakes, is the correct order driver rear, pass rear, driver front, passenger front? Any tips on bleeding? Links to the proper procedure would help...the FSM doesn't tell a lot.

Also, has anyone else tried speed bleeders? I got this link from another thread, called the store, but the guy there said the info he had for my truck was too ambiguous, and suggested I measure the bleeder screws, which is something i obviously don't want to do. Any info on the sizes I need? 92 BASE reg cab 2wd truck, built 4/92 JT4RN81A0N0xxxxxx
Speed Bleeder - Speed Bleeders

Thanks in advance for any info.

 

[jprissel]

If the brake light didnt come on and the brake fluid resevoir wasnt empty, then you're right, no air in the system. That is normal for the fluid level to drop as the pads and shoes wear. Now that your resevoir is full, if the fluid level drops soon you have a leak some where.

Have you tryed pumping the brake pedel when stopping? Does pumping firm up the pedel?

Before rebuilding the master I would check to make sure the rear brakes are adjusted up fully, that has been known to cause spongey brakes.

 

[MStars]

I can't contribute that much as I'm much of a beginner but to answer one question for you the correct order to bleed the brakes is :

Drivers rear, Passenger rear, Passenger front, Driver front, rear LSPV valve. I just replaced all the brake lines on my 87, bled the brakes just using the plastic hose and cup of fluid technique and worked like a charm.

Hope this helps, good luck

 

[KLF]

My 92 base 5-speed brakes are getting soft. Fluid level was a little low, but it was night and flashlight died so not sure of the level. I refilled it with perhaps 1-2 ounces of fluid...would that be enough to have let air in my lines? I'm assuming not.

As long as there was some fluid in the reservoir, then no you couldn't have let air into the system by just adding fluid.

So I ordered the rebuild kit for the master cylinder, and it looks pretty straightforward. Any tips or wisdom to impart before i have a go? Does the MC need to be honed out, or am I just looking for trouble...i know one scratch inside and the MC is toast?

There is a really good description of how to rebuild the MC in the FSM, do you have it? I have rebuilt many with good results, and I always hone them. Pay close attention to the order of things as you take them apart, it can be confusing and the FSM doesn't show it clearly which piston goes back in first. Be careful to keep the hone moving in-and-out as you spin it, don't pull it out without spinning it either, and use some good honing oil. Be sure to WASH the MC with hot soapy water after honing, but then quickly get some oil on it or it will start to rust inside. I smear a thin coating of silicone grease inside the cylinder and on the cups before re-assembly.

Also, bleeding the brakes, is the correct order driver rear, pass rear, driver front, passenger front? Any tips on bleeding? Links to the proper procedure would help...the FSM doesn't tell a lot.

MStarts has the order correct, don't forget to bleed the LSPV above the rear axle, passenger side, do it last.

Also, has anyone else tried speed bleeders?

Your bleeders have a M10x1.00 thread pitch, same as the brake line fittings. It's a personal thing, but IMO I think Speed Bleeders are a waste of money. I've had them on previous trucks, I couldn't tell any difference when bleeding. Part of that is due to I always bleed with a pressure bleeder, makes things soo much easier and a much better bleed.

Yeah, check your rear shoes, they can cause you to have to double-pump your brakes if they are out of adjustment. They self-adjust each time you yank on the e-brake, so it you don't use it they will gradually get out of adjustment.

 

[GRM]

I ran the speed bleeders before. They worked, but not good enough for me to spend my money on them again. I always gravity bleed my truck. It takes an hour or two, but gets the job done.

As far as rebuilding the master cyl, a rebuilt one is $33 plus core. I don't see it being worth your effort to rebuild it.