Alright the leak is found, the rear seal of my master cylinder is leaking (and corroding everything in it's path ) and I'm sick of dumping in brake fluid. Tommarow I'm replacing the whole MC which is only two months old. Here come the Q's...

1. Now do I need to replace the whole thing or just the seal? I'm new to brakes so give me a break .

2. If I need to replace the whole thing the 1LE MC works right? Is there any diff. between that and an Autozone replacement?

3. Which is the best way to bleed the brakes here? How much $ and time does this take a first timer?

Thanks in advance everybody,
Matt

 

TTT. Anyone? Also what's this about the thread change halfway through 84? Is there any diff. in MC's?

 

Replace the whole thing. You have to spend almost the same money and do twice as much work to replace the seal, so save yourself the work and just swap it.

The threads on the fittings changed sometime during 84 production. The easiest way to make sure you get teh right thing is to take you old one with you when you buy the new one, and make sure they match.

AFAIK the 1LE MC is the same as the disk/drum one, in later years with metric fittings and PBR rear calipers. I can tell you that my 83 car's brakes work flawlessly with the OE MC & proportioning valve and a 91 model rear with PBR calipers. I did have to use the end of the 91 brake line, and flare it to a SAE size and use a union to hook it up to my car.

 

Thanx, RB83L69 !

You are right on the money!

 

Thanks, okay I've got a new MC, now how do I bleed the system. I've heard of bleeding the MC or just the lines but can I so the whole system at once with the MC in place? I have major air in my lines now, as it ran dry last night. Will someone explain step-by-step how to bleed all four cornors with the MC in place? I'm an idiot when it comes to brakes, details are needed...

Thanks again I'd be lost without your assistance,
Matt

 

Have an assistant pump the brake pedal until some resitance is felt keep holding the pedal down. Open the bleeder at the right rear wheel. As soon as air or fluid stops coming out of the bleeder valve. Close it. Then continue doing this until only clean bubble free brake fluid comes from the bleeder. Then repeat this process at the left rear wheel, right front wheel, and finally the left front wheel.

Duing this proceedure you must do two important things. Keep refilling the master cylinder resevoir, and keep the cap on it.

I hope this helps.

Thanx,ANDYZ28

 

Also you should start at the wheel furthest from the mc and work your way to the master cylinder.

EXAMPLE:

1) pass. rear
2) driver rear
3) pass front
4) driver front

 

The other posts are right on about bleeding the system once you get the MC bled & installed. However, you MUST bench bleed the MC before you put it on, because the fittings aren't at the highest point in its cylinders; air will get trapped in there and will never come out, not even if you run a gallon of fluid through there.

To do that, you need the little adapters that screw into the fittings and have pieces of clear plastic tubing that you can stick the end of back into the reservoirs; clamp it in a vise, dead level; and use a screwdriver or some sort of rod or something to pump the fluid through the cylinder until no air appears in the tubing. Then leave the fittings and all that on there until the MC is back on the car, until the absolute last possible minute before hooking up the lines to it.

 

Cool, now I understand. Thanks again, I'd be getting robbed by Midas if you guys wouldent have helped. I don't have a bench vise but I have some of those Craftsman squeeze clamps that should work. Now when I do the bench bleed do I leave the hose ends in the MC resv. or can I plug them up. Also what AN size are they so I can ask for connectors and hoses.

I can't thank you enough,
Matt

 

You leave the ends of them submerged in the fluid in the MC reservoir, so there's no chance of them sucking air back into themselves.

MCs come with the little fittings included sometimes... they're little plastic POSs, but that's OK. They're all you need. If yours doesn't, ask the guy at the counter for a bench bleeding kit.