rx7will

iTrader: (6)

I recently had to change my brake master cylinder and i was rushing to finish it. It would appear that if i actually took my time to look at everything the job would have been a lot easier. This job is simple but looks complicated. Use flare wrenches, but when you are bleeding the master cylinder you can use a regular 10mm wrench, just tighten it with a flare wrench whe you are done. The new master cylinders are reman units, they are not new. And do not come with a resviour tank. You will need to transfer the old tank onto the reman unit. There is a hidden screw that holds the resviour to the master cylinder!!!!! You can see it easily with the unit out of the car, but very had to see when its on the car. Remove as much brake fluid as you can, I used a turkey baister. Disconnect the clutch line and cap it off on the resviour. Make sure to twist the hose off, do not pull. You take the master cylinder out with the two lines that wrap under the master cylinder, the metal block the two lines are attach to and the metal bracket. You disconnect the two lines on top of the metal block. Loosen the two 14mm banjo bolts on the master cylinder and tighten it a little so it does not leak.
Disconnect the low fluid connector, not the switch itself. Remove the two 12mm nuts on the brake booster. Take out the whole brake master cylinder assembly with the two lines. Remove the 2 14mm banjo bolts and fish out the two lines and metal bracket. Do not bend the lines, or you will have some trouble putting it back. Do not loose the washers, they do not come with the reman unit. Remove the screw on the resviour. Place the master cylinder on a vise and gently pop off the resviour. Transer the resviour onto the new master cylinder. The seals on the reman unit were lube alread so i did not need to lube it. Make sure you put the resviour back on the correct way. If you dont have a vice, you can try to remove the resviour on the car, just make sure to remove the screw first. Connect the two meal lines and the bracket to the reman unit, dont forget the washers. Tighten the 14mm nuts finger tight. Put the master cylinder back on the car and tight the 12mm nuts on the booster and the 14mm banjo bolts. Connect the cluth hose and the low pressure switch. Connect the two top brake lines to the metal block, but do not fully tighten. You will need to bleed the master cylinder. Put some towels underneath the metal block, this will catch the brake fluid when you bleed the master. Fill resviour with fluid and bleed the master cylinder first. Bleed the two top metal lines one at a time. So its pump, bleed one of the top line, then pump and bleed the other top line. Do this until the fluid comes out smoothly. It should take about 10 times total per line. Then bleed the brakes. If you bleed the master cylinder firts, it takes out a lot of the air and will make bleeding the brakes a lot easier and faster. If you are changing you brake hoses like i was, do the hoses after you bleed the master cylinder. Doing it this way will save you some time in bleeding the brakes, which needs to be done anyways. Some of the old brake fluid will come out while you are changing you brake hoses. You are basically gravity bleeding the brakes and flushing out the old brake fluid in the line while you are changing you brake hoses.

I did a search and didnt find any write ups on changing the brake master cylinder so i decided to write one. Hope this helps someone.

Mahjik

iTrader: (1)

Paragraphs are your friend.

BoostFrenzy

Your tips are t3h suck, my brain hurts. format it ******

rx7will

iTrader: (6)

BoostFrenzy if you dont have anything to add why dont you just go somewhere else. I'll revise it when i have time. I just wrote what i was thinking. I did not think it would come out like it did.

fd0

iTrader: (8)

Thanks for the write-up. I'm subscribing to this thread although you're formatting is something to be desired.

You should update it with the proper formatting. It'll be better to comprehend.

GARCO MOTORWORKS

With some welding and easy machine work a 929 master cylinder will bolt in without bending any lines or adding a line . Less stroke and a tight feel are your friend .Replacing the unit is an easy job but your directions may be helpfull to someone in need .They will thank you for your time, formatting or not .

rx7will

iTrader: (6)

I recently changed my brake master cylinder, the job is pretty simple but can easily become a headache. This job is simple but looks complicated. If you take the time to look at the job before you rush into it, it will save you a lot of time. Make sure you use flare wrenches. And make sure you take you time when reinstalling the metal brake lines. You dont want to strip them. Do not brake fluid on you paint, it will eat it up.

The new mazda master cylinders are reman units, they are not new. They do not come with a resviour tank. You will need to transfer the old tank onto the reman unit. There is a hidden screw that holds the resviour to the master cylinder!!!!! You can see it easily with the unit out of the car, but very hard to see when its on the car. I would suggest to take out the master cylinder and remove the resviour off the car. But if you dont have a vice, just make sure you remove the hidden screw on the bottom first.

1. Remove as much brake fluid as you can, I used a turkey baister. Place some towels under where the 14mm banjo bolts are.
2. Disconnect the clutch line and cap it off on the resviour. Make sure to twist the hose off, do not pull. You dont want to damage the resviour
3. Loosen the two 14mm banjo bolts on the master cylinder and tighten it a little so it does not leak.
4. Disconnect the two lines on top of the metal block.
5. Disconnect the low fluid connector, not the switch itself.
6. Remove the two 12mm nuts on the brake booster.
7. Remove the master cylinder with the two lines that wrap under the master cylinder the metal block and bracket.
8. Remove the 2 14mm banjo bolts and fish out the two lines and metal bracket. Do not bend the lines, or you will have some trouble putting it back. Do not loose the washers, they do not come with the reman unit.
9. Remove the screw on the resviour.
10. Place the master cylinder on a vise and gently pop off the resviour.
11. Lube the seals on the master with brake fluid, where the resviour goes onto.
Transer the resviour onto the new master cylinder and tighten the screw. Make sure you put the resviour back on the correct way. Or the fitting for the clutch maste cylinder will be on the wrong side.
12. Connect the two meal lines and the bracket to the reman unit, dont forget the washers. Tighten the 14mm nuts finger tight.
13. Put the master cylinder back on the car and tighten the 12mm nuts on the booster and the 14mm banjo bolts.
14. Connect the cluth hose and the low pressure switch.
15. Connect the two top brake lines to the metal block, and snug the two fittings.

Now you need to bleedk the brake hydraulic system. When bleeding the two lines its easier if you use a regular wrench. The fitting just hast to be snug to preven the fluid from leaking. But after you are done tighen the fittings with a flare wrench.

1. Place some towels underneath the metal block, this will catch the brake fluid when you bleed the master.
2. Fill resviour with fluid and bleed the master cylinder first. Leave the cap off.
3. Bleed the two top metal lines one at a time. You will have to repump the brake pedal after you bleed each line. Do this until the fluid comes out smoothly. It should take about 10 times total per line.
4. Next you bleed the brakes at each corner of the car. Then pump the brakes a few times to make sure the pedal is nice and firm. Top off the fluid. Clean up everything with brake cleaner and make sure everything is properly tighten. And check for leakes.

Make sure you check the fluid lever when you are bleeding the brakes. You dont want to run the maste cylinder dry of fluids. If this happens you will either have to rebleed the master cylinder or bleed the four corners over and over again till all the air is out. If you are changing your brake hoses like i was, do the hoses after you bleed the master cylinder. Doing it this way will save you some time in bleeding the brakes, which needs to be done anyways. Some of the old brake fluid will come out while you are changing you brake hoses. You are basically gravity bleeding the brakes and flushing out the old brake fluid in the line while you are changing you brake hoses. Make sure you check the fluid when you are changing you brake lines. Again if the fluid runs too low you will have to rebleed the whold system.

Hope this newly formated version helps.

maxcooper

If you ever have any trouble with a flare nut, you can use a flare nut wrench and clamp a vise-grip on the outside to hold it tight.

Thanks for sharing the info, with or without the formatting.

-Max

rx7will

iTrader: (6)

Yeah, the vise grip trick works great if the flare nut is all chew up

jimlab

The best $14 you can spend when working on your brake system (assuming you already have a torque wrench rated in in-lbs.)...

http://www.harborfreight.com/cpi/cta...emnumber=47928

93silverbullet

iTrader: (7)

Went through this last winter... didn't think to do a writeup. Nice job!