How to perform brake master cylinder swap?

[xagna]

I need to do a brake master cylinder swap. This will be the very first time I do this. I searched about this on zilvia and here and could not find any threads with detailed how to do steps.

Is any one willing to teach me how to do this? Thanks.

[navysnail]

ok, changing the master cylinder is one of the easier things you can do on a car. first step is to losten hardlines on it and undo the bolts attatching it to the car. make sure you have some towels under it because the brake fluid will make paint bubble and peel. next, remove all the lines and take the cylinder out. drain all the fluid out of the resovoir and pull it off (it will require a moderate ammount of force). next, put the resovoir on the new cylinder and replace the assembly on your car. after the cylinder is bolted back up on the car, fill the resovoir and allow it to sit untill fluid starts to drip. Now, replace all the hardlines, starting each one by hand to make sure you don't strip the cylinder. after they are all started, tighten them down and bleed the brake system as normal, making sure the fluid level does not go below MIN.

if you have any questions, feel free to ask.

[teddy]

The hardest part of the swap is finding someone to help you bleed the brakes.

[fatboy]

umm, i dont bleed each individual brake. you dont have to mos the time. bench bleed the master cylinder before putting it in the car. (bench bleeding is purging air from the actual master cylinder before putting it in or at least purging the majority of the air). make sure the fluid level is good. bolt it back up, put lines back on. get someone to pump it up, crack master cylinder lines open one at a time like you're bleeding a caliper. do teh same until theres no more air coming out of the lines. check for pedal feel. you're good to go.

[navysnail]

you still opened the system when you changed the cylinder, so you would have to bleed all brakes. you may get lucky with bench bleeding and not have much air, but it is still good practice in addition to getting all the old fluid out to preserve the life of caliper seals.

[fatboy]

you still opened the system when you changed the cylinder, so you would have to bleed all brakes. you may get lucky with bench bleeding and not have much air, but it is still good practice in addition to getting all the old fluid out to preserve the life of caliper seals.

that is true. the way i explained is the way ive been taught and have always done it. never screwed up yet(knock on wood!) pedal feel always. road tests are a must

[navysnail]

just remember when your done, make sure you hit the brake pedal 10 times or so just to make sure you are building pressure.

[jr_ss]

umm, i dont bleed each individual brake. you dont have to mos the time. bench bleed the master cylinder before putting it in the car. (bench bleeding is purging air from the actual master cylinder before putting it in or at least purging the majority of the air). make sure the fluid level is good. bolt it back up, put lines back on. get someone to pump it up, crack master cylinder lines open one at a time like you're bleeding a caliper. do teh same until theres no more air coming out of the lines. check for pedal feel. you're good to go.

FatBoy has a huge point right here.

Bench bleeding is a must if you are swapping in new mastercylinders. If you just throw it on the car and fill it with fluid "and let it sit until fluid starts to drip" you are going to be SOL when you need the brakes.

There are air pockets that form in the mastercylinder when simply pouring fluid into it. The best way to remove these is to attach the reservoir to the new M/C fill it with fluid, and with a towel(use it to protect the piston from the head of the screwdriver) and a screw driver(preferably phillips head) push the M/C piston in until it bottoms out. Watch the reservoir, as bubbles should appear in the fluid. I would also attach rubber hosing to the brake ports and set them down in some brake fluid as well this will also have bubbles appear in it. Repeat until all bubbles are gone and add fluid to the reservoir as needed.

The brake department is something you don't want to mess around with. If you don't know what you are doing, take the M/C to a auto shop tell them what you are doing and ask them to bench bleed the M/C for you, if you don't feel comfortable doing it yourself.

Glenn

[S14KoukiMonster]

YOU MUST BENCH BLEED!!!! Don't install it before you do like navysnail said. That's WRONG!!!Do what jr ss said, he's exactly right, but I use a piece of wood. Most master cyls come with a bench bleed kit, so ask the parts guy if it does or not.I assume you the PROPER bleed sequence? RR(pass), LR(dr), RF, LF.

I suggest people don't offer advice unless they know what they're talking about! :bonghit

[xagna]

Thanks so much guys!

[teddy]

Bench bleeding is a very good idea. And not to jinx myself, but last summer when I put on my bmc, I did not bench bleed it bc I was in a hurry. I bled all the brake lines individually....no problems with braking at all so far.