Master Cylinder Upgrade
In my upgrade I used a NON-ABS Brake master (BM44) from a R32 Skyline. Why NON-ABS? because it has the correct number of outlets! ABS have only two instead of three which our cars have (two for front left and front right and one for the rear) You could use a R33 Brake Master if you had one. Also a Brake booster to match.
All other skyline Boosters should all have the same bolts in the same locations with the exact same 12mm nuts on the brake pedal end, however on the Brake master end of the R31 booster, the mounting bolts are on a different angle to the R32 one meaning mounting a R32/R33 master to R31 booster would result in a tilted position, not good! this thing needs to be horizontal for gravity feeding the fluid!
Tools[edit]
- Socket wrench
- 12mm Deep socket
- 13mm spanner/socket
- 11mm flare nut wrench
- Small flat head screwdriver
- Double flare kit
- Something to straighten the brake lines
- Something to bend them
- Funnel and container for draining the brake fluid
- Rag
Replacement[edit]
Removing old master[edit]
Pop the bonnet and position your funnel/container arrangement under a brake line outlet with a rag close by in case you get it dripping on paint. Undo one of the lines and let the fluid run out. Repeat this step with the remaining brake lines.
Undo the two nuts with a 13mm spanner/socket and washers that are holding the brake Master to the Brake Booster, slide the old one out and put it somewhere out of the car, you don't want fluid to drip on stuff. Put the nuts somewhere safe.
There is a bracket which sits on here that holds the vacuum hose up, you will need to grab your thin flat head screw driver and undo the hose clamps, the easiest way to do this I found was to undo the hose clamp to the right of the bracket and leave it attached to the booster, removing it while it's out of the car is far easier!
Removing old booster[edit]
Get in the car under the steering wheel and make yourself comfortable. You will need to remove a retaining clip and a pin that holds the Booster to the brake pedal, just put that on the floor and then grab your deep socket and socket wrench. you need a deep socket because there is a metal frame that surrounds the bolts and it's very tricky to get a regular spanner in there. I could manage about 1-2 cm of turn before I had to remove and reposition, way too time consuming and frustrating!! A deep socket solves this problem instantly! Put the nuts somewhere safe.
Back in the engine bay, you will need to un-clip the spring holding the charcoal canister in place and just move it out of the way so you have some room. if you feel the need to you can unscrew the holder to make taking the booster out easier, I didn't.
Installing new booster[edit]
With the old booster off, get that hose off and put it on your new booster, leave the hose clamps loose for the moment. Put your old booster away and install your new booster so that the hose is in the same position as previous, and the brake pedal mount is facing vertical. Tighten the hose clamps. You will notice the bracket holding the hose will not go over both holes. This doesn't matter, you can use one nut and it won't go anywhere.
Go back to in the car, install the pin and retaining clip to the booster/pedal and put your nuts back on the booster, don't worry about them not going all the way through, just start tightening one and they will pull themselves through the holes, just double check that they're pushed through from the engine bay, the thread likes to get stuck on the holes, tighten the nuts good but not ridiculously tight.
Ensure that the push-rod for the brake booster is adjusted correctly. Failure to do so can cause your brakes to lock on.
Modifying brake lines[edit]
Now here comes the fun part! Grab your Double flaring tool and put it nearby, you will need to bend your lines straight so that you can move the fittings out of the way so your flaring tool will fit.
If you have the right tools to bend them you've done better than me. I used some vice grip pliers, grabbed the bottom end of the fitting (where your spanner attaches to) and while holding the lines before they bend, carefully straighten them without twisting them too much.
Put your hard lines in the 3/16 hole. Make sure you have the bevelled edge on the flared side! Tighten it up making sure they're straight and the line is but up against the vice.
Slide on the yoke and tighten by hand, you don't need any attachments for this. Using your socket wrench and while holding the vice very firmly with one hand to stop the line twisting, tighten it up a good couple of turns!
And now you will have a double flare! As you can see the line on the right compared to the one in the vice
Do this to the remaining lines.
Installing new master[edit]
Grab your Master and sit it over the booster, You will now be bending the lines so they match up! Look at your master cylinder and you will see 'F' and 'R', This is important that you lines go into the right outlets or you will have some explaining to do when you slide into the next car!! You will see one line that goes straight down under the car, that is for the rear 'R' (obviously) and the front lines fit up to the 'F'.
Bend the lines carefully so they line up with the outlets on the master, you may have to straighten out some bends to give some more length, especially the rear line as it's originally fitted underneath close to the booster, now it's at the end of the master too the side.
Double check everything is secure and tight. Check the brake pedal is smooth!
All that is left to do is bleed the brakes!
Contributors[edit]
Timbo3185