Honda Brake Master Cylinder rebuild
The following is provided as a GUIDE ONLY, and I do not take any responsibility
for the outcomes of someone else doing the following. You follow these steps at
your own risk!
Aim: to stop your brake pedal from creeping
to the floor. (Help make your car stop)
- OEM Brake master cylinder rebuild kit ( from your local Honda dealer )
- 500ml Brake fluid
- cir clip pliers
- Allen key set
- 10mm spanner
- 12mm spanner
Do you have a Honda that has a dodgey brake pedal ?
does your pedal creep to the floor when you press the pedal ?
is it worse on hot days/weather ?
if so, then your brake master cylinder is rooted. You can try to bleed the brakes, but if the brakes are ok most of the times and sometimes it does the above symptoms you will have to replace or rebuild it.
a rebuild kit will cost you about 90 to 100 bucks, a new master cylinder will set you back about $250 to $280 depending on your car.
you will most defiantly have to replace your master cylinder if it bore is badly scored causing bypass, but 9 times out of 10 its due to wear on the seals on the two pistons.
Caution; during any part of DIY make sure you do not spill brake fluid on your paint work. It will get damaged from the brake fluid.
suck out the brake fluid from the master cylinder reservoir
undo the two brake lines using your 10mm spanner (red circles bellow). Be careful not to round the nuts. if you do carefully use vice grips.
undo the master cylinder mounting bolts that hold it to the booster. ( blue arrows above and bellow pic )
remove the seal from the booster if it isnít already on your master cylinder ( red arrow bellow pic ). do not damage it as you will have to reuse it on some cars, most kits will have a replacement. also you do not want to do a double sealer. causes vacuum leaks
place your master cylinder on a bench, use a rag as you bench will cop some brake fluid. undo the Allen key bolt in the pic bellow ( red circle ) and slide the pin out. note it has an aluminum crush washer.
undo the cir clip at the end of the master cylinder ( red arrow pic bellow ), then pull out the 1st piston along with the sleeve.
remove the 2nd piston from inside the master cylinder ( red arrow pic bellow ), use long nose pliers, careful not to touch the bore ( blue arrow pic bellow ).
inspect the bore for severe damage
replace the pistons, start with the 2nd piston, the last one you removed. before we put it back in the master cylinder you have to lube the seals with the pink grease that comes with the kit.
Apply grease to the two seals shown in the pic bellow by the 2 yellow arrows.
reinsert the 2nd piston back into the master cylinder. Spring end in 1st. Make sure the slot in the piston lines up with the ( green arrows in the pic bellow ). Use your long nose pliers to put the piston in the bore, then slide it in using a screw driver.
change the aluminum crush washer on the long Allen key bolt. red arrow bellow.
Push the 2nd piston in compressing the spring maintain the pressure on the spring and slide in the long Allen key type bolt into the master cylinder. if you have lined up the 2nd piston correctly it should slide right in. do not force it.
now tighten the Allen key bolt.
lube up your new 1st piston seal. ( yellow arrow pic bellow ) and slide it into your master cylinder.
now its time to replace the seals in the sleeve. first replace the outer seal, gently remove the old one with a screw driver. apply the pink type grease on the sleeve itself then on the new o ring, then put the new O ring on the sleeve.
now pay extra attention to the way the inner seal sits in the sleeve. take it out with a small screw driver and apply pink grease in the channel where the seal sits. apply pink grease to the new inner seal. push the new seal into the sleeve and move it with your fingers to sit in its channel the same way the old one did.
time now to fit your lubed up sleeve to the master cylinder. lube up the shaft of the 1st piston with the pink grease.
put the 1st piston in the master cylinder if you took it out to fit the sleeve. put the new cir clip on and push it down with a screw driver to make sure 100% it is seated in its channel.
open up your white grease sachet and apply some to the booster seal and to the master cylinder and the shaft of the 1st piston. smear it all around
now fit the master cylinder to the vehicle in reveres from the way you took it off. do not put the brake lines on just yet.
bleed the master cylinder.
- put a small plastic bag under the two holes where the lines go into the master cylinder. the idea is to catch brake fluid as you bleed the master cylinder.
- fill your master cylinder with brake fluid.
- get your helper to press down on the brake pedal then block the two holes on the master cylinder with your fingers ( to seal the holes ) then get your helper to lift the pedal. uncover the holes. press down on the master cylinder then cover the holes then up on the pedal.
repeat this until you get a good steady stream of brake fluid coming out from both holes.
refit the brake lines to the master cylinder. tighten them up nice and tight ( not superman style )
and now its time to bleed the brake as normal. bleed all four wheels.
this should take half an hour to complete, but take your time do not rush.
Disclaimer: The following is provided as a GUIDE ONLY, I do Not† take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!