master cylinder replacement

i was wondering how hard it is to replcae a master cylinder on a 67 A100.

Replacing one is pretty straight forward, it is in a rough location to get to underneath the van, and also the standard hard time getting the lines broke loose without twisting them off. I would plan on replacing those lines at least, if not all of the lines on the van due to age.

Tom

Have you done the job before?
There are a bunch of small but significant steps.

My master on the 66 A100 is rusted and the fluids gone,I plan on pulling it and putting on a repro off ebay,after I pull the old and bolt on the new the plans to hunt down hardlines,a tube bender and rubberlines for the four corners of the rig...I feel like my approach will be to take pictures,so I see how everything goes back together...since I've never done this...pull one line,take some new line and the bender and mimic the bends of the old ones,bolt up the new master,reattach all the new identical bent line, use the white tape around the threads like a plumber would and tighten down everything,by the time I'm finished,I want everything new to look the same as all the old stuff....Then get a buddy to help me bleed all four corners,so Rod(or anyone else who knows this game well,what significant steps have I missed? remember,I'm a rook.

soak the fitting with b blaster for a few days before you try to remove the fittings. follow the instructions on the m.c. and bench bleed it and no tefflon tape.

Bench bleed the M.C....,I don't understand....I figured pull all the old,put in all the new,fill the m.c. with fluid and bleed all the corners in no particular order,no teflon tape,soak all the bits in b blaster...What's wrong with this picture.....or is that all there is to it....

Im not sure if you dont get the term "bench bleed" or not, I cant tell by reading above so this is not an insult to your skills my friend. Bench bleed means that you try to get all the air out of the master BEFORE you hook the brake lines to it. It basically eliminates the possibility of the master pushing air into the lines that may have been stuck in the master.

What to do: Take all your pictures of the master and surrounding area, remove the old master after soaking the lines for a few days. This will ensure you dont ruin the lines when removing, if the worst happens you may need them for refrence...No use having them all twisted up. USE A FLARE NUT WRENCH to bust them loose, once they are loose you can use a regular wrench. Lines removed? good. Master out? Great. Install new master like original, do not attach the lines. there are "bench bleed kits" out there, some masters come with them. Plastic fittings you screw in the master where the steel lines would go. They accept rubber hose that you then route back into the open top of the new master, so the fluid cycles back into itself. Fill it with fluid carefully. Brakefluid REALLY SUCKS TO GET IN YOUR EYES. look into master from an angle not directly over it, it WILL SQUIRT RIGHT UP IN YOUR FACE if you're not careful. Super super super gently gently gently slowly slowly move the brake pedal back and forth, full travel. You will see air bubbles come up from inside the master. make sure when you release the brake pedal you also do it slowly, it will squirt here too if youre not careful. Do this until you can not see any air coming up from inside the master, then do it for a few more minutes. You have successfully "bench bled" the master... Or pseudo bench bled lol... I find it easier to have the pedal attached for leverage purposes.

Side note, later, when you're bleeding the brakes there IS a specific order. The wheel thats furthest from the master first. so Right rear, left rear, right front, left front. This gets the most air out of the system the quickest. And like Dix said, no teflon tape, the fittings are self sealing if you dont cross threads them or leave them loose. Another thing... use ONLY the brake fluid recomended for the master, and NO mixing other types in (dot 2, 3, etc). ALSO use only new fluid. Brakefluid is hydroscopic, which means its inherent properties absorb water, thus using old open brake fluid can cause your shiny new lines to rust out from the inside. Hope this helps amigo! Its a sucky project, but by FAR one of the most rewarding (you wont die from bad brakes after!)

so Rod(or anyone else who knows this game well,what significant steps have I missed? remember,I'm a rook.

Sorry I'm a rookie on this stuff compared to the east coasters.
I've done ONE (1) full system replacement due to living in the SW my whole life. I've known techs in the NE that do one a month!
As said, soak the old connections and fasteners a while before trying to break them loose. This includes the clips for the (3) hoses!
Find as many of the parts as possible before starting. It really sucks to have the job 80-90% complete and be held up by one thing you can't get. It's better to go back to the store in the van to return a couple things than to go to the store in your other driver 6 times!
Make sure to get all Standard thread stuff. Metric will mess with you!
Every fitting is a double flare fitting that should seal itself without tape/sealer. Test fit each part before bending/cutting. Manufacturer QA is lacking these days...

There is a guy in Brazil selling the hoses for a good price on Ebay. The lines will all be too short, so you will need line-to-line adapters. Measure each line (a sewer's fabric tape is handy here) for over all length and figure out what you need. It's a good idea to practice on one new line if you need to cut and flare. There are tutorials on this online. Always put the nut on the right way before flaring!

DONT USE TAPE ON YOUR FITTINGS ALL YOU'LL DO IS RUN THE RISK OF GETTING TAPE IN THE SYSTEM!

just about all after market master cylinders have instructions in the box on how to bench bleed

OregonVaner wrote:i was wondering how hard it is to replcae a master cylinder on a 67 A100.

you will now say words you never even knew existed!! it is not easy but it can be done by yourself ,if needed.while you have the belly pan off ,might I suggest you grease the brake pedal pivot. sometimes forgotten.but totally needed

Lol! I just had to do this last weekend. I was driving around on a master cylinder that had a leak at the passenger rear wheel cylinder, and the master would bleed through itself in the front section of the master. I was in the hills of rancho santa margarita and lost the front section of the master. No big deal since Im used to driving junk im working on that has lots of problems haha. Changed it out in 3 hours. problem was it took my parts place 3 hours to get me the new master! lol. Easy job, just be careful!