No brakes!, Brake pedal went to the floor Options

[mburkhart]

So I was out for a cruise around the neighborhood the other day and things were going great until the brake pedal went to the floor. I was able to pump it a few times and restore pressure and crawled home in a low gear. Each time I used the brakes the pedal would go to the floor until I pumped it a few times. Scary!

Once home I looked under the car and inspected the soft lines at each caliper but they looked fine and no leaks. The brake fluid reservoir is still full. I'm not sure where the problem is.

What should I be looking for?

[mepstein]

Master cylinder

Look for fluid under the pedal assembly in the car.

[DRPHIL914]

Master cylinder

Look for fluid under the pedal assembly in the car.

(IMG:style_emoticons/default/agree.gif) if no leaks at the MC underneath, look under pedals, this just happened to me this year but the last one i had fail i could get some pressure like you did after a few pumps of the pedal but will not maintain pressure, if that is the case you may not have any leaking but just failed seal internally and you still are in need for a new one.

one of my least favorite jobs to do

Phil

[mburkhart]

I haven't had time to lift the car up to be able to easily see what's going on with the master cylinder yet, but I'll check that next.

I did find a really nice youtube video from a member who installed the 19mm master cylinder upgrade from 914rubber. Unfortunately it looks like the "easy install" version isn't available right now.

Replacing the master cylinder looked fairly straightforward, what makes it your least favorite job?

[brant]

if the MC leaked on the pedals
make sure you rebuild them with the bronze bushings...

the nylon will swell once they have been wet with brake fluid and cause binding a month after the fact.

[solex]

When was the last time you replaced your brake fluid?

If there is any condensation at all in the fluid it will make the fluid compressible and will fail to transfer pedal force to the brake calipers.

[fiacra]

Master cylinder

Look for fluid under the pedal assembly in the car.

(IMG:style_emoticons/default/agree.gif) If you are not finding any obvious failure at any of the other point in the system then almost certainly a seal in your MC has failed. This is consistent with a sudden brake failure. In my experience a slow buildup of condensation will cause more gradual symptoms, such as a progressively worsening spongy feel to the brake pedal. As Phil pointed out you may not see any leaking of the MC with an internal failure, but you also might find fluid around the pedal assembly. Brake fluid is nasty stuff and it was astute of @brant to recommend refurbishing the pedal assembly if it has become fouled with brake fluid. Because it's easy for me to spend your money, I also recommend you get a Motive pressure bleeder. You've already seen Ian's @iankarr video on replacing the MC and he also has one on bleeding the brakes with the Motive. You need to order the one that comes with the European adaptor (0100 I believe). This is also one of my least favorite jobs as it does require some contortion to get things hooked up and I HATE working with brake fluid. If it has been a while it's also a good time to replace all of the rubber hoses and fully flush the system. If you didn't already know it, you've just discovered how important your brakes are to your safety and this is one of those jobs that you just have to do before it becomes a problem. As you can see a failure of one component of the braking system should lead you to consider refurbishing the whole system. Again, easy for me to spend your money AND time! Wear gloves, safety glasses, and keep lots of rags handy.

Glad you made it home safely!!!!

[DRPHIL914]

I haven't had time to lift the car up to be able to easily see what's going on with the master cylinder yet, but I'll check that next.

I did find a really nice youtube video from a member who installed the 19mm master cylinder upgrade from 914rubber. Unfortunately it looks like the "easy install" version isn't available right now.

Replacing the master cylinder looked fairly straightforward, what makes it your least favorite job?

laying on my back with no lift just on jack stands trying get the freaking line pushed into place and to seat- not much room to work, sometimes it goes easy- the last one i did the “easy” install one from 914rubber. still took all day to pull out old one install and bleed lines, etc. i don’t have a power bleeder,
pro tip- loosen the reservoir and attach the lines at the mc before bolting it in tight and also bench bleed the mc will help too.
don’t forget the washer it’s traditional hose attachment will leak without those washers, i found that out the hard way too

[mburkhart]

What are folks thoughts on the original 17mm vs 19mm master cylinders?

Would you guys recommend waiting until the "easy install" 19mm master cylinder becomes available again? Is it really that much easier to install than the non-easy version?

Edit: Here's the link - https://914rubber.com/easy-install-19-mm-master-cylinder

[76-914]

RE; the non-easy install MC version; You can get a good grip on those lines if you use the block from a flaring tool to hold the line while you pull it in. (IMG:style_emoticons/default/beerchug.gif)

[ClayPerrine]

What are folks thoughts on the original 17mm vs 19mm master cylinders?

Would you guys recommend waiting until the "easy install" 19mm master cylinder becomes available again? Is it really that much easier to install than the non-easy version?

Edit: Here's the link - https://914rubber.com/easy-install-19-mm-master-cylinder

IIRC... the 17mm master cylinder is NLA.

[mepstein]

Im pretty sure I have the 19mm easy install version still in a box. I can check tomorrow when I’m get home. PM me if you are interested.

[Tdskip]

Check me on this - the only difference between regular and easy is how the lines from the reservoir fit/are located into the master cylinder, correct?

The regular version requires you to push the hard lines into the rubber grommets, right?

[mepstein]

Check me on this - the only difference between regular and easy is how the lines from the reservoir fit/are located into the master cylinder, correct?

The regular version requires you to push the hard lines into the rubber grommets, right?

Yes.

I asked Bob Russo how he does it. He was the crew chief for the Holbert 962 race team among other Porsche experiences. He said he wrestles them in. There is no real trick. I was told it's way easier to assemble the MC to the lines on a bench and then feed everything up from the bottom. Fuel tank has to come out but sometimes that would be easier.

[DRPHIL914]

Check me on this - the only difference between regular and easy is how the lines from the reservoir fit/are located into the master cylinder, correct?

The regular version requires you to push the hard lines into the rubber grommets, right?

Yes.

I asked Bob Russo how he does it. He was the crew chief for the Holbert 962 race team among other Porsche experiences. He said he wrestles them in. There is no real trick. I was told it's way easier to assemble the MC to the lines on a bench and then feed everything up from the bottom. Fuel tank has to come out but sometimes that would be easier.

that certainly would make it easier, both having the tank out and bench installing the lines. This was one of the first jobs i did on my 914 after purchasing it. First time i left the washer out and found out the hard way it was necessary, but once done correctly , was leak free about 8 years. The next failure was back last winter right before going to Amelia island, puddle on the floor inside under the pedal cluster. remembering my previous experience i ordered the new 19mm easy install one from 914 rubber.
being i have no lift and therefore limited space under the car, it was still very difficult to attach the lines and tighten the clamps.
If i had to do it again(Lord i hope not ever!) i would do exactly like Mark and Bob Russo suggest if you can, and do that part on the bench. .

Let us know how your experience goes.

Phil

[Optimusglen]

When I did mine I installed on a bench, just the lines not the reservoir, then connected the rest up top. It was really pretty straightforward but I forget if I had the tank in or not.

grommets on the line first, then push the line/grommet assembly into place after verifying the washer is there.

[mepstein]

Never forget the washers. They are 100% mandatory. It’s fine to reuse the old ones out of a failed mc. I got a couple extra from my local Porsche dealer. They are ~ a dollar each.

[dcheek]

What are folks thoughts on the original 17mm vs 19mm master cylinders?

Would you guys recommend waiting until the "easy install" 19mm master cylinder becomes available again? Is it really that much easier to install than the non-easy version?

Edit: Here's the link - https://914rubber.com/easy-install-19-mm-master-cylinder

I installed the 17MM in my stock '76. I didn't want a change in the pedal feel after driving it for 44 years!

An easy way to install the "hard install" reservoir fill lines is to disconnect the reservoir completely from is mount in the frunk and pull everything up a little bit. Install the new MC then pull the lines back down to insert in the rubber grommets on top of the MC. I had no problems at all using this method. Of course I emptied the reservoir first to avoid getting fluid all over the place.

Dave

[billh1963]

I'll throw out another possibility....

One day while while driving the 6 conversion in my avatar, I came up to a stop and much to my chagrin I discovered I had virtually no brakes. Fortunately, my emergency brakes worked quite well and I was able to stop. (BTW...when driving my older cars I ALWAYS slow down early and give the brakes a little test tap. It's a habit I developed early in life when driving another car that experienced brake failure.)

Anyway, as I sat waiting over an hour for a AAA tow for some reason I hit the brake pedal. I had brakes! I drove the short distance home and as I walked around the car I could feel the heat coming off the right front wheel. The right front caliper was dragging so badly that the fluid was boiling ..causing a loss of braking. I replaced the rubber brake hoses (in case they were collapsed) and with a set of rebuilt calipers a few days later I was back in business!

That may not be your problem. But, worth a check especially if you aren't seeing any fluid loss.

[VaccaRabite]

The difference between the 17mm and the 19mm is only pedal feel and travel. You need a bit more foot to push in the 19mm piston. Some like that, some don't. Stopping power isn't different, but you have less travel with the 19mm so brake modulation will be a little different too. Bigger piston pushes more fluid...

If you can find one, I'd stick with a 17mm if your brakes are stock. That said I have a 19mm on mine (at the time I thought it was an "upgrade") and I'm used to it now.

Zach