I have a 1975 914 1.8 and I keep having various brake problems with the car. Replaced leaky master cylinder last summer. Installed PMB rebuilt rear calipers last Fall. The flexible lines at all four corners have been replaced in the last few years.

I last drove the car about 6 weeks ago. Stopped after driving for about 20 minutes and the front left wheel was hot. Obviously, the front left caliper wasn't releasing and pads were rubbing.

Didn't have any tools with me so I tried to let it cool down a little. I drove about a mile and checked it again and the wheel was at normal temperature. Made it home and it was still normal temperature.

Finally had a chance to pull the front left wheel off last weekend. I had my wife apply the breaks and that caliper didn't work. I was able to move the wheel with my hands and couldn't see any movement on the caliper.

I couldn't see any leaks and the flexible hose on the front left has been recently replaced with the stainless type.

Any ideas of what I need to look for? Is it time to have the front calipers rebuilt?

Rebuild/replace them as soon as possible!

Everything else has been replaced or rebuilt, so I guess the front calipers should be too. The car sat a lot before I purchased it, but the calipers didn't look that bad and one had been rebuilt recently so I didn't expect to have as much trouble with them as I've had.

I guess I'll send them off to Eric Shea and hopefully that will be the end of my brake problems.

Great looking car.

I would imagine that you're having a piston hang up due to some carmelized brake fluid. You could be having problems with the internal "knock back" mechanism as well. These were designed to knock the piston back toward the rotor to maintain a tall pedal. If the fluid sat in there for a while these might be gummed up and sticking.

Based upon the wife story I'd say you have some gummed up pistons.

Eric, what is the "knock back" mechanism?

Seeing as the car sat, I'd guess that there is corrosion on the pistons too.

The "knock back" mechanism is the pin you see in the center of the bore. I have a PDF of an old engineering paper from ATE that explains them. I had a discussion with one of their engineers while we were rebuilding S-Calipers. The decision was made to remove them so as to re-anodize the calipers. As described above, they were engineered to knock the piston back toward the rotor keeping the pedal high. That idea was dropped around 1974 but carried on with all 914 calipers. Later 911 M-Calipers came with "cup" type pistons which had much more surface area for cooling. This eliminated the pin. You can still see where the pin would mount in those later calipers... they simply left them out and used the newer style pistons.

On 914 calipers and almost all, steel to steel calipers (M-Calipers, A-Calipers) I don't see much pitting or standard corrosion. Again, with S-Calipers mentioned above this is fairly common (their pistons were chromed). Usually it's just old brake fluid that's gotten past the seal and is gumming things up.

Maybe I'm naive, but I'd say clean 'em before going to a full rebuild or replace, (If it ain't broke, ...), meaning: first, take it off, open it up and clean it. Yeah, you can put in new rubber if the old ring is stiff (you should feel the ossified one that came out of my'86 VW van clutch slave), but if it's soft and unblemished, just wipe the inside of the cylinder vigorously with rough cloth (like the back of denim--both dry and wet w/ brake fluid-- not silk, and certainly not emery paper), clean everything, and reassemble. Not yet mounted over the disc, but with a slightly a slightly thinner (by about two mm) spacer substituted for the disc (tape it loosely in place), mash the pedal to see that it's clearly (and smoothly) gone past the old limit. Back on the car on the disc, it should be fine--start with the wheel up and spun by hand, then on the ground going slow, then at slow road speeds, then faster. Hard stops in an empty parking lot. If there are still problems, a full rebuild or replacement might be required.

I agree they don't need to be replaced but doing all your mentioning does sound a bit naive...

The later model calipers have the intigrated clip in the dust boot. This will make them dificult to remove w/o possible tearing and it would be a good idea to have a rebuild kit on premises.

Put in new rubber if the o-ring is stiff? Now you are talking about a basic rebuild. I mean, if he's popping pistons, cleaning out bores and replacing o-ring seals... what's left? And, if you've gone that far, why put it back with old seals?

If, as he states, that caliper didn't work... it's time.

Thanks for all the suggestions.

I will probably just send them to Eric and let him rebuild them after I do a little more troubleshooting. At this point, I am tired of dealing with the brake issue and would feel better knowing they have been rebuilt by a professional. Hopefully, this will cure my brake problems on this car.

My new 1973 914 2.0 needs new pads and a couple brake lines replaced, so I'll probably put my own energy into those projects and send the calipers off the blue car to Eric.

Also, I want to get the blue car right because I may sell it soon. I am looking for a 914-6 and would probably keep the '73 2.0 over the '75 1.8 as a stablemate for a six. Even though I love the lagoon blue with white interior combination.

Eric, do you still charge $225 a pair for rebuilds?

yup