Brakes not releasing

drawbardude · 12-03-2005, 10:19 PM

Just purchase my first Porsche - project car - 1970 - 914. Some rust, hope not too much. I can't get the front brakes to release. Anyone got a clue?

M. Hendrix · 12-04-2005, 06:53 AM

Take your foot off the pedal.

Liners in soft lines. Replace soft lines. Has the car been used lately? The pistons stick.

M

Lyle Detwiller · 12-04-2005, 08:58 AM

When you take your foot off the brake pedal, does the pedal return all the way to the stop and do so freely? If not, the master cylinder may be causing residual brake pressure. One cause (not the only one) is a leaking rear seal on the master cyl.
The leaking fluid gets into the original plastic bushings on the pedal cluster, they swell up and then the brake pedal doesn't fully return. Remove the floor carpet and the plywood board that covers the pedal cluster and look for evidence of fluid around the pedal pivot bushings. If you find fluid, then its time to rebuild or replace the MC AND rebuild the pedal cluster using bronze bushings.

AaronM · 12-04-2005, 09:31 AM

If a 914 has "some rust" then it has a lot more that you just don't know about yet...

Dave at Pelican Parts · Dave at Pelican Parts's Garage

In addition to the two causes already mentioned (rubber brake lines starting to fail, sticking pedal cluster bushings), the pads could simply be rusted to the rotors.

--DD

drawbardude · 12-04-2005, 08:58 PM

Thanks for the input - car is in the garage tonight, first time - Aaron M, oh, you are so right! Found more rust under the - guess where - battery. Actually pretty SCARY - I think the main support on the passenger side is half way eaten out. Huge buyers remorse, but my son is excited about the prospect of working on "the porsche". As for the brakes, I think it may be the rubber brake lines, but I will dig in and find out. Thanks for the help - I guarantee, I'll be back. I just bought the 914 Restoration book. Any thoughts?

genrex · 12-04-2005, 09:53 PM

Hey, you have a PM.

drawbardude · 12-04-2005, 11:36 PM

Whats a PM?

genrex · 12-05-2005, 02:07 AM

Private Message... you can access them by clicking on the "user cp" icon near the top of the page... or by scrolling down past this message to the "forum jump"
(click on that, and a list will appear; Private Messages is near the top of the list).
Sorry to get off-topic, mate.

Have you gotten under the car to look at the "long" (longitudinal) on the passenger side, or at the right-rear suspension mount? If those have rust issues, the repairs are kinda major.

drawbardude · 12-06-2005, 07:02 PM

Okay, so I dig into this brake mess - AND - the cap to the brake reservoir is cracked and doesn't seal. Now, my sense is that without pressure on the backside of the reservoir, the brakes won't retract. Am I out to lunch?

drawbardude · 12-06-2005, 08:00 PM

That wasn't it!

drawbardude · 12-06-2005, 10:12 PM

Okay - I found it - stuck piston on the caliper - any suggestions on how to get the piston out of the caliper?

Darksidelarry · 12-07-2005, 10:58 AM

I had the same brake stick problem on my 1975. My Problem was the Brake Petal. The assembly was worn. Replaced and problem solved

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Get the piston out of the caliper by using the pedal. You can generate an unholy amount of pressure with your foot on the brake pedal, expecially if you block the other pistons in all of the brake calipers from moving!

Alternately, you can take the caliper off the car and work on it on the bench. Use a clamp to hold one piston in place, and apply compressed air to the brake line fitting on the caliper. If that doesn't move the stuck piston, try a grease gun instead of the air. Make sure to put the caliper in a bucket covered with shop rags if you do this, or you'll spend hours and hours cleaning up grease from everywhere when the piston finally moves.

Oh, and the piston will move with a lot of force either way, so don't put anything next to the piston that you want remain un-crushed. (Things like fingers work better when not smashed into a bloody pulp.)

--DD

drawbardude · 12-10-2005, 05:57 AM

Thanks for all the advice on the brakes. Finished the rebuild and took the car for it's first spin around the block. Have to work on that shift pattern - a little goes along way.

Looking forward to more 914 adventures!

Eric_Shea · Eric_Shea's Garage

Quote:

try a grease gun instead of the air. Make sure to put the caliper in a bucket covered with shop rags if you do this, or you'll spend hours and hours cleaning up grease from everywhere when the piston finally moves.

Ut Uuuuuuuuuuu will not, will not, will not...

I agree to use the grease gun. That's how we get all of our stubborn pistons out.

They do not send grease and pistons flying around the garage though... just a slow slide and a simple "plop" and the piston falls out. It is a ***** cleaning up the caliper but many times it's the only way.

Don't even both with air. If it was stuck enough that your pedal had a hard time with it then air will do nothing. Air compresses. Fluids don't. Buy a cheap Harbor Freight grease gun and remove the nozzle. The thread pattern is exactly the same as your caliper. "Viola"