70' 914 1.7L Brake issues
06-13-2010, 02:14 AM
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70' 914 1.7L Brake issues
Ok. I just got this 914 not long ago. It's a 1970 Porsche 914, 1.7L.
It has new brake lines installed by the previous owner before I bought the car. We took it out and drove it, all was fine. I purchased the car, and on the way home, out of nowhere I had no pedal pressure. Pumping it up worked and there was again good pressure. Then they went out again. Again.... pumping it up gave me pressure.
If pedal pressure was applied - it would not go to the floor, it would STAY FIRM. If you let off and re-applied, no pressure till you pumped it up fast enough to get some pressure to hold it down.
Oddly as it was... I limped it home and about 5 minutes into the issue the issue went away and never re-appeared. I bled the brakes and there was no air. I took it for a drive, it was fine.
Today... weeks later, the issue again appeared. Having thought perhaps it was a stealth bubble I bled, the issue was again the same symptoms.
This is leading me to believe I Have a bad master cylinder. I DO have an extra master cylinder for the brakelines that the previous owner has supplied which is for a 911 (but will fit).
Brakes are far too important to skimp on. I thought the issue was air but I'm thinking it's not - could someone confirm my suspicions? Another thing - there is NO FLUID LOSS. I also appear to pull slightly to the right and the front right brake appears to be working overtime compared to the others? I've got massive amounts of brakedust there and she pulls to the right pretty hard, dragging a brake perhaps?
It has new brake lines installed by the previous owner before I bought the car. We took it out and drove it, all was fine. I purchased the car, and on the way home, out of nowhere I had no pedal pressure. Pumping it up worked and there was again good pressure. Then they went out again. Again.... pumping it up gave me pressure.
If pedal pressure was applied - it would not go to the floor, it would STAY FIRM. If you let off and re-applied, no pressure till you pumped it up fast enough to get some pressure to hold it down.
Oddly as it was... I limped it home and about 5 minutes into the issue the issue went away and never re-appeared. I bled the brakes and there was no air. I took it for a drive, it was fine.
Today... weeks later, the issue again appeared. Having thought perhaps it was a stealth bubble I bled, the issue was again the same symptoms.
This is leading me to believe I Have a bad master cylinder. I DO have an extra master cylinder for the brakelines that the previous owner has supplied which is for a 911 (but will fit).
Brakes are far too important to skimp on. I thought the issue was air but I'm thinking it's not - could someone confirm my suspicions? Another thing - there is NO FLUID LOSS. I also appear to pull slightly to the right and the front right brake appears to be working overtime compared to the others? I've got massive amounts of brakedust there and she pulls to the right pretty hard, dragging a brake perhaps?
06-13-2010, 09:55 AM
#2
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Sounds like you have 2 things. I would say the right front caliper is sticking and the MC is bad. The 911 MC is considered an upgrade, so if the replacement MC is new, I would put it in. Try working the caliper to see if you can unfreeze it, or just rebuild it.
06-15-2010, 04:31 PM
#4
brakes
I've owned and race 914's for years.
The 911 MC is 19mm and is a good upgrade especially for racing.
Caliper rebuilding kits are relatively inexpensive and I would do all of them.Remember this car is 30 years old.Also,totally flush the brake fluid and use something like ATE blue.
If the pistons are badly corroded or rusted you can buy replacements.
Buy a good street pad,one that is gentle on the rotors.BTW measure your rotors for minimum thickness and run-out and repack or replace the front wheel bearings.
All of these fall under the catagory preventative maintenance.
Don't take anybodys word on what they may have or have not done.
Feel free to ask any questions along the way.
Tom B.
The 911 MC is 19mm and is a good upgrade especially for racing.
Caliper rebuilding kits are relatively inexpensive and I would do all of them.Remember this car is 30 years old.Also,totally flush the brake fluid and use something like ATE blue.
If the pistons are badly corroded or rusted you can buy replacements.
Buy a good street pad,one that is gentle on the rotors.BTW measure your rotors for minimum thickness and run-out and repack or replace the front wheel bearings.
All of these fall under the catagory preventative maintenance.
Don't take anybodys word on what they may have or have not done.
Feel free to ask any questions along the way.
Tom B.
