Alfa Romeo Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
961 Posts
Discussion Starter #1 (Edited)
I'm stumped. Last fall the car got a soft pedal fairly suddenly. I had finished an autox and so I bled the brakes but it made no difference. This spring I re-bled the system and it still felt terrible. i suspected the master given it was original and one of the few parts that hasn't been replaced.
The car is a 68 euro 1750 with single circuit and standing pedals.

I put in a new master I got from CA a couple years ago. On advice from a local mechanic I inspected it before installing to make sure there was no material in the cylinder and the seals were good. it checked out.
Since the old unit fittings were stripped I redid the lines from the reservoir and to the Lockheed booster. What a chore. Two size lines, two fitting and a mix of double flare and bubble flare. Geez.

I bled the system again with my motive pressure bleeder. The sequence is RR, LR, RF, LF but the pedal goes up and down like there is nothing there. I ran out of fluid so I'll try bleeding again tomorrow. May try a manual bleed.

I just don't get it. I don't see any leaks.
 

·
Premium Member
Joined
·
1,334 Posts
The pedal is activating the m/cyl piston and being pushed back by its spring, yes (I.e. the piston isn’t stuck)
You could also try cracking open the hard line exiting the booster to see if there’s any air trapped in there. Put a rag under its nose!
I also like to reverse-bleed from the calliper nipples with a 20cc syringe and some plastic tubing when bleeding isn’t straightforward. I don’t have a power bleeder tho.
Why your soft pedal occurred suddenly? Without visible leaks elsewhere, it’s possible a booster seal has failed and It is leaking into the vacuum chamber.
 

·
Registered
Joined
·
740 Posts
I'd try looking in the vacuum chamber if you can't see where the fluid is going it is collecting somewhere and that would be the first place I'd go to.
If you open it up and it's full you have your culprit. Regards John.
 

·
Registered
Joined
·
961 Posts
Discussion Starter #4
I'll check the booster out. It is a newer unit as the original was seized when I restored the car. I'll block off parts of the system and troubleshoot it. There has to be air or a leak somewhere
 

·
Registered
Joined
·
961 Posts
Discussion Starter #5
OK, yesterday I put a bleeder on the end of the booster and pumped the master until I moved a bunch of clean fluid through it and the booster. Next I made a small line with the end crimped and put this in the end of the booster to see if I could get a hard pedal feel. This worked so I felt good about this part of the circuit. Next I reconnected the line to the end of the booster and manually bled the system with an assistant. The rear was clear but the fronts had more air in them which I bled out - may have come from opening the system at the booster - who knows. After all this I have brakes again. Yeah! Now I wonder if I replaced a good master? I'll rebuild it as a spare but am glad to be out on the road again.
 

·
Registered
Joined
·
740 Posts
Good news
 

·
Registered
Joined
·
961 Posts
Discussion Starter #7
Tip for everyone. The brake fittings on these cars are not all commonly available from your local autoparts store - at least in the U.S. If you are planning a restoration you can get them but for a weekend repair you may want to re-use everything. The 12mm double flare fitting for the master feed line was frozen and rounded off so I cut the line going to it. Once the line was cut I could get a socket over it and the impact wrench was able to break it free. Impact wrenches are really great with stubborn fittings - get one and an impact driver for screws. I was able to tap the old line out using some heat on the fitting. To save the fitting I carefully filed the rounded hex head down from a 12mm to 11mm. Most of the other fittings are 11mm bubble flare so I think I did the next person a favor. I just wanted to share this as I was back up and running with the original part vs. waiting for a new one in the mail. My backup would have been a trip to the local alfa mechanic who usually has these fittings lying around.
 
1 - 7 of 7 Posts
Top