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Discussion Starter #1
Hello,

Last week the brake boosters on my "69" gtv seemed to have given out leaving me with a brake pedal on the ground and a bit of a scare. The brakes have been serviced recently as the car had not been driven much before I purchased it early this year. I replaced the lines, pads, disk and the special "69" style MC. Now that the brake boosters need replacing I am wondering if it might be better to simply modify the brake system with something like the Alfaholics pedal box/dual MC set-up that from what I understand will eliminate the need for the boosters. Sad thing is that I already purchased the expensive MC.

Let me know what you think. Want to keep the car pretty true to period but I am planning to increase the power of the engine a bit upon rebuild so newer styled brakes might not be a bad option.
 

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But Mad North-Northwest
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I can't see how the booster going out can cause a pedal on the ground. That's either a bad MC or a fluid leak somewhere in the system.
 

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Discussion Starter #3
Yeah it is a bit of a mystery to me too. I do not see any signs of leaks so my mechanic is thinking the fluid might have been sucked in by one of the two boosters. I am new to how the whole system works and I have yet to bring the car in so I can not say 100% what is causing the problem. Since the boosters are showing signs of their age and are some of the only parts that have not been replaced they do seem like the could have caused the problem.
 

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Replace the mechanic rather than the boosters........
He doesn't know how they work either !
 

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But Mad North-Northwest
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No, his input is right. If your mechanic thinks that the boosters can cause this problem by "sucking in fluid" he really doesn't know how brakes work.

The boosters may be bad, but even if they fail they won't cause your pedal to go to the floor. And if there's fluid in the boosters, root cause is a failed MC seal, not the boosters.

Unless you misunderstood what your mechanic said, I would suggest finding someone who has more of a clue.
 

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Discussion Starter #7
No, his input is right. If your mechanic thinks that the boosters can cause this problem by "sucking in fluid" he really doesn't know how brakes work.

The boosters may be bad, but even if they fail they won't cause your pedal to go to the floor. And if there's fluid in the boosters, root cause is a failed MC seal, not the boosters.

Unless you misunderstood what your mechanic said, I would suggest finding someone who has more of a clue.
Hi guys, I really appreciate the input. As I mentioned, I am new to this so can not even start to say what is causing the problem. My mechanic is one of the most well respected Alfa mechanics in California so I would think it is more possible that I misunderstood him than that he does not know how the system works. I simply want dependable brakes so I can drive my great car again:)
 

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Actually....
replacing all parts until finding the defective one is a time honored Alfa tradition !

Carry on !

Next question.....

Why are Alfas so expensive to repair ??
 

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Discussion Starter #9
No, his input is right. If your mechanic thinks that the boosters can cause this problem by "sucking in fluid" he really doesn't know how brakes work.

The boosters may be bad, but even if they fail they won't cause your pedal to go to the floor. And if there's fluid in the boosters, root cause is a failed MC seal, not the boosters.

Unless you misunderstood what your mechanic said, I would suggest finding someone who has more of a clue.
Actually....
replacing all parts until finding the defective one is a time honored Alfa tradition !

Carry on !

Next question.....

Why are Alfas so expensive to repair ??
I really do not see how your comments are helpful.. I am simply looking for information since I am new to this car. Sorry if my questions are bothering you in some way.
 

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I am wondering if it might be better to simply modify the brake system with something like the Alfaholics pedal box/dual MC set-up that from what I understand will eliminate the need for the boosters.
No, that's not a good alternative. It would be more work to do the cutting, welding, brake line fabrication, etc. required to make that modification than it will be to simply fix your brakes.

And unless Alfaholics have solved that pesky "perpetual motion" problem, their system doesn't eliminate the need for the boosters - it just substitutes longer pedal travel (to achieve the same pedal force), or greater pedal pressure (to achieve the same pedal throw).

Gubi said:
I can't see how the booster going out can cause a pedal on the ground. That's either a bad MC or a fluid leak somewhere in the system.
Yes, but couldn't that "fluid leak somewhere in the system" be in the booster? E.g., the booster is leaking fluid into its vacuum side and that fluid is getting drawn into the intake manifold where it is burned along with the fuel/air? I know this is a problem with the later, hanging pedal system. I've never heard of it happening with the standing pedal system, but don't see why it couldn't.
 

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But Mad North-Northwest
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Yes, but couldn't that "fluid leak somewhere in the system" be in the booster? E.g., the booster is leaking fluid into its vacuum side and that fluid is getting drawn into the intake manifold where it is burned along with the fuel/air? I know this is a problem with the later, hanging pedal system. I've never heard of it happening with the standing pedal system, but don't see why it couldn't.
Yes, the MC could leak into the booster (at least, on the hanging pedal cars. I think on the '69 with the remote booster this is more difficult). However, if that is happening then the MC is bad, not the booster. Just replacing the booster won't help.

Also, that sort of a leak is on the non-pressurized side of the MC, so it won't cause pedal-to-the-floor unless you've lost enough fluid to empty the reservoir.
 

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Discussion Starter #12
Yes, the MC could leak into the booster (at least, on the hanging pedal cars. I think on the '69 with the remote booster this is more difficult). However, if that is happening then the MC is bad, not the booster. Just replacing the booster won't help.

Also, that sort of a leak is on the non-pressurized side of the MC, so it won't cause pedal-to-the-floor unless you've lost enough fluid to empty the reservoir.
The large reservoir is empty. Strange thing is that I do not see any signs of a leak. Will have to take it in for real inspection.
 

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Yes, the MC could leak into the booster (at least, on the hanging pedal cars. I think on the '69 with the remote booster this is more difficult). However, if that is happening then the MC is bad, not the booster. Just replacing the booster won't help.
Gubi: Is that what you meant to type? My suspicion is that odanota's booster has an internal leak, allowing fluid to get drawn into its vacuum side. Under that scenario, it is the booster that would be bad, while the MC is probably be OK.

My clues are that odanota reported: " leaving me with a brake pedal on the ground", which I interpreted as losing so much fluid that his pedal went to the floor. He went on to say: "Strange thing is that I do not see any signs of a leak". It is tough to leak a whole canister of brake fluid without leaving any evidence, but when it gets burned the only hint is exhaust smoke while braking.
 

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But Mad North-Northwest
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It's true on the hanging pedal cars. In thinking about it, though, I remembered that the '69 has those goofy remote boosters and the floor MC. So for this particular car the booster is on the pressurized side of the braking system and it's possible that the seal in the booster could cause the fluid leak, which would cause the low reservoir lever, which could cause the failed brakes. So sounds like I'm the one who made a mistake.
 

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Discussion Starter #15
No, that's not a good alternative. It would be more work to do the cutting, welding, brake line fabrication, etc. required to make that modification than it will be to simply fix your brakes.

And unless Alfaholics have solved that pesky "perpetual motion" problem, their system doesn't eliminate the need for the boosters - it just substitutes longer pedal travel (to achieve the same pedal force), or greater pedal pressure (to achieve the same pedal throw).



Yes, but couldn't that "fluid leak somewhere in the system" be in the booster? E.g., the booster is leaking fluid into its vacuum side and that fluid is getting drawn into the intake manifold where it is burned along with the fuel/air? I know this is a problem with the later, hanging pedal system. I've never heard of it happening with the standing pedal system, but don't see why it couldn't.
Thanks for the help Jay
 

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Thanks for the help Jay
Well, thank me when it works! No one can diagnose a problem remotely with 100% accuracy. Heck, it's hard enough when you can see and feel the car.

However, I am confident that my advice to repair rather than modify the braking system is good. If you had it stripped to its shell and were building a full-on race car, then modifying the braking system would be part of the "fun". But if your problem is just a leaking booster, changing the all of the pedal - master cylinder - brake line components would be like doing an engine swap just because your plugs were fouled.
 
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