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Discussion Starter #1
hello,

i am working on a 2600 sprint to make it roadworthy again. Engine is running (but with white smoke - due to longstanding?) and now we are working on the brakes.

Front has new caliper set. Brake master cilinder has been checked and is good. Air is out of the lines. But now during a small testdrive the left front brake was stuck and did not release. Brake pedal only came slow up again. Anyone an idea what is the problem. Can it be the brake servo unit?

hope to get some information
 

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Yes, could be brake booster (see this thread for more info). A failed brake booster may also cause the engine to smoke (when brake fluid gets sucked into the last two cylinders through the vaccuum hose. This is easy to check: Disconnect the vacuum hose (and plug it so that no air gets sucked into the engine) -- then see if the engine behaves differently.

Another reason for stuck brakes --- especially when it's only one side -- may be brake rubber hoses, which have a tendency to collapse internally and lock up the calipers. I would suggest to replace them all.

If the master cylinder has been checked and is OK, the pedals returning slowly may is most likely due to friction in the pedal bearings (grease getting sticky) or a weak spring.
 

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Discussion Starter #3
brake problems

hello Ruedi,

thanks for the answer. i will let you know the results soon. there was also a lot of old fluid oil in the brake booster. also cleaned the booster now.

so lets see.

thanks,
john
 

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Might be related to use of American type brake fluid

With all due respect, in the years I have tried to rework Alfa car brakes when others have found them sticky, one constant problem stands out. The previous owner was careless as to what brake fluid was used. I do know that using Bendix or Prestone is the quick kiss of death. I have ALWAYS used Castrol LMA because the Girling rubber pieces last longer and don't start going gooey immediately and start sticking. Initially when the factory gave its information as to what brake fluid to use with the then "new" 2600 disk brakes, it specified we were to use "Girling Amber" (as compared to the previous "Girling crimson" for 102/2000 vehicles). But one cannot get either Crimson or Amber, and the Castrol LMA has always worked for me.

However, I once came across a 2600 sprint that had been sitting on the dock for over ten years. It took a bit to start, but I was amazed that the brakes and clutch were still working perfectly. I asked the previous owner what he had used. He said that since he operated a wharehouse on the dock with Hyster forklifts he had started using the green silicon he used in them after the brakes on the 2600 had gone bad years before. But I have never had the guts to try it. I wish some others might comment on their use of silicon based (i.e. Hyster?) brake fluid if they have experience. I know one cannot mix and one must start with all new seals and fluid on a changeover. In Seattle it does rain a lot, and even LMA gathers moisture and eventually becomes bad. I've often wondered if I shouldn't have tried switching years ago.
 

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Jay,

I've driven a couple of cars (none owned by me) that used silicone. I wouldn't recommend it. The first noticeable problem is a slightly more spongy feel. This would not be a plus on our drum-type, unboosted brakes. The other is that silicone does not dissolve water. That does not mean water does not get into the system, just that it puddles in low spots in the system rather than get dispersed over time. One can always change to fresh LMA every year or so, but replacing silicone can leave little globs of water at various low points, causing localized corrosion.
 

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Well guys, I am in wet Florida and when I restored my 2600 Spider, I was in even wetter South Florida. At one time, I had used silicone brake fluid in my 69 Porsche, which does not have boosted brakes. After a short time, I changed back to regular DOT 3 because I did not like the feel. Remember that changing to or from silicone is a big undertaking and should be done only after all components have been overhauled and everything completely purged. Even considering that, I decided to use silicone fluid in the Alfa, hoping that the vacuum boosted brakes would mask the spongy brake feel. That was in 2003 and I have been happy with the result. This car sits for long periods and I have not done a single thing to the brakes. There is, sometimes, a problem with bleeding the brakes and, because of that, I use a pressure bleeder which works very well.
Larry Bono
 

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Pressurised brake bleeder

Serge

I have used the "junior" version of this Gunson unit for many years - it uses the preesure from a tyre rather than a pump system.

It works well and is a one man system.

The major problem I have with this system is that it relies on a connection onto the top of the brake master cylinder. A standard brake master cylinder screw cap with an air /brake fluild pipe inserted into it.


I have always have problems achieving a good seal , normally brake fluid leaks out as I try to use it. The first warning is do not use too much pressure as it will casue more leakage. So a 30 psi tyre is a no go , it only needs a few psi to push the brake fluif through , so you must deflate the tyre if you use the cheaper version or not over pressurise on this expensive version youa re looking at.

However, with your near concourse car , I wouldn't risk spraying brake fluid around. I woiuld try the convetional two man , down /up method of blleeding first.

rgds

Ian
 

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My pressure bleeder is a home-made unit which uses air from an air compressor and pressurizes the fluid reservoir through a sealed cap held tight with a chain. It simply applies pressure to the reservoir and does not contain fluid, so it must be removed periodically to add more fluid. The pressure is limited to about 12 psi (pounds per square inch). I have two filters in the air line to try to absorb as much moisture as possible. With my wife operating the brake pedal, I was never able to get them bled but with this pressure bleeder it is a one-man job and has worked very well and takes very little time. Since these pictures were taken, I have modified the hose to include quick-connect fittings which allows fast and easy removal for topping up the reservoir.
Larry Bono
 

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The major problem I have with this system is that it relies on a connection onto the top of the brake master cylinder. A standard brake master cylinder screw cap with an air /brake fluild pipe inserted into it. I have always have problems achieving a good seal , normally brake fluid leaks out as I try to use it.
Ian
Boy have we hit common ground here! I have tried a lot of different methods to bleed brakes and have a fairly expensive 'Blue Point' brake bleeder and still am not 100% satisfied (more like 80% for the reasons previously mentioned). I have had better luck lately by first allowing the fluid to just naturally drain (gravity bleeding) from the furthest bleed nipple, then the next furthest until each wheel cylinder has been bled and closed. It takes a while but not really much brake fluid.

Jay said:
I have ALWAYS used Castrol LMA... has always worked for me.
But I have never had the guts to try....synthetic. I've often wondered if I shouldn't have tried switching years ago.


Jay, I probably got it from you 25 years ago but I always use Castrol LMA too and I suspect that you have been using synthetic brake fluid without knowing it; like me! When I had the brakes 'brass sleeved' by White Post I searched all over for the Castrol LMA. Apparently it has been discontinued as well. I finally found a quart container at Pep Boys that was well hidden behind all the other brake fluid containers. I believe it said in small print synthetic but everything else looked good & right so I got it. When I got home I compared the half dozen older Castrol LMA containers that I had and they all said "compatible with conventional brake fluid" but they left out the part about it being synthetic.:cursing: If it was conventional brake fluid they would not need to state that it was compatible with itself or would they?

Next time I do brakes, I intend to try Don's old fashioned pump oil can method attached with clear tubing to the brake nipple to force the air back up and out of the system the way God intended bubbles to go.:wink2:
Mark
 

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The Castrol LMA brake fluid now says "synthetic" but, remember this is conventional DOT 3/DOT 4 fluid! It is what I have used in my Porsches and Alfas since the 1960s. In my previous posts, we were discussing silicone brake fluid, DOT 5. Be sure you do not confuse the two; They ARE NOT compatible. Bleeding the silicone fluid is sometimes more difficult than conventional fluid and that is where the pressure bleeder makes it easy.
Larry Bono
 

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I just rebuilt the right caliper on my 1967 Super Cub on Wipline amphibious floats. Used the pump can connected to the caliper bleed screw. Just imagine the amount of bent tubing, hoses, and fittings to connect the caliper to the master cylinder, as it wanders through a float, up the gear leg, etc. lots of places for bubbles to collect.

Took one try, and about 45 seconds. Solid brake pedal.

Never failed on any car, and an oil squirt can is cheap.
 

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Hi everybody and thank you for your answer and pictures.

Don, could you please give us more detail about your method ?
 
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