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Discussion Starter #1
I have a serious problem with my 1970 GT Jun. The brakes have are not working at all. It started with a longer travel required on the brake pedal to stop and then the pedal now goes to the floor and back again with no braking effect. After checking all the seals in the system there appears to be no leaks, including around the boot seal on the master cylinder. Pumping the pedal has only caused the brake fluid to back up into and over the top of the resivor. Could it be the servo or master cylinder? The mast cylinder is a new one with not much use.

Has anyone else ever had this problem? A few pointers would be helpful.
 

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If you press the brake pedal and up get bubbles in the reservoir, I would check your master. Open one of the brake lines on the master and see if fluid comes out under pressure. I know you mentioned that your master was new, but I have seen aftermarket units fail right after installation. I prefer to use only ATE units.
 

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It certainly sounds like the MC is the problem. If the MC is pumping fluid back into the reservoir I would think that something bad happened to the piston seals between the front and rear sections so that the rear piston is pumping into the front cylinder. In any event, rebuilding a MC is not that tough.

Remove the (4) brake lines and the (2) 13mm nuts and it will pull right out. There is a circlip retainer to remove and then a little compressed air and it should pop out (get ready to catch it if you apply too much). More than likely you will see one or more of the seals (I think there are five?) ripped.

Check the cylinder for any scoring. If it is in good shape, you can order a rebuild kit from IAP or centerline. If scored, your best bet is getting a rebuilt or new MC.

Since you said it is a newer MC, if it is the MC you might want to ask why it failed. If there is crud in the system that led to the failure you probably want to flush the whole system. OTAH, I concur with AndrewG - I have also seen "new" MC's go bad quickly because they were bad to start with.

I would also recommend bopping over to the brakes subsection and doing a search. Papajam and others have some excellent technical write ups on these systems.

Good luck.
 

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Discussion Starter #4
Re:No Brakes!

Thanks for the reply from both of you guys. I will remove and inspect the master cylinder.

The car was inspected by a mechanic doing a MOT test in Britain. They test the strength of the brakes and a government computer does a calculation of the brake strength against the kerb weight. A low braking efficiency and the car fails the test.

In order for the high efficiency the mechanic stomped on the pedal and this caused the failure to begin. How can they do the same brake test on a 37 year old car as a 3 year old car?
 

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You are REALLY lucky that if it is a faulty M/C, that the problem first came to light whilst on the rollers of an MOT station and not on the road or the track!
 

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In order for the high efficiency the mechanic stomped on the pedal and this caused the failure to begin. How can they do the same brake test on a 37 year old car as a 3 year old car?
If you kill yourself (or someone else) the result is the same wathever the age of the car !!!

I mean that hopefully the MC died during the MOT inspection and not on the road. You should be grateful toward the technician who did his job . (My humble opinion)
regards

Sébastien
 

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Alfa Devil I think you have been extremely lucky. That is why they have safety inspections-to identify any safety issues and the braking system is one of the major components.-Go get yourself a Lotto ticket you could have had brake failure on the road.
Sounds like you`ve had an improperly installed seal go, and if it is a newly replaced m/cyl you should have some recourse with your supplier.

Richard J
 

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Discussion Starter #8
The brakes failed 3 days after the test, on the road. If it is the m/c it had only 400 miles under its belt. It has new braking system as it was restored a few years ago. I will keep you posted on the fault.
 
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