Classic cars forum & vehicle restoration.
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fiatguy23
Joined: 20 Mar 2012 Posts: 32 Location: Australia
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Posted: Mon Aug 20, 2012 11:15 am Post subject: Fiat 130 Brake issues |
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Hi all,
So I've recently gone and bought myself ANOTHER project to work on, not that I needed any more work to begin with! It's a 1975 Fiat 130b Saloon. I'm not sure if it is too modern for the likes of this forum but I thought I'd give it a shot anyway.
To the point of this thread, I'm having a few issues with the brakes on the darn thing. I have a few theories, however my experience with "modern" braking set-ups is next to none.
Firstly, when the brakes are applied with the engine running, they feel spongy, and the car doesn't really like to stop in much of a hurry. So I bled the brakes, thinking there was air in the lines. Nup. I can pump the brakes and pressure does build up, the brake pedal goes rock solid which in my understanding is good! However, when the brakes are held on, there is a constant hissing noise from under the dash, I can't here it in the engine bay. After some Googling I have decided that this is not good.
I decided to check the vacuum hose to the intake manifold, and found it to be tired and cracked, which explains a few other running issues I'm having... However I am now in two minds.
Is the poor braking due to the old vacuum line, or is it due to a worn out diaphragm or seal in the booster unit? The constant hissing leaves me tending to think its the later option, as it sounds like its sucking/leaking air into the vacuum chamber. But if the vacuum hose is leaking, then there would be poor suction on the vacuum side of the booster! I should also point out that the engine rpm does increase when the brakes are applied. Possibly a hint to someone more cluey than me on here! Maybe its running too rich, and the extra air its sucking in with the brakes on balances this out?
Cheers, Brodie. |
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victor 101
Joined: 03 Apr 2009 Posts: 446 Location: East Yorkshire
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Posted: Mon Aug 20, 2012 1:44 pm Post subject: |
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Sounds like the servo is loosing vacuum, what happens to the pedal if you pump up hard with engine off, and then start up with your foot still on the pedal?,does the pedal sink a bit? |
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fiatguy23
Joined: 20 Mar 2012 Posts: 32 Location: Australia
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Posted: Tue Aug 21, 2012 12:16 am Post subject: |
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I did a quick test on this this morning before work. It does sink but only a little bit, and not rapidly like modern cars do. I should mention though that it was a cold start, and it runs terrible when cold |
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Farmer John
Joined: 18 Feb 2010 Posts: 181 Location: Manawatu NZ
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Posted: Wed Aug 22, 2012 10:00 pm Post subject: Fiat brake booster |
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Hey Brodie, how are you going with your Fiat brakes? You have probably replaced the vacuum line, any change?
John |
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fiatguy23
Joined: 20 Mar 2012 Posts: 32 Location: Australia
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Posted: Wed Aug 22, 2012 10:51 pm Post subject: |
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Hi John, to be honest I haven't! It's one of these cars where I've got a million different jobs on the go... I've got a spare parts car, I'll get the hose off of that one as its been overhauled mechanically. The problem is, the parts car is parked out in the open, and the weather has been horrible lately! I'll let you know when I do, I may have to replace the booster though, that's what others have suggested
Brodie. |
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fiatguy23
Joined: 20 Mar 2012 Posts: 32 Location: Australia
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Posted: Wed Aug 29, 2012 12:44 am Post subject: |
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So heres a bit of an update. After taking a sicky for the lovely weather we had yesterday, I've made some progress.
Firstly, I swapped the vac hose. Made some improvements but nothing drastic. So, out came the booster. That was full of brake fluid which I figured was deffinately not a good thing! After some googling I concluded that the master cylinder is leaking, and with a quoted $270 au for a rebuild it looks like I need to part with some money. Unfortunately a brand new replacement isn't available.
I've put the booster in from the other car and that seems to be ok. It had fluid in it too but not as much, and I drained it out the best I could.
In other news I found out that the trams was very low on fluid, and at the parts store they said the Borg Warner 3 speed (which is what I have) holds 10 litres!! I know the engine oil is over full so I'm hoping there isn't some major leak between the two units. I can't imagine it would do much good if there were Oh the joys of old cars! |
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