Callipers Sucking Air!
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,736
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From: Stockton Ca
Callipers Sucking Air!
My 74 has rebuilt budget callipers that are worn. The system is sucking air and has to be bled regularly. This problem is getting worse. My question is: Can I fix the leaking callipers for cheap or should I scrap the old ones and get out my New VB&P catalog? I would like to upgrade at this time but funds are very limited. TIA
Rick
Rick
Tech Contributor
Joined: Aug 1999
Posts: 15,124
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From: Connecticut, USA
Re: Callipers Sucking Air! (Taijutsu)
are the calipers SS or stock cast iron? If stock then get SS lined calipers. You must check the rotor runout no matter what you do to see that it's under .005" TRO. If over then you might get by with O ring calipers but I would rather fix the surce of the problem which usually is runout.
Check the archives there is a TON of info on brakes.
Gary
Check the archives there is a TON of info on brakes.
Gary
Safety Car
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From: St. Charles IL
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Re: Callipers Sucking Air! (Taijutsu)
:iagree: :iagree: :iagree: Doesn't matter what kind of calipers you get, if you have runout you will have problems. :yesnod:
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,736
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From: Stockton Ca
Re: Callipers Sucking Air! (gtr1999)
I thought about runout. To check it would be as much work as changing them I think. I feel it is the calliper because they were the cheapest rebuilt ones I could find. They have over 70K on them. This sucking air has just started and the miles between bleedings is getting less. I am broke but don'ty want to take any chances. Comments? TIA
Rick
Rick
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From: All humans are vermin in the eyes of Guru VA
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Re: Callipers Sucking Air! (Taijutsu)
My brakes only suck air when I drive so I think that its a runout issue. I am going to replace all the wheel bearings and get things all lined up the best I can.
Safety Car
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From: St. Charles IL
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Re: Callipers Sucking Air! (Guru_4_hire)
Why not just check the run out first? It's not a tough job. If you find a rotor with excessive runout, pull that rotor and see if the spindle runout is similar. I had 1 bent spindle, apparently caused by an accident the previous owner had and it destroyed a caliper within 200 miles. Bearings usually won't cause a runout problem unless they are really fried.
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From: Lenoir City Tennessee
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Re: Callipers Sucking Air! (Big Fish)
If you already have rebuilt calipers on your car, they should be SS sleeved. Go ahead and take one off and pull it apart and see. If it is SS, you can order the O-Ring kit from Vette Brakes and install them in your calipers. This kit, coupled with setting runout should have you set up for a long time. :thumbs:
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,736
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From: Stockton Ca
Is there an EASY way to measure runout? I do not have a dial indicator or any other fine measuring device. Is there a way I can do this in the driveway? I would hate to change the callipers just to have the same problem. HELP! TIA
Rick
Rick
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Melting Slicks
Joined: Oct 2001
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From: Halifax, Nova Scotia, Canada
Re: (Taijutsu)
I support the runout suggestion. Calipers cannot cause air to be introduced into the system.
Not sure about your part of the world, however, here you can buy an acceptable dial indicator for about $ 35.00 cdn.
That's about $ 1.79 US.
Sure is a lot cheaper than buying calipers.
Not sure about your part of the world, however, here you can buy an acceptable dial indicator for about $ 35.00 cdn.
That's about $ 1.79 US.
Sure is a lot cheaper than buying calipers.
Race Director
Joined: May 2002
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From: Check this riff........
Re: (Barry's70LT1)
I support the runout suggestion. Calipers cannot cause air to be introduced into the system.
Not sure about your part of the world, however, here you can buy an acceptable dial indicator for about $ 35.00 cdn.
That's about $ 1.79 US.
Sure is a lot cheaper than buying calipers.
Not sure about your part of the world, however, here you can buy an acceptable dial indicator for about $ 35.00 cdn.
That's about $ 1.79 US.
Sure is a lot cheaper than buying calipers.
Tech Contributor
Joined: Aug 1999
Posts: 15,124
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From: Connecticut, USA
Re: (Taijutsu)
No other way to get accurate results other then using a dial indicator. Check with http://www.MSCdirect.com for a decent 1" indicator and mag base. You should isolate the rotor too, disconnect the 1/2 shaf tnad pull the caliper up out of the way.Then you're only movinghte rotor and bearings less chance of a false reading. You must have the base and indicator tight so there's no movement. I use a "C" clamp on the base to be sure it's not moving around. Are the rivets still in the rotor/spindles? If so then you may be in luck,if not then it's anybodys guess as to if they were ever turned. The front are easier and you can true them in a brake lathe if you find a good operator who knows how to read a caliper or micrometer. I wouldn't buy calipers until you know the runout. You may need both but it's possible you only need a true rotor(s).
Gary
Gary
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From: St. Charles IL
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Re: (Taijutsu)
As others mentioned, they are not all that expensive. Sometimes you can get really good deals at flea markets. You could also take your car to a shop that does brakes and pay a small service charge to have the runout checked.
Race Director
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From: Waterloo ontario Canada
Re: Callipers Sucking Air! (Taijutsu)
The lip seal in a caliper is designed for .010 flex maximum. Any movement beyond this amount and they suck air.
The bearings must be properly adjusted before taking runout readings. The rear bearings are within specs with up to .008 free play and that leaves only .002 for runout.
If you have a bad rotor new calipers won't help it.
So do it right , buy a cheap dial indicator and start checking and shimming.
The bearings must be properly adjusted before taking runout readings. The rear bearings are within specs with up to .008 free play and that leaves only .002 for runout.
If you have a bad rotor new calipers won't help it.
So do it right , buy a cheap dial indicator and start checking and shimming.