Testing brakes |
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Turbo301
Senior Member Joined: 11-March-2007 Location: London, Ontario Status: Offline Points: 331 |
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Posted: 28-January-2011 at 11:55PM |
This may be a dumb question (most of mine are LOL), but can you test (accurately) drum brakes for functionality, alignment, etc. with the back end in the air and the rear wheel and drum off? I was thinking this would be a good way to see how everything's working back there - have someone depresss the brake pedal as I watch the brake in action), but I didn't want to do it without checking first in case all of my springs go flying without the drum part attached :D.
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1977 Cougar XR7
1980 turbo Trans Am 2009 Pontiac G8 GT |
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Psquare75
Admin Group Member of the Stroker Club Joined: 26-November-2005 Location: United States Status: Offline Points: 4591 |
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I've done this before. Try this
Pull the drum inspect everything. leaks? around the wheel cylinder? greasy? fix that. LOTS of brake cleaner. (I like to have the wheel off, and a small bucket or pan under the backing plate... spray away.. it'll all dribble off into that pan. Get a can of this, or something similar (permatex makes one) Lift the shoes up a bit (like 1/4" or so) from the backing plate. Apply this grease on the contact points for the shoes on the backing plate. Have a friend press the ebrake pedal... does everything move? Good Release it. As for pressing the pedal... Don't slam the pedal, or even press hard. When I do checks like this I will actually do one wheel at a time. Have a friend sit in the car and go SLOW. When you see the shoes move, have him/her stop. That's it. You don't want to go too far as it can damage the wheel cylinders. Do you have a drum brake tool kit? It makes it easier to adjust the shoes for good pedal (rear drums control the pedal height to an extent).
Edited by Psquare75 - 29-January-2011 at 2:06AM |
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Paul
77 XR7 460/C6/3.00:1 *SOLD* 78 XR7 523/C6/3.5:1 79 F100 460/TKO500/3.25:1 'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500 |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6059 |
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the truck safety lane has a brake percentage test, if you can get a read-out, you can tweek the rears by adjustment until they're equal
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Turbo301
Senior Member Joined: 11-March-2007 Location: London, Ontario Status: Offline Points: 331 |
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Thanks for the tips! I don't have a drum brake tool kit, but I was thinking of getting one. So, e-brake and regular brakes can be checked with the car off its wheels, that's good to know. I guess, if I want to do multiple tries, the car should be running to build up hydraulic pressure? Or should the brakes only be applied once, and with the car off?
Thanks, as always, for the great help!
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1977 Cougar XR7
1980 turbo Trans Am 2009 Pontiac G8 GT |
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Psquare75
Admin Group Member of the Stroker Club Joined: 26-November-2005 Location: United States Status: Offline Points: 4591 |
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Get a kit, it's worth it.
The car running has nothing to do with hydraulic pressure for a test like this.. Just do once per wheel and you're fine. Several pumps do nothing for a properly functioning system with no leaks.
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Paul
77 XR7 460/C6/3.00:1 *SOLD* 78 XR7 523/C6/3.5:1 79 F100 460/TKO500/3.25:1 'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500 |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6059 |
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i guess i didn't read the OP very good... all you're gonna do by stepping on the pedal with drum off to see the shoes move is prove that the line is actually connected from the master to the wheel cylinder, it could even have straight air in it and the shoes will move
but, the springs are not all the same so that the Primary shoe moves first. if you step on the pedal far enough to cause the secondary shoe to move you may blow the primary side out of the wheel cylinder before your 'helper' tells you to stop. or both sides
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Turbo301
Senior Member Joined: 11-March-2007 Location: London, Ontario Status: Offline Points: 331 |
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I remember from when I looked at the brakes last that there was no sign of any leak, but the entire insides of the brakes were a muted brown tone from dust generated over decades of use. I'm betting I should probably clean that off with some brake cleaner, eh? Or is it a "if it ain't broke, don't fix it" sort of situation? I definitely want to try and get that one rear brake bled; I couldn't get the bleeder open last year, but this time I'll try really leaning into it. I'll buy a new bleeder for it if I maul the old one... and I guess a new cylinder if I screw that up LOL!
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1977 Cougar XR7
1980 turbo Trans Am 2009 Pontiac G8 GT |
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Psquare75
Admin Group Member of the Stroker Club Joined: 26-November-2005 Location: United States Status: Offline Points: 4591 |
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It was my impression that's all he wanted to see. Turbo, take a pic of your shoes if you want.
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Paul
77 XR7 460/C6/3.00:1 *SOLD* 78 XR7 523/C6/3.5:1 79 F100 460/TKO500/3.25:1 'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500 |
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stanman
Senior Member Joined: 23-March-2007 Location: Nova Scotia, Ca Status: Offline Points: 1432 |
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Yes, brake cleaner will remove all the old brake dust. Wouldn't hurt to spray it, clean a bit with a paint brush or equivalent, then rinse it again. If the bleeder screw is rusted, you should heat it up before you try to turn it. They twist off quite easily, so don't be suprised if it happens. As you said, worst case is you have to buy a wheel cylinder, and they're relatively cheap.
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Turbo301
Senior Member Joined: 11-March-2007 Location: London, Ontario Status: Offline Points: 331 |
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Yeah, I basically just wanted to make sure that everything was moving. And I have to get in there to look at the parking brake anyway!
The car stops well enough that I think the front brakes are okay; and they bled fine when I did them last year. I could be all wet on that, but my suspicion is that the problem's at the back.
I'll take lots of pics, of pretty much everything, in the spring, and let you all weigh in on it! It should be a fun project!
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1977 Cougar XR7
1980 turbo Trans Am 2009 Pontiac G8 GT |
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