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Old 02-26-07, 09:31PM   #1
Rons67
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Default Who still has drum brakes up front?

I've been running the same drum brake system on the front that I bought my car with over 20 years ago. They seem to work fine, and there is no problem with slowing down at the end of the 1/4 mile at 137 mph. I replace the shoes every season & the drums are new. My concern with changing over is the addition of extra weight with rotors & calipers. Do manual discs stop better than manual drums?
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Old 02-26-07, 09:59PM   #2
Gach
 
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Default Re: Who still has drum brakes up front?

Definitely disc's stop better than manual with drums. Had drums on my 68 Goat. The 70 has Disc's. But hey if your not having problems stopping I leave the drums. It's a real bitch to switch over and unless you get it right it'll stop worse. They guy who bought my 68 changed over to disc and it took him a while to get it right, can't remember all the details. But I can tell you I drove it after he made the change over and it wasn't right I had a hard time stopping at 133 mph. Unless you have some one who did it with good success and knows all the ins and out of the complete set up I wouldn't do it.
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Old 02-26-07, 10:11PM   #3
Rons67
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Default Re: Who still has drum brakes up front?

I was told the front lines for the discs should be a larger diameter? I have a complete disc setup from a cutlass, including the master cylinder to spindles in my garage.
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Old 02-26-07, 10:32PM   #4
Gach
 
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Default Re: Who still has drum brakes up front?

Quote:
Originally Posted by Rons67 View Post
I was told the front lines for the discs should be a larger diameter? I have a complete disc setup from a cutlass, including the master cylinder to spindles in my garage.
I think he had trouble with the perposching ( sp ) valve. Yeah the lines are bigger to the disc's front, the front gets more pressure then the back brakes. If I remember correctly he was trying to use the block on the fire wall, that wasn't adjustable.
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Old 02-26-07, 10:35PM   #5
Rons67
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Default Re: Who still has drum brakes up front?

The proportioning valve is different. The guy who sold me mine gave that to me also.
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Old 02-26-07, 10:44PM   #6
INJUNTOM
 
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Default Re: Who still has drum brakes up front?

Simple swap.

One thing to consider is there is less drag with the drums....disc brakes drag the rotor. drums have springs that pull the shoes back away from the drums.

....which is the reason that you can't use a drum master with disc brakes - the drums have a "residual pressure valve", which holds about 15 psi on the system at all times to compensate for the spring pressure.
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Old 02-26-07, 10:45PM   #7
Gach
 
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Default Re: Who still has drum brakes up front?

Yeah that was his problem, cool sounds like you have it all science out, now all you have to do it get up the energy to do it.:Gach2
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Old 02-26-07, 10:49PM   #8
Rons67
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Default Re: Who still has drum brakes up front?

I bought the complete setup 5 years ago & it still lays under my bench in the garage. Maybe one day! I originally bought it for my 68 firebird street car, but who knows where it will end up.
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Old 02-26-07, 10:53PM   #9
Gach
 
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Default Re: Who still has drum brakes up front?

You sound like me...LOL Hey there's always s.hit going on, some day you'll decide and then jump right on it.
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Old 02-26-07, 10:58PM   #10
INJUNTOM
 
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Default Re: Who still has drum brakes up front?

The last time around it was real easy - found a car at pick n pull that had recent pads and rotors, so i was able to toss the whole assy onto my wife's bird in a couple hours.

when you go for the master, ask for one for a '70 Chevelle with MANUAL discs if that's what you want. That's what i used on the Bird because i had it on the shelf waiting to go on the LeMans. I had planned to put a power setup on it for her later if it was too hard to stop, but she said it was fine, and to leave it alone.

I ended up going with 4 wheel discs on the LeMans, which meant that i needed a 4 wheel disc master - a mid 70s vette uses one, and that's what i used.
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Old 02-26-07, 10:59PM   #11
INJUNTOM
 
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Default Re: Who still has drum brakes up front?

That's a swap that i shyed away from for years, but it's really no big deal.

my first swap was putting the 2nd gen F-body setup on my Tempest conv. back when not many people had heard of it. a little more complicated.
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Old 02-26-07, 11:01PM   #12
Rons67
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Default Re: Who still has drum brakes up front?

The setup I have has a master cylinder with the booster. Is there a difference in master cylinders?
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Old 02-26-07, 11:11PM   #13
INJUNTOM
 
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Default Re: Who still has drum brakes up front?

Quote:
Originally Posted by Rons67 View Post
The setup I have has a master cylinder with the booster. Is there a difference in master cylinders?
yep, you have power and manual disc, power and manual drum, and power and manual 4 wheel disc.

you may get away with different combos, and i have in the past by just using whatever i had lying around, but one thing you will need to make sure of is that you aren't using a drum master on disc brakes - the residual pressure valve will put the 15 psi of pressure on the disc pads, causing over heating, warped rotors, and frozen calipers. My buddy had been given a drum master for his '69 Bird by Kragan's, and it even went so far as to start eating his tires in the front. badly warped his rotors, and calipers.

He had it jacked up showing me, and when i couldn't turn the rotor by hand, i looked at his master, and knew right away that it was a drum master....the disc is the one that has the bigger resorvoir in the front - because of the disc caliper displacing more fluid than a drum wheel cylinder.

Kragen didn't even show a listing for discs on the '69 Bird then.

When i went with him to explain it to them, they fell over themselves to get him all new parts, and had him bring in the receipt for the tires.
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Old 02-26-07, 11:21PM   #14
Rons67
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Default Re: Who still has drum brakes up front?

That's good to know! I have a friend that just changed over, but never changed the master cylinder. He hasn't even fired it up yet. I'll let him know.
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Old 08-13-12, 10:23PM   #15
jenwhite
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Default

Howdy… just came across on this thread… wondering if anyone could suggest a good brake rotor for my pontiac g8 ’09 im thinkin to replace it since I want to have upgrade my brake system. Thank you
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