Disc vs. Drum Brakes - To Upgrade or Not - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 05-22-2006, 02:08 PM   #1
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Default Disc vs. Drum Brakes - To Upgrade or Not

Hey trying to help the ongoing discussion along here by moving it from Bill'* good brake bleeding thread to its own. I've cut and pasted a bunch of what was said there into my post here (below) without trying to discriminate between posters, but also without too much repetition. Some item annotated for brevity...

Quote:
Originally Posted by Greyhare
Where brake upgrades make a difference is repeated hard use. Most stock brakes are designed for one or two hard stops, after that they start to get too hot and stopping distances get longer. Larger rotors (more heat capacity), better pads (more heat tolerance), and ducting (better heat dissipation) allow the brakes to be used harder before fading. Brake upgrades can make a big difference in feel and ease of modulation (ability to keep on the edge of wheel lock up).
Quote:
Originally Posted by Mr Bean
larger rotors require a different caliper setup...what is available for the 96-99?
Quote:
Originally Posted by BillBoost37
There is currently nothing available to upgrade to. Therefore making the best of the system we have is where I headed.
Quote:
Originally Posted by toastedoats
nothing directly cross compatible, but i am pretty sure that f-body brakes could be made to work, as they are on w-bodys.

for you pre-99 guys - GET REAR DISC
Quote:
Originally Posted by marauder307
While my car is still new (2005 GXP with only about 1200 miles) this will be an issue at some point in time. I've noticed that this thread seems to deal only with the older models equipped with frt disc/rear drum brakes; what about us Bonnie operators with the full 4-wheel disc setup?

Has anybody seen any upgrades out there that would take care of the GXPs?
Quote:
Originally Posted by Greyhare
The only advantages of rear disc brakes are:
1) Better self cleaning. (great for going mudding)
2) Easier to inspect. (are you that lazy? I am but that'* not the point)
3) Easier maintenance. (see #2)
4) They look cooler. (Not an advantage but, they look cool)
5) No special actions to activate the self adjusters. (see #2)

Disadvantages:
1) Often more expensive. (most of us are on a budget)
2) Retracting the self adjusting piston is a PIA. (Some what lessens 3# above)

Reality is:
1) That most people will never be able to tell the difference between rear discs and properly adjusted drums.
2) Rear discs won't stop the car any better that properly adjusted drums.
3) Car makers put them on as a marketing tool. (We think they are better because the car companies told us they are.
Quote:
Originally Posted by daman
RE: The only advantages of rear disc brakes are:
You forgot one the best one;

they break better than drums
Quote:
Originally Posted by toastedoats
how many people regularly have their brakes adjusted?
Quote:
Originally Posted by Greyhare
Not many. That is the biggest reason most people think rear discs work better than drums.
Quote:
Originally Posted by daman
I know the diff. between the two,, and four wheel disk will always
out perform 2 wheel period ! ! !,,, i've been around a wile i've diven them all ,,i have both.

rear wheel disk always when breaking perfomance is needed
Quote:
Originally Posted by Logan
Yes and no. You would get increased breaking performance with discs. Since they are more exposed to the elements, after a long session of braking and then splashing through a puddle, you would be more prone to your discs breaking. Spider cracks may be present which would cause the discs to break creating a safety hazard.

Although I am no expert (neither are you apparently), the only advantages I can find to having REAR discs is that they are lighter, self cleaning, and they disappate heat better. They may be better for long hills, but for the random panic stop there appears that there will be minimal differences. Remember that this is for PROPERLY ADJUSTED drums.

I, like you and probably every other forum member, have driven cars with drums and discs in the back. Unless you have driven a car with drums, and then converted it to discs, you comparision is going to be apples to oranges. My cavi (with drums) stops better than my bonneville (with drums). Why? Vehicle weight. My mom'* Sante Fe (4-wheel discs, lighter than the bville) stops better than my bonneville, but won't even come close to my cavi.

... I say with confidence that the braking perfomance is minimal in a disc conversion (for our purposes), although the breaking performance increases because of spider cracks being possible on the back brakes too.
All right...........GO!
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Old 05-22-2006, 02:32 PM   #2
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Not for me. I chose to upgrade to premium rotors and pads up front, and new drums and premium shoes in back.

To the best of my knowledge, there still is no kit for the rear of an 87-99, and nobody to the best of my knowledge has attempted to fab one up or found compatible components.
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Old 05-22-2006, 02:37 PM   #3
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As Willwren said..it'* moot because there is nothing available.

Now...if someone were to start pulling things apart and measuring..maybe we could find a donor vehicle, although the speed sensors might be off and the ABS hardware on our cars was probably designed for drum, not disc and may not work well.
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Old 05-22-2006, 02:40 PM   #4
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Quote:
Originally Posted by willwren
Not for me. I chose to upgrade to premium rotors and pads up front, and new drums and premium shoes in back.

To the best of my knowledge, there still is no kit for the rear of an 87-99, and nobody to the best of my knowledge has attempted to fab one up or found compatible components.
And I take it you don't have any issues with stopping, even at the track?
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Old 05-22-2006, 02:54 PM   #5
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My car stops extremely well with the items I've done (Similar to Willwren) and I couldn't imagine much more could be gained by having rear disc'*.

1993 was wtih me on the test run of the brakes one evening and the car amazed me. All systems are up to part though.

Front'* have ceramic and good rotors
Rears are well adjusted, ceramic drum shoes and good drums
Fluid is clean and fresh synthetic

The car nosedives as a matter of physics and the back end becomes lighter than it already is.... the majority of the braking is on the fronts at that point.
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Old 05-22-2006, 02:54 PM   #6
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Quote:
Originally Posted by lash
Quote:
Originally Posted by willwren
Not for me. I chose to upgrade to premium rotors and pads up front, and new drums and premium shoes in back.

To the best of my knowledge, there still is no kit for the rear of an 87-99, and nobody to the best of my knowledge has attempted to fab one up or found compatible components.
And I take it you don't have any issues with stopping, even at the track?
I warped the stock rotors. I then warped 2 consecutive sets of RSM'*. I recently warped my RF Powerslot (mildly).

2 days ago, I had my rotors turned, and upgraded my rear drums and shoes. I've never had any complaints about the rate of braking, only the warpage. I suspect I have a hub/caliper issue on the RF. I upgraded the rears to take some of the braking load off the front.
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Old 05-22-2006, 03:01 PM   #7
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Again I am no expert. At this point in my life I don't have the time or money to even look into fabing my own stuff.

With that said, how much different are our rear wheels from the front? Clearly a caliper bracket would have to be fabbed, along with the plumbing. Both the front and the rear use independant suspention. With our cars being sorta (I use sorta loosely) for rear steer, I would imagine those parts are similar as well.

I don't even own a bonneville, but what would be necessary to change?

-Rotors that would fit
-Calipers that would fit
-Fab a bracket
-Change the Plumbing
-Check to see how the EBCM reacts
-I'm guessing the proportioner valve (i think that is what it is called)

Some of these parts (I'm thinking brake control module and proportioner valve atlest) could come off of a W-Body.

But then we end up back around at functionality and practicality. Worth the time and money? Probably not since I firmly believe there is not that big of a difference between a solid set of drums than a set of discs on the REAR.
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Old 05-22-2006, 03:16 PM   #8
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Quote:
Originally Posted by Logan
But then we end up back around at functionality and practicality. Worth the time and money? Probably not since I firmly believe there is not that big of a difference between a solid set of drums than a set of discs on the REAR.
Particularly since, as stated above, most of the weight shifts to the front upon hard braking anyway.
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Old 05-22-2006, 03:50 PM   #9
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I've read as much as 90%. True?
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Old 05-23-2006, 01:38 PM   #10
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Pesonally the 95 SSE I had stopped better than my GXP with 4 wheel discs.
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