Rear Drum vs. Rear Disc - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bob Moore · 10-24-2006, 10:26 PM

Working on a SWB 1/2T that has 5lug discs upfront. I have a 5lug 12 bolt rear axle. My question is Drum Brakes or Disc Brakes?

I have seen several 73-87 Chevy truck/or van rear axles with bigger brakes than mine. Mine are the standard 2" wide shoes. The bigger ones look like 2 1/2"(did not have a ruler). Will these fit my axle? I understand the width has to come from somewhere - are the backing plates tucked in or what? Is the axle housing and therefore the axle shaft a completely different animal?

I would use the entire brake from backing plate to drum.

Or------

Should I go discs in the back?

Has anybody upgraded their rear brakes to the larger drums?

TIA - Bob

powell72 · 10-24-2006, 11:06 PM

You only need from the backing plate out for the bigger rear drums, 71-72's had them also, there is no width issue with them. I'm not sure if rear discs will stop any better than correctly adjusted big drums. I am doing a rear disc conversion though, mainly for the "wow" factor, not because I feel like I need them.

Bob Moore · 10-24-2006, 11:15 PM

Chris - That is exactly my thought also.

Werewolf · 10-25-2006, 07:07 AM

It should be noted .. just because I feel like noting it .. that Chevrolet has abandoned rear discs on the current model year trucks. They've gone back to drums. I don't recall the exact reason, although I do think it was a performance issue. That's not to say rear discs suck. When it comes to you and your truck, really, the biggest factor is, how much work do you want to do and how much money do you want to spend?

kbs71 · 10-25-2006, 08:42 AM

If you think about it, drums actually have an advantage over discs. there's probally 4 to 6 times as much surface area diffrence between the two. Why do you think 18 wheelers stayed with drums. Cosmetically and price wise it was cheaper for the OEM's to use calipers than drums.

cableguy0 · 10-25-2006, 08:56 AM

the main factor is that drums do not stay adjusted for very long. you have to adjust them. everytime you hit the pedal they will work a little bit different. with disks they are self adjusting and its always going to stop exactly the same. disks are more efficient. drums trap heat and gas between the shoe and drum which makes them fade out quickly and become useless.disks vent a ton better because they arent enclosed and get a lot more air flow.

67ChevyRedneck · 10-25-2006, 09:14 AM

Quote:

Originally Posted by Werewolf

It should be noted .. just because I feel like noting it .. that Chevrolet has abandoned rear discs on the current model year trucks. They've gone back to drums. I don't recall the exact reason, although I do think it was a performance issue. That's not to say rear discs suck. When it comes to you and your truck, really, the biggest factor is, how much work do you want to do and how much money do you want to spend?

They had issues with the E-brakes and the calipers staying adjusted. I think they dropped them in '01 or '02 BUT the '07 trucks will have rear disks.

junkyardjohn · 10-25-2006, 09:23 AM

Quote:

Originally Posted by Bob Moore

Working on a SWB 1/2T that has 5lug discs upfront. I have a 5lug 12 bolt rear axle. My question is Drum Brakes or Disc Brakes?

I have seen several 73-87 Chevy truck/or van rear axles with bigger brakes than mine. Mine are the standard 2" wide shoes. The bigger ones look like 2 1/2"(did not have a ruler). Will these fit my axle? I understand the width has to come from somewhere - are the backing plates tucked in or what? Is the axle housing and therefore the axle shaft a completely different animal?

I would use the entire brake from backing plate to drum.

Or------

Should I go discs in the back?

Has anybody upgraded their rear brakes to the larger drums?

TIA - Bob

BOB.. YES I'VE DONE IT WITH THE REAR BRAKE ASSY. OUT OF A 75. THEY ARE 2 1/2" INSTEAD OF TWO INCH. YOU NEED EVERTHING TO & INCLUDING THE BACKING PLATES. THEY HAVE 25% MORE BRAKING AREA & SEEM TO WORK NOTICABLY BETTER. I HAVE NEVER SEEN THEM ON A 71 OR 72 FROM THE FACTORY THAT WAY. I'D KINDA LIKE TO SEE SOME PROOF OR DOCUMENTATION. I LEARN SOMETHING ABOUT THESE OLD TRUCKS EVERYDAY, BUT RUMORS ABOUND & TILL I SEE PROOF... IT'S STILL A RUMOR. (NO OFFENCE INTENDED)
ANOTHER OPTION IS A COMPLETE REAR END... SAY... A REAR OUT OF A 75 LINCOLN MKIV. IT'S A 9" THATS WITH IN AN INCH OF OURS, HAD FACTORY DISC.S & HAS THE SAME 5 ON 5 BOLTPATTERN AS 71 -72 TRUCKS. JOHN

glock35ipsc · 10-25-2006, 09:24 AM

Just an FYI - both my old 03 Silverado and my current 02 Sierra has rear discs.

**N2TRUX** · 10-25-2006, 09:41 AM

The reason GM has gone back to drum brakes has nothing to do with the ability of disc brakes performance. It was done because they weren't using quality materials and sufficient size rotors and the brakes were warping. In stead of fixing the problem correctly, they went back to drum brakes for simple economical reasons.

This always opens up a can of worms when discussed. If drum brakes are better than disc brakes why did 100% of all manufacturers quit using them on the front of every vehicle made?

If drum brakes are better than disc brakes, why don't you see huge drum brakes on high performance cars?

It's a simple answer. Drum brakes do not "perform" better than disc brakes when it comes to stopping forward motion.

You can certainly argue the pro's and con's of better wear, cost to replace, etc. It would be hard to argue the pro's and con's based on performance.

jacobs · 10-25-2006, 10:09 AM

Quote:

Originally Posted by kbs71

If you think about it, drums actually have an advantage over discs. there's probally 4 to 6 times as much surface area diffrence between the two. Why do you think 18 wheelers stayed with drums. Cosmetically and price wise it was cheaper for the OEM's to use calipers than drums.

I believe if you could talk to the engineers, the only real advantage disks have over drums is weight. Large trucks do still use drums and it seems to me if disks were so much better, they would have converted over many years ago. Automotive and pickup drum brakes are self adjusting, large trucks are NOT.

Even large earth movers used in highway construction still use drum brakes. To me it’s obvious that it’s a matter of weight savings not better braking or safety. I can’t think of a single instance where large equipment manufactures have gone to disks.

C10-Driver · 10-25-2006, 11:14 AM

My 2 cents worth. These trucks will have plenty of stopping power with rear drums. Discs are cool but I went with drums on mine for economic reasons and also, the parts are readily available and standard equipment on a many models of trucks and vans.

I also had a 2001 Silverado with rear discs. I did not find that it stopped way better than any other Chevy truck I have owned that had drums. The one thing I did find, however, is that I had to service the rear brakes at 35,000 miles. All the road crap flying back at the rear brakes caused the calipers to cease. Depending on how a person intends to use their truck (mine is mostly in fair weather) drums may be the way to go for maintenance reasons.

**N2TRUX** · 10-25-2006, 11:21 AM

For those of you interested in improving your rear brakes take a look at this thread- Better brakes inside

jake60 · 10-25-2006, 12:05 PM

Having had both disks and durms, in my opinion, the only real advantage of disks is if you get into a lot of mud. I totally ruined a set of drums and shoes years ago when I got stuck in deep mud while four wheeling. The mud and rocks got trapped inside and wore out the drums and shoes before I could get it cleaned out. Disks would have been self cleaning.

Bob Moore · 10-25-2006, 02:38 PM

Thanks JYJohn. I always have faith in your info. I will look alot closer next time at the larger drum brakes at the yard. I think the discs look cool with the newer wheels(larger and more open) but I am going to run ralleys so nobody would see them. I think the upgraded drums will be as good as discs and cheaper also.

KCW · 10-25-2006, 03:48 PM

My 2006 GMC sierra has drums in the back. Stops really well.

Werewolf · 10-25-2006, 04:15 PM

My '04 Avalanche has discs, and interestingly enough, hydroboost power brakes. That truck loves to stop. GM had a major problem with earlier rear discs flaking to the point where they couldn't even be surfaced; cheap materials. I had a '01 Silverado, and never had a problem with any of the discs flaking or warping, although I did replace the fronts and all the pads because the stock brakes did *not* want to stop 32" BFG all terrain tires well.

Longhorn Man · 10-25-2006, 05:58 PM

There's only a few circumstances where disks in back make more sence than drums...
mud running.. as mentione, it cleans the brake surface
Heavy hauling... if you are loaded down, hhey will help
to replace drums that are no longer avalible... one ton owners here know what I'm talking about
If you really want the bling

The disadvantages of the discs in back,
they weigh more in most cases
brake pad replacement... they do wear faster
lots of money for maybe an inch improvement in your 60 to 0 tests. I understand an inch or two can be the line between gettin the crap scared outta you, and plowing into someone, but, IMO, it just isn't worth the money in most cases.

For the record, bot chevy and ford have junk rotors, both up front and in back. We refer to them as plated rotors... mild steel with good rotor plating. This is noticed on there trucks and vans... we don't get enough cars to notice a trend.

10-24-2006, 10:26 PM	#1
Bob Moore Registered User Join Date: Feb 2004 Location: Tacoma WA Posts: 1,365	Rear Drum vs. Rear Disc Working on a SWB 1/2T that has 5lug discs upfront. I have a 5lug 12 bolt rear axle. My question is Drum Brakes or Disc Brakes? I have seen several 73-87 Chevy truck/or van rear axles with bigger brakes than mine. Mine are the standard 2" wide shoes. The bigger ones look like 2 1/2"(did not have a ruler). Will these fit my axle? I understand the width has to come from somewhere - are the backing plates tucked in or what? Is the axle housing and therefore the axle shaft a completely different animal? I would use the entire brake from backing plate to drum. Or------ Should I go discs in the back? Has anybody upgraded their rear brakes to the larger drums? TIA - Bob __________________ 67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow Last edited by Bob Moore; 10-24-2006 at 10:35 PM.

10-24-2006, 11:06 PM	#2
powell72 Senior Member Join Date: Jan 2005 Location: Loveland Co. Posts: 3,098	Re: Rear Drum vs. Rear Disc You only need from the backing plate out for the bigger rear drums, 71-72's had them also, there is no width issue with them. I'm not sure if rear discs will stop any better than correctly adjusted big drums. I am doing a rear disc conversion though, mainly for the "wow" factor, not because I feel like I need them. __________________ Chris 74 Custom Deluxe SWB 350/350/3.73’s 99 2wd Silverado RCSB 5.3/4L60/3.90’s http://www.classictrucks.com/feature...short_bed.html

10-24-2006, 11:15 PM	#3
Bob Moore Registered User Join Date: Feb 2004 Location: Tacoma WA Posts: 1,365	Re: Rear Drum vs. Rear Disc Chris - That is exactly my thought also. __________________ 67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow

10-25-2006, 07:07 AM	#4
Werewolf Woof? Join Date: Jun 2005 Location: Raleigh, NC Posts: 276	Re: Rear Drum vs. Rear Disc It should be noted .. just because I feel like noting it .. that Chevrolet has abandoned rear discs on the current model year trucks. They've gone back to drums. I don't recall the exact reason, although I do think it was a performance issue. That's not to say rear discs suck. When it comes to you and your truck, really, the biggest factor is, how much work do you want to do and how much money do you want to spend? __________________ 1968 LWB CST BB 2004 Avalanche Z71 LT3. 2003 S-10 ZR2 (hers). 1997 Astro 1992 Caprice wagon, 500k stock miles. Nursing wounds after a bad wreck. 1997 Saturn - need gas mileage from something!

10-25-2006, 08:42 AM	#5
kbs71 71 rustless in texas Join Date: Aug 2004 Location: Houston, TX Posts: 257	Re: Rear Drum vs. Rear Disc If you think about it, drums actually have an advantage over discs. there's probally 4 to 6 times as much surface area diffrence between the two. Why do you think 18 wheelers stayed with drums. Cosmetically and price wise it was cheaper for the OEM's to use calipers than drums. __________________ "The secret to creativity is knowing how to hide your sources." "No one really listens to anyone else, and if you try it for a while you'll see why" 71 C-10 LWB presently in a perpetual state of disassembly '96 Toyota (my work car) '04 Mustang Convertable (wife's car & other money pit) Latest aquesition and why my trucks still in the garage covered with junk.. 2010 Aqua Blue metallic 6 speed Manual LS3 2SS/RS Camaro (I want one of these in my truck FAQ here VENDORS here SUPPORT THE BOARD here My second favorite SITE

10-25-2006, 08:56 AM	#6
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: Rear Drum vs. Rear Disc the main factor is that drums do not stay adjusted for very long. you have to adjust them. everytime you hit the pedal they will work a little bit different. with disks they are self adjusting and its always going to stop exactly the same. disks are more efficient. drums trap heat and gas between the shoe and drum which makes them fade out quickly and become useless.disks vent a ton better because they arent enclosed and get a lot more air flow. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

10-25-2006, 09:24 AM	#9
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,684	Re: Rear Drum vs. Rear Disc Just an FYI - both my old 03 Silverado and my current 02 Sierra has rear discs. __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE

10-25-2006, 09:41 AM	#10
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,021	Re: Rear Drum vs. Rear Disc The reason GM has gone back to drum brakes has nothing to do with the ability of disc brakes performance. It was done because they weren't using quality materials and sufficient size rotors and the brakes were warping. In stead of fixing the problem correctly, they went back to drum brakes for simple economical reasons. This always opens up a can of worms when discussed. If drum brakes are better than disc brakes why did 100% of all manufacturers quit using them on the front of every vehicle made? If drum brakes are better than disc brakes, why don't you see huge drum brakes on high performance cars? It's a simple answer. Drum brakes do not "perform" better than disc brakes when it comes to stopping forward motion. You can certainly argue the pro's and con's of better wear, cost to replace, etc. It would be hard to argue the pro's and con's based on performance. __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"

10-25-2006, 11:14 AM	#12
C10-Driver Chevy Truck Addict Join Date: Aug 2006 Location: Kelowna, BC Posts: 1,176	Re: Rear Drum vs. Rear Disc My 2 cents worth. These trucks will have plenty of stopping power with rear drums. Discs are cool but I went with drums on mine for economic reasons and also, the parts are readily available and standard equipment on a many models of trucks and vans. I also had a 2001 Silverado with rear discs. I did not find that it stopped way better than any other Chevy truck I have owned that had drums. The one thing I did find, however, is that I had to service the rear brakes at 35,000 miles. All the road crap flying back at the rear brakes caused the calipers to cease. Depending on how a person intends to use their truck (mine is mostly in fair weather) drums may be the way to go for maintenance reasons. __________________ . 1970 Chev C/10 SWB, 355 SBC, 700R4, 3.73 Posi, Air Ride (Click to view Build Thread) (SOLD) 1978 Chevy C/10 SWB 1970 Pontiac Lemans .

10-25-2006, 11:21 AM	#13
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,021	Re: Rear Drum vs. Rear Disc For those of you interested in improving your rear brakes take a look at this thread- Better brakes inside __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"

10-25-2006, 12:05 PM	#14
jake60 Registered User Join Date: Jul 2006 Location: Buffalo Park Posts: 75	Re: Rear Drum vs. Rear Disc Having had both disks and durms, in my opinion, the only real advantage of disks is if you get into a lot of mud. I totally ruined a set of drums and shoes years ago when I got stuck in deep mud while four wheeling. The mud and rocks got trapped inside and wore out the drums and shoes before I could get it cleaned out. Disks would have been self cleaning.

10-25-2006, 02:38 PM	#15
Bob Moore Registered User Join Date: Feb 2004 Location: Tacoma WA Posts: 1,365	Re: Rear Drum vs. Rear Disc Thanks JYJohn. I always have faith in your info. I will look alot closer next time at the larger drum brakes at the yard. I think the discs look cool with the newer wheels(larger and more open) but I am going to run ralleys so nobody would see them. I think the upgraded drums will be as good as discs and cheaper also. __________________ 67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow

10-25-2006, 03:48 PM	#16
KCW 1972 GMC 2006 GMC Join Date: Feb 2005 Location: Everett, WA Posts: 96	Re: Rear Drum vs. Rear Disc My 2006 GMC sierra has drums in the back. Stops really well.

10-25-2006, 04:15 PM	#17
Werewolf Woof? Join Date: Jun 2005 Location: Raleigh, NC Posts: 276	Re: Rear Drum vs. Rear Disc My '04 Avalanche has discs, and interestingly enough, hydroboost power brakes. That truck loves to stop. GM had a major problem with earlier rear discs flaking to the point where they couldn't even be surfaced; cheap materials. I had a '01 Silverado, and never had a problem with any of the discs flaking or warping, although I did replace the fronts and all the pads because the stock brakes did not want to stop 32" BFG all terrain tires well. __________________ 1968 LWB CST BB 2004 Avalanche Z71 LT3. 2003 S-10 ZR2 (hers). 1997 Astro 1992 Caprice wagon, 500k stock miles. Nursing wounds after a bad wreck. 1997 Saturn - need gas mileage from something!

10-25-2006, 05:58 PM	#18
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Rear Drum vs. Rear Disc There's only a few circumstances where disks in back make more sence than drums... mud running.. as mentione, it cleans the brake surface Heavy hauling... if you are loaded down, hhey will help to replace drums that are no longer avalible... one ton owners here know what I'm talking about If you really want the bling The disadvantages of the discs in back, they weigh more in most cases brake pad replacement... they do wear faster lots of money for maybe an inch improvement in your 60 to 0 tests. I understand an inch or two can be the line between gettin the crap scared outta you, and plowing into someone, but, IMO, it just isn't worth the money in most cases. For the record, bot chevy and ford have junk rotors, both up front and in back. We refer to them as plated rotors... mild steel with good rotor plating. This is noticed on there trucks and vans... we don't get enough cars to notice a trend.



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