How noticable is a swap from rear drums to discs?

[Robb235]

I've got a '95 Monte Carlo LS with the 3100, and unfortunately it has drums on the rear. I was thinking about swapping to disc brakes that came standard on the '96 and later Monte Carlo and Luminas. I'm not looking to dump a whole bunch of money into a small project like this, but was curious as to how much of a difference I would notice since most of the braking power comes from the front. For what it's worth, I'd use carbon metallic pads on the rear to match the ones I have on the front.

[robertisaar]

"disc brakes that came standard on the '96"

nope. drums were still standard, all the way to 99 IIRC. hell there are 95+ Z34s with drums from the factory. why the general decided to switch the lumina from disk to drum in 1995 and take the MC with it, i have no idea.

[60dgrzbelow0]

I've got a '95 Monte Carlo LS with the 3100, and unfortunately it has drums on the rear. I was thinking about swapping to disc brakes that came standard on the '96 and later Monte Carlo and Luminas. I'm not looking to dump a whole bunch of money into a small project like this, but was curious as to how much of a difference I would notice since most of the braking power comes from the front. For what it's worth, I'd use carbon metallic pads on the rear to match the ones I have on the front.

The difference in reliable stopping power and smoothness is like night to day! I'm not certain the difficulties I encountered with doing an LS1 Brake Swap to the Drum Brake Set Up on my Son's 1994 Chevrolet Camaro can translate here exactly...but so often ...the engineering is changed in such subtle ways... that these following lengthy admonitions might still apply in your situation... and save you and many others... an enormous number of headaches:

(1) This only applies to RWD situations...but If you are NOT replacing the entire Rear Axle/Differential to include all the Disk Brake Hardware....MAKE DAMNED CERTAIN YOU OBTAIN THE AXLES, HALF MOON CLIPS AND BRAKE MOUNTING BRACKETS AND HARDWARE OFF OF THE JUNKYARD SKELETONS YOU SCAVENGE YOUR PARTS FROM....and these parts MUST include: ALL OF THE EMERGENCY BRAKE CABLING, GUIDES AND HOLD ON-HOLD DOWN BRACKETS FOR THEIR MOUNTING ONTO THE REPLACEMENT DISK BRAKES ON BOTH SIDES!

(2) Get yourself a quality pair of snug fitting Mechanics Gloves. And obtain a FULL CLEAR FACE SHIELD to protect your eyes from all the crap, oil and dirt that will fall in you face when working on trying to put back in all the planetary gears and washers that can fall out suddenly when your Spotter pulls on the old axle shafts out and the the Planetary Gears let go and fall out from inside the Rear End Gear Box...and yes...if you get hit in the mouth with the falling parts...the gears can shatter your front teeth! While the axles are out of the axle tubes...why not replace the Rear Axle Bearings as well? You can rent of borrow a Slide Hammer Puller from the local Autozone to get this portion done.

(3) If you cannot easily replace or re-work your old Brake Tubing at the same time with New Components... Check with getting the Metric Easy Flex Brake Tubing Lines from NAPA Auto. This trick will save you hours of trying to re-bend and re-fit Brake Lines that are in all probability...filled with rust and corrosion anyway...and may not even reach the replacement Disk Brake Housings. These NEW LINES come in a wide variety of lengths and fitting sizes and can also be shaped and molded into position very easily by hand.

(4) Don't forget to obtain the SPARE TIRE FOR THE REPLACEMENT DISK BRAKE SET. Your old Spare Tire may NOT fit over the Disk Brakes!

(5) Plan your Disk Brake and Axle Replacement carefully. You will need a liter (or two for a smidgen more) of New 75-90 Wgt Gear Oil... a New Rear End Cover Gasket...Some Gasket Tack...Some Liquid Thread Locker ...Several Plastic Gasket or Paint Scrapers to clean the mating flanges of both the Gear Box and Differential Cover and about SIX CANS OF SPRAY BRAKE CLEANER TO WASH ALL THESE AREAS DOWN...BEFORE DURING AND AFTER THE WORK IS DONE. Spray down all rusted fasteners with a penetrating dose of Liquid Wrench the night before you begin your project. You will also need a Hand Crank Vacuum Brake Pump and plenty of liters of New Brake Fluid compatible with your Replacement Disk Brake Set. Organize your tool set in advance and get yourself a 24 Pack of Terry Cloth Wipe Towels from Home Depot to help keep the Oil and Mung off of you and all those parts while working. Get some large seal-able Plastic Bottles and Jars (like the huge ones that Peter Pan Peanut Butter come in)...to use to capture old, leaking fluid at each wheel and let you see what kind of condition the Brake Fluid looks like as it drains out at each Wheel location. Use one for your Mitek Brake Pump. Drill out a small hole in the lid and clean away the metal shards. Then ...push the plastic down drain tube through the top of the lid and submerge the end of it in about three inches of Brake fluid so that when you are squeezing the pump handle ...you won't accidentally vacuum air back into the lines. To break loose the Bleeder Valves and all of the Brake Line Fittings ...use a 12mm (or whichever flavor/sized tool is required that is unique to your vehicle) Brake Fitting tool...and here is an important trick...get the smallest pair of Vice Grips you can get...and just close them tightly around the OUTSIDE of the 12mm wrench BEFORE you try to loosen each brake line bleeder fitting...and you will never strip them off!

(6) You can use Jack Stands if you choose to support the car while thrashing around underneath...but instead...to be supremely safer...build yourself some of what I call "Car Stackers" like I created and then you can lower the car down onto them with two car ramps first as a base on either side of the car. Then you will have ever so much more room to move around from front to back ...especially when installing the Emergency Cables and not have to worry about yanking the damned car down on top of you while trying to break so many difficult bolts loose. When I was doing the LS1 brake conversion on this RS, I was getting so physical at one point that I damned near pulled the car off the jack stands! So I thought I better make something that is adjustable and stack-able...similar to Leggos, that I could place further back under the square frame members and then settle the car down on top and not have to worry about jacks or stands slipping.

So what I came up with is what I now call “Car-Stackers”. These consist of -8- eight square support members made up of two sections of 4"X4" treated fence post wood cut to a length of about 10-12" long. I wrapped these four-by sections completely in Duct Tape and then fastened them together on the post ends with short sections of oak furring strips, using high carbon steel masonry screws to stabilize them side by side. This way I could use them in many ways of different stacking combination on top of two truck ramps and get the car lifted to the height I wanted to work at. This was very helpful when putting in the emergency brake cables and installing the rear axles and gear box work. Most importantly, it was safe and helped make concentrating on the work easier. This also meant that I would have more room to move around under the car and gain access to places the stands would usually block. The attached photos will illustrate what they look like.

I'm not trying to discourage you from attempting this job... but trust me... I had to learn the hard way...and it takes longer to do without knowing all that is involved in advance. I hope this information helps. Don't overlook shopping eBay for Complete Used Disk Brakes Sets with all the needed components. What you find there will save you days on end of scouring the Junk Yards for partial pieces here and there and most times...these used sets are quite affordable.

[robertisaar]

good advice(although the RWD stuff doesn't apply much). there may be a thread on the w-body forums for switching them, i remember reading something about it when i was planning on doing the swap myself. i KNOW the e-brake cable and other things related to it are different on the disk and drum setups.

[Robb235]

Thanks for the advice, but the swap is pretty well documented on other forums. I was just curious to see if switching to discs in the rear provided an enormous increase in stopping power, or if it was marginal.

[robertisaar]

i would call it noticeable, but you can only add so much friction to the rears before they lock up. i can get my drums to lock all the time, i imagine it could be easier to do with disks...

[Weatheralls Auto]

I think you will have to swap the proportioning system as well or you will get the rears locking up constantly and will become unsafe.

[Azrael]

Drum brakes take less effort to create the same braking force as disks (one of it's few advantages). A straight swap could actually cost braking force without re-proportioning the brake fluid.

[IsaacHayes]

Yup, you might actually loose clamping force. Generally for the work I'd only do it for looks. Sure changing pads is easier, but how often do the rears need changing?....

[robertisaar]

i think i got 75K miles out of the original shoes on the MC, then the next set lasted to 150K...

so 75K for me.

[60dgrzbelow0]

Thanks for the advice, but the swap is pretty well documented on other forums. I was just curious to see if switching to discs in the rear provided an enormous increase in stopping power, or if it was marginal.

The difference is HUGE in the LS1... I cannot say for your particular switch because I don't know how extreme the Disk Platter diameters can get. But....regardless...once you have them in there...You can say "Bye Bye" to Brake Fade under the most hectic of conditions from the moment you get a "Hard Pedal" after the Vacuum Bleed Procedures are completed (...with a friend hovering attentively with an open liter of Brake Fluid over the Master Cylinder fill hole... like a "Reservoir Dog"...

[3400-95-Modified]

I never noticed a difference... Granted I also went from 10" fronts to 12", so I think I picked up on that change more. I did drive it with 12" fronts and drum rears before going to the Neon disc setup though, so I did have a comparison but I didn't really feel much change.

[RedZMonte]

well my drums where shot.. leaky wheel cyl. and saturated pads.. when i did the swap i noticed a huge improvement... stock proportioning valve. I have never done drums in my life... lol so i figured what the hell... again my drums where in sad shape to start with so i noticed a good improvement over what i had..

Its an easy swap, the park brake cables can get a little screwy making them work properly, ended up using a couple spacers and longer bolts under the park brake bracket to make them work right.

S

[Weatheralls Auto]

Drums have more "Clamping" power to reuse the term, but are more prone to lockups, where Disc has greater stopping power without lock ups.