Yes, you're right, disc brakes offer better heat dissipation and drum brakes do have more surface area.
I was only trying to give the briefest of demonstrations on how much better disc brakes "feel", but it's way more complex than that, comparing discs to drums.
There are pros and cons and different vehicles respond to different systems.
One area I definitely don't agree with you though is wet weather performance---I think discs are far superior. Also drum systems are more complex than disc brakes.
One reason that semis use drum brakes is that drums last a lot longer than discs might on such a heavy vehicle.
But that is rapidly changing. Truckers are very conservative about change but Peterbilt is now offering all-wheel air disc brakes and you will see most trucks using this technology in the next ten years I think. Europe is already switching over to air discs on heavy trucks.
Having said all that, I think front disc/rear drum on most light passenger cars is plenty good enough.
Perhaps the mix of disk and drum systems has some yet-to-be-quantified advantage when both are used on a vehicle. Conditions that diminish disk brakes may be different than conditions that diminish drum brakes, thus favoring mixing the two styles of brake on one vehicle.
There is a certain amount of engineering that goes into the disc/disc and disc/drum combinations. Suffice to say I think that lower costs might be a major reason.
I remember the days (1950's up) of front V-8 engines with rear wheel drive train. (more even balance front to rear) In those days, one pretty much changed both front and rear drum brakes. Even then, the rears still wore a lot easier.
If you fast forward to today, most and a majority % of the cars have front wheel drive front engine. For example, my VW Jetta has a 60/40 static weight bias. During most operations it can shift to as high as 90/10 with 80/20 being pretty normal. So for example, how they overcome this engineering problem is to make the rear rotors and pads app half as potent and use apportioning valves, etc to supply more initial force to the rear disc brakes. This type of set up is also pretty similar on my Z06 Corvette, which is probably one of the shortest stopping production machine on the market.
Just when I thought I have seen disc/drum combination pass into history, I had need of a commute car and got a 2004 Honda Civic, which has the disc/drum combination. It will be interesting to live with this old/new combination.
With a little practice, they are not too hard to replace as needed, but pay attention! All those pieces have to go back to place. Some time ago I acquired a "beautiful" tool from Eastwood. It measures and then transfers the measurement of the diameter of the brake drum. It speeds up preliminary adjustments to the diameter of the braking circle you are constructing as you put the new shoes and other pieces to place on the backing plate. This means a lot less "spooning" of the brakes, post assembly.
Ahhh yes, Spooning drum brakes. There is a lost art. I have seen modern (Young) mechanics PRY and HAMMER a drum to get it off. Then they wonder why the shoes and other brake components are all bent up!?!
The art of spooning. (holding the adjuster away while loosening the star adjuster) thru a slit the size of a couple quarters edgewise, takes a certian finesse.
I wonder if most folks even realize that they must hit the brakes firmly while reversing to adjust the drum brakes? Insdead, the drums get less and less effective forcing the front brakes to wear out faster.
Boring the drum brake cylinders with an egg beater kinda tool, did it as a "dad's apprentice" on a '57 Chevy; using strings to align the wheels; stethoscope to check the pistons/valves (I think?); poking the the drum brake star adjuster through a slot with a straight slot screw driver. ;-)
Was "brake doctor". They worked well but when I was in the tool business all they would do was collect dust on the shelves. Few mechanics found any value in them.
That's probably because it's just as easy to expand the adjuster until the brake drums just slip back on and then make final initial adjustments. The procedure to expand the adjuster until the drum is tight and then back it off never made much sense to me. Unless you arc grind the shoes to the drum when installing you will probably need to re-adjust soon anyway when the high spots on the linings wear away. Professional brake service shops (mostly gone now) or even those guys that used to drive vans from shop to shop (also mostly gone now) always had arc grinders to match the shoes to the drums for a perfect fit, and unless a problem occurred later (or no self adjusters) the brakes didn't need any adjustment over their life.
Honing brake cylinders with those egg-beater cutters is a skill you'd probably not want to remember. Good way to over-bore the cylinder and ruin it...those egg-beater stones are TOO COARSE!
Don't use 'em!
I used to wrap a 3-prone stone hone in 600 wet/dry paper and hone slowly with WD-40. Got a nice mirror finish with very little metal taken off.
I think a fair mumber of posters gave good examples about why drum brakes are cost/time/parts/maintenance "hogs". The first time ANY one comes back for any real or imagined symptom; you just lost whatever money you made, plus as a min, you have to trouble shoot!! When I was a boy, I used to help my father do many a "brake job". As I was able to "do it in my sleep" he would either do another axle or another car and be the ultimate quality control of my work. Of course, this is not to even mention the special tools you needed to have on hand.
In those days my friends and I were broke most of the time. I remember using Vise-Grips on the return springs and pliers on the hold down springs. We never had our drums turned unless they were really bad.
Once when I was especially broke, I blew a rear grease seal on my 1951 Ford Woody. The rear shoes were soaked with oil so I dipped them in kerosene and lit them on fire!
Well a man's gotta do what a man's gotta do, as John Wayne once said (Was it in "The Searchers"?), but these days it would be a last ditch attempt to save a few dollars.
Thinking of painting the calipers on my new vehicle. I live with 5 months of salt on the roads and after a year or 2, the calipers look rather lousy, and would be very noticeable behind the wheels of my new car. I bought Dupli-color caliper paint kit that comes with black brush on paint, brake cleaner and the brush.
Question 1. Can I spray the brake cleaner over the entire caliper assembly while it still mounted?
Question 2. Will doing the above remove the antisqueal compound that is clearly visible on the back of the pads/guides on my new vehicle, or damage any of the seals?
If so, is there any method of cleaning/preping without removing the assembly and pads?
Question 3. Can the same paint be used to paint the exterior of the rotor hub and edge (obviously not the rotor surface where pad contacts).
Thanks Steve for pointing me to the appropriate thread.
1)Yes (choose a brake cleaner that is rubber-safe)
2)Not likely (but take care with the pressure-point surfaces of the pads that are LUBRICATED. Re-lube with proper brake-grease afterwords)
Removing the pads is VERY trivial to do. Even removing the rotor may even be easy. (I can have the rotors off my truck within 5 minuts per side and the pads off in another 27 seconds) Do not touch rotor with fingers. (use rubber gloves) Also scrub rotors thoroughly with degreaser before re-installing. Protect the rotors as if they were in a hospital envronment.(wrap with a towel)
If you must leave the rotors in place. (with calipers pulled and pads removed) Cover the rotors with a cloth to protect from any contaminants while you are wire-brushing the caliper-housings and painting. Still... you should degrease the rotor before putting back into service.
QUESTION: What material are your calipers of? (aluminium, castiron, Steel...??)
3) NO! (The rotors normal operating temp will burn off any coating. Even chrome/nickle plating would not survive on the rotor itself. Also, you risk contaminating the braking-surface. Even touching the rotor with your FINGERS can affect braking performance.)
I don't think painting the calipers and the rotor "hat" while they are still on the car is a good idea. The chances of getting a nice job out of this aren't very good.
Thanks folks. Duplicolor e-mailed me late Friday and indicated that their brake cleaner is meant for assembly with pads OUT. Also popped a wheel off this weekend, and taking assembly off will take a couple of bolts. Since they are new (no rust) I presume they should be come off without too much difficulty. All this to say, I you have convinced me that the best approach is to pull everything off and have some anti-squeal compound handy for re-install of the pads. Just a little hesitant as this will be the first time I've played with brake components.
One more question. I believe all bolts have torque specs. Should I borrow a torque wrench for when I reinstall the calipers, or a good hand tightening should be OK? Cheers.
Torque things to spec. If you have aluminium wheels, do not forget that they need to be torqued TWICE. (once when you put them on and again after a couple days of driving)
BTW: Incase you do not know some of the cautions; *)DO NOT let the caliper hang by the rubber hose. (either wedge it somwhere where it will not fall out or use an old metal coathanger to secure it to a suspension part)
*)DO NOT PUSH ON THE BRAKE PEDAL while the caliper is removed. There is danger of pushing the pistons clear out of the calipers.
*) If you push the piston all the way in, (C-clamp or waterpump pliers) it will be MUCH easier to remove/install the caliper.
MOST IMPORTANT: Verify brake operation BEFORE driving.
I need some info and I'm hoping one of you that does their own maintenance on their Accord or Civics can help me, my wife has her mind set on a new 2004 Accord or Civic, and I know that years ago in order to cut the rotors on Honda's you need to take them to the dealer to have them cut because it took a special cutting machine that mounted to the axle to cut the rotors while they were still on the car, because the rotors were pressed on and were a bear to remove, so can anyone one on here tell me if this is still the case, or can the rotors be removed on the newer Honda's (Accords & Civics) just like any other vehicle.
I picked up some brake quiet, and found two products. Not sure which to use. One is AGS sil-glyde brake lubricant. It says it stops pad squeal and lubricates caliper slides and contact points. The other is Permatex Disc Brake Quiet. The grease thats currently on my pads is copper in colour (new Subaru Wagon). Which is better, or should I try to get the original product from the dealer?
I think you have two different things here. I've used Permatex Disc Brake Quiet which is a coating that goes on the backing plate for the pad and is allowed to set before installing them. It more or less cushions them in the caliper. In my opinion it's not very effective since it seems to be quickly displaced by the piston on the inner pad. It sounds like the other product is silicone grease for the slide pins and the points where the side of the backing plates ride against the calipers.....
Years ago, I bought a very inexpensive brake tool that is a specialized clamp to squeeze the caliper piston back into the caliper body. It is easier to use than a standard C clamp, due to its specialized contour/shape. Now, as I understand it, the screw type calipers are only used on rear wheels, and are of this configuration to accommodate the need for an emergency or parking brake. Is this correct?
If the parking brake mechanism is incorporated into the rear calipers (not all are) the piston is mounted on a jackscrew. To seat the piston, pressure is applied to it as it's rotated clockwise back down the screw. Make sure the outer dust boot isn't stuck to the piston or the boot will tear. A quick shot of WD40 helps there.
To remove the rotors from current Civics and Accords, remove the wheel and install 8mm x 1.25mm bolts into the 2 threaded holes in the rotor. Tighten the bolts incrementally to push the rotor off the hub.
Actually, on-car machining equipment is preferred since it virtually guarantees no runout in the rotor after machining.
I now own two vehics that have 4 wheel disk brakes, and I will eventually face brake work. Have you found the rear brake piston tool (for sale in most parts houses) a good item to use? Would you recommend them?
I use the kit with the push bolt and adapters for all the various pistons, but I do a lot of rear brakes. You can get by with the "cube" tool from Lisle. It has provision for a 3/8" drive extension, and has tabs on each of the 6 sides which match the recesses on most pistons. Select the side which matches your pistons, attach it to the end of the extension, then use the ratchet to rotate it clockwise as you push in on the piston. Works ok. Just make sure the piston is rotated to where it's notches line up with the tabs on the back of the inboard brake pad.
Thanks for the great info! The cube was the tool to which I referred. I've seen 'em, and put 'em back down on the counter. Maybe I'll buy one. And thanks again.
We're considering purchase of the new Volvo V50. We hear there may be a problem with frequent pad replacements, more so than other vehicles. If true, is Volvo making any improvements in this area? For anyone with Volvo experience, how often might the pads need replacement? Are there any other issues with Volvo brakes? Are some of the models more prone to brake problems than others? Any comments from anyone driving the V50? Thanks.
I have a 2000 accord V6. The rear disc brake tool was bought at pep boys for 11.00 dollars. Made the pad replacement in the rear a breeze. Make sure you get the one specified for honda.
Painted my calipers and rotors this past weekend. Used duplicolor caliper paint kit (black) and tremclad hi-heat (rated to 1200F) aluminum spray for rotors. Taped the contact area on the rotor with close precision using blue painters tape. May have overlaped contact area by no more than 1/32" in some areas, but that came off easily on first braking, to leave a clean line. Taping added about 10 min per rotor. Turned out great.
Ended up using copper antiseize for the guides and on the calipers where they contact back of pads. Pads have shims attached (which I did not disturb) so no need for anti-squeal. This is what car had from factory, so did not want to mess with other products (ie.warranty). Funny thing is that in speaking with some shops, they are also using antiseize to lubricate guides.
I don't have a V50, but my mother has owned a succession of Volvos. Like most other European cars, the brakes put off a tremendous amount of dust, and the pads last about 30,000 miles for fronts under normal driving (and 40-50,000 for rears). I'm not sure if the Volvo service plan now included on the new Volvos pays for brakes. If it does, you might get the first set free. There are aftermarket pads available which produce less dust and supposedly last longer, but I have no experience with them. Brakes would be the least of my worries on a Volvo.
Help! I have a 2001 Accord. I had to get new brakes 14 months ago when my car had approx. 15,000 miles. Now, at almost 30,000 miles, I have been told that my front and rear brakes are at 2%(?). I need new brakes again! My previous car, a 1990 Accord, did not have this problem. Is this normal? The dealership suggested it might be my driving, but I haven't changed the way I drive since I had my old car. Aren't brakes supposed to last longer???
Hey, carclueless, your name confuse me, not sure what to advice. Well, first check if this is a true, do you REALLY need new pads. It is very simple task, just remove the wheel and check pads lining thickness, not the metal backing plate thickness, if it less than 1/16" or 2mm change it.Ask somebody help if you...OK, if you do need to change, we can talk whole day long why why why.May be Honda use soft organic compound on pads, may be your driving style, may be caliber not moving freely and riding the pads, may be you got mfg defect.Yes, brakes suppose last longer.I see you have two choices. You can just put aftermarket pads and see what happen. I recommend Raybestos PG Plus, they usually work for me for 3yr/40K mi. Or you can ask shop go though all brakes in great detail to find may be something stack. As I remember, on my 1995 Accord original pads lasted on the back to 30K mi and on front a some longer to 40K mi. Well...one time I was forced to change earlier, 3 pads were still like 6/32" and 1 was almost 0, no caliber was not stack, I changed pads and it work fine now.
brakes work, but sometimes out of no where al least about every 10 stops they lose all pressure and i have no brakes. all i do is re pump the pedal and they come back. now i am getting a trailer very soon and need some immediate help or noledge before i take it to a shop! Chevy Van G-30 78k mi
Comments
I was only trying to give the briefest of demonstrations on how much better disc brakes "feel", but it's way more complex than that, comparing discs to drums.
There are pros and cons and different vehicles respond to different systems.
One area I definitely don't agree with you though is wet weather performance---I think discs are far superior. Also drum systems are more complex than disc brakes.
One reason that semis use drum brakes is that drums last a lot longer than discs might on such a heavy vehicle.
But that is rapidly changing. Truckers are very conservative about change but Peterbilt is now offering all-wheel air disc brakes and you will see most trucks using this technology in the next ten years I think. Europe is already switching over to air discs on heavy trucks.
Having said all that, I think front disc/rear drum on most light passenger cars is plenty good enough.
I remember the days (1950's up) of front V-8 engines with rear wheel drive train. (more even balance front to rear) In those days, one pretty much changed both front and rear drum brakes. Even then, the rears still wore a lot easier.
If you fast forward to today, most and a majority % of the cars have front wheel drive front engine. For example, my VW Jetta has a 60/40 static weight bias. During most operations it can shift to as high as 90/10 with 80/20 being pretty normal. So for example, how they overcome this engineering problem is to make the rear rotors and pads app half as potent and use apportioning valves, etc to supply more initial force to the rear disc brakes. This type of set up is also pretty similar on my Z06 Corvette, which is probably one of the shortest stopping production machine on the market.
Just when I thought I have seen disc/drum combination pass into history, I had need of a commute car and got a 2004 Honda Civic, which has the disc/drum combination. It will be interesting to live with this old/new combination.
The art of spooning. (holding the adjuster away while loosening the star adjuster) thru a slit the size of a couple quarters edgewise, takes a certian finesse.
I wonder if most folks even realize that they must hit the brakes firmly while reversing to adjust the drum brakes? Insdead, the drums get less and less effective forcing the front brakes to wear out faster.
http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemTyp- e=PRODUCT&RS=1&itemID=2438&keyword=49012
Professional brake service shops (mostly gone now) or even those guys that used to drive vans from shop to shop (also mostly gone now) always had arc grinders to match the shoes to the drums for a perfect fit, and unless a problem occurred later (or no self adjusters) the brakes didn't need any adjustment over their life.
Don't use 'em!
I used to wrap a 3-prone stone hone in 600 wet/dry paper and hone slowly with WD-40. Got a nice mirror finish with very little metal taken off.
Once when I was especially broke, I blew a rear grease seal on my 1951 Ford Woody. The rear shoes were soaked with oil so I dipped them in kerosene and lit them on fire!
It actually worked!
Actually, they saved a lot of time and trouble.
HMMMMM...may have to change my mind about rear drum brakes after all
http://www.erborrico.com/206raba.wmv
Question 1. Can I spray the brake cleaner over the entire caliper assembly while it still mounted?
Question 2. Will doing the above remove the antisqueal compound that is clearly visible on the back of the pads/guides on my new vehicle, or damage any of the seals?
If so, is there any method of cleaning/preping without removing the assembly and pads?
Question 3. Can the same paint be used to paint the exterior of the rotor hub and edge (obviously not the rotor surface where pad contacts).
Thanks Steve for pointing me to the appropriate thread.
2)Not likely (but take care with the pressure-point surfaces of the pads that are LUBRICATED. Re-lube with proper brake-grease afterwords)
Removing the pads is VERY trivial to do. Even removing the rotor may even be easy. (I can have the rotors off my truck within 5 minuts per side and the pads off in another 27 seconds)
Do not touch rotor with fingers. (use rubber gloves) Also scrub rotors thoroughly with degreaser before re-installing. Protect the rotors as if they were in a hospital envronment.(wrap with a towel)
If you must leave the rotors in place. (with calipers pulled and pads removed) Cover the rotors with a cloth to protect from any contaminants while you are wire-brushing the caliper-housings and painting. Still... you should degrease the rotor before putting back into service.
QUESTION: What material are your calipers of? (aluminium, castiron, Steel...??)
3) NO! (The rotors normal operating temp will burn off any coating. Even chrome/nickle plating would not survive on the rotor itself. Also, you risk contaminating the braking-surface. Even touching the rotor with your FINGERS can affect braking performance.)
One more question. I believe all bolts have torque specs. Should I borrow a torque wrench for when I reinstall the calipers, or a good hand tightening should be OK?
Cheers.
BTW: Incase you do not know some of the cautions;
*)DO NOT let the caliper hang by the rubber hose. (either wedge it somwhere where it will not fall out or use an old metal coathanger to secure it to a suspension part)
*)DO NOT PUSH ON THE BRAKE PEDAL while the caliper is removed. There is danger of pushing the pistons clear out of the calipers.
*) If you push the piston all the way in, (C-clamp or waterpump pliers) it will be MUCH easier to remove/install the caliper.
MOST IMPORTANT: Verify brake operation BEFORE driving.
I picked up some brake quiet, and found two products. Not sure which to use. One is AGS sil-glyde brake lubricant. It says it stops pad squeal and lubricates caliper slides and contact points. The other is Permatex Disc Brake Quiet. The grease thats currently on my pads is copper in colour (new Subaru Wagon). Which is better, or should I try to get the original product from the dealer?
Thanks.
Now, as I understand it, the screw type calipers are only used on rear wheels, and are of this configuration to accommodate the need for an emergency or parking brake. Is this correct?
Actually, on-car machining equipment is preferred since it virtually guarantees no runout in the rotor after machining.
Ended up using copper antiseize for the guides and on the calipers where they contact back of pads. Pads have shims attached (which I did not disturb) so no need for anti-squeal. This is what car had from factory, so did not want to mess with other products (ie.warranty). Funny thing is that in speaking with some shops, they are also using antiseize to lubricate guides.
If you try to pull the drum BEFORE removing all slack from the automatic adjuster, the "ridge" on the drum will catch on the brake shoes.