W123 brake pads - Page 2 - PeachParts Mercedes-Benz Forum

fahrvergnugen · #16 11-21-2015, 04:38 PM

Quote:

Originally Posted by mannys9130

Locking up the tires means nothing about braking power. Braking power comes from the ability of the brakes to change kinetic energy into thermal energy RAPIDLY and in large amounts. Locking the tires dissipates no heat. Braking at the threshold and holding dissipates LOTS of heat and speed by proxy.

You're are not hearing me; if you aren't Able to lock up the tires, then you are missing out on braking power, and therefore not braking efficiently as the one fella with the 85 TD with ceramic pads said above. No squeal regardless of how hard you press the pedal means something ain't working as well as it could, be they pads, hydraulic or even mechanical problems.

mannys9130 · #17 11-21-2015, 10:57 PM

How do you know he wasn't just SHY of locking his wheels? That would actually be the ideal braking system.

I see what you're saying. I'm saying locking ability is no indicator of performance. A caliper with worn pads and a thin rotor can lock a wheel, and then once released go 250 feet at 75mph and experience brake fade where braking power is seriously diminished. Your brakes only need to be strong enough to the point where they just barely fall short of locking up the wheel. Anything after that traction loss point is pointless and means nothing.

durzigl · #18 11-22-2015, 09:55 PM

Quote:

Originally Posted by thatguy

I just use the usual suspects and have nothing but good luck, Textar, Pagid, ATE.

Check.

ATE for the rotors.

Brakes work fine.

Replacing brake hoses is a good idea if originals are still on the car.

dac · #19 11-23-2015, 12:48 PM

I went with Textar pads and ATE rotors. I've got hubcaps, so the brake dust isn't as big a problem as it is on the bundts, and didn't feel like sacrificing stopping for that while still paying twice as much. Thanks for the help, everyone.

Daniel

jabstick420 · #20 11-23-2015, 12:53 PM

textar pads, ate rotors is what I got too

t walgamuth · #21 11-23-2015, 02:48 PM

Quote:

Originally Posted by fahrvergnugen

You're are not hearing me; if you aren't Able to lock up the tires, then you are missing out on braking power, and therefore not braking efficiently as the one fella with the 85 TD with ceramic pads said above. No squeal regardless of how hard you press the pedal means something ain't working as well as it could, be they pads, hydraulic or even mechanical problems.

I have to agree if you cannot lock the brakes on a non abs car, something is likely wrong with the system. I'd suspect the booster or the vacuum.

BillGrissom · #22 11-23-2015, 03:14 PM

A few minor comments. A few years ago, I researched what "ceramic" means re brake pads and found there is no standard. Manufacturer's can pretty much label any mixture "ceramic". Probably the same for organic and semi-metallic. I did buy ceramic pads for a few vehicles to hopefully avoid the nasty cow-poop stuff on the wheels. They were expensive (~$60) and can't say I noticed a big difference, but at least lifetime warranty.

Be careful of "racing" pads. I understand many don't give much friction until they are hot, so intended for constant braking like road-course racing. No personal experience, but I read that on some classic sites, especially when posters ask "why don't these expensive pads work?".

I agree that brakes should be able to skid all the tires, preferably the fronts skid slightly before the rear. Watch the FantomWorks show where laying down skid tracks is their standard checkout. I also agree that you can stop faster by not skidding, but you must know where the limit is. Since nobody can judge that, the classic method is to brake until you skid then slightly release & repeat, i.e. "pulse the brakes". That is what ABS does. But it hasn't proved out in practice. To use ABS, you must jam the pedal down and hold it. Most drivers are alarmed by the pulsing, which feels like something broke in your pedal, and they let up on the brakes. The suspicion it that is why ABS hasn't proven itself. It only works well with driver training. But, it does shine in icy weather where the driver can brake and still steer.

mannys9130 · #23 11-23-2015, 04:32 PM

You are all still not understanding.

Go ahead and skid, but don't be shocked if you skid right into what you were trying to avoid. If skidding was effective, ABS would not be necessary. Threshold braking is proven. It's plain physics people.

t walgamuth · #24 11-23-2015, 05:33 PM

Quote:

Originally Posted by mannys9130

You are all still not understanding.

Go ahead and skid, but don't be shocked if you skid right into what you were trying to avoid. If skidding was effective, ABS would not be necessary. Threshold braking is proven. It's plain physics people.

Show me the physics that shows abs equipped cars stopping faster than skidding cars. The abs is there to give you steering while holding the brake pedal down.

mannys9130 · #25 11-23-2015, 07:40 PM

Quote:

Originally Posted by t walgamuth

Show me the physics that shows abs equipped cars stopping faster than skidding cars. The abs is there to give you steering while holding the brake pedal down.

You seriously need me to explain to you why rubber gliding across asphalt is not better than thousands of PSI pushing friction material against 20 pounds of Iron X4 wheels? Like, REALLY?
https://www.youtube.com/watch?app=desktop&persist_app=1&v=mKiTAcXK6M4

C'mon.

MBeige · #26 11-23-2015, 07:54 PM

Quote:

Originally Posted by mannys9130

You are all still not understanding.

Go ahead and skid, but don't be shocked if you skid right into what you were trying to avoid. If skidding was effective, ABS would not be necessary. Threshold braking is proven. It's plain physics people.

You can hit the object you were trying to avoid by two ways: locking up the tires and sliding/skidding into the object, or not having sufficient braking power to actually stop the vehicle. Folks are talking about the latter, you are talking about the former.

If you can demonstrate that the brakes can actually lock up the tires, then it means they have sufficient force to reach the threshold.

In a real panic stop, brake "at the limit" to prevent skidding at the vehicle/object in front, because you know you can as demonstrated above. If you go beyond this limit (this is where you come in), then of course you skid and may hit the object you were trying to avoid.

If you cannot demonstrate that the brakes can actually lock up the tires in a non-ABS car, with maximum brake pedal force applied, then you cannot reach this threshold. This means that in a real panic stop, your brakes are ineffective and you may hit the object you were trying to avoid, simply by not having sufficient braking power to stop the vehicle.

fahrvergnugen · #27 11-23-2015, 08:40 PM

Quote:

Originally Posted by mannys9130

You are all still not understanding.

I understood perfectly.

fahrvergnugen · #28 11-23-2015, 08:42 PM

Quote:

Originally Posted by MBeige

You can hit the object you were trying to avoid by two ways: locking up the tires and sliding/skidding into the object, or not having sufficient braking power to actually stop the vehicle. Folks are talking about the latter, you are talking about the former.

Exactly! Thank you for the concise description. I don't think he understood me.

atypicalguy · #29 11-24-2015, 01:43 PM

Seems like abs systems don't necessarily stop faster on dry pavement. But some do, because they manage the tire slide well.

Max possible KE dissipation on dry is apparently with the tire sliding about 20% which maximizes the sum of static and dynamic friction, puts more torque into the wheel while still rotating, so brakes can exert max force and dissipate max energy.

All these physics discussions seem to go around in loops on forums. For a laugh look at the DDWFTTW stuff on forums and youtube.

Sent from my SAMSUNG-SM-N910A using Tapatalk

t walgamuth · #30 11-24-2015, 06:35 PM

Quote:

Originally Posted by mannys9130

You seriously need me to explain to you why rubber gliding across asphalt is not better than thousands of PSI pushing friction material against 20 pounds of Iron X4 wheels? Like, REALLY?
https://www.youtube.com/watch?app=desktop&persist_app=1&v=mKiTAcXK6M4

C'mon.

That was a nice promotional video promoting ABS. It did not resemble science to me. Your condescending attitude will not deter me. I am pretty strong on science and I have been reading about 8 car magazines per month for about 40 years.