Brake Caliper Maintenance

[Donald]

I put a tiny dab on light bulb threads. They don't get "stuck" this way. Also, on outside lights as well as the garage door opener lights, the bulbs seem to be lasting longer

I would use dielectric grease on anything electric rather than sil-glyde. They are probably very similar.

 

[supton]

It is probably just a cultural decision at one company to do things a certain way.

Exactly. That's why sometimes I take what a manufacturer says with a grain of salt. If it can explained, then fine, otherwise, maybe it does not matter (or not matter greatly).

I use Dow Corning Molykote M-77, a silicone based moly grease, on my Subaru pads. The pad ears can corrode at the contact point with the bracket, and get frozen in place, especially at the rear pads.

Honda also recommends it:
https://www.amazon.com/Honda-HN-08798-9010-MOLY-PASTE/dp/B0083BWUYW

That's actually what I've taken to using, per The_Critic's advice--albeit it on Toyota's.

 

[Donald]

Exactly. That's why sometimes I take what a manufacturer says with a grain of salt. If it can explained, then fine, otherwise, maybe it does not matter (or not matter greatly).

That's actually what I've taken to using, per The_Critic's advice--albeit it on Toyota's.

So unsure if this applies, but I buy high quality pads with properly machined and painted or powder coated backing plate and this no need to file the ear to get it to fit properly. Some like to file the ears for a better fit and the first thing that gets removed is paint or powder coating.

 

[supton]

So unsure if this applies, but I buy high quality pads with properly machined and painted or powder coated backing plate and this no need to file the ear to get it to fit properly. Some like to file the ears for a better fit and the first thing that gets removed is paint or powder coating.

I do a dry fit and file if necessary. I know rust on the bracket can often be a problem, but I try my darnedest to get that off--but sometimes they just don't feel loose enough. I know that opens up the opportunity to rust, but in my experience, I've seen new from the factory seize up, if given enough time, so, to me, it's ok: I was going to be in there once a year anyhow, making sure all is well.

 

[doublebase]

In modern cars, I don't think the 70% number is accurate anymore. Systems are closer to 50/50. That said, the automaker still are using smaller calipers, pads, and lighter-duty rotors and this is why people see faster wear on rears.

Really? I disagree, but if I’m wrong I’m always interested in learning something new.

When you step on the brake - let’s say on the highway for example - the weight shifts to the front as the body squats to the front. That places a tremendous amount of weight/pressure/force, on those front brakes. The rear end actually lifts up, leaving the rear brakes doing less. I don’t see how any sort of modern technology could change this, even active suspension systems, traction control, lane assist, sensors, etc. The weight is still going to shift to the front...object in motion stays in motion, inertia, physics, etc. A 5,000 pound car, with four passengers adding an additional 800 pounds...every thing is going to be forced forward upon stopping, especially sudden stopping. You can stiffen the suspension up front upon stopping, you can modulate the brakes...the weight is still going to go up front and the front brakes are still going to have to do most of the work. Am I wrong here? I could be...perhaps the rear brakes now apply before the fronts? But they always used to anyway (metering valves, which they don’t use anymore). I would imagine that no matter what they do, the weight will still have to shift to the front, unless you’re driving in reverse.

 

[supton]

Under hard braking, yes the fronts do the work. But under gentle braking the rears can do all the work, as weight does not have to shift.

 

[willbur]

Under hard braking, yes the fronts do the work. But under gentle braking the rears can do all the work, as weight does not have to shift.

Odd lesson in physics. Weight has to shift, just with less force because of gentle braking due to lower speed. Rears do not "do all the work". Electronic brake force equalization applies rears first so car does not dive under braking, IIRC.

 

[supton]

Odd lesson in physics. Weight has to shift, just with less force because of gentle braking due to lower speed. Rears do not "do all the work". Electronic brake force equalization applies rears first so car does not dive under braking, IIRC.

They most certainly can do all the work.

When I ride my bicycle, sometimes I will only use the rear brake. I most certainly can come to a stop using only the rear brake. Hell the first automobiles didn't even have front brakes...

Without a doubt, as deceleration rate rises, the front brakes become more important, and at some point they are doing the lion's share of braking. But as you indicate, under gentle to moderate braking, the rears can be engaged early (or at a high percentage of braking force) to prevent nose dive. As braking effort rises, weight is going to shift (regardless of what wheel is doing the braking) and the front brakes are going to have to do more work.

My poorly worded answer (hobbled by typing on an iPad) was not meant to indicate the rears do all the work. Just that they could, under light braking, and OEM's take advantage of that by using EBD to engage the rears early to make the driving experience "more gentle". Which in return causes some cars to abuse the old notion that front brakes should last twice as long as rear brakes (or rears should last forever, in the case of drum brakes).

 

[Donald]

The rear pads on my Subaru Crosstrek are tiny compared to the front. Assume the front does the bulk of the braking.

 

[Hall]

The rear pads on my Subaru Crosstrek are tiny compared to the front. Assume the front does the bulk of the braking.

Have you had to replace them ? How often compared to the fronts ?

 

[wolfox03SS]

In modern cars, I don't think the 70% number is accurate anymore. Systems are closer to 50/50. That said, the automaker still are using smaller calipers, pads, and lighter-duty rotors and this is why people see faster wear on rears.

Cutting edge modern cars can modulate rear brake force dynamically. Mostly it's ABS modulated in an attempt to control vehicle attitude (Think of the fancy pants Subaru symmetrical drive that modulates each brake independantly) or Stabilitrack systems. Others use it as part of the traction control system and limits wheel slip.

More recently another level of control is added where brake force is split dynamically from nose to tail to prevent nose dip on hard braking.

Your modern car works the rear brakes harder than you think. ;>

 

[wolfox03SS]

View attachment 53858

Bound caliper pins do this. If they were more parallel worn, I'd suspect a soft brake hose segment that was clogged and needed replacement too.

 

[meep]

Cutting edge modern cars can modulate rear brake force dynamically. Mostly it's ABS modulated in an attempt to control vehicle attitude (Think of the fancy pants Subaru symmetrical drive that modulates each brake independantly) or Stabilitrack systems. Others use it as part of the traction control system and limits wheel slip.

More recently another level of control is added where brake force is split dynamically from nose to tail to prevent nose dip on hard braking.

Your modern car works the rear brakes harder than you think. ;>

I learned something here - with 3-4 posts going this way. I didn’t realize this was a thing. Is it more prevalent with performance/high end makes? All 3 of our recent vehicles have rear pads substantially smaller than the front (2015 crv, 2014 GS350, 2018 F150). I doubt the truck or the honda would be this intelligent. Perhaps the Lexus might be... but toyota tends to be a late adopter. The Lexus does seem to have magical limited slip properties where it does its thing but I don’t perceive abs manipulation. where are we beginning to see this implemented?

 

[wolfox03SS]

The Lexus does seem to have magical limited slip properties where it does its thing but I don’t perceive abs manipulation. where are we beginning to see this implemented?

I would hazard a guess around the same time they started to silently implement tire pressure monitors in '03. They became mandatory on the latter year factory manufacturing split. My '03 Nissan doesn't have TPMS, but the light was there on the dash, not used.

But it has a deep thinking module somewhere that spies on vehicle speed, ABS, relative wheel rotation, throttle and cruise control and steering angle input. It will and does control nose dive and actively controls brakes through a 4 channel system for vehicle stability. It will and rather handily controls the car, even keeps it straight in a hydroplane situation and deactivates cruise with no user input. It's insane!

And it does it on these stupid, micro-disc brakes in the rear.

I'm guessing it is still something of a manufacturer's whim, but it does indeed exist. It may or not be made a selling point or equipped.

Brakes that are smarter than me happen.

 

[meep]

Yeah.... I’ve noticed some pretty well-dialed in esp programs. Even the Ford truck .... hit a sandy patch on an S-curve and it was uncannily tuned to give a couple of very quick brake pulses which corrected a skid before I noticed it was there. Now, I wasnt pushing it and this was probably well within its design limits but it was still quite impressive - and this thing doesn’t have performance calipers or anything on it....just stock.

the nose dive thing is probably a little different. The moment of torque won’t matter which wheels the brake force is coming from. any torque applied by the brakes will provide an equal nose-down rotation, whether from the front or back. And since the weight of the car doesn’t change, the total spring force of the front and rear will remain unchanged. The center of applied torque, whether front/rear, won’t change the weight of the car. So if torque is applied, the front will dip from an additional, say 100lbs, and likewise the rear would let up 100lbs. What Does change is suspension behavior. If there is a trailing arm, or pseudo-trailing arm suspension in the rear, any rear brake force will cause the rear to squat from brake forces, which is separate from vehicle pitching forward. Honda did a remarkable job in the late 90s civics and accord, by getting brake balance and suspension geometry and tuning dialed in, the rear would squat by brake forces on the suspension while the nose dropped from forward rotation, and the end effect was the vehicle stayed level.

so my GUESS is, they would be further tuning rear brake actuation to use rear squat to compensate for nose dive. Come to think of it.... I think I questioned if the lex was squatting in the rear during braking before. Maybe what you say is what it’s doing? That’d be pretty cool.

m

 

[Hall]

I doubt the truck or the honda would be this intelligent.

There's nothing overly fancy here. This is done via the existing safety features (ABS primarily controls it). It's easy to test. It might be more controlled on the CR-V and truck because they have such light (or lighter) rear ends which would normally make them easier to lock up the rear wheels. This will make the ABS really kick in, I think.

 

[Jetronic]

I learned something here - with 3-4 posts going this way. I didn’t realize this was a thing. Is it more prevalent with performance/high end makes? All 3 of our recent vehicles have rear pads substantially smaller than the front (2015 crv, 2014 GS350, 2018 F150). I doubt the truck or the honda would be this intelligent. Perhaps the Lexus might be... but toyota tends to be a late adopter. The Lexus does seem to have magical limited slip properties where it does its thing but I don’t perceive abs manipulation. where are we beginning to see this implemented?

mid to late nineties in euro cars