Brake maintenance - How to avoid seized brakes

Oilpan4 said:

I used Raybestos h6016 springs.
I calculated how much power it will save, looks like about 200 to 300 watts at 65mph.
Which works good for me because about 80% of my driving is on the highway.

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How did you calculate the brake drag loss?

lorenfb said:

Oilpan4 said:

I used Raybestos h6016 springs.
I calculated how much power it will save, looks like about 200 to 300 watts at 65mph.
Which works good for me because about 80% of my driving is on the highway.

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How did you calculate the brake drag loss?

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Easy.
I tested a spring, found how much force they remove from the pads.
Looked up the brake pad to rotor friction coefficient.
Now that I figured how much drag the pads put on the rotors I just had to figure the number of linier feet of pad travel on the rotor over a given amount of time at speed. It was obvious that the pad drag losses were going to be much higher at highway speeds so that's what I went with. Then I knew foot pounds of torque at RPM, aka power.

If you have rear drums they shouldn't drag. If they do drag, take them apart and fix them.

Oilpan4 said:

If you have rear drums they shouldn't drag. If they do drag, take them apart and fix them.

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If there is some shoe drag, the efficiency gain is a function of the amount drag, and typically it's very insignificant.
So an efficiency gain can't be typically realized by just updating with new brake shoe springs.
Brake shoe drag can always be checked when rotating tires, if one is concerned.

lorenfb said:

Oilpan4 said:

If you have rear drums they shouldn't drag. If they do drag, take them apart and fix them.

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If there is some shoe drag, the efficiency gain is a function of the amount drag, and typically it's very insignificant.
So an efficiency gain can't be typically realized by just updating with new brake shoe springs.
Brake shoe drag can always be checked when rotating tires, if one is concerned.

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You NEED to have some drag on brake shoes. When you adjust the rear brake shoes, you should tighten them until they start to grab... Otherwise, your rear brakes will not be adjusted correctly.

You NEED to have some drag on brake shoes. When you adjust the rear brake shoes, you should tighten them until they start to grab... Otherwise, your rear brakes will not be adjusted correctly.

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I believe the idea is to get just enough drag to know that the shoes are as close to the drum as possible, with the expectation of a little material wearing away when the brakes are applied on the first drive and the drag being removed. You aren't supposed t have continuous, long term drag in the drum brakes.

With disk brakes, the rotors are supposed to have a minute amount of 'wobble', to push the pads out to just barely beyond the point of continuous contact with the rotor. That's what makes them self-adjusting.

Testing excessive seize:
Use some chocks so vehicle won't move.
Raise one wheel off the ground.
When testing front wheels engage neutral and parking brake. Try to turn the wheel with one finger. Should be easy.
If ok, push the brake, release, try again. Repeat with other side.
When testing rear wheels engage P but disengage parking brake.
Try to spin the wheel with one finger. If successful, push brake, release, try again.
If successful. Apply parking brake, release, try again. Try also reversing after releasing parking brake.
Rinse and repeat with other side.

If one wheel requires lots of effort - do the maintenance on all of them. No need for springs or other porn.

for what its worth, i went ahead and installed the springs, and was not able to record any discernible difference after a week of driving with my miles/kwh reading. The clips do install super simply on the front brakes though. The front brakes also have a small spring built into the pad holder that might push the pads back also, not quite as effectively though, but the rear ones are a bit tight so i only installed a single clip there, not two.

here is what it looks like with the clips on the front pads, the pads should still be able to wiggle around and not feel bound up by the clip in any way.
https://photos.app.goo.gl/CdnooqVkVFVGxnxb9

here is the rear single clip installed, i did also modify and cut the last quarter inch bend off of them or else they didnt want to fit very well.
https://photos.app.goo.gl/oLNpmDKKTXK1b9eX8

got the tires rotated and brakes inspected/cleaned/pins lubricated though, so this experiment didnt take much extra effort

Marko

Looking at that I can actually see extreme hazard.
Stop modifying things. Somebody will get killed sooner or later :|

If those springs will retract pads more than 0,2-0,4mm you will lose instantaneous brake action.
1 full stroke of brake pedal equals just a hair of movement for pads.
If pad is too far you will not have braking capability.

Jesus.

dude.. you are over reacting, having done this, it made no difference to brake feel, the spring force is a few ounces and will not push the pads back into the caliper to possibly cause the situation you are concerned about.

Also, if you ever push on the brake pedal when the caliper is out, then you will see the pistons move quite a bit more than a hair on each press. Enough to pop them out of their seals even.

Brake maintenance on a Leaf is weird topic. Many of us are seeing little or no wear on the pads. I am at 50+K on the pads and they would go another 100k I bet, even more, which means a way longer service interval than ICE brakes.

When I was replacing a right front wheel bearing recently, I noticed the pad metal edges were rusted and consequently oversized--the pads would not move freely along their guides. I don't know if I would call them seized, but they certainly were not releasing all the way and spinning the wheel whilst up in the air you could hear some scraping. I hit the rust lightly with sandpaper to get back to correct size and greased (brake) all the moving contact surfaces. Ended up doing the left front as well. I think in climate with a lot of corrosion, it is a good idea to pay attention to whether they are releasing as they did while new. Also, I would have put new pads in there if I had them, because it would be longer till they rust. If there is a stainless steel backed variant out there, that would be perfect. Rotors are wearing very slowly too.

Pins on this one were clean and grease was clean, no need to refurbish.

Speaking of brakes, is there a thread on MNL on brake fluid interval change vs water-cause brake system damage? I can see why Nissan wants frequent changes if there are a lot of high dollar parts with fluid in them, but what has been learned about actual damage from not doing yearly changes?

MikeinPA said:

Speaking of brakes, is there a thread on MNL on brake fluid interval change vs water-cause brake system damage? I can see why Nissan wants frequent changes if there are a lot of high dollar parts with fluid in them, but what has been learned about actual damage from not doing yearly changes?

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I don't know of a special thread but there have been mentions about this before and some folks have tested their brake fluid with some sort of chemical indicator strips. Bottom line, the brake fluid in a Nissan Leaf is hygroscopic (like most brake fluids) and will absorb water over time. LIke any car, water in the brake fluid can damage the steel brake parts internally and in extreme cases, the water can boil under hard braking causing loss of hydraulic pressure. Personally, I don't worry about the latter and I'm changing my brake fluid every 3 years to prevent the former. YMMV.

I also keep an eye on brake fluids and I can tell that 3 years is definitely safe, even in hard climate with salt and snow and moist air.
Even 4 years is acceptable. But not much more. In addition to water there are other things dissolving into fluid.
Measuring expansion tank fluid doesn't tell the whole story. Fluid from caliper is in much worse state. Fluid doesn't circulate.
Rust on brake pad base plate guiding edges is important. This area must be greased by special lubricant designed for that area.
TRW makes one. Over-the-counter greases are no good. Also guiding pin boots will be swollen if incorrect chemical is used.

Maximum interval for brake "cleaning/greasing" for Leaf in not good winters is 2 years. It will definitely start to seize on third.

Those "springs" - well. They are not calibrated. You got from Walmart, uncle John gets from local barber. Eventually somebody
will make them out of stainless steel or any other tougher metal and it will eventually create a hazard.
Brake pads touching brake disc and creating few newtonmeters of drag is NORMAL and actually designed to be that way.
This process dries braking surface in rainy weather. 10-20W of heat per wheel is acceptable loss.


PS: Did you know that BMW has "dry" guiding pins. Service manual clearly states: clean pins and DO NOT GREASE.
I did grease my rear axle guiding pins (because I thought "who needs to read manual for such easy things") and it got worse
compared with front ones. So I removed grease and it went back normal. Interesting tech. It actually slides perfectly when clean.

Even 4 years is acceptable. But not much more. In addition to water there are other things dissolving into fluid.

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Arnis and I agree on this. There is a very long thread on this, probably in another topic about something else. The conclusions drawn in the other topic about brake fluid changes every year?

*Yes!

*NO!!

* SHUT UP!!!

MikeinPA said:

...Speaking of brakes, is there a thread on MNL on brake fluid interval change vs water-cause brake system damage? I can see why Nissan wants frequent changes if there are a lot of high dollar parts with fluid in them, but what has been learned about actual damage from not doing yearly changes?

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A flush every 2 years did sound excessive at first to my American ears, but european makes have been advocating this for some time. ABS braking systems aren't like the simpler braking systems in years past. ABS controllers are replaced as an assembly, with very large price tag. It's well worth a bit of preventive maintenance to keep the system pristine, imho. Your LEAF won't turn into a pumpkin on day 730, but 2 years seems like a reasonable schedule to shoot for. You can measure water and/or Copper on a regular basis, but heck if I'm going to go through all that trouble, flushing the system gives me brand-new fluid for not much more effort.

arnis said:

Rust on brake pad base plate guiding edges is important. This area must be greased by special lubricant designed for that area.
TRW makes one. Over-the-counter greases are no good. Also guiding pin boots will be swollen if incorrect chemical is used.

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This is another good point and I tend to forget it on my Leaf since it's new but on my ICE cars (average age = 15+ years) it is something I check and maintain every time I do the brakes on them. I haven't seen any stainless steel backing plates but I've used calipers that come with a stainless steel sheet metal insert that is used between the pads and the calipers. Here in Colorado, rust isn't a problem and a quick touch up with a file and an application of real brake grease is all I've ever used. If you're in a rust belt area though, I'm sure it would be a different story.

IMO, brakes on a EV are no different than brakes on an ICE car, except the pads/rotors last longer. All the other maintenance should still be kept up to date and since that is often done when the pads are replaced, it's something new to consider.

goldbrick said:

Here in Colorado, rust isn't a problem and a quick touch up with a file and an application of real brake grease is all I've ever used.

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The only reason I have ever gotten rid of cars was rust. Around here "rust never sleeps". I am getting ready to put my white Leaf up on stands and start going after some rust I was quite surprised to see last fall when doing a rear bearing. First new car I ever bought, planning to keep it a while. Backstory, I was at a client's in fall of 2013, saw her's, she said "take it for a day", next thing I knew I was down at the dealership with a check. I had been wanting an electric vehicle for decades (even called the SoCal EV1 dealership to see if I could get one), somehow had missed the arrival of the Leaf. Love the car, hate rust.

I use the grease that comes in the little packets with disc brake pads. Sparingly.

I went to school at the U in Minnesota so I understand rust. And I understand you're opinion of the Leaf. I just towed a used one to my folks in NE Iowa. My dad just rode a few times in mine while visiting last year and called me up and asked if I could find him one. He's had it a month now and just loves it.

Nubo said:

A flush every 2 years did sound excessive at first to my American ears, but european makes have been advocating this for some time. ABS braking systems aren't like the simpler braking systems in years past.

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Well, I am at 36 month intervals on the white one, don't know the history of the blue one, carfax does not show flush. I have one of the power bleeders and will get caught up. Two year intervals is not much effort for decreasing $$$ repairs.

LeftieBiker said:

*Yes!

*NO!!

* SHUT UP!!!

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Experts often disagree.

Had my 2011 Leaf for 2 years now. Checked the maintenance history, never been done, ever. Works perfectly--no issues at all.

I'll be taking it in for a brake flush.

In our climate, I've been taking ours in for a full flush every 3 years.

Audi recommends every 2, but color me skeptical. I think that's them padding their service numbers.

Modern brake fluid is not as water hungry as it used to be.

-b