lorenfb
Posts: 2485
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Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Brake maintenance - How to avoid seized brakes

Mon Apr 13, 2020 10:03 am

Oilpan4 wrote:
Sun Apr 05, 2020 8:13 am
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.
How did you calculate the brake drag loss?
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=73, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

Oilpan4
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Leaf Number: 004270

Re: Brake maintenance - How to avoid seized brakes

Mon Apr 13, 2020 9:45 pm

lorenfb wrote:
Mon Apr 13, 2020 10:03 am
Oilpan4 wrote:
Sun Apr 05, 2020 8:13 am
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.
How did you calculate the brake drag loss?
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.
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lorenfb
Posts: 2485
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Brake maintenance - How to avoid seized brakes

Tue Apr 14, 2020 10:39 am

Oilpan4 wrote:
Mon Apr 13, 2020 9:45 pm

If you have rear drums they shouldn't drag. If they do drag, take them apart and fix them.
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.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=73, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

powersurge
Posts: 1743
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Location: Long Island, NY

Re: Brake maintenance - How to avoid seized brakes

Tue Apr 14, 2020 12:03 pm

lorenfb wrote:
Tue Apr 14, 2020 10:39 am
Oilpan4 wrote:
Mon Apr 13, 2020 9:45 pm

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

LeftieBiker
Moderator
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Re: Brake maintenance - How to avoid seized brakes

Tue Apr 14, 2020 12:25 pm

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.
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.
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arnis
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Re: Brake maintenance - How to avoid seized brakes

Tue Jun 23, 2020 2:42 pm

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.
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estomax
Posts: 279
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Leaf Number: 424033
Location: Seattle

Re: Brake maintenance - How to avoid seized brakes

Tue Jun 23, 2020 3:02 pm

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
2013 Leaf SL Premium
27k, 93% SoH 2/17 32k, 96% SoH 6/17
46k, 94% SoH 2/18 52k, 88% SoH 6/18
62k, 87% SoH 2/19 68k, 84% SoH 6/19
75k, 83% SoH 2/20

arnis
Posts: 1027
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Leaf Number: 015896
Location: Estonia, Europe

Re: Brake maintenance - How to avoid seized brakes

Wed Jun 24, 2020 10:27 am

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.
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estomax
Posts: 279
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Leaf Number: 424033
Location: Seattle

Re: Brake maintenance - How to avoid seized brakes

Wed Jun 24, 2020 11:12 am

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.
2013 Leaf SL Premium
27k, 93% SoH 2/17 32k, 96% SoH 6/17
46k, 94% SoH 2/18 52k, 88% SoH 6/18
62k, 87% SoH 2/19 68k, 84% SoH 6/19
75k, 83% SoH 2/20

MikeinPA
Forum Supporter
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Joined: Wed Jul 08, 2015 7:20 am
Delivery Date: 21 Dec 2013
Location: SE Pennsylvania

Re: Brake maintenance - How to avoid seized brakes

Wed Jun 24, 2020 12:30 pm

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?
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