I did a search and didn't find anything. We bought our FEH a few months ago, and i noticed lately the brakes are screeching sometimes. I had this on our older mercedes benz which is notorious for squeeky brakes, and thought i would be done with hearing that horrible sound... but sure enough... i am hearing it again. It is cold out.. around 20-30 degrees out.. so maybe that has something to do with it.
anyone else experience the same thing?

 

As for the recent weather, there are a number of posts regarding the brakes in cold weather. Apparently, in certain cold conditions, the system will not allow regenerative braking to occur and so the motor braking is not used and friction braking is implemented (Check the thread called "cold causes brake failure" or something like that). Even in warmer weather the brakes will squeek from time to time because they are used so little. Most of the braking in the FEH and MMH is done with the motors to recharge the battery. In fact, the friction brakes only come "on" in hard braking and when braking at (I believe) 7mph or less. Due to a lack of use, you will probably get more rust and other "stuff" on the rotors and pads that would rub off on a normal vehicle.

Also, some owners have reported their E-brakes being a little "sticky" and say that by pulling up on the brake while the vehicle is moving (carefully and at slower speeds) it eliminates that occasional squeek.

 

Thats been claimed a couple of times... but I've seen mine regenerative brake all the way down to temperatures of 0F, once the battery and ICE has warmed up. I have video of the charge/assist needle and NAV moving at 13F and the magnitude of the movement is the same as any other temperature I've driven mine at, so I'm less than convinced on that statement.

In reference to the problem I completely agree with your statements about the parking brake and the fact that since they are little used stuff does build up on the pads.... I've encountered symptoms I believe are caused by those facts.... Mine have never sqeeked though.

 

Yep - I've been noticing consistent use of the regen braking, even with the temps in the teens and 20's lately - once the ICE and HVB have warmed. [and.....I thought I remembered reading in the shop manual a description of how regen was limited below 32F ? myth?]

 

I'm wondering if what it says is that regen is limited when the battery is below freezing (for obvious reasons) and people read it wrong. Of course I don't have a shop manual to check.

Frankly... I'm not convinced its any more dangerous for it to regen with roads that might be slippery than a normal vehicle. Automatic transmissions also drag on drive wheels when you let off the gas and in a manual if you let off the clutch when you downshift (which technicially is how you are SUPPOSED to downshift--but you have to be careful when it slippery) you can experience a fair amount of engine braking.... I have driven both, and neither has thrown me into a ditch when slowing down. I'm going to assume its because I know what I'm doing when driving in the snow... I've been doing it for 20 years both in a manual and an automatic.

The drag on the wheels from regen feels to me much less than downshifting in a manual and doesn't seem like its more than an automatic... so I don't see how it would be any less safe than driving either of those vehicles in the same conditions.

There is alot of hyperbole out there about driving in snow... I've seen posts somewhere where a guy basically implies that all FWD vehicles are deathtraps in the snow.... which I find amusing since many cars are now FWD and I haven't seen any huge accident increase in the winter since they switched over from RWD.

 

This is probably due to one of two things:
1. Worn brake pads
2. Defective brake pad installation

If your FEH is new then probably isn't problem #1
Brakepads have an audible wear indicator which scrapes the wheel disk, making noise to alert you of a near worn-out pad.

Problem #2:
Picture a bicycle brake as it squeezes two surfaces against your wheel rim and making you slow down or stop.
Your car has a sort of hydraulic press which squeezes the brake pads against the wheel disk making you slow down or stop.

As the pads are pressed against the rotating wheel disk it can cause them to vibrate, sounding like a squeal.
Think of it as a very high pitch tuning fork.

The fix is to have a mechanic put an insulator or type of silicone plastic over the back of the brake pads which stop the vibratins from happening.

Problem #1 requires immediate attention.
Problem #2 is annoying but not serious.

If you can't tell the difference between the scraping sound of #1 and the squeal of #2 have them checked out.

-Steve

 

Back on topic as Steve steers us... there is a third possibility down that line and that is cheap brake pads. I've had several instances in other cars where pads I've bought from discount stores do not come with the appropriate shims that are there to prevent vibrations and squealing.... its one of the ways they undercut the manufacturer's price... you can sometimes save the shims off the old set if you remember to do it.

You don't have to buy Ford pads, but you do want to stay with a reputable brand in my experience.

 

But since we don't have clarification as to WHEN the original poster hears squeaking, it is possible that it occurs during the warmup phase and is related to the regen not operating when still cold. At low temps this could be 10+ minutes. I figured I would post all the possible causes.

 

Thanks, It is a pretty new car... i will have ford take a look at it just to be safe.
Thanks.

 

Let us know what you find.