So I finally took my FEH on the trail we all use to go Hang Gliding around here. It is rocky, steep, twisty, and goes on about 2.5 miles. The altitude gain is about 2000 feet. You have to sign a waiver with the park to drive it and if has rained recently they will close the trail anyway because the surface becomes virtually frictionless. At some stretches you have a 600 foot sheer drop to one side and a cliff face on the other. Most places you can pass two cars but there are spots where you don't.

First the good part. With three guys aboard, three hang gliders and gear, makes up a payload of about 900-1000 pounds, we went up the hill like a champ. We couldn't of one any races against a Xtera or Cherokees, or Tacomas, or F150s or whatever else, but the FEH did not balk at anything. It just went up. The handling was superb, and I had no problem with bottoming-out where I have with some other cards I have ridden in or driven on that trail.

Only pause is about 2/3 of the way up I smelled something burning. Typically on the tach for the steepest parts I would read 2500-3000 RPM, and some EV assist. I can't say just what that was. It didn't seem like anything was straining but unfortunately I didn't have my scangauge set up.

So we get to the top, set up, and launch. There were about 20-30 other hang gliders and para gliders already up there. Great conditions for flying although I came down sooner than I had to since it was cold.

Typically you can find someone who can drive your car down for you but in this case I declined, since this car had never been on this road before so I had no basis of knowledge to instruct the driver from. I knew I could get a ride up with someone else and drive down to the landing zone myself.

So I did. Here is where the bad part come in. I start down the trail with the gearshift in L and right off the bat since the engine isn't up to temperature it insists on running it, and worse it is deciding to charge the battery. However the bigger problem (to make a long story short) is that the regen braking and the compression braking have absolutely no effect below 10MPH and very little below 20MPH. It is simply not safe to go down 80% of that trail faster than 5-10MPH. In any conventional SUV or truck with a transfer case in the low range you simply put it in the low range and ride it down with both feet off the pedals. You don't ever need to touch the brakes except to stop.

Not so the FEH. You simply have to ride the brakes, and in that configuration you are riding the FRICTION brakes almost that whole time. When I had to get out to open gates I checked the rotors, and they were so hot that it was uncomfortable to even put your fingers inside the wheel spokes, let alone touch the rotor. So much for getting 100K miles+ on a set of pads.

Not good. In my opinion the FEH is not safe for this kind of mission for any but an expert driver and with new-condition brakes. If you have to use the car for that kind of driving on a routine basis, you will have to buy new brake pads regularly. I'm wondering if any kind of fix for this is possible in software, or if it is going to take a significant re-tooling of the CVT/EV system.

 

Interesting Mr.

I myself would have tried going down much different but I don't know how it would have worked not being there.

First I would start the ICE and drive to the downhill where the FEH would roll down on it's own. Then, shift to "N" and turn the key off and back-on within 3 seconds. Leaving the key on will still provide power steering and power brakes. With the key on and using power steering, brakes and everything else, the HV battery will drain fairly fast, but your burning no fuel. In neutral, you cannot restart under 6mph so you would have to increase above 6 to key start or stop and shift to park. Depending on how cold it is, I may get to use regen in "L" to let the rotors and pads cool down, but I would have to restart the ICE for that. Of course if you run long enough to go EV while in "L", you would start saving gas again. At any rate, your brakes would get some time to cool on the way down.

GaryG

 

Gary, you missed the WHOLE POINT of the OP.
( This is about brakes, not MPG! )

I can see where this is a case where you would have to rely almost 100% on the friction pads. But, #1 you said it was only ~2.5 miles. That is not very far... and not too much to worry about. #2 you are only going about 5 to 10 miles per hour. While constant dragging the brakes will get them hotter than you are used to, this is not nearly enough heat to warp the rotors or glaze the pads or cause damage.

Warping rotors and damaging pads occurs when the brakes are nearly hot enough to glow. This would happen driving down steep grades at high speeds for longer than 2.5 miles. ( Colorado Rocky Mt. Passes where there are steep paved roads, with higher speed limits, and still require braking... ) Ford has engineered for this second senario, with the engine compressional braking.

So in summary, at 10 MPH or less, you have little or zero regen brake.
At 10 MPH or less, you have basically zero engine compression brake.
At 10 MPH, it is perfectly O.K. to drag your brakes for 2.5 miles.

If you don't like the smell ( if there was a smell ) stop 1/2 way down for 5 minutes. That's enough of a rest for your brakes, although this is not necessary.
-John

P.S. And whatever you do, ignore any advice about "turning the key off" on steep dangerous roads with 600 foot cliffs!

 

Not a big deal. 2.5 miles of riding your brakes is about the same wear as 10 stops from highway speed.

 

I hope you're right but intuitively it doesn't seem like it. Fortunately I have to do this only once a month on average.

That hill is no place to lose control due to failing brakes. About two years ago one gal was driving her husband's truck down that trail. I forget the model but I recall it was something much heavier than an Escape. Somebody failed to train her adequately and she rode the brakes down rather than justing the low-range. About halfway down -- fortunately past the big drop-offs -- she lost all braking and ended upside down alongside the road. She was not hurt.

Next time I do that run it I'll set up a cam so I can post a video, and crunch some numbers as to just how much energy we are talking about here.

The thing is I am very happy about all other aspects of its off-road performance; it just seems like something is "missing" about the drive train not being able to absorb the energy of a controlled descent the way a conventional SUV or truck does. I strongly suspect that the design can actually do it and it is just the control system that isn't sufficiently flexible enough to take advantage of it. If true that is sort of frustrating.

End result is I would not recommend the FEH for the average driver for this kind of work.

 

I'm not in this situation often, but when mine was new, I took it off-road... above snow line to boot, on some dirt trails in the Rockies.
Like you, it was great going up, and I recall a little scary going down, and I didn't have cliffs, but I was on mud and snow and slush, and there were plenty of trees to hit. I think the FEH is very capable... remember, it has 4 wheel discs, and most vehicles only have front wheel disc.. so in theory, this car has some advantage... the "load" is more equally split over 4 wheels. But I agree, it "feels" different enough to be un-nerving.
Good Luck! And post back often how it does in the future. I'm so glad to hear when people are actually using this as a "Ute".

-John

 

keep your brake fluid flushed once a year with dot 3 Ford spec or dot 4. Most brake failures at high temps are due to brake fluid boiling because it has 2-3 % moisture content which lowers the boiling point to 300 deg or lower and the bluid boils which makes the fluid foam and is the same results a air in the system. This happened to me at 140 mph at Texas world speedway in a turbo porsche. Good thing there was a runoff area.

 

I've seen several posts here complaining about the lack of engine braking in the FEH. But I haven't seen anyone document fade or failure problems from overheated disks. From my experience driving off-road, the brakes are really good. Yes, it's uncomfortable to have to learn to rely on them when you're used to gearing down, but you'd really have to push a FEH hard to fade the brakes.
Besides, brake pads/discs are a lot cheaper and easier to replace than transmissions!

 

This surprises me a bit. I drove mine up and down Pikes Peak without the problems you mention. I put it into low and barely touched the brakes. About halfway down they check your brakes, and commented about how cool mine were. No I don't remember the temp.

It's been a while, but I don't think I was going 10 mph. I have found, though, that if you are going fast it doesn't tend to slow you down. I had to slow myself down and then it seemed to hold the speed fairly well.

That road has some good dropoffs that I didn't want to visit.

 

Mark, you are so right. Most people ignore brake fluid for their entire ownership. I love wrenching my cars, and the inexpensive hand operated vacuum brake bleed kits (using tubing and a dual ported plastic cup), is pretty simple. I've changed a lot of brakes, and I'm sure I'll pull the wheels and just 'inspect' the disks/rotors in the FEH long before they need changing