David Noland suggests Model S pedal placement is a safety hazard

[jerry33]

Don't these kinds of accidents where someone pushes the wrong pedal happen on other cars as well? Do we know it is worse on the Model S?

They happen on the Prius, and the Audi. I've never had a problem on the Model S although I have pressed both pedals on occasion (usually when backing up or not sitting normally for one reason or another). I did have one instance of pedal confusion on the second day of ownership. I pressed the accelerator rather than the brake pedal. Only went a couple of feet and no harm done, other than I was surprised. Hasn't happened since. This was due to broken brain rather than broken car.

 

[nirvanaman]

I've never had this happen, but now I wanna go test it. Just for laughs.

 

[mnx]

I think my brake pedal is definitely spongier than the loaners I've had recently.

Also did the driveway shuffle the other day with my old BMW (now my dad's). The brake pedal feel and the grabbiness of those brakes was a million times better (I think they were roughly the same initially).

It's been my experience that the brake pedal is spongier than it was at first. I have a suspicion that the less frequent use means the brake fluid never gets warmed up, and this might be having an impact.

I'm not just basing this on Model S. After two years my Roadster's brake fluid looked like coca-cola. I had to specifically request a brake fluid flush, because IIRC service said it wasn't supposed to be done until the fourth year. However you could see with the naked eye that the brake fluid was done, and flushing it made a significant improvement in the brake feel.

 

[FlasherZ]

I have size 13 shoes (boats) and really haven't had that problem; however, I think it's because I was taught to drive a bit differently. When you drive a car without power brakes, simply moving your toe over to the other pedal while keeping your heel in the same place (what seems to be taught nowadays) doesn't work. Instead, you have to pick your foot up off the floor and apply the brakes squarely.

Once you learn to drive using this method, it solves that "both pedal" problem pretty quickly.

I get a bit of a laugh out of watching younger drivers in my 1964 1/2 Mustang... they get this "it's not stopping! it's not stopping!" look in their eyes as they try to use the brakes for the first time.

 

[jbt100]

Low Vacuum

I think my brake pedal is definitely spongier than the loaners I've had recently.

Also did the driveway shuffle the other day with my old BMW (now my dad's). The brake pedal feel and the grabbiness of those brakes was a million times better (I think they were roughly the same initially).

I don't know if this could be the problem but with my Miata converted to electric I had to install a vacuum pump to build up vacuum for the power brakes. I recently had the problem of a vacuum leak and the car would not hold the vacuum to the set amount. I'm sure Tesla uses a system similar to this and it could be
the problem. With the strong regen the brakes don't get used that much and if there is a small leak it would let the brake pedal travel further to the floor thus allowing certain drivers feet to catch the accelerator.

 

[Canuck]

Hmm, I'm indeed dangerously close to slipping off the edge of the brake pedal with my size 11.5 shoes. Hasn't happened but, is likely if I'm not careful.

You have the same size foot as I do. With winter boots we are even closer to the 'gas' pedal. But cars are designed for the most common shoe size which is 9 to 9.5 for men and obviously a lot smaller for women. Spacing the pedals further apart may make it more dangerous for the masses. Small feet could get caught between pedals that are spaced appropriately for size 11.5 feet with winter boots. The author of the article seems to think that his car should be designed for his feet instead of for the most common feet size. That makes no sense to me.

 

[dsm363]

I agree. If you pick up your foot to apply the break it is a non-issue. If you don't then maybe a slight adjustment in pedal position from Tesla would help but certainly doesn't sound like Tesla is so far out of the norm that it is dangerous like Nolan writes to get hits on his article.

 

[mknox]

I wonder if those not having issues drove a sports car before the Model S, and those having issues ran more standard vehicles.

Nope. My tastes have always run in the direction of "luxury" and not "performance". The first new car I ever bought at age 21 was a Chrysler Cordoba!

 

[tomas]

OK, I'm one of the ones who has experienced this real issue, never for 15 months, then 3 times in last month, see prior posts. Just back from SC to try to diagnose.

My theory going in: spongy brakes cause excess brake travel, increasing possibility of accelerator contact while braking. Need hydraulic flush/refresh so that brake pedal travel to achieve braking goes back to normal range. SC diagnosis of hydraulic system: no problems, fluid fine.

SC's theory: Due to regen, MS brakes don't get much of a workout. They can get "glazed" with only light use - meaning a layer of dust/debris accumulates that reduces braking effectiveness. Therefore, you can mash the "glazed" brakes and get far less response than you expect, and also get your foot in accelerator territory. Prescription: Once every week or so, turn regen on low, and give the brakes a hard workout. This actually ought to be good for both the hydraulic system and any possible "glaze" accumulation.

To me, this intuitively makes some sense, so I'm going to try to remember to do it.

As a footnote, I really cannot recall - in the 3 instances where my braking was insufficient - whether I actually did have foot on both brake and accel. It is possible that it was just brake and brake was just underperforming, which this new theory could also explain.

At any rate, for those of you who experience this, you now have some plausible explanations and prescriptions. For those of you who haven't, please heed the suggestion to give the brakes an occasional workout so they're there when you need them.

 

[mhpr262]

I strongly doubt that aging braking fluid will do anything to alleviate this issue (if it does indeed exist).

Brake fluid spoils because it is hygroscopic, i.e. it attracts and absorbs moisture/water. Water is just as incompressible in an hydraulic system as the brake fluid itself, it is just that the water lowers the boiling point of the fluid and if your whole brake gets extremely hot, steam bubbles will form in the system and cause your pedal to fall to the floor.

 

[markwj]

The original article has been updated with this extra section:

Halfway solution

Ironically, the Model S is already programmed to cut off power to the wheels in case of an inadvertent double-pedal situation--but it only does so part of the time. And unfortunately, it's the wrong part.

If you're driving along at 40 mph and happen to step on the brake pedal with your left foot--a highly unlikely situation--the power will indeed cut off.

But if the brake pedal is pressed first, followed by the gas pedal--the usual double-pedal scenario, and the one that happened to me before the near-accident--power to the wheels is not cut off.

The electric motor, which produces peak torque at low rpm, thus strains against the brakes, which greatly increases the stopping distance.

The software logic of the Tesla system seems to be "whatever pedal is pressed last gets the priority."

The human logic? I haven't a clue.

 

[jbt100]

It is also my theory that this gets worse over time as braking system loosens up and gets spongier… I'm in at SC tomorrow to have them look at this and see if a fluid refresh improves. Please don't ridicule people reporting this, it is real.

Just saw a u tube video of tesla brake pedal going all the way to the floor. You could hear the electric vacuum pump going on and building vacuum and shutting off but pedal kept on going down. this indicates a vacuum leak in the pump or in the lines to the vacuum pod. The only other thing it could be is air in the brake lines. This could be a defect in some cars and not others so it could explain the random nature of it. This is not a normal action and should be corrected by Tesla with a recall or they are going to have a big suit somewhere down the line.

 

[strider]

SC's theory: Due to regen, MS brakes don't get much of a workout. They can get "glazed" with only light use - meaning a layer of dust/debris accumulates that reduces braking effectiveness. Therefore, you can mash the "glazed" brakes and get far less response than you expect, and also get your foot in accelerator territory. Prescription: Once every week or so, turn regen on low, and give the brakes a hard workout. This actually ought to be good for both the hydraulic system and any possible "glaze" accumulation.

To me, this intuitively makes some sense, so I'm going to try to remember to do it.

Well, glaze is the wrong word. Glazing is caused by overheating the pads. But build-up of "crud" was/is a very real problem w/ the Roadsters as they came with the Lotus Elise "performance/track day" brake pads and crud would build up and with light use would not get burned off. The fix was to switch to a pad with less metal content and higher ceramic content. Many of us have been using CarboTech 1521 or AX6 compounds to eliminate this issue. I have a set for my wife's Model S sitting in my garage - just haven't gotten around to installing them.

 

[JRP3]

Just saw a u tube video of tesla brake pedal going all the way to the floor. You could hear the electric vacuum pump going on and building vacuum and shutting off but pedal kept on going down. this indicates a vacuum leak in the pump or in the lines to the vacuum pod. The only other thing it could be is air in the brake lines. This could be a defect in some cars and not others so it could explain the random nature of it. This is not a normal action and should be corrected by Tesla with a recall or they are going to have a big suit somewhere down the line.

One car with faulty brakes and you are already looking for a recall?

 

[huntjo]

Just saw a u tube video of tesla brake pedal going all the way to the floor. You could hear the electric vacuum pump going on and building vacuum and shutting off but pedal kept on going down. this indicates a vacuum leak in the pump or in the lines to the vacuum pod. The only other thing it could be is air in the brake lines. This could be a defect in some cars and not others so it could explain the random nature of it. This is not a normal action and should be corrected by Tesla with a recall or they are going to have a big suit somewhere down the line.

You have to include a link or else people will assume you are lying and trying to instill FUD. Just sayin' ...

 

[dsm363]

A link would be nice.

 

[huzz1970]

This reminds me of the Toyota fiasco where people pushed the gas and brake and blamed Toyota (my opinion- no snarky remarks, please). But so far, in 45 years of driving, this has not happened to me in any type of vehicle including RVs, 10 wheels, Ferrari, Porsche, Nissan 350, Lexus, Oldsmobile, Buick, Audi, Chevy, Ford, Dodge, Mazda RX8, and Formula Ford racing. Some of the pedals were REALLY close together, as well, and I have size 11 feet.... Hmmmmmmmm

 

[rlcordeiro]

Two people have mentioned this and I agree. The brake pedal should be at least 1/4" above the gas pedal. In fact when I was readying my 911 for track day I was advised to make sure that the brake pedal was exactly at the level of the gas pedal when fully engaged to facilitate heel and toeing. I have already rear ended someone due to this problem and it does exist especially with thick soled shoes. Just because some people are perfect does not mean that the car cannot be made more suitable for the rest of us.

 

[JRP3]

You have to include a link or else people will assume you are lying and trying to instill FUD. Just sayin' ...

Looks like a bad master cylinder or leaking brake line to me.

Plus the guy posting the video is going crazy in the comments, obviously trying to drum up FUD.

 

[dsm363]

Looks like a bad master cylinder or leaking brake line to me.

Plus the guy posting the video is going crazy in the comments, obviously trying to drum up FUD.

Yeah. His proof is a Norwegian forum it looks like. Seems a lot like someone who used to post here and did the same thing.