Smart tries to kill me.

[Peter DLM]

So I'm on one of Milton Keynes' many 70mph sections heading downhill towards a roundabout and a queue of cars. The dashboard lights up advising that Brake Assist is offline. I curiously tap the brake pedal conscious that I'm going to need them imminently only to discover the pedal is rock hard and there's no braking effort at all!

So I have to hulk stomp the brake pedal and change from 5th straight to 2nd whilst tugging the handbrake up and re-engaging the clutch as quickly as I dare. Luckily there was an escape route available so I wasn't panicking too much but was still able to just pull up in time.

I pulled over and restarted the car, lots of messages about there being a malfunction and to visit a workshop and that the BAS was still offline. I limped it home carefully and had it recovered by Smart Assist.

I'm not having a lot of luck with this car right now, what with people driving into it and now it trying to commit suicude with me in it.

The video below is from when I'd pulled over, the revs are fluctuating like they are by themselves, I'm not touching the throttle.

http://youtu.be/89mivimF7NA

 

[Deleted member 37751]

I think your car wants to die and it's not bothered if it takes you with it pal!

 

[renault12ts]

Video private.

 

[Peter DLM]

Yup, it has a confidence issue I think. When I get it back from having both its issues fixed I'll treat it to a full valet to cheer it back up again.

 

[Peter DLM]

Video private.

Thanks, and fixed.

 

[Deleted member 37751]

Yup, it has a confidence issue I think. When I get it back from having both its issues fixed I'll treat it to a full valet to cheer it back up again.

I was thinking more like stuff a Hyabusa engine in it.

 

[grober]

Evilution - Smart Car Encyclopaedia Don't know if this applies to your model or not|? Is it possible the ABS reluctor ring/sensor got damaged with that recent accident damage?

 

[Meldrew2]

Evilution - Smart Car Encyclopaedia Don't know if this applies to your model or not|? Is it possible the ABS reluctor ring/sensor got damaged with that recent accident damage?

Certainly sounds like something has been jolted loose or broken. Repairer & Insurer needs to be told ASAP.

 

[Peter DLM]

Evilution - Smart Car Encyclopaedia Don't know if this applies to your model or not|? Is it possible the ABS reluctor ring/sensor got damaged with that recent accident damage?

It's possible. I'll mention it to the workshop on Monday.

 

[C240Sport97]

are these issues anything to do with the fact that the Smart platform was jointly developed with Renault ...

 

[h17n dj]

I live in MK and glad you wasn't behind me..!

On a serious note - I'm glad you're ok and that MB rectify the issue so that a repeat doesn't occur.

 

[Peter DLM]

I got the car back yesterday. The vacuum hose had popped off the servo. I asked if a modified/updated part had been put on but no, just the original refitted. I asked what would prevent of popping off again and was reassured that it wouldn't, I assume from this that it was incorrectly fitted from the factory or missing a hose clamp?

Anyway, I'll be braking a bit earlier for the roundabouts for a while, just in case.

They also performed the alarm recall whilst they had it, the alarm went off by itself a few times.

 

[st13phil]

Just goes to show how much pedal assistance the servo gives. As an experiment, I suggest people try pumping the brake pedal with the engine off to see how many stops they'd get if the engine's not running before the assistance stops. Clue: it won't be more than two, so use them carefully!

 

[Peter DLM]

Well if the Smart is anything to go by you won't get even one assisted pedal press !

 

[Deleted member 37751]

Maybe you should cut a hole in the floor about the size of your feet for next time Pete.

 

[st13phil]

Well if the Smart is anything to go by you won't get even one assisted pedal press !

Back in the early 1980's a friend of mine was part of the design team at Rolls-Royce Motors responsible for fluid systems on the car.

At the time, RR were one of the few - maybe the only? - car manufacturers who used true power brakes, rather than power assisted brakes. They included an hydraulic accumulator in the system that provided enough reserve pressure to carry out 20 full power stops without the engine running. After that you had no brakes. At all

 

[Charles Morgan]

Back in the early 1980's a friend of mine was part of the design team at Rolls-Royce Motors responsible for fluid systems on the car.

At the time, RR were one of the few - maybe the only? - car manufacturers who used true power brakes, rather than power assisted brakes. They included an hydraulic accumulator in the system that provided enough reserve pressure to carry out 20 full power stops without the engine running. After that you had no brakes. At all

It is Citroen system pioneered in the DS in the 50s and adopted by RR for the Silver Shadow. Ditto rear self-levelling (also adopted by MB). The Citroen system maintains a central accumulator for the brakes so they will be the last to fail if the system leaks. First you will get a warning light, then as the fluid leaks you'll get steering effort increasing and ride quality dropping. If you haven't got the hint by then and pulled over, they still let you brake to be safe.

Hint to RR and Bentley owners - buy your hydraulic fluid at Citroen (LHM+). It's much cheaper!

 

[Charles Morgan]

Well if the Smart is anything to go by you won't get even one assisted pedal press !

Having driven numerous cars with only brake master cylinders and no servoes, that is alarming. The servo merely aids the pressure applied to the brake cylinder - did you pump the brakes as hard as physically possible?

(I've had to brake one such car without a functioning master cylinder going downhill. Now that was truly alarming...)

 

[Bellow]

I got the car back yesterday. The vacuum hose had popped off the servo..

My first suspicion - the fluctuating idle speed providing the second clue.

Just goes to show how much pedal assistance the servo gives. As an experiment, I suggest people try pumping the brake pedal with the engine off to see how many stops they'd get if the engine's not running before the assistance stops. Clue: it won't be more than two, so use them carefully!

Well if the Smart is anything to go by you won't get even one assisted pedal press !

You likely used up the available vacuum reservoir then the warning appeared on the dash.
Having performed st13phil's experiment (while rolling down a steep hill) in a 450 fortwo, there were two to three applications in the tank, but.....

Having driven numerous cars with only brake master cylinders and no servoes, that is alarming. The servo merely aids the pressure applied to the brake cylinder - did you pump the brakes as hard as physically possible?

.....stopping the car took enormous pedal pressure.
The hydraulics are I suspect 'sized' with the servo in mind so need for hydraulic advantage so shorter pedal travel pursued instead. Possibly to suit ABS requirements.

(I've had to brake one such car without a functioning master cylinder going downhill. Now that was truly alarming...)

I once had a 1275GT with a leaking master cylinder. Just at the point when the whole plot should
be coming to rest - it didn't. Damned near hit the back of a bus at a junction.

 

[Peter DLM]

did you pump the brakes as hard as physically possible?

I did "hulk stomp"* the pedal and got some braking effort, but not a lot. Not enough to stop the car by itself from 70mph down a slight decline in the space I had available.

Without wanting to create another 600psi punch instance, I squat 230kgs and therefore have somewhat strong legs, I think a lady wouldn't have had much or any braking effort.

My Caterham is obviously without servo and that's pretty easy to haul up but with a bit more effort than a typical road car.

*this reference only understandable to those who have watched the recent Avengers Assemble movie.