Yes, I as the tactile person was often called upon to put in the new cable for the speedo on my Dads cars, as invarably the place it was screwed into had little space and was out of direct sight. So why did they move away from the drive shaft method if it was directly connected to the wheels?
I'm assuming then which ever method you use, if you fit bigger wheels you can drive faster to get the same speedo reading? Brian
It's optional. I just taught myself how to manage the auto box using both. Having done so I have the following benefits:
- I never have to use the handbrake, (which doesn't exist. I have a parking brake instead!) which is a switch, not something usable on a hill start.
- I don't have to force the box into manual mode to drop gears when driving fast. Admittedly these days with flappy paddle override this isn't a big deal.
- I can get far better getaways by fully getting the engine up to speed and the torque converter raring to go while holding the car on the brake. Cf drag racers.
- I have far more precise control at low speeds: Elderly friend reversing up a slope in a auto demolished a bit of his garage. Didnt switch from accelerator to brake in time.
- since I am always covering the brake, I have about a 300ms speed advantage in an emergency braking situation.
These may not matter to you, but for me its worth it just for the precise low speed control. Autos and engines lag. a clutch or a brake allows an engine to be at a set speed, while you use the left foot to precisely control the car.
I think you'll find that's because cars which have "automatic engine stop when stationary" only do that when the footbrake is used. My Jazz does that - but as soon as I take my foot of the brake the engine restarts. It simply won't work with handbrake only.
There are a lot of weird programming ideas that Honda has. That "auto-engine stop" also ends when the seatbelt is unclipped! So, if I'm waiting for the garage door to open (it has a motor), with my foot on the brake, and the engine has stopped, if I unclip the seatbelt a few seconds early before driving into the garage, the engine automatically restarts! Where is the logic in that? It also has a speed limit sensor which reads the road signs and sets the limit so that the car will not exceed it (it is adjustable by a few mph each way). But, make a turn - even at a roundabout - and the speed sensor will turn itself off and reset to "none detected"! So the limiter will be off too. Where's the logic in that? It's particularly annoying in 30 mph areas where there are usually no signs showing the speed limit. Sometimes it does retain the limit set even though there is "none detected" on the display. Methinks some better programming is required.
Point of order on cruise control. (only ever used it in America where there wasn't any traffic on highways).
If you have it set to 60mph and you catch up with another vehicle in a
30 zone, does the car then change to some version of *safe distance* control?Common occurrence here where several miles of 60mph are followed by several miles of limited overtaking opportunity 30mph to find youngish cars annoyingly following at one car length!
Normal cruise control would keep at 60 until a) you cancelled it, or b) you rear-ended the slower car ahead of you.
I presume that adaptive cruise control detects the speed of the car in front while you are still some distance from it and slows you down gradually and then maintains a safe distance - eg 2 seconds. However this is supposition: I've only ever driven a car with manual cruise control. I'm not sure what happens if the slower car in front then accelerates away (eg when it leaves a lower speed limit) - does your car speed up again to the speed that you've set the cruise control to?
All the ones that flash on but just indicate the speed limit seem to be set to trigger at least 5mph below the limit, as do the ones with a smiley or sad face.
The ones around here agree with GPS indicated speed. The car speedo over reads.
My (manual) car has something called hill start assist which holds the brakes on for you. A F*****G nightmare the first time it cuts in when trying to reverse park in a tight space on a hill. This option is now turned off in my car.
Why would a database be more reliable than the speed limit signs on the road? One hire car I had thought, from its database, that a 60mph road had a 20mph limit on it.
MB seem to think it does.
Some do, mine doesn't. Do nothing and you drive into the back of the other vehicle at 30 mph, assuming that vehicle is doing 30 in the 30 zone. Why would you have the cruise set to 60 and on in a 30 anyway? Far more likely to have to have it set to 30 and on.
Not sure how good the "safe distance" systems are. Several times I've been driving on cruise @ 65 ish, along a motorway, car comes up behind at a reasonable speed but doesn't overtake and stays a sensible distance back. Catch up a heavy, I pull out to overtake, car behind accelerates and almost under takes me. Presumably the "safe distance" bit doesn't track me over into lane 2 and just sees the heavy some distance ahead and tries to catch it up.
I tend to only use it on motorways in the 50 average speed road work zones. I set the speed and then judge if I'm catching up or falling behind the traffic in front and nudge the control up/down by 1 mph at a time.
My car's cruise control had no independent knowledge of the cars in front.
I personally find that using cruise control for any length of time with my foot off the accelerator pedal that I tend to lose spacial awareness of where the brake pedal is with relation to my foot.
A few may but overall you are in control and the brake pedal can/will disengage the cruise control.
Simply not so. Many makers build in the tolerance allowed by law, so their speedo deliberately reads high.
It's not new. Some makers have always supplied pretty accurate speedos. Some always read high. Despite there being no need these days for the original tolerance, since pretty well are pulse counting these days and simply don't need it.
If you are approaching slow traffic you'd do as you do without cruise control. Touch the brakes, and the cruise cuts out. Until you press a resume button. You can accelerate past a slow vehicle while in cruise mode by pressing the accelerator and it will revert to cruise speed when you release it.
When I first started to drive a car with cruise control, I thought I'd have this problem. Strangely I haven't (and my spatial awareness isn't brilliant).
It helps a lot if the car has its brake and accelerator pedals roughly the same distance from the floor. Some small cars that I've driven (Ford Fiesta / Peugeot 208 sort of size, though not necessarily those precise cars) have the footbrake much further from the floor than the accelerator which means you can't just slide your foot across from one to the other but must angle your foot a long way back to hit the brake. (*) If such cars had cruise control, I can imagine that your foot remembers where the accelerator was as you bring it back from its "resting" position and then misses the brake which is not at the same level but is a bit higher up.
The main thing to remember with cruise control is that a speed for going along straight and level will not necessarily be correct for a gentle bend or going over the brow of a hill, where with manual control of the throttle you'd ease off on the approach and then accelerate out of the bend or after the brow of the hill. What is weird is that it feels worse to drive at a constant 40 mph with CC than to drive at 60, slowing to 40 and then accelerating to 60, so it's not always the absolute speed that feels wrong - it's the absence of accelerating out of the hazard.
That takes me back to learning to drive in my mum's car. On the rare occasions when she was brave enough to supervise me, she would tell me to slow down as I approached a bend because I was taking it too fast. I tested her: sometimes I'd approach fast, slow down and accelerate out (that was OK), other times (for sheer devilment) I'd approach, negotiate and leave all at the same *lower* speed - and that was "too fast". So again, it was the deceleration and acceleration that she was looking for, not the absolute speed.
(*) You adjust the seat relative to your leg length so the bite-point of the clutch and the position of the accelerator are at comfortable positions, with you legs just slightly bent. But then the footbrake requires you to slide back into the seat back to be able to reach it comfortably because it's several inches too close.
That might be true for your Jazz, but my car's criteria for engine stop are 1) in neutral 2) clutch pedal up 3) stationary 4) additional sense checks such as battery charge > x%
My car also has an electronic parking brake, which I really dislike over a traditional handbrake. It's not conducive to use during temporary stops.
In addition the hill start assist works off the footbrake. The official method of staying stationary with the engine running is therefore the footbrake.
Considering how many of these start/stop, hold assist systems must be made by Bosch, it's amazing how different they work for different cars.
My previous car, I didn't order it with the hold assist and I too found it annoying to have to operate the electric brake by hand, so tended to sit with my foot on the brake at lights/junctions ... Then I discovered I could replace the single parking brake switch with a twin switch, route a couple of extra wires through to the ABS controller, enable the auto hold in software with VCDS, no more brake lights on all the time you're stopped.
When I bought my current car, they made hold assist standard equipment, except on this car after you come to a stop and the green brake light is on ... the brake lights STAY ON :-(
Presumably because he knows he can drive over the limit by a small finite amount without being prosecuted.
It happens that Fred formulated :
It, like most things, have a range of error. Tyre wear if you calculate it, make only a tiny difference to the accuracy.
Electronic complexity for sure but I really don?t miss all that mechanical complexity thrashing around under the bonnet of an IC vehicle.
Tim
Dave Plowman (News) wrote on 06/01/2021 :
The law requires a speedo to be in the range of accurate, or with a small positive tolerance. Manufacturers normally play safe and ensure speedos read a little positive/high. My analogue reads high, it is processed by the electronics to read high, my digital value is just the raw unprocessed value, which is accurate.
I have had vehicles in the past, not perhaps intended for the UK consumer market, where the analogue speedo has read true speed. My guess - part built for police use and accidently diverted for general public consumption.
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