Quote from tristancliffe :

Too little fuel in the tank can allow condensation to build up as water in the tank, which can start to rot it from the inside (and some of that can then get into the pumps and knacker them).

There are companies that sell "fuel stabilzer" to supposedly stop condensation from building up when a vehicle is stored for a while. Does fuel stabilizer really do what is advertised?

Speaking of fuel, there have been stories on the news which claim that it's not a good idea to completely fill your tank because it "wastes fuel". Does this claim have any truth? My car has a 50 L fuel tank and I always put 50 L of fuel in it. I stop pumping when I can see fuel in the pipe, when it stops going down. Is this a good or bad idea?

I'd doubt it - sounds too much like PFM in a can (Pure Fecking Magic)

I think that the worst thing what driving with "empty" tank is that it can brake the fuel pump. when there is very little amount of fuel in the tank the fuel pump can sometimes suck air, making it to run dry. Running fuel pump dry can brake it fast.

Also when this happens it is likely to result in lean mixture in engine and some annoying jerking when driving.
My car did it once, fuel tank was almost empty and I was driving to the gas station and it started to jerk badly, plus the sound of the fuel pump got stronger. Just got to the station before my car would stop.

Quote from shiny_red_cobra :

Speaking of fuel, there have been stories on the news which claim that it's not a good idea to completely fill your tank because it "wastes fuel". Does this claim have any truth?

Well it does increase the weight of your vehicle. The weight of 50L of gasoline is about 37.5kg, assuming a density of 0.75kg/L (according to wikipedia). But having a passenger wastes more fuel then a full tank of gas.

On the subject of refuelling... From the petrol-saving PDF I have at home (which I can probably link to if you like), it recommends a couple of things when filling up.

Firstly, make sure you straighten the hose and empty everything out when you're done, since you've paid for the fuel anyway.

Secondly, and fairly obviously I'd have thought, make sure your cap is airtight and screwed on properly to minimise fuel loss due to evaporation. Likewise, they say that filling right up to the top means fuel up there is more likely to evaporate. And increase the likelihood of wasting it by spillage.

How much you're likely to lose by evaporation is probably fairly questionable, but it all adds up over time.

I never thought I'd be posting an actual answer in this thread

Quote from Dajmin :

Firstly, make sure you straighten the hose and empty everything out when you're done, since you've paid for the fuel anyway.

Not that anybody would actually care about it, but in switzerland, that's forbidden. They even have little signs in some places which tell you. What's in the hose is not yours over here.

Surely if it just falls out of the hose, it's already been pumped therefor they've charged for it! That's crazy.

Depends how you look at it... if the previous customer didn't "steal" what was in the hose, then the next customer will get it. So he gets exactly what will be left after he is done refueling his car, and therefor gets exactly what he is paying for. Still quite retarded, i know.

The hose isn't empty when you start, so should remain just as full when you finish for the numbers on the pump to be accurate.

Some tanks do not like being sealed, and need to be vented to avoid fuel tank depression.

The numbers might be accurate, but if you can squeeze extra fuel out that you either have or haven't paid for is still a good deal in my book.

And if they're using equipment that doesn't function under conditions that can be reached so easily, they really shouldn't be in charge of something as dangerous as a petrol station. And if it's just a case of the equipment not working, then unless you're the owner there shouldn't be a problem.

Isn't it funny how you ARE allowed to drive a red-hot engine with the potential for 80,000V sparks in the engine bay, white hot light bulbs etc into a petrol station, but you aren't allowed to use a mobile phone that couldn't produce a spark even if you pressed into a bench grinder REALLY hard (exaggeration).

Or that you are not allowed to smoke on the forecourt, but everyone is happy to smoke whilst driving past, or to light a new cigarette 20m out of the forecourt with a fuel vapour filled atmosphere in their car?

Considering the HUGE volume of customers in petrol stations I would say they are way, way, WAY safer than your average home.

I'm back again and this time I do not have a question, rather, I want something to read (and possibly source for my science project). For example:This was a very good read. Although it took me a while, I was able to understand the majority of it. However, he did not go into too much detail about suspension geometry. His guide was a very clear and concise guide that helped me understand how weight transfer works in detail. I've tried Google but ended up with some very vague guides and I do not have the time to search for good ones since I have a research report to write up.

So if anyone has any book or website concerning vehicle dynamics and covering it in great detail (like the link above), please post them here. Websites are recommended since I can access them much easier (and probably without money involved).

Edit: If someone can explain why we feel like we were being thrown towards the outside of the corner is still centripetal force instead of centrifugal force, then I will be really happy because I don't know how you call being thrown towards the outside centripetal when it fits in better with centrifugal...

I don't know about websites. Books are better. Caroll Smith, Allan Staniforth and Miliken and Miliken will probably keep you going for a couple of years and you'd end up with a pretty decent understand of vehicle dynamics at the end of them all. Miliken is complex and scientific (but important nevertheless), whilst Smith/Staniforth are relatively simplified (and slightly wrong, which is why you need the complex versions). Reading simple and complex versions will mean you a) understand it and b) can communicate it to others that aren't as boring as you!!!

As for being thrown the outside: Your body is not rigidly attached to the car, so your mass tries to continue in a straight line, whilst the car turns (via grip acting as a centripetal force). Eventually you hit the door (or seatbelts or passenger etc), and the door presses against you with a centripetal force, causing you to turn at the same rate as the car.

There is NO force throwing you to the outside. It is a LACK of forces that causes you to move outwards RELATIVE to the car (but in a straight line relative to the world).

I wouldn't call it a lack of forces, just an inertia to the centripetal force, no?

Again, thanks for the answers! I think I'm going to get Milliken's or Staniforth's books (although I'll probably go for the more complex one). I was going to go with Carroll Smith but it turns out that my local bookstore does not have it! (arrrgghh!)

Milliken's books are a little bit scary because "Race Car Vehicle Dynamics" is a textbook and it's $134.94... used! I'm pretty sure that's the book I'm going to get. There's also "Chassis Design: Principles and Analysis" and "Race Car Vehicle Dynamics: Problems, Answers, and Experiments"

Then there is Staniforth and I don't know how simplified it is nor do I know if it is better than Carroll Smith's book. All that I know is that it's cheaper.

I'm hoping to get Millliken but chances are really slim with prices that steep. Is Carroll Smith or Allan Staniforth the better choice? They're around the same price but it's the content I'm more worried about.

A brake light went out on my car. I removed the whole taillight assembly because the bulbs are screwed into the back of it. This is on the side where the gas filler is. When I took it off, I smelled gasoline. Is it possible that I have a leak in a fuel line or in the fuel filter or EVAP system?

Quote from tristancliffe :

As for being thrown the outside: Your body is not rigidly attached to the car, so your mass tries to continue in a straight line, whilst the car turns (via grip acting as a centripetal force). Eventually you hit the door (or seatbelts or passenger etc), and the door presses against you with a centripetal force, causing you to turn at the same rate as the car.

There is NO force throwing you to the outside. It is a LACK of forces that causes you to move outwards RELATIVE to the car (but in a straight line relative to the world).

Explained more simply (maybe?)... The Inertia of the car turning overcomes the Force of friction (between your ass and the seat, which is carrying the centreptal force), and you get restrained by either a Tension force (seat belt) or a Normal force (Fn) by the door.

Quote from dawesdust_12 :

The Inertia of the car turning overcomes the Force of friction (between your ass and the seat)

I don't see how that would be an accurate description. Inertia is the resistance of the car to a change in velocity. Inertia does not overcome anything. Force, however, overcomes inertia.

well... inertia wants the car to go straight, and the Frictional force is working against the cars motion to pull the car inward (understeer being when the Ff becomes less than the needed amount, causing inertia to be able to act more prominently). The same happens inside the car, your momentum with inertia wants you to keep going straight (in relation to the corner), whereas the seatbelt (tension) or the friction force (the seat) wants to keep you going around.

I dunno, I'm learning this sort of stuff in physics, the (basic) equations relating to centripetal acceleration, centripetal force (which is a "carried" force, meaning that it needs to piggyback on another force, such as Gravity, friction or tension)... Like... I'm likely just wording it poorly, but the theory behind it is:

Going around a corner, your momentum wants you to go straight, so Friction must work against your velocity to pull you around the corner, with a gravity force keeping you on the road, and a normal force keeping you from plummeting to the centre of the earth.

Your person inside the car, also wants to keep going straight around a corner, yet the Friction from the tyres is pulling you around the corner (carrying the centripetal force), and then there's friction under the seat of your pants, keeping you in your seat.

However, once the frictional force is less than your inertia, you begin to slide towards the outside of the corner, being stopped only once another force is acting in the same direction of friction, such as a seatbelt, or a normal force (the car door).

In hind-sight, maybe inertia isn't the best word, more like your momentum, or once your Centripetal force is greater than the frictional force.

you should however be able to understand the general concept.

Don't even need to use the words inertia or momentum at this level. A mass always tries to go at a constant speed, in a straight line unless an external force acts upon it. You (your body) wants to go in a straight line until a force (seatbelt, car door etc) acts upon it, and this movement to the outside relative to the car makes it feel like you're thrown to the outside with a force.

W4H - you could have a leak. It's possible. Or it could be a breather pipe you could smell.

Can someone please explain, in simple terms, how a modern automatic transmission works? I don't know, and nor do a lot of people I know who otherwise know quite a bit about cars. I've been to websites like howstuffworks, but even there I get explanations like this:

Quote :

The input is the small sun gear; the ring gear (large sun gear) is held stationary by the band, and the output is the planet carrier. For this stage, with the sun as input, planet carrier as output, and the ring gear fixed, the formula is:

1 + R/S = 1 + 36/30 = 2.2:1

The planet carrier turns 2.2 times for each rotation of the small sun gear. At the second stage, the planet carrier acts as the input for the second planetary gear set, the larger sun gear (which is held stationary) acts as the sun, and the ring gear acts as the output, so the gear ratio is:

1 / (1 + S/R) = 1 / (1 + 36/72) = 0.67:1

To get the overall reduction for second gear, we multiply the first stage by the second, 2.2 x 0.67, to get a 1.47:1 reduction.

I had a quick look at Howstuffworks, and found this which explains it better than I'd be able to with text. http://auto.howstuffworks.com/automatic-transmission.htm

There are a number of animations (on page two and three especially) there that might help you understand it.

:bump:

Why do race cars and rally cars have an "E" sticker on them? I've been meaning to ask someone this for ages...I couldn't find anything on Google either, apart from "Wall-E Stickers"

The sticker is next to the fire Extinguisher handle