Stupid question ?

Ivrytwr3

so what's the difference?

Lemonade_Pockets

Ivrytwr3 wrote: »

so what's the difference?

Riding the clutch is when you have the clutch depressed but not past the bite point (a bit of a backwards explanation but hopefully it makes sense). Sometimes called slipping the clutch, normally demonstrated by learner drivers revving the nuts of a car but only moving forward very slowly. Also can be used to feather in the power, in full bore starts instead of just dumping the clutch.

Once you have depressed the clutch passed the bite point i.e. its no longer giving any drive. the clutch is just depressed.

See below for wikipedia's definition. Which gives a bit more detail, even if now i've read through it, it does contradict itself a little bit.

Lemonade_Pockets

Slipping the clutch

Slipping the clutch (sometimes referred to as feathering the clutch) is a term used by automotive enthusiasts to describe when the driver alternately applies and releases the clutch to achieve some movement of the car. It's called slipping because the clutch plate will slip against the flywheel surface when such an action is performed. Slipping the clutch is known to be hard on the clutch surface due to the sliding friction created.
Drivers can frequently be observed slipping the clutch when they are trying to stay stationary on a hill without using neutral and the brake. They apply the clutch to climb a bit, then release to roll back, then apply again, etc. so that the car stays in about the same place. The alternative to this technique of staying stationary on a hill would be to put the vehicle in neutral and apply the brake.
Slipping the clutch is a popular term in drag racing culture and is done when launching a car, usually in a drag race. Some contend that slipping the clutch is the best way to launch a front-wheel drive (FWD) car as it prevents Torque steering that many FWD cars experience when too much power is put to the front wheels.


URL="http://en.wikipedia.org/w/index.php?title=Clutch_control&action=edit&section=13"]edit[/URL Riding the clutch

In a vehicle with a manual transmission, riding the clutch refers to the practice of needlessly keeping the clutch partially disengaged. This results in the clutch being unable to fully engage with the flywheel and so causes premature wear on the disc and flywheel.
A common example of riding the clutch is to keep slight continual pressure on the clutch pedal whilst driving, as when a driver habitually rests his/her foot on the clutch pedal instead of on the floorboard or dead pedal. Although this slight pressure is not enough to allow the clutch disc itself to slip, it is enough to keep the release bearing against the release springs. This causes the bearing to remain spinning, which leads to premature bearing failure.
When shifting properly the driver "shifts" to another gear and then releases pressure on the clutch pedal to re-engage the engine to the driveshaft. If the pedal is released quickly, a definite lurch can be felt as the engine and driveshaft re-engage and their speeds equalize. However, if the clutch is released slowly the clutch disc will "slip" against the flywheel; this friction permits the engine a smoother transition to its new rotation speed. Such routine slippage causes wear on the clutch analogous to the wear-and-tear on a brake pad when stopping. Some amount of wear is unavoidable, but with better clutching/shifting technique it can be minimized.
Riding the clutch occurs when the driver doesn't fully release the clutch pedal. This results in the clutch disc slipping against the flywheel and some engine power not being transferred to the drive train and wheels. Most drivers routinely use this inefficiency effectively when driving in reverse (inasmuch as fully engaging the reverse gear results in velocity too great for the short distance traveled) or in stop-and-go traffic (inasmuch as it is then easier to control the throttle and acceleration at very slow speeds).
Riding the clutch should not be confused with 'freewheeling' or 'coasting' where the clutch is pressed down fully allowing the car to roll either downhill or from inertia. While this isn't damaging to the car, it can be considered a dangerous way to drive since one forgoes the ability to quickly accelerate if needed. It is, however, common practice to roll into a parking space or over speed bumps via momentum.

cyclonebri1

Ivrytwr3 wrote: »

i would not "ride the clutch" ie keep it depressed, but i would knock it out of gear for going down hills.

And i think, yes you would save petrol/diesel albeit not a great deal.

No No No.

As mentioned, you then are no longer in direct control of the car, so have to select gear/clutch etc, to make progress.

But more importantly in the spirit of your post about economy, if you leave the car in gear, the overun will shut off the fueling completely when coasting down hill. If you knock it out of gear the engine has to be fuelled to keep it going as no loading is being applied. Meerkat simples;)

DaveMacD

How chuffing high would the hill have to be to make any bloomin' difference?

Just_Incredible

No you wouldn't be saving as much petrol than if you was going down the hill normally

when you dip the clutch in, you use a little bit of fuel to keep the car going where as if you drove down it normally without applying the accelerator, the fuel would be cut of

cyclonebri1

DaveMacD wrote: »

How chuffing high would the hill have to be to make any bloomin' difference?

Doesn't make any difference how high/long/steep the hill is, twist it however you want but you will use less fuel by keeping the car in gear

cyclonebri1

Robson65 wrote: »

Hello,

I've got the feeling that this is a really stupid question but here goes.

If I put my clutch in when I'm going slightly downhill and let the car roll will I save petrol ?

Thanks
Robson the Untechnical !

No such thing as a stupid question OP, only stupid answers;)

DaveMacD

cyclonebri1 wrote: »

Doesn't make any difference how high/long/steep the hill is, twist it however you want but you will use less fuel by keeping the car in gear

But there's the rub. If your car does 30mpg, and coasting or not coasting alters consumption by only a few %, you'd have to do a downhill only journey of miles to see any effect. I'd suggest to the OP that it would matter more when stopping and starting, rather than heading downhill.

When you're taught to drive, you're taught to keep the car in gear until you are almost stopped. There are good reasons to do so, apart from the original question, but I think everyone will put into neutral at some point

Wig

Dave101t wrote: »

no no no, it will cost you money, ee by gum you learn something new every day!

this has been covered in detail before, try a search, oh dont bother ill do that for you as well!:
http://forums.moneysavingexpert.com/showthread.html?t=252562

It has also been discussed where someone disagreed (yours truly )

http://forums.moneysavingexpert.com/showthread.html?p=13368749&highlight=anti+stall#post13368749

There are cars with automatic fuel cut off (in gear, clutch out, rolling down hill) if you have one of these fine, you will not save very much if anything by dipping the clutch on hills. But you would need to be certain your car has this feature -not straightforward to find out- If you dip the clutch even in one of these cars the car will go faster downhill, but you may have to dab the brakes more often so there would be a minimal effect on your pad wear rate.

If you're going to do this it's better IMHO to do this with the clutch in rather than out of gear for a couple of reasons

• It's quicker and safer to re-engage the gears
• trying to re engage a gear by moving the gear stick can easily crunch your gears
• Although it will cause a minimal extra wear on your clutch bearing the safety aspect above override this.

And in any case as long as you always replace your clutch bearing when you replace your clutch friction plates (you're studid not to) There is not going to be any problem for the bearing. [strike]Like I said in that thread[/strike] (must have been another thread), I have many times had to replace a clutch plate, but never had to replace a clutch bearing because it was worn out. I have only ever replaced clutch bearings because I was at the time replacing the friction plates.