Coasting/Freewheeling

[gerry2004uk]

Hi guys,

with the increase in vat/fuel prices I thought I would do a bit of coasting in my 1998 T2 2.7 Diesel to economise a bit.

I used to do this in a 306 I owned with no issues.I have been freewheeling on the downslopes and just coasting to road ends etc by knocking the car out of gear,releasing the clutch,zero throttle input,revs to idle and the gear stick in neutral.

However yesterday I noticed a loudish whirring/winding down noise coming from the front drive train area which seemed to retard the fwd motion.I should say that this was in 2wd mode at the time and i hadnt used 4wd in some time.And when gear selected seemed to stop.

When freewheeling in this type of car does it disengage anything that I am not aware of and potentially damage something ?.Vehicle has done 130K

I am thinking that the first port of call may be to service the transmission fluids as I have not done this since I have owned the jeep.bought last march and only have done 7000 miles,tho i dont know when it was done prior to this.

All the belts are running ok as i checked these when i got home,and i intend to have a good look when it stops peeing it down !!

Maybe it was a false economy:doh

 

[zippy656]

oooohh


dont ... its not safe...

also Plod can charge you ....

 

[Timbo_1975]

On both the TD and TDI, on the over run virtually no fuel (or none at all with the TDI) is injected so idling during coasting will use more.

 

[rayf3262]

The truck will use LESS fuel if left in gear on overrun, as the ECU cuts the fuelling to NIL under these conditions.
If your free wheeling out of gear your engine is effectively using the same amount of fuel as at tickover/stationary.

SNAP

 

[R1cho]

oooohh


dont ... its not safe...

also Plod can charge you ....

yea very dangerouse, your engine doesn't only make you go forward it also aids in slowing you down if the gears are used right, and as zippy said plod will deffo do you for it, not justa fine either, driving without due care and attention or maybe even dangerouse driving

 

[larson]

but can it ause damage?

 

[ssteve]

oooohh


dont ... its not safe...

also Plod can charge you ....

122
Coasting. This term describes a vehicle travelling in neutral or with the clutch pressed down. It can reduce driver control because

•engine braking is eliminated
•vehicle speed downhill will increase quickly
•increased use of the footbrake can reduce its effectiveness
•steering response will be affected, particularly on bends and corners
•it may be more difficult to select the appropriate gear when needed

says nowt in highway code about being against the law!!!

ssteve

 

[illy]

maybe not but you would fail your driving test.

illy

 

[clivvy]

i was told from day one never to do this, you would be better off just plopping it into 5th

 

[lacroupade]

i was told from day one never to do this, you would be better off just plopping it into 5th

you'd certainly be plopping it when it ran away with you LMAO!:lol

 

[gerry2004uk]

wow,a range of different replys.And as an adult I chose the option of coasting for the reason of saving the environment obviously.And thanks to the folks who are concerned for the legal issues but it doesnt help me explaining the mechcanial problems.cheers anyway.but today it made 3 massive clunks when setting off fromn cold and all of sudden was ok.wierd !!

 

[Peasgood]

Sounds like your free wheeling hubs were not doing what they were supposed to.

Besides any legalities or environmental issues etc. I think it has been proven quite a few times that freewheeling does not save any fuel and often makes you use more. I can only guess the extra use comes from revving to match the engine speed when you put it back in gear and the reasons said above.
You do what you like, but don't kid yourself it is saving you any fuel or money.

 

[R1cho]

yea grinding could be the hubs, check the downloads section, as far as free wheeling goes as peasgood said aint gonna save u anything, not only do u have to match the revs up but in most cases when u put it back in gear your engine will over rev to slow down to suit the gear you put it in, using more fuel and emmiting more, best way to save fuel is drive the car in a sensible way, no heavey foot and down hill use a high gear dont free wheel, keeps the revs where they should be if u have to change down gear and also helps with breaking

 

[clivvy]

yea grinding could be the hubs, check the downloads section, as far as free wheeling goes as peasgood said aint gonna save u anything, not only do u have to match the revs up but in most cases when u put it back in gear your engine will over rev to slow down to suit the gear you put it in, using more fuel and emmiting more, best way to save fuel is drive the car in a sensible way, no heavey foot and down hill use a high gear dont free wheel, keeps the revs where they should be if u have to change down gear and also helps with breaking

bingo!

 

[kbekl]

well i have just be reading about a paj with the same problem of a noise when freewheeling it turned out to be a problem with the diff

 

[Kamsin]

Ok im at work, so not had time to read all the post on this bit, BUT i just wanted to help you out if i can "DO NOT FREE WHEEL" you save nothing and have limmited control of the vehicle!
I instruct in SAFED (Safe and fuel effective driving) on HGV trucks and teach 20 year veteran drivers how to dive more fuel efficiently.On avarage i show that each driver can save 4 lts of fuel in every hour they drive. A quick calculation for the company i work for shows up to £100,000 saving in one year. (You wont save that in a car/Truck)
Adapt your driving styles to meet the road conditions, i know what your thinking, what does that mean? If you driving down the road and you see a traffic light on red, take your foot off the gas, there is no point using fuel to get to a red light. (DONT TAKE IT OUT OF GEAR OR PUT YOUR FOOT ON THE CLUTCH) you truck believe it or not does not use ANY FUEL if your foot is not on the gas. I have a computer system fitted to our training vehicle to prove this to our drivers as no one thinks this is true. They believe if they engine is running then its burning fuel, Its NOT! Trust me on this one.
You have 5 gears on your truck, that dont mean you have to use them all. If you pull away in first, go in to second build up your speed and go to 4th, miss 3rd out, ditto if your in 3rd build up speed and go to 5th, miss 4th. it makes a big difference.
Im more than happy to give out more information on this and help people cut the fuel consuption down if they are intreated.:thumb2

PS, I took my boss out in her 320 BMW, it was showing she does 32 mile per gallon on the motorway, i proved it could do 51 mile per gallon in urban conditions. In a 1 hour drive in town and country traffic, i did not stop the wheels turning once. Stopping and pulling off cost fuel, lots of fuel!

 

[zippy656]

sounds like we could all do with more tips if you got them,..

fuel saving download maybe... I for one would read it and use it... try to get over teh 31mpg mark

 

[Peasgood]

I knew a fella that took his HGV test and failed for not using his brakes. He anticipated lights, traffic etc and never had to actually use his brakes. The examiner said he wasn't warning following traffic he was slowing down.
Bonkers and caused uproar with the instructors, but true all the same.

 

[Kamsin]

I knew a fella that took his HGV test and failed for not using his brakes. He anticipated lights, traffic etc and never had to actually use his brakes. The examiner said he wasn't warning following traffic he was slowing down.
Bonkers and caused uproar with the instructors, but true all the same.

I think the point was he was not demonstrating the correct use of the vehicle, you can in fairness drive an HGV with only 3 gears, but that does not show you know how to use all of them, it only shows you can use 3. That’s why part of the test states you have to drive the vehicle from stand still to the current road speed then return to stand still using ALL of the vehicles gears in the correct manor.

If he was allowing the vehicle to slow down on its own, even though its saving fuel, he is not showing he can use the brakes correctly or warn other road user of his intentions to slow down.

Any driving instructor will tell you, he is not teaching you to drive, he i teaching you to pass a test, you learn to drive after that!

 

[Kamsin]

sounds like we could all do with more tips if you got them,..

fuel saving download maybe... I for one would read it and use it... try to get over teh 31mpg mark

Zippy, i will be more than happy to do this. I will start working on it at the weekend. :naughty

I will include some intresting tip and points to help you all out, i hope.:thumbs