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How's best to change down?
Posted: Sun Sep 13, 2009 10:42 pm
by rsawatson
Was just thinking briefly about driving, and wondered...
when slowing down, assuming others (like me) work down through the gearbox, which method causes more/less wear and tear (if any!)...
1. \'Working down\' (e.g. 4 ==> 3 ==> 2)
2. \'Jumping down\' (e.g. 4 ==> 2)
I personally work down, unless I happen to have slowed down enough to just forget about 3rd.
I suppose it\'s a trivial thing but I do want to help my gearbox out as much as I can

!
Posted: Sun Sep 13, 2009 10:58 pm
by Cam
Well, if you want to save wear on your synchros, then if you double declutch going up and down the gearbox (mostly down) then you will extend it's life far more than just missing a gear out every now and then when shifting down.
On a synchro'd gearbox you feel a slight resistance when pushing the stick into the gear (again mostly down the gearbox). This is caused by the synchros matching the speed of the input and output gears (for want of a better description). Actually the engine speed through the input section of the gearbox matching the output of the gearbox.
When you have mastered double declutching there will be no resistance felt as the speeds will be already matched and the synchros won't be doing anything, hence very little wear.
Posted: Sun Sep 13, 2009 11:00 pm
by mike.perry
In fact with a little practice you will be able to achieve clutchless gear changes
Posted: Sun Sep 13, 2009 11:17 pm
by Mick_Anik
These days I don't go down throught the gears - I just ease off the gas coming up to traffic lights, and push the lever into neutral, clutchlessly, at just the right moment. Because I've slowed down well in advance, a light braking brings me to a halt.
This technique is not one you should use during the driving test!
Posted: Sun Sep 13, 2009 11:25 pm
by alanworland
Sounds good to me! I have done that for years! on the basis that it is easier to replace brake shoes/pads than it is to replace gearbox/clutch parts!
Of course, I do chage down when required, and then I will double de clutch (worn synchro, but I find myself doing it on other vehicles too!)
Posted: Tue Sep 15, 2009 8:59 am
by rsawatson
Mick_Anik wrote:These days I don't go down throught the gears - I just ease off the gas coming up to traffic lights, and push the lever into neutral, clutchlessly, at just the right moment. Because I've slowed down well in advance, a light braking brings me to a halt.
This technique is not one you should use during the driving test!
It's interesting you should say that, because when I learnt to drive and took my test (back in 2007) I was taught to drive without utilising the engine at all to help slow down - in fact, if you use engine braking during your test you can fail! I can remember that it was always a nightmare going out with my parents in the car to practise, because they were taught the 'old school' way of using the engine (hence gears) to help slow the car. The standard way must have evolved in the intervening years with the improvement of brakes and ABS.
I feel a lot more in control when using engine braking however, and never like to rely on just the brakes. How does one double clutch, or develop enough skill to change gear without the clutch at all then?
Please share!
Posted: Tue Sep 15, 2009 11:34 am
by mike.perry
The principle of double declutching is to match the engine revolutions with the gearbox revolutions so that gears will mesh without crunching. This was necessary before synchromesh gears were in common use and is still usefull on older design boxes where the synchro cones can wear out.
Changing up simply lift off the accelerator, press the clutch, slip the box into neutral, allow a second or so for the engine to slow down to match the revs of the next gear and then press the clutch pedal again and move the lever into the next gear up.
Changing down the box is similar except that the engine revs need to increase to match the revs of the lower gear, therefore you blip the accelerator whilst the box is in neutral.
With a bit of practise and a few crunched gears you will get the hang of it. When you have managed to match engine and gearbox revs you wil be able to dispense with the clutch and change gear on the accelerator pedal.
Double declutching is particularly useful for changing down from second to first (which has no synchro) when climbing a steep hill.
Posted: Tue Sep 15, 2009 5:27 pm
by Alec
Hello Rsawatson,
I have never understood the modern method of slowing down, and fail to see any benefit. I know some modern cars have little engine breaking effect, but surely a lot have?
In general I notice that traffic around me is braking far earlier and so for longer than I. Since the introduction of brake pads that do not contain asbestos the wear rate on discs is far higher and replacing both pads and discs is quite commonplace now, which it did not use to be.
I remember a television programme where the presenter was advocating the gears for go brakes to slow method. He then said the only time I would use gears to slow is on slippery or snowy conditions. I can see drivers unused to regularly changing down to slow selecting a lower gear on a closed throttle and promptly sliding off into the scenery, due to having no practice at adjusting engine speed to road speed and gear.
Alec
Posted: Wed Sep 16, 2009 9:22 am
by mike.perry
Always use the gears for controlling the speed of a car decending a hill. The brakes are then in reserve in case they are needed for extra slowing and will not overheat and suffer from brake fade
Posted: Thu Sep 17, 2009 10:14 pm
by Sidney'61
rsawatson wrote:It's interesting you should say that, because when I learnt to drive and took my test (back in 2007) I was taught to drive without utilising the engine at all to help slow down - in fact, if you use engine braking during your test you can fail!
I too was surprised too to find that they didn't teach engine braking at all, I learned to drive earlier this year and was taught that when slowing down from any speed just press the brake and then press the clutch at about 5-10 mph, nowadays I use the clutch more than the brakes when slowing down as it just feels right, I think if I was still driving exaclty like I'd been taught I would have struggled a lot on some of the roads in the lake district.
Posted: Thu Sep 17, 2009 10:36 pm
by mrmorrisminor
A friend of mine was following me recently and tried to tell me that both my brake lights were not working!...... the wonders of engine braking I said!! I tried to explain about it but he just looked at me.... newly trained driver! However, last weekend the same friend had a go in the Mog, he soon realised what I was on about as he gently brushed his foot on the brake pedal, to little effect!! (Corsa diver)
Having experienced brake fade on a steep hill loaded with passengers, it's not an experience I'd wish to repeat!! So I always change down through all the gears, even in the plasic Eurobox!
Posted: Thu Sep 17, 2009 11:36 pm
by bigjohn
phaa try doing it in a seddon atkinson 411 with an eton twin splitter gearbox a normal 4H shift pattern but with 2 splitter gears on each shift 12 speed box lov em

most of the truck drivers on here should know what im on about

Posted: Fri Sep 18, 2009 9:57 am
by mike.perry
Our company Volvos had 12 gear auto boxes, no need to double declutch there, in fact just set the cruise control and relax in fully adjustable heated seats, easy life, apart from watching all the mirrors.
Posted: Fri Sep 18, 2009 6:14 pm
by MarkyB
mrmorrisminors experience probably explains the reason for teaching people to drive this way.
For the same reason I want to fit a high level brake light and a reversing light.
Driver these days seem to need very obvious signals about what other cars are doing.
I avoided rear ending the car in front of me because I'd noticed how hard everyone in front of him was breaking (rear of the car lifts up) only to be crashed into by a Renault whose driver wasn't paying attention at all

It wasn't a very hard hit but the front of the Renault mostly fell off

Posted: Fri Sep 18, 2009 9:28 pm
by alanworland
Drivers dont look any further than about 20ft these days - Which is why they have to drive up your boot.
I was shunted by a driver from behind and pushed into the car in front (I was stationary), turned out a lorry wasn't looking and shoved 7 vehicles into a pile of written off metal.
Remember - only a fool breaks the 2 second rule!
Posted: Fri Sep 18, 2009 11:37 pm
by mike.perry
If you are driving correctly you should not have to use your brakes between entering the motorway and leaving it. Try it some time.
Posted: Sat Sep 19, 2009 2:24 am
by Chris Morley
mike.perry wrote:If you are driving correctly you should not have to use your brakes between entering the motorway and leaving it. Try it some time.
Err, that assumes all the other Motorway drivers are driving correctly, which often isn't the case.

Posted: Sat Sep 19, 2009 9:50 am
by mike.perry
That's what makes it interesting. Commuter traffic is probably not the best time to try it.