Tips about shifting

[PlagueWielder]

Hey guys,

Where can I find tips about shifting? Like how to take care of the syncho, how and why to double shift and so on...

Thanks

[Ford Prefect]

check this out:
http://turnfast.com/tech_driving/driving_shifting.shtml

as far as double clutching is concerned you should probably have a look at the discussion in the double clutching thread... in my oppinion its utter nonsense in a modern car.. but apparently some people would disagree...

[epp_b]

as far as double clutching is concerned you should probably have a look at the discussion in the double clutching thread... in my oppinion its utter nonsense in a modern car.. but apparently some people would disagree...

Such as me, since I created that thread

Modern gearboxes have synchromesh that will last several hundred thousand KMs. You might double clutch for fun, for sport or to make your synchros last really long

The only way to tell if you've double-clutched correctly in a synchronized gearbox is if there is no resistance when shifting into gear.

Do you need the theory of double-clutching explained?

[PlagueWielder]

Thanks.

Yeah, Id like to if you dont mind.

[klutch]

Haha, well then read the other thread!

If the car isn't jerking around, or reeking of clutch, you're shifing is fine.

[epp_b]

The concept of double-clutching exists to relieve the synchros of their job (in which case, it's optional), but is absolutely necessary in vehicles that do not have synchronized gearboxes (most semis/loris have unsynchronized gearboxes because they last longer and require less maintenance).

First you need to understand the respective jobs of the associated components (I'll simplify it here, because, to be perfectly honest, I don't know the precise terms for the parts, but hopefully you'll be able to understand this).

Clutch
It's job is to cut off power from the engine to the gearbox. When the clutch is disengaged, the gearbox cogs for each gear will spin according to the wheel speed when the car is moving; the gearbox cogs that connect to the clutch to the gearbox will spin according to how fast the clutch is spinning.

Synchromesh
When you disengage the clutch (push the clutch pedal in), the moving parts connecting the clutch to the gearbox are still moving, as are the cogs connected to the clutch; and they are slowly winding down as the clutch is now cut off from engine power. The synchromesh acts as a sort "mini-clutch" for each gear so that when you are shifting, the cogs that are in sync with the clutch become synchronized with the cogs that are in sync with the wheels.

Double-clutching is used to take on the work of the synchromesh, and simply put, it works like this:

Shifting Up
1. Clutch in
2. Out of gear, into neutral
3. Clutch out, match revs if necessary *
4. Clutch in
5. Into the higher gear

* The reason that you only might need to match revs is because you're doing this whole process to slowly (and you probably will for a while; I still do). If you've let the revs drop lower than the corresponding wheel-speed for the higher gear before you've put the clutch in the second time (step 4), you'll need to bring up the revs to match all of the gearbox cogs' speeds.

Additionally, you should match revs slightly higher (maybe 100 or 200 RPM, depending on how quickly your engine drops revs) than you would if you were just matching revs without double-clutching. This will give you a few extra milliseconds to put the clutch in and slide it into the next gear. The key is learning the "magic" timing for your specific car to get it just right.

Shifting Down
1. Clutch in
2. Out of gear, into neutral
3. Clutch out
4. Match revs for the lower gear
5. Clutch in
6. Into the lower gear

Again, match revs slightly higher than you normally would for the same reason stated above.

I find that double-clutching while down-shifting is actually easier because matching revs is required down-shift double-clutching and I've practiced a lot of plain-old rev matching while not double-clutching.


As with anything, it takes practice beyond the theory to perfect (I'm not very good at it, but I know the theory).

How to tell if you've double-clutched correctly is if you feel no resistance as you put it into gear -- it should glide in effortlessly.

Obviously, for unsynchronized gearboxes where double-clutching is absolutely necessary, you can tell when you've done right if there are no horrible grinding noises

[PlagueWielder]

Thank you.

[Blind Man]

Thanks

[oldschoolvolvo]

i can understand double-clutching when downshifting (for the rev-matching part, however you don't have to double clutch in order to rev-match), but upshifting? i don't think that would serve much purpose or be practical...but hey, just my opinion.

[epp_b]

i can understand double-clutching when downshifting (for the rev-matching part, however you don't have to double clutch in order to rev-match), but upshifting? i don't think that would serve much purpose or be practical...but hey, just my opinion

Well, for unsynchronized gearboxes, you need to double-clutch no matter where you're shifting.

On a synchronized one, it still does make the shift smoother and easier when done correctly.

[niteriyder]

just take Vin Diesels advice and double clutch man!...and don't granny shift it!

No but really, double clutching when you downshift does smooth out the gear change and it also lets the engine revolutions settle down so when you do put it into gear there is less bog if you were to release the clutch abruptly.

But all that is fine in slow or moderate moving traffic, on a track or during spirited driving, its faster to rev match or heel toe. I do it in either cases...double clutching is a slower process and is too much work for what it does.

[oldschoolvolvo]

Originally Posted by niteriyder

But all that is fine in slow or moderate moving traffic, on a track or during spirited driving, its faster to rev match or heel toe. I do it in either cases...double clutching is a slower process and is too much work for what it does.

yea exactly

[epp_b]

just take Vin Diesels advice and double clutch man!...and don't granny shift it!

I propose a 2 month ban for making any reference to such a ghey movie!