Some shifting technique concerns

[MountainBikeMike]

Hello,

I've been driving a manual for a year now and have been thinking about some technique related things.

Firstly, when down-shifting to approach a turn or traffic lights, which would it wear the clutch less to quickly dump it, or to gradually lift your foot? And by quickly dump it I don't mean anything drastically fast.

I'm not sure which would cause less wear because:

Dropping it quickly means
-More of a flinch of the whole car, as the clutch hooks up and the front dives when the engine comes up to speed
-More pressure on all moving engine components
-More pressure on the clutch friction surface at a larger speed difference between the plates
-Less actual time that the friction surfaces has to rub against one another

A slow lift
-More time that you hear the engine come up to speed, and more time the clutch is rubbing
-More time you're on the brakes, and the car isn't being slowed down by the engine
-Less pressure on engine components
-Leg seems to get more tired

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Second thing with my Skoda Octavia RS, and some other manuals I've driven:

It seems like most gearboxes have a safeguard to prevent you shifting it to first from above say 15kmh. I noticed that when I'm coming down to first from a higher gear, its easier for me to clutch in, and put a bit of forward pressure on the gear knob towards first. Once I've reached the safe speed the knob automatically moves forward under my hand pressure, and off I go.

However, some times when I do this I feel an obvious double click. Its quick fast, like a jolt through the gear knob. Whatever it is, it never feels good, and it doesn't always happen. When it does happen though, I don't like it. I just wonder what is actually happening here, and whether I should ditch this habit.

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If anyone has any other shifting technique concerns feel free to post them.

Thanks

[wai]

The clutch is there to be used. The rate of engagement is to reduce overall stress on the drive line.

The clutch is replaceable, the gearbox is not designed to be something you replace like a clutch. A sudden take up is going to stress the gearbox. It is like brakes. They are a wear element to do their job. You do not want to make it so that you take ages to engage the clutch. You can tell if you are doing it too quickly or too slowly.

[h100vw]

The clutch is there to be used. The rate of engagement is to reduce overall stress on the drive line.

The clutch is replaceable, the gearbox is not designed to be something you replace like a clutch. A sudden take up is going to stress the gearbox. It is like brakes. They are a wear element to do their job. You do not want to make it so that you take ages to engage the clutch. You can tell if you are doing it too quickly or too slowly.

I second the above comments, it's a replaceable item like brake pads. Not slipping the clutch from a standstill is going to be the biggest wear situation I reckon.

The std clutch should last anywhere between 100-160000km in my eyes.

One comment I have to make is about changing to first while still rolling. I have seen lots of flogged out MK1 gearboxes with dead syncros for first gear. The engine should have more than enough tq to pull away in second if the car moving at all.

I'd rather slip the clutch a touch, than wear the gearbox.

Gavin

[mb1907953]

One comment I have to make is about changing to first while still rolling. I have seen lots of flogged out MK1 gearboxes with dead syncros for first gear. The engine should have more than enough tq to pull away in second if the car moving at all.


Gavin

Or double de-clutch into 1st

[h100vw]

Or double de-clutch into 1st

We are well past the 1940s now you know. Even I don't remember them

Gavin

[gazzmo]

Double de-clutch will both allow for an easier shift in to 1st and reduce damage to the synchro, yes it is old hat but matching engine revs to gear speed still works.

Flash back to my first car EK holden with the grey 132 cu inch non synchro 1st gear did plenty of 2nd to 1st down shifts, needed to with the small drum breaks poor hydraulics and no power assistance

[kaanage]

Double de-clutch will both allow for an easier shift in to 1st and reduce damage to the synchro, yes it is old hat but matching engine revs to gear speed still works.

This. And it makes for smoother power transfer when pressing on meaning the car is less likely to misbehave on the downshift (important when hard on the brakes at the end of a straight). I double declutch with all downshifts out of habit and need to consciously downshift the 'normal' way. And it's a great feeling when you get it just right and the box shifts more smoothly and quickly than an upshift.

I regularly shift into 1st at around 40kph.

[wai]

The thing about double de-clutching on a box with synchromesh is that not everyone actually gets it just right and the synchro srill does its bit. To know you have it right, you have to do it in a box without synchro. Many non-synchro boxes are designed to literally crash change. Even many racing drivers don't actually get it right and heel/toe so that there is no sudden change in engine speed that can upset the car in heavy braking.

[Bora Sport]

You don't need to double de-clutch. As a matter of course I always give the throttle a little blip when I down change and it doesn't take too muh practice to get the revs just right so that it slips staight into gear and you let the clutch out so that there is no shock or slipping of the clutch. My Bora 4mo has nearly 300,000 k's on it now and no sign of needing a new clutch.

[kaanage]

The thing about double de-clutching on a box with synchromesh is that not everyone actually gets it just right and the synchro srill does its bit. To know you have it right, you have to do it in a box without synchro. Many non-synchro boxes are designed to literally crash change. Even many racing drivers don't actually get it right and heel/toe so that there is no sudden change in engine speed that can upset the car in heavy braking.

Of course, the synchro normally "still does its bit" when double declutching with a normal box, hence my

it's a great feeling when you get it just right and the box shifts more smoothly and quickly than an upshift

comment. The synchro "still does its bit" on the upshifts so you can feel a slight hesitation and resistance while the clutch is decelerated to match the gearbox input shaft revs and that is why you can engage faster when you match the revs really well on a double declutched downshift.

And any non-synchro box is inherently "designed to literally crash change" as the lack of synchro means that the dogs used for engagement are much larger and hence, much stronger. The race drivers call them crash boxes for a reason (you crash on the upshift since no one is going to take the time to let the engine revs fall) but you still need to get the revs close on a downshift to be able to shift, else the dogs move past each other more quickly than you can force the engagement.

And as for "heel/toe so that there is no sudden change in engine speed that can upset the car in heavy braking", isn't that exactly what I said with ?

the car is less likely to misbehave on the downshift (important when hard on the brakes at the end of a straight).

And it's easy to tell if you are able to "actually get it right" with a normal synchromesh gearbox (besides downshifting into first). Just try shifting without the clutch - if you know how to do it, you can drive around quite happily without using the clutch except when starting or stopping (not that I recommend it as you can damage the synchro if you try forcing the shift past the baulk rings when your revs aren't close to the being correct).

I'm not saying any of this is required on the road but it is one of the joys of driving a manual (I was forced to learn with my first car since the syncro in 2nd was worn out)

[wai]

I'm not saying any of this is required on the road but it is one of the joys of driving a manual (I was forced to learn with my first car since the syncro in 2nd was worn out)

But did you learn to do it in an XM Ford Falcon with "3 on the tree" and no synchro on 1st at all

[gldgti]

I was tempted to move this thread (because its in the WRONG SECTION ), but its in a section that hardly sees any traffic so I'll let it fester a while

The rodshift 020 gearboxes (mk1-3 and some 4's) are lovely to change without the clutch (up and downshifts) as long as you are careful with the accelerator. I cant say the same for the later cable shift boxes, which seem to take a lot more skill to clutchless shift.

With respect to clutch wear - downshifting technique will have next to no impact on the life of a clutch as it really is the difference between the torque required to accelerate the vehicle vs the torque required to accelerate the engine a bit, and those 2 values are orders of magnitude apart.

How you use the clutch to accelerate from a standstill and during upshifts (particularly in the lower gears) will determine 99% of the clutch wear.

As you might imagine, utilising the minimum speed differential between the driven plate and the clutch disk to affect torque transfer is the best way to minimise wear (e.g. take off without revviing the engine high).

Its not good for the gearbox, but in an older diesel (pre PD and CR with emissions controls, i.e. VE pump diesels) you can basically takeoff at idle without using any accelerator and in short order, with practice. This would prolong the life of the friction surface for sure, but its bad for gearbox bearings and its also bad for the shock springs in the clutch plate (very 'lumpy' torque transmission).

I agree with sentiments regarding looking after your gearbox aswell, but I do find amusing the old backyard mechanics logic that tyres are easier to replace than clutches