Avoiding BGOL around town

[akirk]

It is also worthwhile noting that that the concept of BGOL as wrong is misleading...
It is about the result of BGOL (not the actual process) and in particular ending up with a mismatch or abrupt change in revs as you change gears... or a possible lack of control by being in the wrong gear / etc...
The reason it is discouraged is particularly the fact that with three pedals to control you have only two feet - so how can you brake / operate the clutch / match revs with the accelerator all at the same time...?

- An automatic has no issue with BGOL - it is its default position and as we have seen from comments there are cars which will auto-blip to aid this process...
- Heel & Toe is one solution which allows BGOL
- separation (i.e. not BGOL) is another route forwards...

but ultimately - any approach you take which leaves the gear change smooth and not noticed / leaves you in control of the car / allows you to brake as desired and be in the gear you want - then that is a good solution

Alasdair

[waremark]

It is also worthwhile noting that that the concept of BGOL as wrong is misleading...
It is about the result of BGOL (not the actual process) and in particular ending up with a mismatch or abrupt change in revs as you change gears... or a possible lack of control by being in the wrong gear / etc...
The reason it is discouraged is particularly the fact that with three pedals to control you have only two feet - so how can you brake / operate the clutch / match revs with the accelerator all at the same time...?

There are many other advantages of separation

[Rainmaker]

Some fantastic replies and interesting discussion. I'm soaking it all up and after a five hour blast up to, and through, Saddleworth Moor this afternoon I'm looking forward to the next RoADAR meeting on Sunday. Thanks for taking time to reply everyone.

[Synchromesh]

A gear is simply a ratio between road speed and engine speed, ergo, the two are directly proportional. The amount of throttle at a given speed has no affect of revs (unless your clutch is slipping!). Just bear than in mind in your calculations!

In answer to the original question, (1) would be my choice. If you're slowing down from 30 you're not out of gear for long, as and you say it gives you the option of selecting a new gear if the situation changes (e.g. if the lights change to green before you've stopped you can just take 2nd straight away).

I really wouldn't get to fussed about avoid BGOL around town though. When you're selecting gears at low speeds there's so little mismatch is revs vs road speed that as long as you bring the clutch up smoothly it's perfectly sympathetic.

On faster/rural roads, this is where I'd agree that avoiding BLOG or learning to heel and toe are your best options.

[Astraist]

I really wouldn't get to fussed about avoid BGOL around town though. When you're selecting gears at low speeds there's so little mismatch is revs vs road speed that as long as you bring the clutch up smoothly it's perfectly sympathetic.

That's all true, but there is a fundamental issue that I have with this approach. When a tool is fit for the job, you use it (or try to) for every single instance where it is suitable.

It's a self-coaching thing, because it helps build a driving style up into a habit, so it quickly goes into a subconscious level of competency and you are left with more attention to go around the whole task of driving.

[Mr Cholmondeley-Warner]

Hear hear. I went out with a driver today who's hoping to take his RoSPA test soon, and he'd never heard of rev-matching (I shall be talking to his tutor about this ). His gear changes were pretty smooth, because he dragged the clutch for long enough to mask it, but there was no attempt to be more sympathetic with the car.

Re revs / speed ratio James, yes, that's the theory. Now take your car out in 2nd gear at a fairly low speed - say up to about 20 mph. Accelerate (gently) up to the 20 mph, and then take your foot straight off the throttle. Watch the rev counter and the speedo, and see if they actually drop in exact proportion.

[waremark]

Re revs / speed ratio James, yes, that's the theory. Now take your car out in 2nd gear at a fairly low speed - say up to about 20 mph. Accelerate (gently) up to the 20 mph, and then take your foot straight off the throttle. Watch the rev counter and the speedo, and see if they actually drop in exact proportion.

How could it be otherwise?

[Synchromesh]

Re revs / speed ratio James, yes, that's the theory. Now take your car out in 2nd gear at a fairly low speed - say up to about 20 mph. Accelerate (gently) up to the 20 mph, and then take your foot straight off the throttle. Watch the rev counter and the speedo, and see if they actually drop in exact proportion.

Ermm, yes they do move in proportion (in any speed and gear).

Of course, in my (torque converter) auto, the revs do all sorts of weird and wacky things, but in a manual, yep, they revs and speed always move together.

[true blue]

Unless you have a particularly laggy instrument response on either engine revs or wheel speed...

[Pyrolol]

As far as the choice of gear goes, I seek to balance the gear to the amount of throttle. If I'm off the accelerator entirely I'm happy with the highest available gear (4th or 5th down a slight hill at 30 is fine), but if anything near full throttle is required I'd like to be at about 1/3 revs or above. You'll probably find this is a factor in the vibration: the engine mounts will be able to absorb some shaking at low frequencies (revs), but perhaps not enough to support large amounts of torque smoothly.

This might go some way to explaining the high 27mph observed threshold for juddering in 4th: the higher gear requires more engine torque, overloading the engine mounts that might otherwise cope at equivalent revs and resultant acceleration (wheel torque) in 1st or 2nd.