Inputs & Outputs (split from BGOL thread)

[TripleS]

Drive train in a straight line?? Don't understand that last line.

It is to engage a gear with the engine under power - matched revs which put less strain on the mechanics and waste less energy. It is not always possible but generally preferable.

So most of us would use the terminology 'Rev-matched block gear changes'. And most of us use them, changing gear directly from wherever we are in the gearbox to whichever gear has now become most appropriate - in some cases 1st to 6th, as I think you suggest.

Sorry, but I'm still confused by this bit: "It is to engage a gear with the engine under power - matched revs...."

This might seem pedantic, (and/or wrong), but you can only engage a gear when there is no load on it, i.e. the clutch is disengaged. In that case the engine can not be under power, i.e. throttle being applied, otherwise the engine speed would rise and there would be no rev matching.

This is from PH a few days ago:

whiteside67 said:
"Say I am going up a hill in 5th gear and need to change down to 4th for acceleration e.g. to overtake. My foot is already half way down on the accelator pedal. When i press clutch to change down does this not cause clutch wear beacause my foot is a good bit down on the accelerator (quite high revs going through clutch)
Yes, if you dip the clutch at half throttle, the revs will go up and almost certainly by too much for your rev match anyway. So I think you'd reduce the throttle before pressing the clutch (blending the two I guess) to avoid both problems."

BertBert replied:
"As I am carp at rev matching, I use a blip anyway, so I do let the revs drop. I find it easier to blip the throttle and find a good clutch engagement point rather than try to find the right revs and hold them there."

I agree with Bert, having realised that I do the same. It may be unusual but I find it works well.

Best wishes all,
Dave.

[GJD]

So most of us would use the terminology 'Rev-matched block gear changes'. And most of us use them, changing gear directly from wherever we are in the gearbox to whichever gear has now become most appropriat - in some cases 1st to 6th, as I think you suggest.

6th to 1st I can see, but I think opportunities to go from 1st to 6th might be quite rare...

[sussex2]

So most of us would use the terminology 'Rev-matched block gear changes'. And most of us use them, changing gear directly from wherever we are in the gearbox to whichever gear has now become most appropriat - in some cases 1st to 6th, as I think you suggest.

6th to 1st I can see, but I think opportunities to go from 1st to 6th might be quite rare...

If you could comfortably go from 1st to 6th there wouldn't seem much point in having the rest of them.
Mind you thousands of mini-cab drivers can't be wrong

[GJD]

Sorry, but I'm still confused by this bit: "It is to engage a gear with the engine under power - matched revs...."

This might seem pedantic, (and/or wrong), but you can only engage a gear when there is no load on it, i.e. the clutch is disengaged. In that case the engine can not be under power, i.e. throttle being applied, otherwise the engine speed would rise and there would be no rev matching.

A rise in engine speed is exactly what you want for a rev matched down change. The throttle can be applied a bit with the clutch disengaged. If you don't want the revs to drop to idle when the clutch is disengaged, you have to apply a bit of throttle.

It's unlikely to be as much throttle as you would apply when you're in gear driving up a hill though.

[TripleS]

Sorry, but I'm still confused by this bit: "It is to engage a gear with the engine under power - matched revs...."

This might seem pedantic, (and/or wrong), but you can only engage a gear when there is no load on it, i.e. the clutch is disengaged. In that case the engine can not be under power, i.e. throttle being applied, otherwise the engine speed would rise and there would be no rev matching.

A rise in engine speed is exactly what you want for a rev matched down change. The throttle can be applied a bit with the clutch disengaged. If you don't want the revs to drop to idle when the clutch is disengaged, you have to apply a bit of throttle.

It's unlikely to be as much throttle as you would apply when you're in gear driving up a hill though.

Yes, I accept all of that. The dubious bit was the reference to the engine being 'under power', which to me meant pulling. Of course the engine revs have to rise to match the change to a lower gear, but with the clutch disengaged the amount of throttle needed is tiny, otherwise the revs will be off the clock PDQ. It isn't really an 'under power' situation.

[waremark]

So most of us would use the terminology 'Rev-matched block gear changes'. And most of us use them, changing gear directly from wherever we are in the gearbox to whichever gear has now become most appropriat - in some cases 1st to 6th, as I think you suggest.

6th to 1st I can see, but I think opportunities to go from 1st to 6th might be quite rare...

Works fine with my 6 litre V12.

[zadocbrown]

Waremark I'm struggling to think of a modern car with V12 and conventional manual

Put me out of my misery!

[waremark]

AM Vantage

Last mainstream manual V12 - will it be a future classic. It is fabulous to look at - and not too bad to drive.

[MGF]

I was thinking about steering inputs today and particularly Silk's point about needing to be able to amend steering if necessary so decided to try and anticipate the precise amount of steering need for a corner/junction/roundabout.

I noticed that I significantly underestimated the amount of steering necessary for the latter and was reasonably precise although somewhat overestimating the amount necessary for bends.

I shall experiment further tomorrow. Obviously the more steering needed the greater the scope for error but I am unclear why I am underestimating or overestimating consistently depending on the extent of the steering.

[Gareth]

Obviously the more steering needed the greater the scope for error but I am unclear why I am underestimating or overestimating consistently depending on the extent of the steering.

Might the degree and direction of inaccuracy depend on the person rather than the situation?

I think most drivers steer in a reactive fashion, rather than being proactive. That is, developing the skill of steering assessment doesn't figure in the lives of most.


ETA: I was thinking also that I've seen many people move their hands a large amount round the wheel rim (PP style) in preparation for a bend only to find they didn't need that much steering lock and, in fact, only a minor steering deflection was required. I remember StressedDave saying something about how the application of power before applying the steering can reduce the amount of steering lock required; this would be harder to do for a junction turning so would result in needing more steering lock.

[TR4ffic]

Obviously the more steering needed the greater the scope for error but I am unclear why I am underestimating or overestimating consistently depending on the extent of the steering.

Might the degree and direction of inaccuracy depend on the person rather than the situation?

I think most drivers steer in a reactive fashion, rather than being proactive. That is, developing the skill of steering assessment doesn't figure in the lives of most.


ETA: I was thinking also that I've seen many people move their hands a large amount round the wheel rim (PP style) in preparation for a bend only to find they didn't need that much steering lock and, in fact, only a minor steering deflection was required. I remember StressedDave saying something about how the application of power before applying the steering can reduce the amount of steering lock required; this would be harder to do for a junction turning so would result in needing more steering lock.

Braking, on the over-run or under power will promote varying amounts of understeer or oversteer in a turn and affect the steering input required (fwd and rwd will differ). Power promotes oversteer, reducing the amount of steering lock required - I'm always aiming for the latter - under power (even if it's only a little bit) and be on the power before steering…

IMO, getting on the power before the turn shifts the weight back and sets the car up for the turn. If you go from over-run to power mid turn that weight shift is going to affect the balance - understeer to oversteer - requiring more adjustment in steering input.

When I was in the TR, I always enjoyed one particular bend - open road, a left hander on a slight incline - brake on the approach (full separation), 3rd gear (DDC), power on and into the turn. Increase the power as the bend unwinds, steering and car balanced, it felt like the nose was tucked into the nearside and the rear end was steering you round… Onto the straight and into O/D 3rd to save the slower gear change into top… Great fun!

[sussex2]

That's the beauty of the MX5 as long as it is properly aligned which is important.
You can once the car has been set up for the bend get around some purely with the use of the throttle and levels of grip on a dry road are high. It's a bit different in the wet but not as bad as many think and it is a controllable machine.
I wouldn't say the steering is lightning quick as it isn't (on the power steering models)but it is this cornering 'ability' which is the beauty of the thing.