What's the name for "constant speed" gear changing again?
Discussion
When accelerating, unless I really need/want to push it, I tend to stabalise the car at the change up speed smoothly before chaning gear, so the change is impercetable to a passenger who ain't listening to the engine. That's a very common technique but I can't for the life of me remember what it's caused. I thought it was constant speed or constant revs but neither of them pass the google test. Someone here will know, what is it?
rb5er said:
Rev matching... but i thought this was just when slowing, not sure how you rev match when accelerating.
It's not rev matching I'm talking about really, all that's about is ensuring the engine is at the right speed for the gear + car speed. It's the pausing acceleration in a smooth manner, changing gear (yes with matched revs ideally, and to answer your question you do it by synchronising clutch throttle and gear lever!) and then resuming the acceleration smoothly again.As opposed to when you are squeezing every last bit of performance out of the car, in which case you floor it to rev limiter, move gear selector to next gear and then carry on accelearting - you probably will rev match this (probably not very precisely depending on how much of a flywheel you have) but may even powershift!
Somewhatfoolish said:
vonhosen said:
Sustained rev.
I'm talking about upchanges not downchanges. Although your response is a totally valid one to the thread title. Just not at all the OP
You increase revs & hold at the sweet rev count for down changes.
You decrease revs & hold at the sweet rev count for up changes.
vonhosen said:
You can actually do it up & down the box.
You increase revs & hold at the sweet rev count for down changes.
You decrease revs & hold at the sweet rev count for up changes.
Ok dokey. In fact, with most proper cars since you mention it, and I hadn't really thought of this but you are right, you are going to have to be doing sustained revs during the downchange. But with some cars the downchange is going to have to wait for the engine to slow down so that ain't sustained revs - and I'm really talking about the car speed rather than engine speed.You increase revs & hold at the sweet rev count for down changes.
You decrease revs & hold at the sweet rev count for up changes.
rb5er said:
You change gear without using the clutch?!??
No not as a matter of course but I can do. It's worth doing so if you never have done it because it will help your gear changes. As you not above, it's not a very good idea to adapt it as a habit cause better to wear the clutch than the box.That answer is geared at standard manual cars with syncromesh. In other circumstances, gear changing without clutch me be either totally normal (e.g. most motorbikes going up the box, a lot of trackcars I have driven with dog-thingy boxes) or a terrible idea (old cars without syncrhomeh, bikes without slipper clutch going down the box*).
*My bike experience is very limited although I do have a full bike licence. Welcome correction on that.
tristancliffe said:
Clutchless gear changes don't harm the gearbox. It's like the myth that slowing with engine braking somehow wears the gears out.
When the gearchange does not go 100% smoothly then yes it will cause wear on the gearbox. Slowing with engine braking will not wear the gears out but will obviously increase wear on the gearbox over not using it. tristancliffe said:
Clutchless gear changes don't harm the gearbox. It's like the myth that slowing with engine braking somehow wears the gears out.
They will if you get it wrong though. I did a driving course where we had we asked to do that on one of the first days when we were familiarising ourselves with the cars. I could generally 'feel' when the gear lever was ready to slip through the gate at the right speed and come off cleanly, the lad I was with wasn't quite so clean and probably smoothed a few rough edges as he went! Not that there was any purpose to the exercise other than to demonstrate various points about smooth changes and how the gearbox works.
The extra gearbox wear from engine braking is so negligible that it's not worth mentioning. Easier and safer than using the middle pedal.
Baryonyx said:
They will if you get it wrong though. I did a driving course where we had we asked to do that on one of the first days when we were familiarising ourselves with the cars. I could generally 'feel' when the gear lever was ready to slip through the gate at the right speed and come off cleanly, the lad I was with wasn't quite so clean and probably smoothed a few rough edges as he went!
Not that there was any purpose to the exercise other than to demonstrate various points about smooth changes and how the gearbox works.
Quite hard to get it wrong though - especially on gearboxes with syncromesh. You can feel what everything is doing, and the syncro still tries to help as best it can. Part of my winter training has been learning to left foot brake properly (rather than just occasionally), sometimes against an open throttle, whilst changing gear (i.e. clutchless), and mixing in some heel and toe, right foot braking and clutch as required for safety/convenience. It's so easy in a road car, but lack of foot room is now a problem in the race car...Not that there was any purpose to the exercise other than to demonstrate various points about smooth changes and how the gearbox works.
There's a very good reason for knowing how to make clutchless gearchanges. Why would anyone not want to be proficient in a useful emergency technique? Cluth cable snapped in the middle of nowhere? Sit and wait rescue like a mere mortal (joking) or drive yourself home and replace cable at your leisure?
I've found down changes are very easy sans clutch, up-changes can take a bit of finessing (sp?) if you don't slip it through first time. Just massage the revs until it catches.
As for the original point about making your up-changes as imperceptible as possible, I'm not sure if it has a name. I try to do it and, again, doing everything gently and smoothly seems to work. If you put gentle pressure on the lever as you declutch you can feel the sweet spot when the lever falls toward the next gear.
I've found down changes are very easy sans clutch, up-changes can take a bit of finessing (sp?) if you don't slip it through first time. Just massage the revs until it catches.
As for the original point about making your up-changes as imperceptible as possible, I'm not sure if it has a name. I try to do it and, again, doing everything gently and smoothly seems to work. If you put gentle pressure on the lever as you declutch you can feel the sweet spot when the lever falls toward the next gear.
There's no way to completely avoid any deceleration while changing gear - you do have to disengage drive at some point which is going to cause the car to slow unless you are going downhill.
The smoothest way of changing gear (up or down) is to rev match so that the clutch isn't necessary to match the speed of the engine to the speed of the gearbox.
The smoothest way of changing gear (up or down) is to rev match so that the clutch isn't necessary to match the speed of the engine to the speed of the gearbox.
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