May have done something a little silly, advice please!

[Clay1990]

Hello fellow petrolheads. I've had my MX5 ND since July now and it's fair to say that it's my pride and joy. I've learned quite a lot about advanced and performance driving and i'm always looking to improve and learn new skills. In terms of gear shifting, I first learned to rev-match, then mastered heel-toe, which has become part of my normal driving habits. But then I saw a few videos, articles etc, and heard a few guys at one of my karting events talking about clutchless shifting and some of its advantages. particularly on upshifts, and thought ''cool, that's obviously the next step'', or at least, a new, useful skill to have. So I went out and practiced a few clutchless shifts on a fairly chilled, evening drive around town. Most of them were pretty smooth, I didn't loudly grind any gears like when you mess up a shift and only one or two were at above 3500 rpm, and those felt pretty smooth. There was a LITTLE bump on a few, but no worse than if you were slightly too quick off the clutch. On a few shifts, there was a little bit of resistance before the gear slotted in, but nothing serious and I didn't just ram it in. Again, no loud grinding or anything.

What I didn't realise, however, was that it was really bad for your synchros and transmission if you do it poorly (I only read this after i'd tried it). Thing is, how poor is poor? Does it sound likely i'll done any damage, or is it one of those things that's going to cause damage if you do it all the time, for a long time? I feel like such an idiot. I was only trying to get better! I've driven it normally today and I didn't feel any grindy gears or resistance when I engaged them (with the clutch this time, obviously)

Sorry for the essay, any advice would be appreciated.

Thanks.

[Cambs_Stuart]

I'd swap out the gearbox oil ASAP. It's not hard or expensive to do, and if you've got lots of fine metallic glitter in it, you may have done something bad. If you have got bits of swarf in there you really don't want them circulating in the oil and around the bearings

[2 sMoKiN bArReLs]

There's a slim chance you've done any harm. If there's only been a little resistance it'll be no worse than the odd cruncher we all do.

I drove around in my Viva for two months with the clutch pedal on the rear seat. I did plenty of bad crunches and everything kept going (terrified my mum one day though)

[Clay1990]

Cheers guys, i'll not do it again. The car's going in for a service in the next couple of days, so i'll mention it and get them to swap the oil. I'll probably just tell them I crunched a gear or something, don't want them thinking i'm abusing the car.

On the other hand, I also read that clutching but not rev-matching is probably worse for your synchros than what I did, is that true? Because if that's the case, it probably needs changing anyway, because probably <90% of manual drivers don't even know what rev-matching is, so, chances are, the previous owner didn't. I'm quite impressed that you managed to drive like that for months though, that's mad! I'll re-iterate, it was for one half-hour drive, not spirited or anything like that. But still, not doing it again!

[Pica-Pica]

I often practised clutch-less shifts in my BMW E36. A pointless, but somewhat satisfying skill. The synchromesh should prevent any gears gnashing, you will feel the synchro baulking the change if you don't rev-match.

[Clay1990]

And that doesn't damage the synchros? Like I say, I never felt or heard any grinding gears, but did, as you say, feel the synchos block the change a handful of times until the revs were right.

[Inbox]

Performing clutchless changes on a standard manual box is a quick way to wreck it as it is not designed for that, yes you can do it but it could chip gear teeth, damage the syncromesh plus it puts strain on the gear shift mechanism.

Probably best to change the oil just in case you have got bits of metal in there.

[GreenV8S]

Clay1990 said:

''cool, that's obviously the next step''

Clutchless gear changes are absolutely NOT 'the next step' on a car, unless you have either a full throttle gear shift controller or a gearbox designed for this - neither of which you'll find on any sensible road car.

Save your clutchless gear change practice for when the clutch has failed and you need to gingerly limp the car home.

[Inbox]

GreenV8S said:

Clay1990 said:

''cool, that's obviously the next step''

Clutchless gear changes are absolutely NOT 'the next step' on a car, unless you have either a full throttle gear shift controller or a gearbox designed for this - neither of which you'll find on any sensible road car.

Save your clutchless gear change practice for when the clutch has failed and you need to gingerly limp the car home.

This, the OP is a future breakdown waiting to happen.

[Clay1990]

GreenV8S said:

Clutchless gear changes are absolutely NOT 'the next step' on a car, unless you have either a full throttle gear shift controller or a gearbox designed for this - neither of which you'll find on any sensible road car.

Save your clutchless gear change practice for when the clutch has failed and you need to gingerly limp the car home.

Well I know that now and I won't be doing it again. Like I say, it was a daft experiment I carried out based on dodgy advice and watching too much bloody YouTube. One I feel thoroughly embarrassed about. We live and learn. Clutched and rev-matched all the way from now on.

[Richard-D]

You'll have done no harm at all. It's pointless of course, as advised above. If you are desperate for something new to try, maybe learn to heel and toe (which there is a point to) or double declutching (which is only almost pointless) if you already heel and toe proficiently.

I wouldn't go changing gearbox oil or anything like that either (on account of this). As alluded to above, previous owners' occasional fluffed gear shifts (and yours unless you're a robot) will have caused more wear and particles than a few careful attempts at shifting without the clutch.

[M4cruiser]

My 2p worth:-

No harm in changing the gear oil, provided it's done properly and with the correct oil as specified for the car.

As for clutchless gear changes, it was used by rally drivers to allow left-foot braking on bends, being better and more accurate than heel-and-toe.

All a bit out of date now though ....

[Clay1990]

Richard-D said:

You'll have done no harm at all. It's pointless of course, as advised above. If you are desperate for something new to try, maybe learn to heel and toe (which there is a point to) or double declutching (which is only almost pointless) if you already heel and toe proficiently.

I wouldn't go changing gearbox oil or anything like that either (on account of this). As alluded to above, previous owners' occasional fluffed gear shifts (and yours unless you're a robot) will have caused more wear and particles than a few careful attempts at shifting without the clutch.

That gives me some peace of mind. I'm sure we've all done the odd stupid thing when trying to improve. Re. double declutching; you say ''almost'' pointless. So when would it come in handy? Certainly not in a drag race, Mr. Torretto, lol! Heel and toe is great, that one really did make a night and day difference to my driving, especially as i'm regularly in the Peak District and North Wales, where there's a lot of roads that require numerous shifts.

[Gary C]

You will have done no damage from the description you have given. The syncro hubs are friction devices. When you do a clutchless change you do put a little more pressure and slip it longer than with a clutch but doing it a few times wont have done it any harm ( unless you were really shoving it hard with huge rev mismatch).

And you will never grind the gears as they are always meshed ( apart from some old gearbox reverse idlers)

The baulking rings and dogs on the other hand can get a rattling

[Richard-D]

Clay1990 said:

That gives me some peace of mind. I'm sure we've all done the odd stupid thing when trying to improve. Re. double declutching; you say ''almost'' pointless. So when would it come in handy? Certainly not in a drag race, Mr. Torretto, lol! Heel and toe is great, that one really did make a night and day difference to my driving, especially as i'm regularly in the Peak District and North Wales, where there's a lot of roads that require numerous shifts.

If you're driving something with really tired synchros you'd get a nicer shift. Or maybe you might have a need to drive something with a non-synchro 'box. It'd be genuinely useful then. It's just really rare for anyone to need to do so now. Do you ever drive old tractors maybe?

[chrisch77]

Gary C said:

You will have done no damage from the description you have given. The syncro hubs are friction devices. When you do a clutchless change you do put a little more pressure and slip it longer than with a clutch but doing it a few times wont have done it any harm ( unless you were really shoving it hard with huge rev mismatch).

And you will never grind the gears as they are always meshed ( apart from some old gearbox reverse idlers)

The baulking rings and dogs on the other hand can get a rattling

Not true.
The synchronised clutches are tiny devices designed to operate ONLY against the inertia of the gearbox input shaft and connected gears to bring the speed in line with the next gear.

You can do whatever you like with engine revs during a shift so long as the clutch is open and it will make no difference to the life of the synchroniser as they are sized to cope with the worst case scenario (e.g a 2nd to 1st downshift at max target revs).

However, if you don’t open the clutch during a shift, the synchroniser clutch has to try to synchronise two massive inertias to a common speed (even if the attempted rpm match is quite good), meaning the synchroniser will overheat in a instant and lose all friction torque. Without friction torque generated by the clutch the baulk mechanism can do nothing and you smash the dog clutch teeth into each other. What then happens is the quality of normal clutched shifts deteriorates until the point the gearbox starts to jump out of gear.

In short - clutch less shifts are for dog gearboxes only, like motorbikes and racing cars. The OP might have got away with it this time, but an oil change might show otherwise and the gearbox could deteriorate in the near future.

The reason why clutchless gearshifts don’t work in a synchro box is the same reason that multi speed gearboxes are not common in EVs. With an electric drive there is no need for a clutch for pull away situations, but without the clutch a typical synchroniser would struggle to synchronise the speed of a free rotating electric motor without either a very slow shift or risk of overheating.

[Clay1990]

Richard-D said:

Clay1990 said:

That gives me some peace of mind. I'm sure we've all done the odd stupid thing when trying to improve. Re. double declutching; you say ''almost'' pointless. So when would it come in handy? Certainly not in a drag race, Mr. Torretto, lol! Heel and toe is great, that one really did make a night and day difference to my driving, especially as i'm regularly in the Peak District and North Wales, where there's a lot of roads that require numerous shifts.

If you're driving something with really tired synchros you'd get a nicer shift. Or maybe you might have a need to drive something with a non-synchro 'box. It'd be genuinely useful then. It's just really rare for anyone to need to do so now. Do you ever drive old tractors maybe?

Fair enough. I've never driven any tractor, let alone an old one, but i'd definitely like to give it a go at some point. I'm from Gloucestershire, I can't die having never driven a tractor, that would be sacrilegious!

[Inbox]

Clay1990 said:

Richard-D said:

Clay1990 said:

That gives me some peace of mind. I'm sure we've all done the odd stupid thing when trying to improve. Re. double declutching; you say ''almost'' pointless. So when would it come in handy? Certainly not in a drag race, Mr. Torretto, lol! Heel and toe is great, that one really did make a night and day difference to my driving, especially as i'm regularly in the Peak District and North Wales, where there's a lot of roads that require numerous shifts.

If you're driving something with really tired synchros you'd get a nicer shift. Or maybe you might have a need to drive something with a non-synchro 'box. It'd be genuinely useful then. It's just really rare for anyone to need to do so now. Do you ever drive old tractors maybe?

Fair enough. I've never driven any tractor, let alone an old one, but i'd definitely like to give it a go at some point. I'm from Gloucestershire, I can't die having never driven a tractor, that would be sacrilegious!

https://www.bbc.co.uk/news/articles/cly949187xeo

[Maxdecel]

chrisch77 said:

Not true.
The synchronised clutches are tiny devices designed to operate ONLY against the inertia of the gearbox input shaft and connected gears to bring the speed in line with the next gear.

You can do whatever you like with engine revs during a shift so long as the clutch is open and it will make no difference to the life of the synchroniser as they are sized to cope with the worst case scenario (e.g a 2nd to 1st downshift at max target revs).

However, if you don t open the clutch during a shift, the synchroniser clutch has to try to synchronise two massive inertias to a common speed (even if the attempted rpm match is quite good), meaning the synchroniser will overheat in a instant and lose all friction torque. Without friction torque generated by the clutch the baulk mechanism can do nothing and you smash the dog clutch teeth into each other. What then happens is the quality of normal clutched shifts deteriorates until the point the gearbox starts to jump out of gear.

In short - clutch less shifts are for dog gearboxes only, like motorbikes and racing cars. The OP might have got away with it this time, but an oil change might show otherwise and the gearbox could deteriorate in the near future.

The reason why clutchless gearshifts don t work in a synchro box is the same reason that multi speed gearboxes are not common in EVs. With an electric drive there is no need for a clutch fr pull away situations, but without the clutch a typical synchroniser would struggle to synchronise the speed of a free rotating electric motor without either a very slow shift or risk of overheating.

Oh yes, nail on head.
Perhaps the OP should've watched Youtube Vids such as this to give him some mechanical sympathy.

Incidentally I know someone who used mechanical sympathy with a Dog Box and was told to stop using the clutch for down changes as that too accelerated wear on the dogs !

[richhead]

Clutchless shifts are great in a dog box, infact using a clutch in said box is worse for it.
In a syncro bow then use the clutch.