Mick F said:

Always always always leave your car in gear and with the handbrake on.
Belt and Braces.

As for engines slowing down when you depress the clutch, they do. Try it. May not on a Fiat500 or other modern cars, but on every older car I've ever owned it certainly has. Absolutely no doubt about it.

As for the input shaft producing more friction than the clutch release bearing plus the main journals, I think you'll find that the friction of an input shaft fully lubricated on ball bearings and roller bearings has negligible friction. Dunno if anyone else on here knows how a car gearbox works, but I do.

Any road up, the instruction manual states that you should start a petrol 500 in neutral with the clutch depressed. I can assure everyone reading this that if you don't depress the clutch every single time, you'll find it won't start sometimes. Not every time, just sometimes .......... and I don't know why.

I would welcome someone telling me why.

Cheers,
Mick.

Click to expand...

Now you've got me wondering Mick! I've always automatically depressed the clutch to start since my learner days in the early 70's but now I want to try starting mine with the clutch engaged just to see if it does it or not.

I've always started with the clutch depressed and it turns out that Hyundais enforce this (as has already been mentioned). I figured that out one day when a friend couldn't start his wife's car - seemed like a flat battery, I jumped in and it started straight away, took us a while to spot why!

Also in certain cars I've had (of the FWD persuasion but with large-diameter clutch discs, eg 164 V6), the clutch had a tendency to stick (damp conditions leading to rust on the friction surfaces) and in these cars the clutch would free off with a bang as the engine cranked, assuming it was left parked in gear. Not starting with clutch pressed would make it impossible to select a gear, as pressing the pedal with the engine running would not release a stuck clutch.

Selespeed operating logic (as defined by the designers) disengages the clutch before cranking, and the Dualogic 500 does this (it is just a later Selespeed version, after all). Remember that Selespeed/Dualogic is not the same as an 'automatic' and therefore has a clutch of identical design to manual transmission versions. Incidentally the Dualogic re-engages the clutch when in neutral after a few minutes - older versions would hold the clutch disengaged whenever the vehicle was stationary.

It's interesting to learn (thanks!) that sometimes the TA will start without clutch depressed and sometimes it won't - sorry I have no answer to that. Perhaps it thinks the gearbox is in gear sometimes. Or maybe it's just similar variability to the Hill Holder function on my 500. There's a hill near work which is, some days, steep enough for Hill Holder to activate, and some days it's not. I highly doubt the gradient changes day-to-day

-Alex

alexGS said:

I've always started with the clutch depressed and it turns out that Hyundais enforce this (as has already been mentioned).

Click to expand...

This is good practice ; it reduces the gearbox drag, lessening the load on the engine when starting and if you've forgotten to put the car in neutral, could also prevent a nasty incident.

Nope.
Gearbox drag is less than crankshaft push.

Pushing the crankshaft pushes the whole engine forwards and produces drag on the main journals and cylinder bores. The main journals are designed to run central and simply, and the pistons go up and down without producing sideways thrust. Pushing them produces friction and is not what the engine wants. You are pushing the whole assembly forwards.

Gearbox input shaft is a unit that is located into the flywheel by either a plain bearing or a roller bearing. The shaft goes into the main housing of the gearbox via a ball bearing and the other end is fitted into the main gears via a roller bearing.

Without the clutch depressed, the input shaft turns with the crankshaft and as you're in neutral the gearbox is motionless whilst the input shaft rotates. It's a free system and the whole thing rotates. The only friction to retard the engine is the roller bearing into the (stationary) gearbox cluster and the ball bearing into the housing. As both of these are immersed in gearbox lubrication, the drag is minimal.

Now, depress the clutch.
This pushes the whole engine forwards whilst it's still rotating. The gearbox doesn't see any of this and carries on as before, but perhaps the input shaft stops. It doesn't necessarily stop because although the clutch has disengaged, it doesn't totally disengage. It's not a switch on/switch off situation, though it does to some degree.

Meanwhile, the engine has to cope with extra friction and it will slow down because of it. These days, we have ECUs and computers and stuff and the tickover revs are set and regulated so maybe the revs don't drop, but the engine has more load nonetheless.

In the old days with a carburretta and distributer, the engine would slow down. Tickover was set manually by a grubscrew and wasn't load-dependant so it was quite evident that the engine tickover speed varied with load and slowed down when you depressed the clutch in neutral.

Regards to all,
Mick

Mick F said:

Nope.
Gearbox drag is less than crankshaft push.

Click to expand...

Interesting thought and I must confess I hadn't considered the thrust loading on the crankshaft with the clutch depressed.

That said, if the crankshaft end float and other engine tolerances are correctly set, it shouldn't put any additional side load on the pistons and the effect should be minimal. Gearbox oil drag can be significant; most cars will turn a wheel if the engine is running in neutral with a driven wheel lifted.

The best test I can think of is to disable the ignition in some way and then turn the engine over on the starter, alternately pressing and releasing the clutch and looking (or listening) for any change in rpm. It might be easier to observe any difference if the battery is on the way out - you still got your old one?

The answer may also be different depending on whether the engine is warm or cold.

Certainly I remember my old van would spin faster when cold if started with the clutch depressed.

jrkitching said:

........... if the battery is on the way out - you still got your old one?

Click to expand...

This is subject to another thread.

Yes, I still have the old one, and it's now in another car and so far is performing admirably. I'll give it a few more weeks, and I'll get back to this subject.

As for clutch drag/crankshaft loading/etc, I think it depends on the car and the gearbox as well as the age and design. You cannot state that depressing the clutch on all cars produces less drag. They are all different.

Remember, the clutch unit is bolted to the flywheel and the clutch pedal system pushes HARD against it.

It remains to be seen, but I profess that any engine and gearbox at tickover in neutral without anything being pushed is at its happiest.

Maybe with the clutch disengaged there isn't any actual measurable drag, but pressure pushing the engine won't result in a happier engine.

US regulations require cars be fitted with a clutch interlock device. I was really surprise to find that Euros are still being made without. The Koreans insist on fitting them to all their cars.

jrkitching said:

The best test I can think of is to disable the ignition in some way and then turn the engine over on the starter, alternately pressing and releasing the clutch and looking (or listening) for any change in rpm. It might be easier to observe any difference if the battery is on the way out - you still got your old one?

Click to expand...

Easier way is to put a clamp meter on the starter and measure peak current with/ without the pedal pressed. Since I do my own stop start, I am quite interested to find this out. I'll do some tests and see what I can figure out. I use my non-S/S starter motor at least 40 times a day so reducing load on it would be good thing.

Having the clutch engaged also increases inertia, it's not just about friction.

As far as why a TA won't start with the clutch engaged, I'll have to try it for myself.

Thanks UFI,
I'd be very interested in your findings.

Remember, it was only occasionally that ours wouldn't start, and since deliberately depressing the clutch (alien to me!) it's started 100% of the time.

If and when the car doesn't start, I'll report back, but I doubt the symptoms will be there when the clutch is depressed as per the instructions.

If I can go for another month with 100%, I'll go back to my old habits and see if the fault recurs.

Cheers,
Mick.

jrkitching said:

This is good practice ; it reduces the gearbox drag, lessening the load on the engine when starting and if you've forgotten to put the car in neutral, could also prevent a nasty incident.

Click to expand...

When I first started driving all those 14 years ago mother would always go on about me starting with the clutch pushed down. Think my dad does it too. And they've both been driving around 40 years.

So it was worth listening to them! :worship:

Ha! Just remembered, my old Chrysler Neon R/T would only start if the clutch was depressed first and as was mentioned earlier, all American vehicles are produced this way anyway and as the Chrysler Neon was built in the USA, I can see why even the right hand drive models were shipped this way.

Odd that it's SOP's (standard operating procedures) for lots of driving instructors out there to teach their students to dip the clutch prior to ignition and to depress the handbrake button when applying the handbrake, that there are seemingly so many people out there who don't adhere to these fairly routine driving habits. I've personally be doing those things for almost 30 years. To be honest, they should be as automatic as putting on your seat belt, though for some, even that still appears to be an alien concept!

Starting the car is the last thing you do.

First, you get in and any passengers too.
You confirm that the handbrake is on and then you make sure you're in neutral.
Then, you make sure you are correctly seated and connect your seatbelt and confirm all your passengers are correctly seated and belted too.
Make sure the doors are closed properly.

Only then do you insert the key and start the engine.

Mick.

I'm reminded of the Alfa 164 handbook - quite the best in this regard (items in quotes are exact wording, others are paraphrased:

- Walk around the vehicle and check for broken lights
- "Check under the vehicle for fluid leaks or other anomalies"
- "Sit in the driver's seat and check that you can reach the controls"
- "Check the horn proper operation"
- Turn the key to AVV and release as soon as the engine starts
- "Do not tread on the accelerator when starting the engine"
- "Do not demand top performances until the engine is warmed up"

I loved the priority given to the testing of the horn. I thought it was all a wonderful joke - until I visited Rome. There, I learned about "top performances" and "horn proper operation". Especially in places where the road has no lane markings.

The same handbook section included a few line drawings showing how to clip the seat belts neatly to the pillars using the provided clips, to prevent the unfastened buckle from knocking against the trim. The fact that a clip was fitted on the driver's side told you all you needed to know about superstitious Italian behaviour ("why would you not have confidence in your driving?" as someone from that part of the world once explained to me...)

Happily, things have moved on since the 80's - mainly thanks to the NCAP programme. It's also worth knowing that early (American) large airbag systems were designed to protect the occupants even if seat belts were not worn - this is NOT the case for the European designs and seat belts MUST be worn to allow the smaller airbag(s) to work properly - otherwise, the airbag(s) may cause additional injuries due to the body being in the wrong place. Leaning on the door trim etc. is also no longer allowed!

-Alex

Mick F said:

Starting the car is the last thing you do.

First, you get in and any passengers too.
You confirm that the handbrake is on and then you make sure you're in neutral.
Then, you make sure you are correctly seated and connect your seatbelt and confirm all your passengers are correctly seated and belted too.
Make sure the doors are closed properly.

Only then do you insert the key and start the engine.

Mick.

Click to expand...

These days by the time I'd done all that I'd have forgotten where I was going!

Just made a test on my TA:
It starts independent from clutch position of no gear in.
If gear in, it only starts with clutch pressed....

larslarsen said:

Just made a test on my TA:
It starts independent from clutch position of no gear in.
If gear in, it only starts with clutch pressed....

Click to expand...

nice so thats a good safety feature actually!

Please remember .......... if you are testing the starting of your TA ...........

I found that I had the No Start Situation only after the car had been standing unused for a couple of days. Once started and driven, it would start irrespective of the clutch being depressed or not.

Why there should be a difference, I don't know, and I don't know why you should ever need to depress the clutch to start. I understand that some cars are built that you MUST depress the clutch, but our TA seems to vary.

Regards,
Mick.

Mick F said:

Starting the car is the last thing you do.

First, you get in and any passengers too.
You confirm that the handbrake is on and then you make sure you're in neutral.
Then, you make sure you are correctly seated and connect your seatbelt and confirm all your passengers are correctly seated and belted too.
Make sure the doors are closed properly.

Only then do you insert the key and start the engine.

Click to expand...

Nice checklist, but you forgot to press the clutch pedal!

Oops, I should have said that!

larslarsen said:

If gear in, it only starts with clutch pressed....

Click to expand...

UFI will crank in gear. It's a useful way to move a car that won't start out of a dangerous position (although at ~900kg you could generally just push it).

Just a thought: Could the starting problem be related to the way the engine was stopped? Maybe it makes a difference if you let S&S stop the engine end then turn the key to STOP or if you stop the engine yourself by turning the key to STOP. Maybe S&S gets confused if do the first and then try to start the engine without pressing the clutch pedal, since normally a start after a stop performed by S&S is always with the clutch pedal pressed.