Safe Speed Forums

When I learned to drive in the mid-70s I was taught to only use first for starting off, to get into second almost as soon as I was rolling, and never to engage first when actually moving.

The only instance of selecting first when moving I can think of was when climbing a steep hill behind a very slow lorry.

_________________
"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

A few years before that (1972), my 1963 mini had no synchromesh on first gear (by design). If you came to a stop in second (or a higher gear) it could be slow and clunky to engage first for pulling away again.

But there's a 'golden moment' just before you come to rest where the shaft speeds match and you can snick it into first ready to pull away again. The clutch never came up in first until you were ready to pull away, but it was cool not to fight the gearbox after you had stopped.

I still find this 'golden moment' on more modern metal. You can feel that the synchro has no work to do and it just slips in (ooo er missus).

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Ach! Not really "bad habits" as such. Cars which your Papa und Mama learned to drive und cut their eye teeth in were a "breed apart" from today's cars. I know this because of the "toy boys" in our garage.

Longest time ago when Mad Doc und self first married .. our home here was a derelict shell of farmhouse which we buy at auction. Listed building .. we do it up in keeping und jazzed it up too "in keeping" Part of attraction to us were the barns which had possibilities to us for our "toys und hobby" We currently have a Vitesse in bits.. have restored the body.. searching for engine parts und blokey on PH has been very helpful to me

I mention because we accumulate und store the some of the beauties from across family und some of these jewels do go to the "show off" displays of "vintage engineering loveliness" Someone was kind enough to remark that we should rival the museum in Keswick as we have a collection here of some real gems.. from Cousin Siegli's lurid pink shabby Trabi to my sister Krissi's "lech mobile" of a Capri

But enough of this.. those old cars scream und beg for mercy in towns in third gear where a modern car (from super stealth Merc to say a .. "Smart" or a "Kia" or whatever ... ist perfectly happy enough in third.. at 30 mph .. ). These elderly "wannabe toy boys" were designed to perform at 30 mph upwards in gear 4 .. und 5 if an Austin Maxi - which I think was one of the late British Leyland "pave-way success cars" like the Mini und Moggie und Dolly Sprint before it. But then - these cars built when I was baby - I just play, tinker und feel that these cars are under-valued, under-estimated und should be held to be a great BRITISH achievement.. und these cars were just as well designed as the Mercs etc of the heady days of the "Wirtschaftswunder" or "economic miracle" of German competence from 50s to 90s.

We are talking of a generation who learned to drive in these cars.. und - you know - progress improves handling und performance. Ist why we - Swiss family as whole - think we are on a right track when we say NO to a re-test .. but that we should at least have the skill re-assessed or even have lessons in the new cars so we are "au fait" with what these new machines can und cannot do

_________________
Nicht ganz im Lot!
Ich setze mich immer wieder in die Nesseln! Der Mad Doc ist mein Mann! Und ich benutzte seinen PC!

UND OUR SMILEYS? Smile ... und the the world smiles with you.
Smiley guy seen when you read
Fine me for Safe Speed
(& other good causes..)

Greatest love & Greatest Achievements Require Greatest Risk
But if you lose the driving plan - don't lose the COAST lesson.
Me?
Je ne regrette rien!

You didn't Dixie - possibly the use of a smiley or two would have been appropriate!

Paul... WRT having a 'golden moment' just before stationary to get into 1st - my old bike is like that. If I miss the moment I have to rock her back and fro whilst stamping on the gear lever to get her into 1st.

_________________
Science won over religion when they started installing lightning rods on churches.

I agree.
When I used to drive the other half's Mondeo ( V plate 2 litre Zetec), it was very easy to find the 'sweet spot' (which was moderately wide) where you could almost 'flick' the gearstick with 2 fingers up & down the box to find the next cog.

On the bike (1976 Kawasaki Z1), the only time I find myself using the clutch on the road is when pulling away from stationary.

_________________
What makes you think I'm drunk officer, have I got a fat bird with me?

I wish! The XS doesn't have a cush drive

_________________
Science won over religion when they started installing lightning rods on churches.

Neither does my Z1 since the standard wheels were changed for 3 spoke alloys and a 160/60/18 was fitted Sixy.

_________________
What makes you think I'm drunk officer, have I got a fat bird with me?

Sorry, I don't get this. How do you anticipate the lights?

Fair comment!
I MIGHT (depending whether or not it'll fit) be putting a CBR1000 back end in the XS...

_________________
Science won over religion when they started installing lightning rods on churches.

easy, in most situations observation will give you a clue, can you see the light cast in the hoods of the other lights? do you know the sequence? if so then you can have a better idea of when the lights will go green, and will be reacting to the light on the other road going red rather than yours going green.

Anything can be made to fit, just make sure whoever is doing the welding for the shock actually knows how to weld......because if they don't, there is only one place that shock will be going if it decides to part company from the frame


Confucious say......"if you see the green light, you have already lost"

_________________
What makes you think I'm drunk officer, have I got a fat bird with me?

The other half's a BS certified (certifiable?) welder.

The biggest problem I see is converting it to a single shock and building up the area aound the top shock mount enough to take the loading.

_________________
Science won over religion when they started installing lightning rods on churches.

Not that this is especially relevant but someone who knows a lot about these things once told me that it's not the oil pump's job to shove oil between the crank and the bearings at sufficient pressure to keep the surfaces apart. To do so, would require an oil pump so big and powerful that it would consume more power than the engine produced just to turn it! When questioned, a bit further, he said "look, oil pressure is what, 40 PSI? the surface area of a big end bearing shell is a couple of square inches so that's about 80lbs force required to push through it. The force on the top of the piston on a pwer stroke will be MANY times greater!

I don't know if it is true but it certainly made sense to me. He said that the viscosity of the oil being "sheared" as the crank went round was what created a "wedge" of oil to support the bearings - exactly like aquaplaning tyres.

Makes good sense - but I'm not 100% sure that it's right. One problem is that the oil spills out of the bearings a lot, and it's the job of the oil pump to replace the oil as fast as it's spilling out. So it isn't just pressure, it's also flow rate. I DO agree that oil pump pressure alone is insufficient to keep the metal apart... So the whole thing is very interesting.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Absolutely agree - flow rate is much more important than pressure - my last post wasn't intending to try and suggest it wasn't! I think pumps are sized to give a particular flow rate and to do that, the pressure they develop is almost incidental. The oil pressure gauge is important because (depending on where the feeds are and the gauge sender is) you'd want to be sure that there was enough pressure to ensure adequate flow to the bearings furthest away from the point(s) where the oil is fed in.

So do we think that low rpm implies low oil pressure implies low oil flow rate and that's what can put the bearings at risk in high load/low speed conditions? (I think I think that )

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

You are right in concluding that low RPM plus high load equals bad news for an internal combustion engine wrt oil pressure and wear. Its a bit more complex than that straight relationship; the oil viscosity also changes with RPM, at lower RPM viscocity is higher.

But, do a Google search for the following term:

"Boundary lubrication"

For an explanation of what happens when the lubricating system cannot maintain an oil barrier between the rotating parts and...

"Film lubrication"

Flow is the most important factor; pumps put out flow not pressure, pressure is generated by a resistance to flow.

Hope that helps.

Bye

When I was riding to and from Blackpool Colege, the lights at Lancaster University turning off the A6 used to go red for exactly 20 seconds - and were situated in the middle of a l o n g straight with really good view ahead, and wide verges.
I surprised many a car driver waiting in lane one, by arriving at the line in the second lane doing 40 mph as the lights went green!

_________________
Time to take responsibility for our actions.. and don't be afraid of speaking out!

Paul, your graph, is the torque scale right? 5000nm is alot of twist. Car only have tiny little drive shafts, are the really transmitting that much torque? Another question/ point, though first gear on a car has a hard time at the moment of start up how long is a car in first for, 3 seconds? Of those three seconds, it's only under any load when is just setting off. It's not as though the transmission is under load for hours at a time and do engines even give full power ijn first gear any more. I'd bet that the ecu turns the power down in first and maybe 2nd too in more powerfull cars.

Regarding high load, low rev situations, it mabe the case in car engines that might wear more, but many heavy duty engine are quite happy chugging away flat out at 1500 revs under full load. Most of the type of engines I use have such a steep torque rise under load that they give more power under full load at 1500 revs and some times below than they do at rated speed of say 2200 revs. More effecient too, thats something to do with reduced parastic power losses, internals moving up and down less but more boost of turbo giving more power. Not sure of the maths or how relavent it is to car engines.

Good point! I didn't notice that. Suppose the engine can manage peak torque of 300Nm (which is a pretty decent engine!)

Let's say that first gear ratio is 4:1 and the final drive ratio is 3:1, the torque just gets multiplied (neglecting losses) by the gear ratio each time - so we'd have 1200Nm coming out of the gearbox and 3600Nm out of the diff. So 5000Nm must be one hell of an engine (or lower ratios)!

In any case, although it's possible to limit engine output in low gears, I think they'd probably just rely on the traction control to back off the throttle a bit once wheelspin started to occur. I think it's important to bear in mind that beyond a certain amount of torque the wheels will just spin anyway.

Also, driveshafts are made of pretty tought steel too!