|83 forum posts|
Hi - I have been reading a book on the pre-war Lagondas and there have been several references to the fact that in times past before the general introduction of syncro mesh the buying public had a great fear or reluctance of changing gear. So much so in fact that manufacturers would advertise that their latest models would/could travel from London to Edinburgh in top gear! This I think was possible because of the manual advance/retard of the ignition control made available on some cars but just how did this work in practice?
4654 forum posts
They didnt have today's traffic to contend with. And vehicles had low compression, flat torque curves and heavy flywheels combined with lower overall gearing than today's vehicles. And the Lagonda had a V12 engine that would have helped! But was geared for 100mph flat out whereas today's highperformers would be geared for double that.
|Nick Clarke 3||11/07/2020 12:28:31|
812 forum posts
Napier were the first to demonstrate this but Rolls Royce felt they could do better and in fact did so in 1911.
The Silver Ghost at that time was designed to do about 75mph flat out, had a three speed gearbox and the engine was 7428 cc and 48 bhp (36 kW) at 1,250 rpm.
There is more info here along with news of an attempt to recreate it this century. **LINK**
|367 forum posts|
In the early 70s I used to drive my sister's 1956 Morris Minor (803 cc) around our small town in top gear "just because I could". It was low a compression, low-revving, under-powered car, under-geared because it had to be. It certainly demanded good clutch control to achieve it.
In contrast, try as I might, my 1960 (948 cc) Minor just wouldn't do it in top. It was far more satisfactory on the open road, however.
|83 forum posts|
What I found interesting in the account of driving long distances without the need for changing gear was the reference to the driver controlled A/R mechansim and just how it would have been used. I gather that although the control might be mounted on the dash, it could also be mounted on stalks alongside the steering wheel implying that it was always within easy reach of the driver. How long did this practice last and when was it phased out and... did it even survive into post war car production?
|Chris Evans 6||11/07/2020 16:18:32|
1702 forum posts
As someone who rides/restores vintage motorcycles I am well versed with advance/retard to get the best engine performance to suit conditions.
I learnt to drive on a "Swift" car and my own first car was a 1929 Lea Francis, think no synchromesh gearbox, centre throttle and right hand brake peddle. This all gave me a good grounding for 40 years of driving series Land Rovers with worn gearboxes. Even today on modern cars I still double declutch out of habit.
|not done it yet||11/07/2020 16:35:09|
|4747 forum posts|
No idea about cars, but tractors were using manual A/R mechanisms with magneto ignition until shortly before, or into, WWII. It usually included a ‘stop’ position where the mag was shorted to ground.
These vehicles of pre WWI are classed as ‘veteran’, not ‘classic’,
Edited By not done it yet on 11/07/2020 16:38:58
940 forum posts
I had a Matchless 500cc single cylinder motorcycle of 1954 vintage which had manual advance and retard of the magneto ignition, I soon learned that you put the advance and retard in the correct position for starting otherwise it could kick back and possibly break your ankle, happy days.
|John Olsen||12/07/2020 01:09:43|
|1049 forum posts|
I once had a gearbox failure on an 1800cc Ford/Mazda van, while towing s light trailer. I drove it about 60 miles to where I could work on it with only fourth gear. (The direct drive gear, it had an overdrive fifth which I didn't try.) The towns I passed through were the only difficult part, especially the traffic light in the last one. So long as you can keep rolling it is all good.
Not really a very good idea, since a gearbox that is mangling itself inside may decide to seize up, which would lock up the back wheels, possibly at a bad moment. But open road running with only one gear is not all that hard, unless you have a real mountain road to drive, which luckily I didn't. Since Britain doesn't actually have any real mountains it should be easy there!
The old manual advance retard did allow avoiding gear changes at times, my Dad used to talk about doing it with a prewar BSA 250.
|Howard Lewis||12/07/2020 03:14:12|
|3394 forum posts|
A long stroke, low compression engine is great help for these sort of feats.
When you hear some of the larger Veteran cars on the London to Brighton run they could do it, since they seem to fire about once every lampost!
My father had a 1947 Vauxhall 10. The ball through which the gear lever passed in to the gearbox, was hard rubber. One day it split, jamming the gear lever, and Dad drove from Coventry to Hereford in top gear. He only needed a tow from a lorry over the one steepest hill.
The 803 cc BMC 'A' Series engine had a 7.2:1 compression ratio and was geared about 14 mph per 1000 rpm, and was relatively long stroke compared to the bore, so would be fairly tractable. We used to start ours away in 2nd gear sometimes.
The 1300 cc Toyota Yaris has good low speed torque, because of its timed port injection, variable inlet valve timing and ECU program, allowing it to pull without protest to just below 1,000 rpm. But geared at 21 mph /1000 I wouldn't be too keen to try driving from London to Edinburgh, in top gear, even with today's gentler gradients roads.
In comparison, some modern turbocharged engines need to be kept within a fairy narrow speed band. Drop the revs and the torque can disappear. Indeed, at one time there was a rotary fuel injection pump configured specifically to do just that, so that the engine was kept in the optimum speed range for economy and freedom from smoke. No doubt, modern ECUs will do the same thing to minimise emissions.
|Nick Clarke 3||12/07/2020 08:53:45|
812 forum posts
An elderly Austin Maxi I drove in the 1980's suffered a broken engine mounting so the whole engine sagged backwards (or forwards I can't remember) jamming the gearchange so it could only be put into 2nd or 4th. I had to drive it round Birmingham like that for a couple of days until the ever efficient Leyland parts department managed to get a replacement part in.
A few months later the front subframe collapsed, the car sank to one side and as the driveshaft was pulled out it spewed oil all over the road.
At 5 o'clock in the afternoon.
On a single lane part of the Birmingham inner ring road.
Outside Winson Green prison!
Funnily enough the police told me to shift it as fast as possible!
Edited By Nick Clarke 3 on 12/07/2020 08:54:16
4654 forum posts
I think the BSA Gold Star had manual spark advance up to its demise in 1964. Not much chance of running one of those through traffic in top gear though!
|5938 forum posts|
The best time to fire the spark depends on the engine's rpm and load, both of which vary. Starting is one extreme: as cold engines are hard to ignite it's worth delaying the spark until after compression has warmed the mix and the pressure has dropped enough to allow a fatter spark. (High cylinder pressure makes the fuel a better electrical insulator.) Late timing for firing the first cylinder is grossly inefficient when the engine is running, so the timing has to change. It was originally left to the driver to adjust for 'best' results, which are a complicated combination of fuel economy, torque, power output, and temperature management.
Drivers aren't particularly good at managing spark timing - the lever is adjusted until the engine feels right. Works well enough when the engine is working at a constant rate - cruising - but drivers aren't quick enough to deal with stop-start town driving and short slopes, nor do they have enough information to get the setting spot on.
Manual advance/retard turned out to be quite dangerous in early aircraft, because pilots would forget to adjust it, particularly when dealing with emergencies! A mis-tuned engine wouldn't deliver full power and might overheat and seize. Manual adjustment was bad news for fighter pilots; not good in a dog-fight to have to keep tuning the engine!
The answer was to adjust timing with an automatic mechanism and it took many years to refine them. For most of my driving life it was done by rotating the points with the engine vacuum, because engine vacuum is a good indicator of load. And, because the points rotate relative to rpm, the mechanism gets the other major clue needed to adjust timing. It's better informed than the driver about the engine's innards, it reacts quickly, and it's always on the job. Although the mechanism is simple, designing it to work properly over the required range was a major challenge, and it was refined many times over the years. It was also designed to work alongside the fuel system - another bit of the engine hard to manage manually. Most vehicles made after 1945 come with automatic advance/retard.
Modern engines get even better performance by replacing mechanical mechanisms with an electronic management unit. Much faster and with many more sensors. Knock, engine temperature, vacuum, exhaust content, air temperature and humidity, oil pressure and whatever else the designer finds helpful. The EMU's ability to manage fuel, timing and pother parameters together is a major advantage. And because EMUs are computerised, they can optimise for several different profiles : sport, urban, low-pollution, cruise-economy, creeping home in an emergency, maybe controlling the suspension as well as the engine.
Most of the detail control of cars has been taken away from the driver, and there's more to come. Extend the EMU with a system of sensors detecting the cars position on the planet, and telling it what's in front, behind, and at the sides, and there's no reason to have human drivers at all!
Edited By SillyOldDuffer on 12/07/2020 11:01:21
|not done it yet||12/07/2020 11:09:31|
|4747 forum posts|
We used to start ours away in 2nd gear sometimes.
Funny you should mention starting in 2nd gear. My Mum learnt (was taught) to start off in second gear unless heavily loaded or on a hill. A consequence of non-synchro bottom gear, I guess?
Even though she then drove a couple or three top-of-the-range 1300cc Escorts afterwards, she always started in second, just as she had been taught.🙂 She likely changed the vehicle early enough to avoid a clutch change.
|john halfpenny||12/07/2020 11:15:15|
|37 forum posts|
The main, almost sole, purpose of a manual advance/retard is to permit starting without drama, ie no backfire or broken wrist if hand cranking (and forgetting to tuck the thumb in). Modern fuels allow the control to be moved immediately to full advance upon firing, where it can stay. I think the Austin 16 of 1948 was possibly the last to have an ignition control on the steering wheel, but I'm sure my BSA Bantam still had it in 1968. Most low compression vintage cars (pre 1930) will happily drive in top gear everywhere, and my Model A Ford will accelerate from rest to 50mph just as fast in top gear as when using the intermediates, such is the delay consequent on getting a silent ratio change.
|Howard Lewis||12/07/2020 21:49:25|
|3394 forum posts|
The majority of buses, if the axle ratio was correct, would pull away in 2nd. First was for starting on really steep inclines, since the governor usually limited speed to about 6 mph. Being unsynchronised, if you waited for the revs to drop, you were likely to be stationary by then! So you either crawled along up to the peak, or snatch changed into second.
Express coaches were higher geared, so with an Eaton 2 speed axle, 1st High could be used for starting, probably reaching a high enough speed to allow a double declutch change into second, before split shifting into third low., as you accelerated.
Once I witnessed a driver take a Leyland 0600 powered coach away from near low idle speed, up to 60+ in fourth High.. Geared at 38 mph / 1,000 rpm! That WAS low speed torque. The later 0680 engines peak torqued at 850 rpm, nothing seemed to stop them!
|Peter G. Shaw||13/07/2020 11:32:34|
1121 forum posts
The trouble with buses and their 5 speed gearboxes was that 1st gear, certainly on what I think of as semi-automatics, ie with an automatic clutch, was that 1st gear required the operation of two levers simultaneously, one of the levers being, as far as I could tell a device to prevent accidental engagement. The problem then, was that lazy drivers who could not be bothered to engage 1st gear would subject the bus, and passengers, to a form of physical abuse. What happened was that on steepish inclines, the driver would engage 2nd gear, press the accelerator whereupon the engine would speed up, the automatic clutch start to engage, and the vehicle start to move. However, as the clutch fully engaged, the engine could not generate enough power so the speed dropped, the clutch started to disengage, the engine then speeding up etc etc. The resultant ride was a series of jerks until such time as the bus reached more level ground. It was noticeable how much smoother the ride was when the driver knew what he was doing and used 1st.
Another nasty habit these lazy drivers had was to slam the gear lever from 2nd to 3rd, ie straight across the gate, without pausing. Again, the poor old bus, and the passengers, were subjected to a mighty jerk as the gears/clutch changed.
Peter G. Shaw
|1134 forum posts|
Once drove from Exeter to Bradford in top, Escort 1.6 CAV engined Diesel Saloon. 70K when bought, 54mpg. 150k when sold,54mpg. Pity about the shell.
|Bill Pudney||13/07/2020 12:20:40|
|454 forum posts|
I used to have a Norton 650SS, which as their top of the line high performance model, had a magneto. The 650SS was made up until 1968/9. However like the previously mentioned BSA Gold Star, the advance/retard wasn't specified for slow speed, high gear use!! In the mid 70s I was stopped on the Andover By Pass for doing 126mph, and in 77 the same bike, two up with panniers and a tank bag, put over 90 miles into less than 60 minutes. Got to love magnetos!!
|Grindstone Cowboy||13/07/2020 12:26:44|
|313 forum posts|
My dad had a straight-six Plymouth in the early 60s that he never took out of second (it only had three gears anyway). Enough torque to start moving and enough revs to reach comfortable cruising speeds on most A-roads.
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