Primary gear reduction.

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
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coaster
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Primary gear reduction.

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Most motorbikes have a gear reduction before the clutch and transmission, would 'quick change' style of primary gear be beneficial?
You have 3-2-1.2-1.1-1 set of ratios and a 3.5 to 4.0 final drive and do only the primary gear to suit the lengths of the straights on any given track?
F1 use a primary reduction after the clutch yes?

Tommy Cookers
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Re: Primary gear reduction.

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coaster wrote:
Sat Nov 07, 2020 11:28 pm
F1 use a primary reduction after the clutch yes?
are you saying they do - or suggesting they should do ?

J.A.W.
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Re: Primary gear reduction.

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coaster wrote:
Sat Nov 07, 2020 11:28 pm
Most motorbikes have a gear reduction before the clutch and transmission, would 'quick change' style of primary gear be beneficial?
You have 3-2-1.2-1.1-1 set of ratios and a 3.5 to 4.0 final drive and do only the primary gear to suit the lengths of the straights on any given track?
F1 use a primary reduction after the clutch yes?
Most motorcycle engines are mounted transversely, so must use a primary step-drive,
but do those with engines mounted lengthwise - BMW & Moto Guzzi - also do so?

An extra gearing step is a point of power loss, albeit rotational speed/torque/weight
& packaging tradeoffs of componentry do also come into it..
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coaster
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Re: Primary gear reduction.

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Im aware of a spiral bevel gear after the clutch and then onto the sequential gearbox.
After the bevel and before the gearbox i recall use of changeable reduction by some teams in the 1990's.

Jolle
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Re: Primary gear reduction.

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With a reduction gear you will out more torque on the gears. If you look at different motorbikes with or without this reduction, the ones without, are a bit clunky but there is considerable less wear.

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Big Tea
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Re: Primary gear reduction.

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coaster wrote:
Sat Nov 07, 2020 11:28 pm
Most motorbikes have a gear reduction before the clutch and transmission, would 'quick change' style of primary gear be beneficial?
You have 3-2-1.2-1.1-1 set of ratios and a 3.5 to 4.0 final drive and do only the primary gear to suit the lengths of the straights on any given track?
F1 use a primary reduction after the clutch yes?
On a motorcycle you can more or less 'swap' the crank to clutch gearing with the differential on a car.
Most motorcycle engines have a transverse crankshaft and transverse gearbox so a 90degre change of direction is needed. I doubt its prime function is that of gearing, just a byproduct that does the same as the dif.
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Tommy Cookers
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Re: Primary gear reduction.

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Jolle wrote:
Sun Nov 08, 2020 9:42 am
With a reduction gear you will out more torque on the gears. If you look at different motorbikes with or without this reduction, the ones without, are a bit clunky but there is considerable less wear.
all motorbikes have some reduction gear
ie all shaft drivers since the late 1960s have a reduction stage between the crankshaft/clutch and the gearbox input shaft
this because the shaft line needed moving outwards to allow wider (than 1940s or 1950s) tyres ...
and because this enabled overall gearing to be varied (for different engine sizes) this way (not at 'CWP' final drive stage)
importantly making the CWP ratio common for eg 3 engine sizes saved money (needing 1 lot of CWP tooling not 3 lots)
Last edited by Tommy Cookers on Sun Nov 08, 2020 5:31 pm, edited 1 time in total.

Jolle
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Re: Primary gear reduction.

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Tommy Cookers wrote:
Sun Nov 08, 2020 1:57 pm
Jolle wrote:
Sun Nov 08, 2020 9:42 am
With a reduction gear you will out more torque on the gears. If you look at different motorbikes with or without this reduction, the ones without, are a bit clunky but there is considerable less wear.
all motorbikes have some 'torque reduction'
ie all shaft drivers since the late 1960s have a reduction stage between the crankshaft/clutch and the gearbox input shaft
this because the shaft line needed moving outwards to allow wider (than 1940s or 1950s) tyres ...
and because overall gearing was varied (for different engine sizes) this way .....
importantly making the CWP ratio common for eg 3 engine sizes saved money (needing 1 lot of CWP tooling not 3 lots)

ideally re F1 etc ....
some gearbox torque reduction would better than none .... because .....
the inertial energy is lower in such a lower speed/higher torque gearbox
some of this energy must be absorbed and even dumped - as F1 does
this energy dump is the price of smoothing shifts with 8 or 7 or whatever discrete ratios

of course other factors may supervene the above in determining the F1 vehicle layout
anyway current F1 has lower speed/higher torque gearboxes from the engine changes since NA days
Not so fast... not all bikes... BMW air and oil cooled boxers don’t, and because of less force on the gears, stuff like pitting is rare, even though the average boxer has three times the mileage of any other bike.

It’s the torque that mangles your gears and upsets the casings, not the rotational speeds. Same you see in electronics. Keep your voltage up and your amps down, else you’ll need one hell of a copper loom.

Tommy Cookers
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Re: Primary gear reduction.

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Jolle wrote:
Sun Nov 08, 2020 2:22 pm
Not so fast... not all bikes... BMW air and oil cooled boxers don’t, and because of less force on the gears, stuff like pitting is rare, even though the average boxer has three times the mileage of any other bike.

It’s the torque that mangles your gears and upsets the casings, not the rotational speeds.
what I'm saying includes BMW air and oil cooled boxers ....
ie they all (from /5 ? series c.1967) have some reduction before the gearbox input shaft
yes the reduction would be small on the largest-engine versions of those bikes (and larger on the smallest-engined)

not so previous BMWs ie from first till 1967ish eg the R69S gearbox input shaft is coaxial and 1:1 with crankshaft
Last edited by Tommy Cookers on Sun Nov 08, 2020 5:32 pm, edited 1 time in total.

Jolle
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Re: Primary gear reduction.

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Tommy Cookers wrote:
Sun Nov 08, 2020 3:02 pm
Jolle wrote:
Sun Nov 08, 2020 2:22 pm
Not so fast... not all bikes... BMW air and oil cooled boxers don’t, and because of less force on the gears, stuff like pitting is rare, even though the average boxer has three times the mileage of any other bike.

It’s the torque that mangles your gears and upsets the casings, not the rotational speeds.
what I'm saying includes BMW air and oil cooled boxers ....
ie they all (from /5 ? series c.1967) have some reduction before the gearbox input shaft
yes the reduction would be small on the largest-engine versions of those bikes (and larger on the smallest-engined)

not so previous BMWs ie from first till 1967ish eg the R69S gearbox input shaft is coaxial and 1:1 with crankshaft

ok I might be wrong .....
Driving a 90’s 1100 cc oildhead. The clutch is directly on the crank. The input shaft has a tiny reduction on the intermediate shaft, but only because of packing concerns, in no way the reduction you see in low maximum torque inline four engines.
The gearbox of a boxer BMW up until they went with water cooling a couple of years ago is about twice the speed of an in-line bike and the main reason why they are bulletproof (except for a dumb input shaft design on the first model year back in ‘95)

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Big Tea
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Re: Primary gear reduction.

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Jolle wrote:
Sun Nov 08, 2020 3:39 pm
Tommy Cookers wrote:
Sun Nov 08, 2020 3:02 pm
Jolle wrote:
Sun Nov 08, 2020 2:22 pm
Not so fast... not all bikes... BMW air and oil cooled boxers don’t, and because of less force on the gears, stuff like pitting is rare, even though the average boxer has three times the mileage of any other bike.

It’s the torque that mangles your gears and upsets the casings, not the rotational speeds.
what I'm saying includes BMW air and oil cooled boxers ....
ie they all (from /5 ? series c.1967) have some reduction before the gearbox input shaft
yes the reduction would be small on the largest-engine versions of those bikes (and larger on the smallest-engined)

not so previous BMWs ie from first till 1967ish eg the R69S gearbox input shaft is coaxial and 1:1 with crankshaft

ok I might be wrong .....
Driving a 90’s 1100 cc oildhead. The clutch is directly on the crank. The input shaft has a tiny reduction on the intermediate shaft, but only because of packing concerns, in no way the reduction you see in low maximum torque inline four engines.
The gearbox of a boxer BMW up until they went with water cooling a couple of years ago is about twice the speed of an in-line bike and the main reason why they are bulletproof (except for a dumb input shaft design on the first model year back in ‘95)
I'm still using a R1100rs. Cant bring myself to change it. ( I have a cruiser too )
Last edited by Big Tea on Mon Nov 09, 2020 6:52 pm, edited 1 time in total.
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saviour stivala
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Re: Primary gear reduction.

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Gear reduction ‘before’ the clutch used in formula 1.
The only 2 examples I know of was that used by the 1950 BRM V16. Longitudinal front engine rear wheel drive. The ‘2’ crankshafts centre take-off gear (27-teeth) mated with (52-teeth) gear on a hollow sub-shaft extending rearward to the clutch. Thus when the crankshaft was spinning at 10,000rpm the clutch at the tail-end of this shaft was doing only 5200rpm, a normal rate for the drive-line technology of the time.
The other example was the Honda RA272E V12. Transverse mid-engine rear wheel drive. The east-west layout was only feasible because Honda was able to design and build the complete power train as an integrated package. In fact the engine’s cam drive gearing was completely merged with the gearing to the transvers transmission. The drive was taken from spur gear at the centre of the crankshaft, which effectively made it 2 short, stiff vee-sixes as far as the crankshaft was concerned. At a reduction of 1.85:1 it drove a short transverse shaft from which 2 skew gears drove shafts going downwards to the gear type oil scavenge pumps mounted in the sump. From the transvers shaft another gear pair drove yet another east-west shaft, this one quite long, it was driven at a further reduction of 1.21:1, so this shaft turned at 44.7 per cent of engine speed. On the right end of this shaft was the multiple-disc clutch that drove the gearbox. 2 more transvers shafts - at another speed reduction of 1.14:1 through a pair of gears that could easily be changed to adjust the overall ratio.

63l8qrrfy6
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Re: Primary gear reduction.

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coaster wrote:
Sat Nov 07, 2020 11:28 pm
Most motorbikes have a gear reduction before the clutch and transmission, would 'quick change' style of primary gear be beneficial?
You have 3-2-1.2-1.1-1 set of ratios and a 3.5 to 4.0 final drive and do only the primary gear to suit the lengths of the straights on any given track?
F1 use a primary reduction after the clutch yes?
None that i've seen.
Usual configuration is input shaft into gear cluster and then a cross shaft with the spiral bevel on the output shaft.

Tommy Cookers
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Re: Primary gear reduction.

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afaik and fwiw

in isolation there's an argument for reduction ie the gearbox designer might like this lower rpm/higher torque situation
because the energies in some of the rotating parts would be less

but the PU inertia as 'seen' by the gearbox would be increased by the square of the reduction ratio
this would increase the energy dump used to make shifts tolerably smooth

anyway post NA engines had greatly reduced rpm and greatly increased torque - enough of a problem to gearbox designers

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Bandit1216
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Re: Primary gear reduction.

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Image

Dunno what 1100 oilhead you have, but this has (and 90% (if not all) of the transverse mounted engined bike have), a gear on the crankshaft to primary shaft. Not at all quick exchange.

The clutch basket is on the primary shaft. This even has a higher rpm then the crankshaft if my memory serves me right. To decrease the torque I guess.

(I've big bored (1216cc) a gsxr engine 10 years ago)
But just suppose it weren't hypothetical.