43 replies to this topic

[rory57]

Just about every sports bike has a similar gearbox arrangement: dog engaged straight cut gears, no synchromesh and single plane, single action lever operation ie pull up once to go up one gear, push down once to go down one gear. They seem to work a treat on road and track.

And just about every car with manual transmission has a completely different arrangement; synchromesh, multi position gear lever moving in a gate.

Any thoughts on why cars never have the bike-style gearbox? My "sports" car has six speeds and the gearbox is easy enough to use but gear changing is so slow compared to a bike.

[carlt]

mass, inertia - longevity 

[kikiturbo2]

well, you can get a seqential dog box for a car... no problem.. there are boxes avaialble for quite a few applications. Problem is... you wouldn't want to drive it on a regular basis... as in daily driver.. Apart from longevity and need for regular service, they are really noisy and have more "slop" in the driveline.

Also, in a DD situation, you do want to skip gears from time to time, or just take the car out of gear and straight into neutral... which you can't do on a sequential..

 

All this is a moot point... twin clutch boxes are so good now, nobody wants anything else..

[bigleagueslider]

Most people would not find the noise produced by spur gears acceptable in a passenger car.

[gruntguru]

They could be helical - I guess strength and axial load are more important than noise for motorcycle designers.

[Kelpiecross]

Without researching - if I remember correctly the early rear engine Fiat 500s had the motorcycle-type constant mesh/no synchro gearboxes. The idea seems to work well only on motorcycles and very light cars.
I don't know how common they are now - but heavy trucks/semis etc. once commonly used the Fuller Roadranger gearbox which was also constant mesh etc. I considered them to be one of the most diabolical devices of all time but they were apparently unbreakable and so were very popular. To change gear without dreadful crunching noises required fairly accurate double-declutching - something which is not needed on the very light 'boxes of this type.

Edited by Kelpiecross, 19 November 2014 - 10:26.

[kikiturbo2]

They could be helical - I guess strength and axial load are more important than noise for motorcycle designers.

 

yes, but the backclash in the dogs themselves is even worse.. Also dogboxes tend to need frequent inspection and maintenance. What is interesting that in the competitive environment the life of the boxes has been extended by installing semiautomatic shifters on the sequential boxes.. makes it much less possible for the driver to fumble a shift and destroy a box..

 

Having said that, if I had milions in the bank, I'd have an old WRC car as a DD... there is something wonderfull about that chakachakachaka sound the dog box makes when you shift it into first..

[rory57]

There are plenty of 100+ hp bikes put there, so I don't buy the "light duties only" story. I have no personal experience of powerful sports bikes but I don't hear that they have gearbox reliability problems or driveline shunt issues.

If bike-style 'boxes wouldn't be saleable in a Golf (hence DSG etc) would they not be worth a try in a more focussed sports car?

[MatsNorway]

Double clutch gearboxes is fancy. And heavy. When Mercedes went racing with the SLS they took out the stock gearbox ("ofc") and saved 40kg by that alone.

 

Koenigsegg believes double clutch boxes to be silly too. Im not saying their self made gearbox is good but they are onto something at least.

 

I have also seen cars with motorcycle boxes retro fitted and they seem to take the abuse just fine even with a turbo and some drop clutch action for extra drama.

Edit: what did Caterham do for their Fireblade powered cars?

Edited by MatsNorway, 19 November 2014 - 21:29.

[kikiturbo2]

all motorcycle powered cars use the bike box.. it is integral part of the engine (most of the time).. and they cope fine.. the ratios are all wrong though..

 

I am not saying you can't drive a dog sequential as a DD... just that you wouldn't want to..  I mean.. imagine having to go trough all the gears to get to first.. .everytime you stop in town...

[Kelpiecross]

all motorcycle powered cars use the bike box.. it is integral part of the engine (most of the time).. and they cope fine.. the ratios are all wrong though..
 
I am not saying you can't drive a dog sequential as a DD... just that you wouldn't want to..  I mean.. imagine having to go trough all the gears to get to first.. .everytime you stop in town...

This is one way around the problem - don't know if any modern 'bikes do this:

[scooperman]

My Bridgestone 175 solved the problem.  It had a lever on the side of the gearcase, in one position you had a normal bike 5-speed, in the other position it let the shift drum spin on past 5 to neutral, it went N-1-2-3-4-N.  So five speed out of the city, but in the city you used the four speed, and stopping at lights was simple, just click up to neutral.

 

Cycle magazine article

[desmo]

That Bridgestone looks like fun. Disc valve twin!

[Greg Locock]

My Yam DT 175 took a similar approach to scooperman, between each of the first 3 gears there was a sort of N. I'm not convinced that yamaha designed it to do that.

[Canuck]

Correct me if I'm wrong (as I'm sure I will be) but isn't load capacity for gearbox (and differential) rated by torque and not hp? The sport bikes with outrageous output have achieved these numbers in large part with RPM increases as opposed to increased torque. They are very much like an F1 engine in that respect. Second, the lifespan of a typical sport bike that is driven hard is not long, hence the term "Bic bike". Having said all that, I'm also not aware of any endemic transmission failure complaints, though the high torque output of some of the modified "American v-twin" engines has prompted at least one dedicated aftermarket high-capacity transmission. I I n stalled one last summer for a friend and must admit that if nothing else, it was much nicer to drive than the original.

[rory57]

Bike gearboxes are often driven via a primary reduction gear. Wiki gives ratios of about 1.6 : 1 for Suzuki Hayabusa and Honda Blackbird, both rated at 150hp plus and max torque around 100 lb/ ft.

So torque seen by gearbox not that much different to small road car numbers.

Having to click down a few gears once stopped at the lights never seems an issue for a bike rider, it is just click, click click so I don't see that as a stopper for a road car. Finding neutral is often a problem on a bike but that would be much less so with a hand control rather than a pedal?

I'd like to try it!

[desmo]

The difficulty should make it more desirable if anything.  Who wants a sports car that your mother could drive?  Motorcycles will thus always be far cooler than cars.

[fredeuce]

I don't know how common they are now - but heavy trucks/semis etc. once commonly used the Fuller Roadranger gearbox which was also constant mesh etc. I considered them to be one of the most diabolical devices of all time but they were apparently unbreakable and so were very popular. To change gear without dreadful crunching noises required fairly accurate double-declutching - something which is not needed on the very light 'boxes of this type.

The Roadranger box is not a constant mesh gearbox of the type used in motorcycles. In fact it is just your conventional gearbox  with twin counter gears all of which are straight cut . It does not have synchos but simple dogs to engage the gears. The shift pattern is a conventional double H pattern and there is no difficulty in slipping it into neutral (angel gear) or skipping gears should the need arise. It also has a splitter section on the back of a typical 5 speed gearbox layout . The splitter provides the high/low or lo/inter/direct  or what ever the ranges are depending on the specification of the box.

 

Learning to shift these gearboxes is a skill easily learned. Just takes some experience. Once you know the gap between the gears , usually around 400rpm , and keeping an eye on the tacho you can shift them with ease. Some operators skilled with boxes would shift them without using the clutch, which you can do with any conventional manual box.

[bigleagueslider]

Actually all auto/truck/motorcycle transmissions are constant mesh, since the mating gear sets never become "un-meshed". With manual transmissions, the gear sets for each ratio are engaged/disengaged by the synchro rings or dog rings. With conventional automatic transmissions, the gear sets are engaged/disengaged by clutches.

 

Spur gears are a bit more efficient and durable than helical gears of similar size and mass. Helical gears also produce axial forces that require a different bearing arrangement than spur gears.

 

The fatigue life of any gear is primarily based on the level of torque it transmits and number of load cycles it experiences. The forces a gear is subject to is a function of transmitted torque, and not transmitted power. The gears in a motorcycle transmission are usually lighter than those in an automobile due to the fact that the much heavier automobile transmits much more torque thru its drivetrain.

[Lee Nicolle]

Correct me if I'm wrong (as I'm sure I will be) but isn't load capacity for gearbox (and differential) rated by torque and not hp? The sport bikes with outrageous output have achieved these numbers in large part with RPM increases as opposed to increased torque. They are very much like an F1 engine in that respect. Second, the lifespan of a typical sport bike that is driven hard is not long, hence the term "Bic bike". Having said all that, I'm also not aware of any endemic transmission failure complaints, though the high torque output of some of the modified "American v-twin" engines has prompted at least one dedicated aftermarket high-capacity transmission. I I n stalled one last summer for a friend and must admit that if nothing else, it was much nicer to drive than the original.

The torque rating is what a gearbox is rated by. High horsepower no torque engines are fairly gentle on gearboxes. Large torquey [passengr car] engines eat them in comparison. Though big horsepower and torquey engines  [read decent V8s and large capacity turbo engines] are even worse.

I am local to a place that prepares rally cars and 'hot' Lancers and Rexs. Lots of growly gearboxes go by!

[Lee Nicolle]

The Roadranger box is not a constant mesh gearbox of the type used in motorcycles. In fact it is just your conventional gearbox  with twin counter gears all of which are straight cut . It does not have synchos but simple dogs to engage the gears. The shift pattern is a conventional double H pattern and there is no difficulty in slipping it into neutral (angel gear) or skipping gears should the need arise. It also has a splitter section on the back of a typical 5 speed gearbox layout . The splitter provides the high/low or lo/inter/direct  or what ever the ranges are depending on the specification of the box.

 

Learning to shift these gearboxes is a skill easily learned. Just takes some experience. Once you know the gap between the gears , usually around 400rpm , and keeping an eye on the tacho you can shift them with ease. Some operators skilled with boxes would shift them without using the clutch, which you can do with any conventional manual box.

Agreed, Roadranger and similar are not hard top drive at all. Just some though and commonsense. And yes you can drive them nearly as easliy clutchless as with clutch. I was forced too a couple of times.

Though drove my road car home in peak hour too with no clutch. That took some anticipation!

[bigleagueslider]

The torque rating is what a gearbox is rated by. High horsepower no torque engines are fairly gentle on gearboxes. Large torquey [passengr car] engines eat them in comparison. Though big horsepower and torquey engines  [read decent V8s and large capacity turbo engines] are even worse.

I am local to a place that prepares rally cars and 'hot' Lancers and Rexs. Lots of growly gearboxes go by!

This statement is not entirely accurate. The tooth bending and contact stress limits of gear teeth are a function of torque and number of load cycles. The scoring/scuffing limit of gear meshes is mostly a function of transmitted power. The same goes for the gearbox bearings. With an automatic trans the torque converter capability is a function of power. The friction clutches used in manual and automatic transmissions are also limited more by power than by torque.

[fredeuce]

This statement is not entirely accurate. The tooth bending and contact stress limits of gear teeth are a function of torque and number of load cycles. The scoring/scuffing limit of gear meshes is mostly a function of transmitted power. The same goes for the gearbox bearings. With an automatic trans the torque converter capability is a function of power. The friction clutches used in manual and automatic transmissions are also limited more by power than by torque.

Given that power is simply a function of torque over any given time period or the rate at which torque is applied, can you expand on these statements?

It seems to me that torque is ultimately an integral ingredient.Perhaps the line between the torque and power in relation to those examples of the problems you highlight is perhaps blurred due to the interrelationship between the two.

[rdyn]

This statement is not entirely accurate. The tooth bending and contact stress limits of gear teeth are a function of torque and number of load cycles. The scoring/scuffing limit of gear meshes is mostly a function of transmitted power. The same goes for the gearbox bearings. With an automatic trans the torque converter capability is a function of power. The friction clutches used in manual and automatic transmissions are also limited more by power than by torque.

For tooth bending: add reversed loads (torque and number)

However most gears are designed to be limited by pittings. Tooth breakage be avoided by reducing the number of teeth to a sufficent low value. Scoring/scuffing seldom occurs in automotive gears - sometimes, when a green hypoid gearset in a new car is treated very badly within the first few hundred kilometers (or if oil is lost due to leakage, or wrong oil, ...)

Edited by rdyn, 23 November 2014 - 12:29.

[bigleagueslider]

rdyn- You are correct. The fatigue life of most automotive gears is typically limited by surface hertzian contact stress levels and load cycles. And the bending fatigue life of a gear tooth is significantly affected if the tooth is subject to reverse bending, such as with an idler/planet gear or when the transmission is subjected to the load reversal produced by engine braking. Scuffing is always a concern with hypoid gears due to the fact that they tend to have greater levels of sliding at the mesh contact. Scuffing damage can occur very quickly if the gears are overloaded.

 

fredeuce- the tangential, separating and thrust forces produced at a gear mesh contact are almost entirely a function of the instantaneous torque moment being applied by one gear and resisted by the mating gear, plus the geometry of the gear teeth. Transmitted power does not have much effect in this regard. However, transmitted power does have a large influence with reagrds to the scuffing limits of a gear mesh.

[Kelpiecross]

The Roadranger box is not a constant mesh gearbox of the type used in motorcycles. In fact it is just your conventional gearbox  with twin counter gears all of which are straight cut . It does not have synchos but simple dogs to engage the gears. The shift pattern is a conventional double H pattern and there is no difficulty in slipping it into neutral (angel gear) or skipping gears should the need arise. It also has a splitter section on the back of a typical 5 speed gearbox layout . The splitter provides the high/low or lo/inter/direct  or what ever the ranges are depending on the specification of the box.
 
Learning to shift these gearboxes is a skill easily learned. Just takes some experience. Once you know the gap between the gears , usually around 400rpm , and keeping an eye on the tacho you can shift them with ease. Some operators skilled with boxes would shift them without using the clutch, which you can do with any conventional manual box.

Obviously there are a lot of differences between a 'bike gearbox and a Roadranger - but I would have thought the dog mechanism etc. was the same in concept.

I used to be in charge (supposedly) of a group of fairly amateur drivers operating semis with Roadranger boxes - I noticed that there quickly appeared an attitude amongst the drivers that it wasn't "manly" to say that the RR was **** and also that it wasn't "manly" to use the clutch. The drivers who said they never used the clutch you could usually hear the crunching gear changes from a few hundred yards away. It finally got to the point where I had to advise them to "Use the clutch for Christ's Sake - that's what it's there for". And when I actually drove with these same drivers their general changing was pretty dreadful as well - but you wouldn't know it from the way they talked.

One of my real problems with the RR was when you might be bombing along in 10th gear (for example) and then be suddenly slowed unexpectedly (by entering traffic or whatever) to about 3rd gear speed - very tricky to get into 3rd. gear from 10th. I also drove occasionally with very experienced RR drivers - and they certainly weren't crunch-free by any means.

But maybe some people are.

Edited by Kelpiecross, 27 November 2014 - 02:49.

[Kelpiecross]

I don't know if anybody else has mentioned it but the main problem with a 'bike gearbox in a car is its distinct lack of a reverse gear. Obviously there have been many suggestions as to how to overcome the problem - but none I would consider to be really practical or convenient. If somebody could come up with a cheap and elegant solution I would imagine just about every light homemade car would use 'bike and 'bike boxes.

[desmo]

Reversible starter motor?

[Lee Nicolle]

This statement is not entirely accurate. The tooth bending and contact stress limits of gear teeth are a function of torque and number of load cycles. The scoring/scuffing limit of gear meshes is mostly a function of transmitted power. The same goes for the gearbox bearings. With an automatic trans the torque converter capability is a function of power. The friction clutches used in manual and automatic transmissions are also limited more by power than by torque.

Just quoting manufacturers websites. Road car, modded road car and full competition boxes

And diffs as well.

[Johan Lekas]

I don't know if anybody else has mentioned it but the main problem with a 'bike gearbox in a car is its distinct lack of a reverse gear. Obviously there have been many suggestions as to how to overcome the problem - but none I would consider to be really practical or convenient. If somebody could come up with a cheap and elegant solution I would imagine just about every light homemade car would use 'bike and 'bike boxes.

I think this http://www.lynxae.co...-Bikesports.htm is quite a good solution.

A gear wheel replaces the nut (or bolt) holding the sprocket on the output shaft, and a (standard or reduction gear) starter motor is used for reverse drive

[Bloggsworth]

well, you can get a seqential dog box for a car... no problem.. there are boxes avaialble for quite a few applications. Problem is... you wouldn't want to drive it on a regular basis... as in daily driver.. Apart from longevity and need for regular service, they are really noisy and have more "slop" in the driveline.

Also, in a DD situation, you do want to skip gears from time to time, or just take the car out of gear and straight into neutral... which you can't do on a sequential..

 

All this is a moot point... twin clutch boxes are so good now, nobody wants anything else..

 

They are seriously noisy, motorbikes, being unenclosed, can get away with it - I used to drive a breakdown truck with straight-cut gears, not something I would want to undertake long journeys with. I quite often, when pootling along the flat, might go 1st, 2nd then 5th; or if setting of onto a down gradient go 1st, 2nd, 5th (or 6th when I had an MX5). I usually when approaching a sharp corner go straight from 5th to 2nd, or knock it out of gear when going down a long gradient; I have coasted many miles down Scottish hillsides and saved a packet of fuel.

Edited by Bloggsworth, 27 November 2014 - 18:22.

[gruntguru]

Same here although I am more of a 1 - 3 - 5 guy.

[kikiturbo2]

yeah, me too... but that is because my gearbox is terribly hard to shift when you drive slowly around town.. LOL

[Kelpiecross]

I think this http://www.lynxae.co...-Bikesports.htm is quite a good solution.
A gear wheel replaces the nut (or bolt) holding the sprocket on the output shaft, and a (standard or reduction gear) starter motor is used for reverse drive

Thank you for that. This Lynx Bikesports company seems to make some very nice stuff. I was especially impressed by their Yamaha powered Mini which was still front wheel drive - and a fairly simple conversion as well - very neat.

The Lynx reverse system would seem to be about the ultimate in the electric powered types - I was more thinking of a simple and cheap purely mechanical type - although I doubt anything could be made to be both simple and cheap.

I have always been impressed by the simple system that outboard motors use for reverse - but it is hard to see how this concept could be adapted to a motorbike gearbox.

[Kelpiecross]

There seems to be a bit of confusion about sequential gearboxes in general. A sequential box in theory could be applied to any type of gearbox - and they have been. Even a "normal" car synchro box could be made to be sequential. As mentioned above somewhere by GG - they don't have to use noisy straight-cut gears, they could be the quieter helical types. And they don't have to have a lot of free play either.

And there is another important method of gear - the sliding gear variety. Well-known to drivers of old Minis and Jags on their first gear - and in the 1930s truck gearboxes were often all sliding.

The ultimate would be to have a manual 'box that could be shifted between H-pattern and sequential.

Edited by Kelpiecross, 28 November 2014 - 10:17.

[kikiturbo2]

Thank you for that. This Lynx Bikesports company seems to make some very nice stuff. I was especially impressed by their Yamaha powered Mini which was still front wheel drive - and a fairly simple conversion as well - very neat.

The Lynx reverse system would seem to be about the ultimate in the electric powered types - I was more thinking of a simple and cheap purely mechanical type - although I doubt anything could be made to be both simple and cheap.

I have always been impressed by the simple system that outboard motors use for reverse - but it is hard to see how this concept could be adapted to a motorbike gearbox.

 

There used to be a special diff made by quaife aimed at bike engined cars that use chain drive.. that had a small planetary transmission included that could be switched on and that would reverrse the diff rotation.. Now they sell a whole box for 2K GBP..

[Lee Nicolle]

I think this http://www.lynxae.co...-Bikesports.htm is quite a good solution.

A gear wheel replaces the nut (or bolt) holding the sprocket on the output shaft, and a (standard or reduction gear) starter motor is used for reverse drive

All of this stuff may be just ok for a very light car. not practical for everyday motoring.

Most bike engines only have liquid cooled heads, not so practical in an enclosed car. All that fairing on a bike is part of the cooling. 

To use for a light open wheeler or sports car they are just practical. And I know cooling can be an issue. That on more than about 10 lap races. Detonation problems as the block gets too hot.

 

A bike engined Mini to me is impractical. A lot of engineering and still too little bottom end torque to be practical in traffic. A hillclimb car or similar may be interesting though.

Though thewre is no end of modern engines that can be adapted,, though why? Just use the modern car the engine came in. 'Normal' front engined older cars are fairly simple and practical for engine upgrades though all the 'little' things are the drama. Making custom exhausts, tailshafts, custom radiators, yet alone accesory mounts. eg Power steer and A/C and just simple things such as speedo drives.

For a base car or a race car easier. Or just use a better [usually later] engine from the same manufacturer which makes most of those problems at least solveable. Just think, scrounge and look. The later radiator may interchange, speedo drives tend to be generic so maybe swap a cable etc. Even accesory mounts can be easier.

Though many manufacturers seem to go out of their way to make things difficult.

I sell parts, often there is 3-4 base radiators for the one model. Starters, alternators, engine and trans mounts have multiple variations. Uni joints and or drive shafts. Why,,, to me very poor planning and design.

[bigleagueslider]

There seems to be a bit of confusion about sequential gearboxes in general. A sequential box in theory could be applied to any type of gearbox - and they have been. Even a "normal" car synchro box could be made to be sequential. As mentioned above somewhere by GG - they don't have to use noisy straight-cut gears, they could be the quieter helical types. And they don't have to have a lot of free play either.

And there is another important method of gear - the sliding gear variety. Well-known to drivers of old Minis and Jags on their first gear - and in the 1930s truck gearboxes were often all sliding.

The ultimate would be to have a manual 'box that could be shifted between H-pattern and sequential.

You can take the guts from an H-pattern manual gearbox (whether dog ring or synchromesh) and convert it to sequential simply by changing the way the shift forks are actuated.

[kikiturbo2]

yes, but a synchromesh box will never ever shift as fast as a dogbox..

[Catalina Park]

But with a bit of work with a die grinder and you can speed them up a bit. (and still stay within the class rules!)

[carlt]

Oh for the day we can have seamless shifts !

[kikiturbo2]

But with a bit of work with a die grinder and you can speed them up a bit. (and still stay within the class rules!)

 

I heard that a drill bit and a couple of litres of ATF is all that is nedeed..

[Kelpiecross]

All of this stuff may be just ok for a very light car. not practical for everyday motoring.
Most bike engines only have liquid cooled heads, not so practical in an enclosed car. All that fairing on a bike is part of the cooling. 
To use for a light open wheeler or sports car they are just practical. And I know cooling can be an issue. That on more than about 10 lap races. Detonation problems as the block gets too hot.
 
A bike engined Mini to me is impractical. A lot of engineering and still too little bottom end torque to be practical in traffic. A hillclimb car or similar may be interesting though.
Though thewre is no end of modern engines that can be adapted,, though why? Just use the modern car the engine came in. 'Normal' front engined older cars are fairly simple and practical for engine upgrades though all the 'little' things are the drama. Making custom exhausts, tailshafts, custom radiators, yet alone accesory mounts. eg Power steer and A/C and just simple things such as speedo drives.
For a base car or a race car easier. Or just use a better [usually later] engine from the same manufacturer which makes most of those problems at least solveable. Just think, scrounge and look. The later radiator may interchange, speedo drives tend to be generic so maybe swap a cable etc. Even accesory mounts can be easier.
Though many manufacturers seem to go out of their way to make things difficult.
I sell parts, often there is 3-4 base radiators for the one model. Starters, alternators, engine and trans mounts have multiple variations. Uni joints and or drive shafts. Why,,, to me very poor planning and design.

Agreed - not very practical for road use. But I grew up with Minis and this one really appeals to me.

[gruntguru]

Do you really agree with all that bunk? e.g.

 

. . . . Most of the big bike engines (the ones likely to be repurposed for car use) have water cooling in the block.

 

. . . . There are lots of successful bike-engined-cars on the road and the track.

 

. . . . In most cases - including the mini + Hayabusa - there is a massive improvement in available torque.

Edited by gruntguru, 01 December 2014 - 02:40.