Seperate gearbox using motorbike gearbox internals?

[DRCAGE]

As per title really, could it be done? Has it been done?

The bike engine/gearbox combos seem to be strong enough for kit cars etc.

How hard would it be to go to a car style clutch and flywheel setup?

Surely the casing's going to be the hardest part, recommended manufacturing technique? casting, machining etc I'm a CNC machinist but can't see it being the best method apart from for finishing off bearing fits etc

Can anyone recommend a lubrication setup? (terrible terminology lol) Once sealed could it be filled with oil a certain amount? (massive over-simplification?) How do bike gearboxs stay lubricated?

I cant see why getting all the various parts lined up, in a "box", with a small flywheel/clutch on one end, and an output on the other end should be too hard? More masive over simplification? I fully accept that there is a good chance that i'm completely wrong

I've got loads more questions, just thought I'd throw a few into the mix!

Thanks in advance for any replies! :thumbsup:

[busta]

What engine are you thinking of using? Bike gearboxes can take the torque of a bike engine but not much more, so would be useless in any car engined application.

[Sam_68]

busta said:

Bike gearboxes can take the torque of a bike engine but not much more, so would be useless in any car engined application.

^^^ This.

Well, any but the very lightest car applications (and even then it's an achilles heel in terms of reliability).

And if you beef up the components to a level that can reliably take the torque, what you are looking for (a sequential dog box) is readily available from several manufacturers (Hewland, Quaife, Sadev, etc.). Oh, and you get a free reverse gear thrown in too!

[DRCAGE]

Thanks for the replys guys!

The actual car an engine combo this would be for is a Westfield XTR2 with a mazda rotary engine, about as light as cars come (about 450kg, hopefully), plus a not very torquey engine! Bonus!

I would've thought that a suitably beefed up version could be used for small engined hatches but who knows.

I should state that this is more of an idea than an actual project but nice to pick at the minds on PH.

I'm aware of the current offerings from the race gbox manufacturers but some of the prices are making my eyes water! No doubts they are incredibly expensive for a reason lol

Can anyone think of a reason that it definatly can't be done?

Thanks

[davepoth]

Wouldn't it just be easier to use the transmission that comes with the engine? It's going to weigh a bit more, but I shouldn't have thought it will be more than 10 kgs, low down, at the middle of the car, which is going to make very minimal difference to the handling of the car. And at least then you'll be able to go backwards if necessary.

[anonymous-user]

This can "deffinately be done", the question is "why would you want to do it"........

I could see that in a bike engined car, repackaging the transmission into a more "longitudinal" layout may help with installation etc, but, doing it, and getting it to work, although both totally possible, would consume a huge amount of time and money, better spent on an "off the shelf" solution.

Also, as the tranmission in usually integrated into the bike engine crankcase, you would also want to machine a new block for the engine to allow that to be optimally installed, so things get even more expensive/difficult.

If you just want a small low mass conventional gearbox, plenty of other sources would be a better starting point imo.

[Sam_68]

davepoth said:

Wouldn't it just be easier to use the transmission that comes with the engine?

I was thinking more that it would be easier to use the engine that comes with the transmission...

To the best of my knowledge, the Mazda rotary has only been used in a front engined/RWD configuration, so the standard gearbox is the wrong configuration for a mid engined car like the XTR2.

The XTR2 is designed for a bike engine, though, so why bother fannying around manufacturing special gearboxes from scratch when you can just drop the engine in that the car was intended to take in the first place?

It even gives you the same characteristics:

• Light weight, compact installation? CHECK
• Not enough torque to pull the skin off a rice pudding? CHECK
• Lack of reliability and frequent rebuilds necessary when used in cars? CHECK
• Really annoying, loud yet characterless noise? CHECK

Course, the bike engines don't use as much oil as petrol, like the rotary does, but if this is an essential requirement I'm sure you could rig up a scottoiler to drip oil into the exhaust for the same basic effect?

[davepoth]

Sam_68 said:

I was thinking more that it would be easier to use the engine that comes with the transmission...

To the best of my knowledge, the Mazda rotary has only been used in a front engined/RWD configuration, so the standard gearbox is the wrong configuration for a mid engined car like the XTR2.

The XTR2 is designed for a bike engine, though, so why bother fannying around manufacturing special gearboxes from scratch when you can just drop the engine in that the car was intended to take in the first place?

It even gives you the same characteristics:

• Light weight, compact installation? CHECK
• Not enough torque to pull the skin off a rice pudding? CHECK
• Lack of reliability and frequent rebuilds necessary when used in cars? CHECK
• Really annoying, loud yet characterless noise? CHECK

Course, the bike engines don't use as much oil as petrol, like the rotary does, but if this is an essential requirement I'm sure you could rig up a scottoiler to drip oil into the exhaust for the same basic effect?

Catty.

I hadn't realised we were going transverse.

In that case there's a slim chance a Ford FWD box will fit.

[Sam_68]

davepoth said:

I hadn't realised we were going transverse.

We're not... we're going longitudinal mid-engined.

The Mazda RX gearboxes all have a propshaft and separate diff hung off the back of them; what the OP will require is a longitudinal transaxle. Something like a Hewland JFR 6-speed sequential would do nicely, but will probably be out of his budget (about £6.5K, from memory).

The bike engines are fitted 'transverse', of course, but that's 'cos they have the gearbox behind and parallel to the crank. Even with an engine as compact as the wankel, I'm certain that a 'normal' transverse gearbox, bolted to the end of the crank, will be far too wide for the XTR2 engine bay. The car engined version (the XTR4, designed to be Audi based) used a longitudinal engine and gearbox installation.

[davepoth]

Sam_68 said:

We're not... we're going longitudinal mid-engined.

The Mazda RX gearboxes all have a propshaft and separate diff hung off the back of them; what the OP will require is a longitudinal transaxle. Something like a Hewland JFR 6-speed sequential would do nicely, but will probably be out of his budget (about £6.5K, from memory).

The bike engines are fitted 'transverse', of course, but that's 'cos they have the gearbox behind and parallel to the crank. Even with an engine as compact as the wankel, I'm certain that a 'normal' transverse gearbox, bolted to the end of the crank, will be far too wide for the XTR2 engine bay. The car engined version (the XTR4, designed to be Audi based) used a longitudinal engine and gearbox installation.

I just looked at a picture of the car and I see the problem. Haters are probably going to hate for this, but VW beetle gearbox? There's a guy running an offroad buggy in "reader's cars" with a rotary bolted to one.

[Sam_68]

Yeah, nothing wrong with a Beetle box - it's what the early Hewlands were based on, after all.

Not sequential, though, and only 4 gears, which isn't going to help the wankel's lack of torque spread very much.

If you're going that route, at least think about holding out for a second-hand Hewland out of a Formula Ford or similar, to give yourself dog engagement and easily interchangable ratios. You can pick them up a damn sight cheaper than the cost of developing your own bespoke box based on bike internals.

I'm guessing the cheapest 6-speed (though still non-sequential) you'll find would be the Audi box that the XTR4 was designed around?

Edited by Sam_68 on Thursday 23 June 08:13

[cptsideways]

You need an Impreza gearbox

[busta]

cptsideways said:

You need an Impreza gearbox

Like this?

Can't see it being cheap TBH.

What about a Triumph Rocket III gearbox? 5 speed sequential for a longitudinal engine, and handles 200NM of torque as standard.

They're shaft drive, so I don't know how you'd go about getting the drive to the wheels. A close coupled diff perhaps?

What kind of power are you expecting from the wankel?

[TallPaul]

How would you actually house the bike "gearbox"? On a bike, the engine and gearsets are all housed within the same crankcase (most bikes anyway), so by the time you've fabricated some way of physically holding the gearset together, you'd be much better just buying a proper sequential gearbox.

[DRCAGE]

Wow guys, thanks for all the replys, most topics I start disappear pretty quick!

A lot of the replys are essentially asking "why?", (join the que lol) I say why not! I'm a really hands on guy and love messing around with this kind of stuff. Also, if you keep asking me why i'll soon run out of reasons!. I'm a CNC machinist so will have access to material and pukka machines (and a spiffing machinist ). I'd like to think i've made much more complex stuff at work (definatly didn't design them though! ) . And, if I actually do it, well, I reckon that would be quite an achievment.

As you guys know that if I want to get a 5/6 speed sequential "race" box then i'll have to pay a fortune. If anyone knows of one that won't then let me know! This will no doubt cost loads but should be spread over time. I'v got a spare hayabusa engine so should have a lot of the parts needed.

I've looked into standard gbox choices (audi bettle etc) but none of them (that I know) are sequential.

The engine would be a highly ported n/a rx7 engine (peripheral ported 13b for the rotor heads ) so would never be huge power.

Sorry if I "missed" anyone, thanks again!

[davepoth]

I thought about it the other way round - has anyone put a Mazda rotary into a bike? - and found this:

http://thekneeslider.com/archives/2007/11/29/mazda...

[DRCAGE]

davepoth said:

I thought about it the other way round - has anyone put a Mazda rotary into a bike? - and found this:

http://thekneeslider.com/archives/2007/11/29/mazda...

You absolute legend! Awesome find

Found a good view of engine/gearbox connection...



Also found this pic, of a standard bike. Seems to have a different casing, best I could find really.



What do you guys think? Already drives a shaft (rather than chain etc), seems to be the right way round as standard. Anyone know much about the standard bike? I'm looking into it as I type!

Thanks

[davepoth]

At a guess that's the end of the bellhousing from a Mazda gearbox grafted onto a flat plate and then bolted to the BMW gearbox. I don't know what the guy would have done about the input shaft though.

[TallPaul]

The "4 VALVE" engine is a BMW boxer, probably an R1150 or something.

[DRCAGE]

davepoth said:

At a guess that's the end of the bellhousing from a Mazda gearbox grafted onto a flat plate and then bolted to the BMW gearbox.

Agreed, is there space for a car flywheel AND clutch in there? doesn't seem long enough.