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Bike Gearbox in a car
nijumaru - 27/7/06 at 11:20 AM

Hello All am new here.
Was told you guys could help me.
I am planning on putting a bike engine into a Reliant Robin, my only problem is the gearbox and how to connect a bike Gearbox in a car.

How do I connect a motorbike gearbox onto a car gearstick? Or is it done differently in kit cars?

and Whats the cheapest solution for a reverse?

Thanks
James
A.k.A NijuMaru


Aboardman - 27/7/06 at 11:26 AM

no need for a car gearbox whilst using a bike engine, just connect the drive shaft direct to the output shaft on the bike engine. and then use a system of levers and rose joints to form a new gear linkage as the new gear lever you want up move down, but the gearbox on the bike engine will move left to right as you have put the engine at right angles to the normal orination.

[Edited on 27/7/06 by Aboardman]


smart51 - 27/7/06 at 11:26 AM

A bike engine has a gearbox built in. Unbolt the sprocket from the splined output shaft and bolt on a prop shaft adapter. Loads of kit car companies do them. Your prop will bolt on to that. Remember that most kit cars are built for ford props and you will have a reliant. the bolt hols may be in different places.

You will need a longer prop as the car gearbox on a Robin extends to between the front seats and the bike box doesn't.

The output shaft on a robin gearbox is roughly central to the engine (the engine takes up a bit more of the passenger footwell than the drivers side. A bike engie has the output shaft all the way to the right so you will lose most of the passenger's foot well.

Your Robin will weigh about the same with a bike engine fitted but will have 5 times as much power. 0-60 in around 4 seconds and just 1 front wheel


Hellfire - 27/7/06 at 11:39 AM

Must admit, it does sound a bit frightening putting a bike engine into a Reliant Robin

Personally, I'd prefer something with two front wheels.

Phil


gingerprince - 27/7/06 at 11:41 AM

quote:
Originally posted by Hellfire
Personally, I'd prefer something with two front wheels.



The bike it came with only had 1 front wheel


NS Dev - 27/7/06 at 12:11 PM

remember DJ Motorsport's bike engined reliant kitten spaceframe rally car that wiped the floor in clubmans rallying a few years ago, that was awesome!!!

A 450kg rally car certainly opened a few eyes, as well as changing RACMSA regs for ever!!!


nijumaru - 27/7/06 at 09:48 PM

I think I will be putting the engine in the back of the Reliant and putting stabalisers out of the back at a slight angle so it will lift the front end but not majorly (will have to sort out sommat for the suspension for that :p )
ok So I know how the insides of a Bike gearbox works, is this the same for a car plus a reverse or something different?

Only reason I ask is because on a car the Gearstick moves more than just back and forth (gear 1 is top left, 2 is bottom left, 3 is top middle...etc)
where as on a bike it is just Down for first and up the rest.

Any Help appreciated


MikeRJ - 27/7/06 at 10:07 PM

The gearboxes work in a simmilar way, but a bike gearbox has a "selector drum" which is just a cylinder with slotted cams machined into it. These cams move the gear selectors to the correct locations instead of a cars gear lever mechanism. On the end of the drum is a ratchet-like mechanism that allows the gear pedal to turn the cam back or forward one gear position.

Bike gearboxes don't have synchromesh either, they use dog clutches, much like a competition "dog box" would on a car.


Hellfire - 28/7/06 at 08:18 AM

quote:
Originally posted by nijumaru
I think I will be putting the engine in the back of the Reliant and putting stabalisers out of the back at a slight angle so it will lift the front end but not majorly (will have to sort out sommat for the suspension for that :p )
ok So I know how the insides of a Bike gearbox works, is this the same for a car plus a reverse or something different?

Only reason I ask is because on a car the Gearstick moves more than just back and forth (gear 1 is top left, 2 is bottom left, 3 is top middle...etc)
where as on a bike it is just Down for first and up the rest.

Any Help appreciated


It may just be me but this is sounding more frightening with every post. With the engine mounted in the rear, all the weight is gonna be at the back, so every time you squeeze the throttle, the front ends gonna go light. As soon as this happens you lose total control of the steering function and have to come off the throttle to get it back.

Try riding a childs tricycle and you'll see what I'm getting at.

I don't want to sound negative and put you off building your project but have you really thought about how it will handle, even with some form of stabilisers?

Phil


Tangerine Scream - 28/7/06 at 09:17 AM

Didn't they build a Reliant Robin on Scrapheap Challenge with a Cologne V6 in the back?
It displayed the very tendencies that Hellfire described, although admittedly, the idea WAS to build a "wheelie car"!
IMHO trikes are always better the other way around (Grinalls, JZRs, etc)