I some a questions concerning changing the gear ratios in the internal transmission. First of all, are different gear sets readily available and how difficult is it to change gears? Also, can the gears already in the transmission be put in a different position. For example, could first gear be put where second gear is and second gear where third gear is and so on? This may seem like a silly question but I am using a CBR 600 engine and transmission for a custom car and I'm looking for some way of having first gear not be below nuetral. Thanks for any advice.

 

What kinda car? and will a 600 engine be able to pull a car?

 

Its a custom formula style car for an engineering competition, check out fsae.com . The cars weigh anywhere between 300-800lbs. The CBR engine will have no problem pushing the little car around, they are really quite fast.

 

Those look like some fun cars

 

Sounds like there will be a need to have a lot of thought that goes into the linkage system or just gear it very low and remove first so it'll be n-2-3-4-5-6, use a gear indicator and a neutral alarm so you dont accidentally overrev in N? Maybe someone has an idea how to just lockout first and neutral and then just use the clutch as neutral. Since I know nothing about bike transmissions you should probably forget everything I just wrote.

 

haha, thanks for that.
We had planned to do what you said, just lock out first and nuetral, and it is possible but not ideal because the sprocket sizes that we would be forced to use dont fit all that well in our frame. If we could have first gear be swaped into the original 2nd gear position that would solve alot of problems for us.

 

The way you stated your problem it seemed like the sequence of the gears was greatest concern, not the torque multiplication problem. Seems like you are creating more problems, use the motor and box as manufactured and work aroung the problems of steering, clutch...

Remember the old engineering adage, KISS- Keep it simple stupid. I've been an engineer (aerospace)for 20+ years and you sound like you have enough work ahead of you then trying to re-engineer a relatively flawless system.

good luck.

 

Sorry if i sounded like an jerk, I very much respect your opinion. However I know that we will not be using the motor and trans as is, it is a very good package but is optimized for a bike not a car. The motor will be opened up to install a dry sump oiling system and various other things. In my opinion it would be much simpler to swap some gears in the transmission rather than designing a shifting and a chain drive system to work around the strange gear pattern. If in fact it is really hard to swap internal gear ratios then we'll have to figure something else out.
*our real problem is that if we were just going to lower our final sprocket ration then we would have a drive sprocket less than 2 inches in diameter. The CBR drive splines will barely fit in a sprocket this small and we would probably have problems with our chain popping off.

 

Lets talk gear ratios. As is, my F4i will go about 72mph in first gear about 100 in second (other people have more accurate numbers I am sure). The tire height is about 23 inches. If you have a small spocket, you probably have a small wheel. With stock gearing using a tiny wheel you will havealot of torque, with a smallrear sprocket, you willhave tremendous torque multiplication, you may need TALLER gears rather than shorter. you may top out at 50 MPH.

This is where I would start out, set up an algorith that allows your variables.

gearing in the tranny (1 thru 6)
Sprocket ratios
Tire sizes
Revs


to spit out MPH in any gear

Find out what track you will be on and look at g's you can expect from the rubber you would use and translate that to speeds and see where you are before you talk about internal tranny mods.

The gear pattern works. You will learn it in 3 minutes. Think of it like a 'slapstick' on a 727 torqueflight transmission in an early 70s chrysler musclecar. You may not even need 1st gear at all.

good luck.

 

I'm very confused, a 2 in sprocket? Let me start by saying I've been on a FSAE team, and you will need a larger sprocket if anything. Your motor with the restrictor plate on it won't make near the power of a stock unit and you will want much shorter gears depending on your tire size. For our shifter we just used hydraulics and just used 2 buttons on the steering wheel to shift up and down. Why not go check out all the other cars at competition?