5 replies to this topic

[useless]

Hi, Please if anybody can help please do!!

I drag race my 1380 mini and i'm going to change the gears/gearbox in order a to get better acceleration up the strip!
I'm using a standard set at the mo thats why i'm changing!

Now, i have ben told to get stright cut close ratio gears and use a 3.7 c/w Thats fine in it's self but when i investegate further i have found that there are many gear kits avalible to use! some with tall 1st gears and some that supply only the 2nd 3rd and 4th clubman i belive it's called, but what will be best at getting the best time over the 1/4 mile??

I know it's best to stay in 3rd gear over the line as this will eliminate the time taken to change gear, thats fine a 3.7 should be ok for that but i dont want to lose time on the start because of the tall 1st gear!

Can anybody point me in the right direction please?

Would using the culbman set (just the 2 3 4 gears) be best as i keep my 1st gear which is fantastic at getting off the line, or will they affect what my 1st gear gets off the line like if i fit them?

Many many many many thanks

Useless!!

[Jimmyarm]

1st gear in a Mini is already straight cut, which is why you get 2,3,4th only in the sets. I believe the tall 1st gears are meant for track racing where you rolling start ?

Guessworks is your man when it comes to gearboxes and there is a calculator somewhere on the site that gives you speeds based on the diff and the gear ratios.

I believe you need to use a dyno print out as well to match the gears to the shift points for your engine (so you are at the right speed against power for each shift and get the most out of the gearing)

Edited by Jimmyarm, 06 March 2007 - 03:05 PM.

[useless]

1st gear in a Mini is already straight cut, which is why you get 2,3,4th only in the sets. I believe the tall 1st gears are meant for track racing where you rolling start ?

Guessworks is your man when it comes to gearboxes and there is a calculator somewhere on the site that gives you speeds based on the diff and the gear ratios.

I believe you need to use a dyno print out as well to match the gears to the shift points for your engine (so you are at the right speed against power for each shift and get the most out of the gearing)

That makes sence! not god for drag racing, and the dyno i'm not going to be able to do as i am needing to get it all done at once the engine mods and the gear box too, hummm! thanks for your help! i am in a bit of a pickle!! oh dear! can you recomend a set to use without seeing my dyno sheet?

Thanks

[Jimmyarm]

Guessworks will have an idea of what to use

An idea of the engine spec will help as well

[The Matt]

Guessworks' link:

HERE

Very handy, takes tyre size into account and FD ratio for different gear kits. I have an SCCR kit, a tran-X one, assembled into my 'box by Guessworks, did a VERY good job of it too. I should be hitting 40-45 in first when I'm caning it, but it aint gonna be super rapid off the line. with a 3.7:1 diff............ play around with the calculator and have a look

[Sprocket]

Look for a GT or Cooper s close ratio gear set. There is a conversion kit available from minispares for just this. Straight cut gears, while releasing that little bit more absorbed power, are not 100% required. It all comes down to what you realy want, Every last bit of power, or cheap and reliable at the same time.

As for the final drive, there are many factors to take into consideration to choose the right one for drag racing. It depends on the output of your engine and the weight of the car. If you cross the line with another gear or loads of revs left then the final drive is too long. Cross the line in fourth with the engine redlining half way down the track and the FD is Too short.

The other aspect of drag racing takes into consideration the Max torque at the wheels in all the gears, the shift point is chosen to drop the least torque at the wheels when going from one gear to the other.

That is the secret of drag racing. Well that and lightning reaction times.