[DAN400ex]

Anyone know the stock front and rear sprocket numbers on an 08 400ex, along with the stock governed top end RPM? I'd like go up one tooth size on my front sprocket to make it go faster after the mods I just put on, hopefully they will compensate for the loss of torque, anybody got anything on that?

 

[400exrider15]

14 front 39 rear for 05 and up. 15 front 38 rear is 99 to 04. I upgraded to the stock 05 and up gearing on my 04 400ex. i needed a bit more bottom end. If you bump that front up, its equal to 2 rear teeth. just remember that....

 

[jgar]

I think 1 in the front is = to 3 in the rear.

 

[DAN400ex]

400exrider15, just out of curiosity why did you go down a tooth size. I don't know a hole lot about gearing and how sprockets can improve performance. My cave man understanding is limited to if you go up a tooth on the front sprocket you'll gain speed but lose some torque/acceleration but if you go down a tooth you'll gain acceleration/torque but lose speed. And I don't know anything about the rear sprocket. Does that sound about right or am I all kinds of screwed up?

 

[Redracer]

400exrider15, just out of curiosity why did you go down a tooth size. I don't know a hole lot about gearing and how sprockets can improve performance. My cave man understanding is limited to if you go up a tooth on the front sprocket you'll gain speed but lose some torque/acceleration but if you go down a tooth you'll gain acceleration/torque but lose speed. And I don't know anything about the rear sprocket. Does that sound about right or am I all kinds of screwed up?

You are kinda correct. Going up on the front sprocket is going to add top speed but you will lose some acceleration. Going down on the rear sprocket does the same thing as going up on the front.

Going down on the front sprocket you will gain acceleration but lose top speed, the same as if you went bigger on the rear sprocket.

The gear ratio is 2.8 (rounded up from 2.795)

Just to make things easier to understand, let's say your gear ratio was 3.0, that would mean changing 1 tooth up front would be the same as changing 3 teeth in the back. Does that make sense?

 

[DAN400ex]

400exrider15, just out of curiosity why did you go down a tooth size. I don't know a hole lot about gearing and how sprockets can improve performance. My cave man understanding is limited to if you go up a tooth on the front sprocket you'll gain speed but lose some torque/acceleration but if you go down a tooth you'll gain acceleration/torque but lose speed. And I don't know anything about the rear sprocket. Does that sound about right or am I all kinds of screwed up?

You are kinda correct. Going up on the front sprocket is going to add top speed but you will lose some acceleration. Going down on the rear sprocket does the same thing as going up on the front.

Going down on the front sprocket you will gain acceleration but lose top speed, the same as if you went bigger on the rear sprocket.

The gear ratio is 2.8 (rounded up from 2.795)

Just to make things easier to understand, let's say your gear ratio was 3.0, that would mean changing 1 tooth up front would be the same as changing 3 teeth in the back. Does that make sense?

Great info! Thank you!

 

[Redracer]

you're welcome

 

[John3]

Tire size to gear size?

It's all about the moment arm of the gear (I derive most of my knowledge from aviation), so basically the front gear is the drive gear, the smaller it is the more torque you get directly from your engine. The rear gear is the shaft gear. The larger it is (the more teeth) the easier it is for the engine to move the shaft which is directly connected to your wheels. hopefully that helps everyone understand how it works, just gotta think about it.

My question is, I have 22x11x9 inch tires as apposed to the stock 20x10x9 ones. Is it safe to go down teeth on the front sprocket? I don't want to break any teeth off, at the same time I do have a limited amount of space between my skid plate and rear gear, (i doubt that i'd be adding that many teeth anyways)

Thanks

 

[Bunkers101]

Don't wanna steal the post or anything, but if 1 tooth is = to 3 on the rear, could you change let's say a 39t rear sprocket to a 36 and it would be the same as going from 14 to a 15 on the front>?

 

[johnbanghart]

this thread is super old bud dont think any ones gonna answer might as well start a new thread or keep searchen