8tooth vs 9tooth drivers gearing

[99summitx]

I swaped out stock 9 tooth drivers for 8 tooth extro's to fit 2" track height in s-chassis, will gearing have to be changed? Went from 136" to 144'' with 8" wheels.

 

[SLEDBUNNYRACING]

Send a PM to summitric on this if he doesn't post. He's been down this road and knows a ton about the gearing.

I swaped out stock 9 tooth drivers for 8 tooth extro's to fit 2" track height in s-chassis, will gearing have to be changed? Went from 136" to 144'' with 8" wheels.

 

[rmk800]

by dropping one tooth size is about a 10% drop in gear ratio, so i would say you wouldn't have to change gears

 

[Summitric]

by dropping one tooth size is about a 10% drop in gear ratio, so i would say you wouldn't have to change gears

UNLESS THE GEARS WERE ALREADY DROPPED A TOOTH!!!???

 

[99summitx]

Thanks Guys, looks like be able to try it out real soon and see what happens.

 

[Summitric]

Good Luck, And Let Us Know How It Turns Out!!!! Which Way Did You End Up Going??? Gears Or Not, And Are Yours The Stock Gears??? Or Was It Already Geared Down A Tooth??

 

[99summitx]

As far as I know they are the stock gears, Planning an Quartz creek trip for Oct 26-27 if the weather gods keep it up, I'll let you know how just the 8 tooth drivers work out.

 

[Summitric]

As far as I know they are the stock gears, Planning an Quartz creek trip for Oct 26-27 if the weather gods keep it up, I'll let you know how just the 8 tooth drivers work out.

IF IT'S STOCK GEARS YOU'LL DOO JUST FINE WITH THE 8TOOTHS..... HERE' MY LITTLE BABY

 

[Dynamo^Joe]

8th/9th=.89
In theory with the lower tooth you have dropped near the equivalent of 2 teeth.
...about 11 mph track speed loss at 1:1 ratio @ 100mph.

Whatever high mph you previously had or can achieve, for lack of better numbers... IF 80mph, THEN 80mph * (.89)=71mph

If you had 21:43 then 2.04 ratio.
2.04/.89=2.29 ratio

43gear / 2.29 ratio = 18.77 top tooth.

You have dropped the equivalent of 2 top teeth [and $ change]

 

[99summitx]

So that should mean with the longer track and deeper paddles causing more resistance the loss of top speed should result in better low end to make up for the resistance...Right?... Wrong? I just want to get up that mountain!!!

 

[SLEDBUNNYRACING]

Your not quite right there 99summitx, you need to maintain track speed to keep climbing. If your track slows down then you climb less. You will have to change the gear ratio to pick up the lost track speed.
43gear / 2.29 ratio = 18.77 top tooth as per Dynamo^Joe and I think he's correct.

So that should mean with the longer track and deeper paddles causing more resistance the loss of top speed should result in better low end to make up for the resistance...Right?... Wrong? I just want to get up that mountain!!!

 

[99summitx]

Bugger!!
But thanks

 

[SLEDBUNNYRACING]

It's not a big deal to change gears, you will be surprised how much it wakes the sled up.

Bugger!!
But thanks

 

[flatlandguy]

Re 8 tooth
I think that with the addition of track you will be using your horsepower more (less track slip) so your clutch will open up less. you will get the effect of more power with the lower gear ratio, I would try it as it is first then if you think you have some power to spare for more track speed go for the gear change.