Author Topic: Possibly stupid question. Sprockets/jacksgaft/etc  (Read 4053 times)

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Offline BuiltTough

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Possibly stupid question. Sprockets/jacksgaft/etc
« on: April 10, 2018, 02:10:43 am »
Ok, this is probably a stupid question for those in the know, but, I, am not in the know.

I’ve looked at so many builds now my eyes are starting to bleed. Some builds use a transaxle, some builds use a relocated transaxle and a live axle, and some use a RAGB  and a live axlet.

On the builds that use a live axle, they have them chain driven, with small sprocket on the transaxle/gearbox and a large sprocket on the live axle.

Doesn’t this somehow counter the ratio being established by having a big pulley on the engine and small pulley on the trans/GB? Or is there something else gained that I’m missing with the sprocket ratio?

Again I’m sorry if this is obvious to some. Right now I’m in planning mode, and want to have a good idea of what direction I’m going in once I get to have a solid look at my donor chassis.

Offline PJG56

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Re: Possibly stupid question. Sprockets/jacksgaft/etc
« Reply #1 on: April 10, 2018, 08:20:16 am »
Lets say you run a 700 peerless trans to live axle and run the 700 in 3rd(with 25/25 gearset in trans).
the out put ratio@ trans out put is 3-1 in trans,so if you use 8"engine pulley and 4"trans pulley(for example) you will have an input ratio @.5 -1 (,5 intput x3 output=1.5 final output ratio @trans) so if you want a final ratio @rear wheels of 6-1 you will divide 6-1 by 1.5-1 =4-1 rear axle ratio (example 12 teeth trans 48 rear sprocket =4-1)

Hope this nelps
Paul Guptill  (oppy) #238modX
2012 slmra mowstock champion(builder/owner)

2013 slmra mowdified champion(builder/owner)
2013 ARMA national champion Mod-X(builder/owner)
2014 ARMA national champion Mod-X(builder/owner)
2014 All American Champion Mod-X/CP(builder/owner)
2014All American Champion FXT (engine builder)
2014 All American 2nd place SP(builder/owner)
2015 All American 2nd place BP (builder/owner)
2016 OutlawTriple Crown FXT Champion (engine builder)

Offline BuiltTough

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Re: Possibly stupid question. Sprockets/jacksgaft/etc
« Reply #2 on: April 10, 2018, 03:19:04 pm »
I guess I’m still a bit confused, why would we go through the process of increasing our ratio on the pulley drive only to reduce it back down on the chain drive? Seems like wasted energy. In my mind, if you would normally just swap pulleys with the transaxle in its original position, wouldn’t it seem logical (at least to me) that when you simply move the transaxle and use the live shaft to go with a 1:1 ratio from the trans to the axle?

Like I said, unless I’m missing some benefit of reducing the ratio back down...

Offline Eatondirt

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Re: Possibly stupid question. Sprockets/jacksgaft/etc
« Reply #3 on: April 10, 2018, 09:37:41 pm »
It's always best to overdrive an 700 transmission.  Increases durability and reliability.
Casey Eaton
Big Dog Mower Racing

 

anything