What is the difference between a spool and diff?

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eddywatson

T3ddy B4gW3LL
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Stockton on Tees, England
Arrma RC's
  1. Typhon 6s
Hey guys
What is the difference between a spool and diff?

to me they look the same (also I’m referring to the center one)

what is the pros and cons of each? I’m running my Typhon on 25T pinion and stock spur (which I believe is 50T) I’m trying to get to 100mph and people have been suggesting installing an arrma limitless spool. I live in England and it’s really hard to find one. So I wanted to look into it first
Thanks for your time
 
A spool is... well, not a differential.
It's locked. Both outputs turn at the same speed. You can turn a diff into a spool temporarily or permanently (just stick something thick enough in there).
 
A diff will allow one side to get more power than the other. A locked spool is a solid axle and will give equal power to both sides.

In a front or rear of a car you normally want a diff to be able to turn easily. If you lock the F/R diffs, turning will suck.

But in the center, if you’re just bashing or speed running, locking with a spool is generally OK. If you were track racing you would want to be able to dial your diff in the center to your driving style. It allows you to let the front tire get more of the power at times.
 
Same principle in a 1:1 drag car, you want a spool on the track, but if that same car sees street duty, you want a limited slip diff so you can make turns.
 
So would this gear fit onto tho spool kit? And simply just slip into place on a typhon v5?

A826F2DE-6042-4910-B3A9-4334BC2B5B45.jpeg


C8968B05-D6DF-4A65-B89B-22604DCC26CC.png
 
So would this gear fit onto tho spool kit? And simply just slip into place on a typhon v5?

View attachment 158465

View attachment 158466
Yes it will fit. But there's more to it than will it fit. Will your motor overheat? Maybe. Will you lose control because it's way faster, likely. You need to understand the way gearing works and the limits of the stock motor mount. And beyond that what these changes do to your car. Does your radio have enough range? Do you have a safe place to open it up? So many pieces to this puzzle.

Basically what I am trying to teach you is to take this slowly and learn as you go. Jumping from a 50T spur to a 34T spool is a freaking huge jump. I would go to a 46T spur on your diff and work from there. You can also get a 40T spur for the diff as well. If all of that works well, then consider getting a spool and buy some various gears for it. I would get a 39T, 34T, and 29T.

At each step down on your spur size, you may need to step up your pinion sizes too. The motor mount requires a very specific range of gears. Too many teeth and you won't be able to slide the motor close enough for the bolts to be inserted into the motor plate. Too little teeth and the motor won't be able to get close enough for the gears to touch.
 
Yes it will fit. But there's more to it than will it fit. Will your motor overheat? Maybe. Will you lose control because it's way faster, likely. You need to understand the way gearing works and the limits of the stock motor mount. And beyond that what these changes do to your car. Does your radio have enough range? Do you have a safe place to open it up? So many pieces to this puzzle.

Basically what I am trying to teach you is to take this slowly and learn as you go. Jumping from a 50T spur to a 34T spool is a freaking huge jump. I would go to a 46T spur on your diff and work from there. You can also get a 40T spur for the diff as well. If all of that works well, then consider getting a spool and buy some various gears for it. I would get a 39T, 34T, and 29T.

At each step down on your spur size, you may need to step up your pinion sizes too. The motor mount requires a very specific range of gears. Too many teeth and you won't be able to slide the motor close enough for the bolts to be inserted into the motor plate. Too little teeth and the motor won't be able to get close enough for the gears to touch.
Thanks for the info!
I live in England and it’s really hard to find arrma drive train products. I have no problems with going from 50T spur to 46T… I am new to all of this and I am still learning and trying to understand gearing/pinions/Spurs/diff/spool etc lol
 
Thanks for the info!
I live in England and it’s really hard to find arrma drive train products. I have no problems with going from 50T spur to 46T… I am new to all of this and I am still learning and trying to understand gearing/pinions/Spurs/diff/spool etc lol
No problem. Take your time.
 
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