Gearing

gumpit

gumpit

#1
#1
I may have found an issue with why my trike isn't revving like it should. My jackshaft is bent after going off a jump and bottoming out on the jump with the driven. I thought it just bent the driven so I replaced it. But after jacking it up and running it. I could see the whole jackshaft was making the driven wobble which leads me to believe once the belt dropped in it was getting stuck in high.

Now with my weight I want to gear it lower if it doesn't fix itself when I replace the jackshaft. I have a 54t on the axle. That is as big as I can go. I have a 9t running to it. That is as low as I want to go. There isn't enough meat on an 8t for my liking. On the other side of the jackshaft is a 7" driven.
What I plan on doing is using a TAV with backing plate and then using the sprocket on the tav to go to another sprocket on the jackshaft where the 7" currently sits. Basically adding 2 more sprockets into the mix.

Here is my question. If I run the 54t and 9t what gears would I need to put on the back of the driven on the Tav and on the jackshaft from that sprocket to give me a 7:1. And what sprockets to give me an 8:1 ratio
I am assuming with my current set up I am at 6:1 with the 54t and 9t without the two proposed added sprockets.
 
C

control4userguy

New Member
#2
#2
Very simple. If you want to stick with the existing 9T/54T sprockets and don't want to go 8T on anything then that narrows it down to just one location- the input side of the countershaft.
(IN/OUT)
10T/9T= 6.7:1
11T/9T= 7.3:1
12T/9T= 8.0:1
 
gumpit

gumpit

#3
#3
So on the opposite side of the 9t is where I use 10/11 or 12t... Do I use the same 10/11 or 12 on the back side of the driven going down to that? So I would buy a pair.
 
pomfish

pomfish

Well-Known Member
#4
#4
Use this calculator;
AGK - Gear Ratio Calculator - Affordable Go Karts

If you are running a #35 chain the TAV output gear could be a 13 tooth, now plug that into the calculator and if you used a 15 tooth on the input side of the jackshaft with your existing 9/54 gearing you would be at 6.923. Close enough to 7 for government work:)
Go to 17 tooth input and result is 7.846

Play around with various numbers and see what you like.
Your engine is going to have to spin harder/higher so take that into the equation as well.
Good luck and have fun!
Later,
Keith
 
FirePowerMinis

FirePowerMinis

Active Member
#5
#5
My mass tends to screw up the power/weight ratio too :) More power is always the answer.
I'd get it back to smoothly functioning first.
Next, see how the clutch is shifting. Getting it to hold a lower gear may be easier than the Rube Goldberg deal.
Is the engine big enough? Torque-increasing mods are common and typically reap big rewards.
If you can move the engine, to "shorten" the belt, it will make it engage at a shorter CVT ratio, giving more snap. We do that on the golf carts.
 
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C

control4userguy

New Member
#6
#6
gumpit said:
So on the opposite side of the 9t is where I use 10/11 or 12t... Do I use the same 10/11 or 12 on the back side of the driven going down to that? So I would buy a pair.
Click to expand...
This is how it would flow if you were to utilize a torque converter:

Driven/Counter-IN/Counter-OUT/Wheel Sprocket
9T/12T/9T/54T= 8:1

That's one combination, Post #4 is another. Neither will get you any kind of top speed you may be missing with an arrangement like this...
 
gumpit

gumpit

#8
#8
18.5 inch golf cart tires...35 chain is not an option. That is for girly men who like their chainds popping off...lol
Motor has the power and I am sure once I replace the bent jackshaft the clutches will function fine if they are not already. This is for the Oval track and TT course race track where I need the torque coming out of the corners. I am racing guys half my weight... Adding the extra sprockets will allow me to swap them easily and be able to change gearing depending on different races... I will keep my stock trike alone for comparison and if I need top speed.
 
pomfish

pomfish

Well-Known Member
#9
#9
If you are only running the 35 chain from the Tav to the jackshaft it should not be a concern as long as you use good chain.
The go cart guys run more power than you are with #35 no problem. They are only running a short chain so it is feasible.

Of course you need to run heavy chain to the rear sprocket.

The advantage of #35 is when you quick change the sprockets you may be able to not have to change the chain length if you have enough engine adjustment available.
 
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gumpit

gumpit

#10
#10
When the Tav is on the chain length to the jackshaft won't be too long. I am hoping I can come up with 2 sets of gearing that I can change in and out that will also work with 2 sets of chains that are the right lengths. So when I change the sprockets I can change the chain. With the 40/41 it is a lot more forgiving if it is a little loose and doesn't come off like the 35 chain does on bumpy terrain.
 
pomfish

pomfish

Well-Known Member
#11
#11
I got ya. Yeah you're right bigger teeth, less chance of derail.
Good idea with the pre made chain.
What size jack shaft do you run, 3/4" ?

Those hopped up 3 wheeler's do look like fun. Wish you guys raced closer to me, would love to check it out.
Later,
Keith
 
gumpit

gumpit

#14
#14
My particular trike was set up for a 5/8" jackshaft from the factory.The clearance to the backbone won't allow a 3/4" without modification. The 5/8" is plenty strong and at the speed I hit the jump it would have bent a 3/4" one too I think.
 
gumpit

gumpit

#16
#16
They werent really made for jumps. There was an option for the race. Go over the pallet jump or weave in and out of the tires. I was afraid that if I was full speed going over the tires that I would have gotten my wheel tangled up in one...So I went the jump route...lol
 
gumpit

gumpit

#18
#18
Ok. I am going to set it up for 6.667 and use a backup set up for 7.333.. With the TAV I am losing my 7" driven and going to a 6"... We will see how this works when I get the gears.But I'll get to use the cover...
 
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