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Old 04-18-2019, 08:21 PM
jboling jboling is offline
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Default Drive train issues 196cc with 30 series

Okay I am new to the forum here, I have a new to us kart that came to me in pieces... Has a 196cc clone motor with a 30 series converter. Has a 10 tooth drive sprocket and a 60 tooth axle sprocket, 19" tires. Issue we have been having since we got the kart back together is it is really struggling getting up to any sort of speed, barely climbing a small hill on flat ground. Belt gets super hot and never picks up enough rpm to expand or contract the clutches at all. When the kart is on jacks the torq converter works like it should. Kart rolls a little rough with the chain installed. Without chain on it rolls perfectly. I am starting to suspect a chain or sprocket pitch issue... I am thinking maybe the pitch is slightly different on the drive sprocket then the axle sprocket causing some binding under power.

Anyone have any thoughts on this? Just to be clear this is a brand new torq converter ( Replaced when we started having issues ), the driven and drive pulleys are aligned and the chain is aligned sprocket to sprocket. I used my calipers to measure the pitch of the axle sprocket from tooth to tooth and it does seem to be slightly different than sprocket behind the driven pulley going tooth to tooth. Chain does seem to fit both though.... Any one with some more experience than us have any information on this?

Thanks!
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Old 04-19-2019, 05:45 AM
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Gear ratio is too high with 19" tires. How much does the machine weigh?
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Old 04-19-2019, 09:25 AM
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I am not sure on the weight, I have a Spiderbox Yerf Dog and I am sure it weighs more than that machine.

What would an ideal gear ratio be after the torq converter? This machine will be used in the hills, but some speed would be nice. It came to us with the current setup....
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Old 04-19-2019, 09:55 AM
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I'd probably go 80-85ish teeth on the axle. Maybe more depending on how big of hills you want to climb.
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Old 04-19-2019, 10:41 AM
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^^ that!

85 Teeth or more are a reasonable assumption,
in order to get you a closer to perfect suggestion we'd need to know the weight of the kart (with all passengers seated that is!)
say 200lbs per adult for example makes a huge difference

But with 750lbs or less 85 teeth are a good idea
with 650 lbs or less 80T might do the trick

the more torque you want (need), the more teeth your axle sprocket needs.

ALSO: make sure you have the CORRECT belt installed on your series 30 TC
A cheap v-belt won't do anything for you.. it'll just fail miserably.
a worn belt (even if correct) may fail as well at the slightest inclination to climb.

So post a pic of your Torque converter and we tell you if you need a new belt.

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Old 04-20-2019, 09:20 AM
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Could I accomplish the same thing by changing the sprocket on the torq converter? I suppose since I am already running a 10 tooth there are not allot of options. Curious because the 60 tooth on the axle seems hug already, if I went to an 80 it would really be close to the ground. I will see if I can get a weight measurement off it today. I guess I could just put a scale under each tire then add that up?

---------- Post added at 08:08 AM ---------- Previous post was at 07:54 AM ----------

Okay I put a scale under each wheel and added that up, got 475 pounds with no rider. I would like to gear it to carry 2 adult riders. So maybe 170 pounds a piece, total weight with riders would be 815 pounds.

---------- Post added at 08:20 AM ---------- Previous post was at 08:08 AM ----------

How come my other kart, Yerf Dog Spiderbox, does so well with a gear ratio in the 4's and this one has trouble at 7:1? Is there a different clutch setup I should be looking at? I mean I understand the RPM ranges are way different, but there must be some major differences in the torq converter as well. Now I am running the 30 series 6" driven clutch, would a 7" driven make a big difference?
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Old 04-20-2019, 12:43 PM
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The TAV combination you have now should provide 2.68:1 multiplication at engagement. Your gear ratio is 60 10 = 6:1, so your total gear reduction for takeoff is 2.68 6.00 = 16.1:1. I think that should be working better than you're seeing.

A photo or three of your setup would be helpful.
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Old 04-21-2019, 03:08 AM
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KartInfo by kartcalc.net:
Code:

KART
RW diameter: 48.26 cm | 19 in Total weight: 369.68 kg | 815 lbs
ENGINE
Original HP: 6.5 Asummed HP: ~6.5 Torque: 12.86 Nm | 9.48 ft lbf RPM: 3600
TRANSMISSION
Final ratio: 6:1 TC type: series 30 6" driven Lowest ratio: 16.2:1 Highest ratio: 5.4:1
PERFORMANCE
Max Wheel Torque: 208.33 Nm | 153.66 ft lbf Min Wheel Torque: 69.44 Nm | 51.22 ft lbf Top Speed: 60.65 km/h | 37.68 mph
PROBLEMS
Min-Torque not sufficient! Min Wheel Torque needed: 89.2 Nm | 65.79 ft lbf Gear ratio too high! Suggested final ratio: at least 8.8:1 You might burn your clutch/belt!
NOPE! 6:1 is not going to work

with that weight we talk 88T axle sprocket
assuming half inch chain pitch (#40 #41 or better 420)
that'd be a 14.3" diameter sprocket

2.5" of clearance

If you feel that's not enough I'm afraid a secondary jackshaft is the best way to go.

keeping the two sprockets you have (10 TC 60 axle)

You can install a 19T JS in and a 13T JS out resulting in 8.77:1 overall chain ratio
and that should work with the weight

KartInfo by kartcalc.net:
Code:

KART
RW diameter: 48.26 cm | 19 in Total weight: 369.68 kg | 815 lbs
ENGINE
Original HP: 6.5 Asummed HP: ~6.5 Torque: 12.86 Nm | 9.48 ft lbf RPM: 3600
TRANSMISSION
Final ratio: 8.77:1 TC type: series 30 6" driven Lowest ratio: 23.68:1 Highest ratio: 7.89:1
PERFORMANCE
Max Wheel Torque: 304.52 Nm | 224.6 ft lbf Min Wheel Torque: 101.47 Nm | 74.84 ft lbf Top Speed: 41.51 km/h | 25.79 mph

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  #9  
Old 04-23-2019, 08:10 AM
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Is there a better motor / clutch combination that I could use that would get the job done without a jackshaft? Also I am pretty sure they make a 9 tooth for the torq converter, where would that put me for the size of the axle sprocket?

By the way thank you for all the help on this! My son is looking forward to getting it going.
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Old 04-23-2019, 08:46 AM
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8.78 times nine -> 79 Tooth axle sprocket

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Old 04-24-2019, 08:38 AM
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Okay I found an 80 tooth sprocket for the axle and I am waiting for an email back to see what the diameter is, that way I can determine if there is enough ground clearance to run an 80 tooth on the axle and a 9 tooth on the torque converter.

Question: If I run the 7" driven pulley for the torque converter how much does that help me out in gearing?
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Old 04-24-2019, 09:01 AM
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#35- 9.77"od
#40/41- 13.03 od
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