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Old 08-31-2010, 06:26 PM
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Default Adjusting The Driven Pulley Tension

I have decided that the low gear ratio that my kart has is making my TAV2 overheat. It shifts to high gear perfectly when cold, and slowly, as it gets too hot, shifts later and later during acceleration until it stops shifting all together. Let the kart sit and it will shift perfectly again. I get about 25 minutes of hard driving until the problem occurs.

I know that there are 3 settings on the driven pulley. The most tension will keep the driven pulley large for a longer period of time during acceleration, thereby reducing the strain on the drive pulley effectively eliminating the problem that my rear sprocket may be too small. This is my assumption, and I believe it makes a lot of sense.

I am looking for hints on how to easily accomplish adding more tension to the driven pulley. I have noticed the 3 holes on the pulley and know that the factory setting is #2 hole(where it is now).

How do I change the setting to the highest tension? Are there any special tools needed other than a snap ring removal tool?
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Old 08-31-2010, 06:35 PM
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Nope, just some snap ring pliers and some muscle. Your final gear ratio may be too high causing the TC unit to work too hard.
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Old 08-31-2010, 07:31 PM
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Okay. Lets start with the basics. We need your rear tire diameter, gear ratios, and engine size, please. Redsox may be right. Too LOW a ratio certainly isn't going to cause any issues with the CVT.
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Old 09-01-2010, 09:10 AM
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Quote:
Originally Posted by toystory_4wd View Post
Okay. Lets start with the basics. We need your rear tire diameter, gear ratios, and engine size, please. Redsox may be right. Too LOW a ratio certainly isn't going to cause any issues with the CVT.

Tire size is 18X9.5-8, 10 tooth front sprocket and 40 tooth rear with a #40 chain, EX27 Robin motor with 9.0 hp.

CVT? Not sure what that is...?
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Old 09-01-2010, 09:18 AM
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what type of torque converter (Continuously Variable Transmission= cvt or tc) do you have? max torque? comet 20, 30, 40 series? gtc? i think no-matter what tc you have your ratio is too high, if thats the problem idk but it is a problem, describe the type of kart you have or give the weight of the kart
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Old 09-01-2010, 09:38 AM
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Quote:
Originally Posted by r97 View Post
what type of torque converter (Continuously Variable Transmission= cvt or tc) do you have? max torque? comet 20, 30, 40 series? gtc? i think no-matter what tc you have your ratio is too high, if thats the problem idk but it is a problem, describe the type of kart you have or give the weight of the kart
Ah, thanks. This is the one.

http://gokartsusa.com/tav301bore4041chain.aspx

Not sure what the kart weighs, but it is a Manco. I have been writing about it in the thread "is my shaft too long?" that I know you have been reading and replying to. Thanks, BTW! I started this new thread to ask the adjustment question. I'm thinking that should help, no? I definately want to try it before regearing, but still am not sure how to do it...
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Old 09-01-2010, 09:48 AM
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it would decrease your shifting speed so you would sty in low gear longer, sry about not recognizing you the ex27 was familiar but i help/comment on alot of threads here.
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Old 09-01-2010, 09:56 AM
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Quote:
Originally Posted by r97 View Post
it would decrease your shifting speed so you would sty in low gear longer, sry about not recognizing you the ex27 was familiar but i help/comment on alot of threads here.
No prob. So maybe go the other way on the adjustment? I want it to shift faster but not overheat. Wouldn't the front pulley shift sooner with tighter rear pulley tension?
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Old 09-01-2010, 09:57 AM
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here is your current low range, http://gokartguru.com/engineering_tool_kit.php
here is your current high range
http://gokartguru.com/engineering_tool_kit.php

fiddle with the calculator a bit i would suggest gearing it to 40mph so you can hit about 38 with decent torque.

EDIT: with you current ratio you should look into shifting later to allow more power, how is your acceleration, do you spin the tires? top speed? where do you ride (terrain, ie hilly asphalt, ect)
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Old 09-01-2010, 10:08 AM
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Kart was doing 40mph with the stock EX17 engine. Took on this project to go 55-60mph which it does now. Acceleration and power are all very good. Will spin tires and drift on wet grass/dirt. I am very happy with how it is performing right now with settings as is, but am afraid the TC is overheating. Mostly driven on flat, but do have some hills in my backyard...

Thanks for that link. Lot's of info there!
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Old 09-01-2010, 10:37 AM
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hmmmm where is blakowzie(sry if i mis-spelled your user name)
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Old 09-01-2010, 01:04 PM
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Quote:
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hmmmm where is blakowzie(sry if i mis-spelled your user name)
Yeah, where is good ol' Blaz?????????? I think we need your opinion here plz.
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Old 09-01-2010, 01:39 PM
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have you been using the dry lube for the driver? mine eats the belts, but i don't use lube. your tension looks right, which pulley is overheating? if driver, the garters may be too stiff, if driven, are you running the green spring? there are three (colored for tension) springs for the driven, but i want to say only one color/weight for driver. if it is dusty where you ride, the dust can get in the driver hindering ratio change. the dust will get on the driven bushing gunmming the bushing.
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Old 09-01-2010, 02:21 PM
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Not sure which pulley is overheating. The driver gets too hot to touch...

Have not lubed anything. TC is brand new with less than 10 hours on it.

Just put a new belt on it and shifted great for 10 minutes. Then slowly started to decrease shifting ability and speed. Belt did not seem too hot, but drive pulley very hot.

It is dusty, but not that bad.

I really want to try the driven pulley tension adjustment but still do not know how to do it...
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Old 09-01-2010, 02:38 PM
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your kart looks muddy! lube the clutch! get the cover!
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Old 09-01-2010, 02:52 PM
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adjusting the driven is easy. remove the steel clip that holds the outer cam half onto the shaft. remove the outer cam slowly. it is 'keyed' to the body of the driven. it is also under tension. you do not have to remove the outer cam all the way, but it helps. hmm, found this, hope it helps. http://www.diygokarts.com/vb/showthread.php?p=19866 post #6 has some links
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Old 09-01-2010, 11:35 PM
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First I'd check to see if the drive clutch has lubrication on the inner angle of the cover on the drive clutch. Check with GTC to see what sort of lubrication they offer and what specific suggestions they as the company who is offering these clutches which they claim perform to the same quality or in their test even better. Is your engine 3/4" or 1"? If its 1" the clutch claims ability to operate at 13hp very easily though Comet never claimed it could operate past 8hp in any boxes I saw.

If the heat is entirely in the drive clutch this may be an issue of overloading on cheap springs, I havn't even seen one of their clutches to judge in any manner. A larger assembly assuming this is 1" may be able to handle what you attempting much better than this one, but possibly it would do the exact same thing and you'd have just spent another 300+ dollars to hear the sad story that you just can't work with this.

My final point is that changing engagement does not change the gear ratio, karts like this were never designed for the speed you are attempting to reach, switch the drive sprocket back to 54 and see what it does.... it it stops overheating then you know you have an absolute answer. Can you give me a solid reason you desire to attain this speed in a kart which was not designed for anything over 35? The steering is all stamped, the wheels are not balanced, all the tires are NHS, this just seems scary to me. If you do in the long run desire to attain these speeds in a kart build a buggy from scratch using a powerplant similar to this, the money does not need to go to waste, you can use the same axle but many changes need to be made for safety.
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Old 09-02-2010, 09:04 AM
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Quote:
Originally Posted by Blazkowiez View Post
I havn't even seen one of their clutches to judge in any manner
is there any pics/measurement i can take of my gtc that can let you give it some sort of quality test? or do you need it in person? if its too much work don't bother, hopefully i will be testing it soon.
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Old 09-02-2010, 09:21 AM
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it's generally not good enough to see alone. taking measurements is only good if he has similar sized things to compare. then there is still the springs tension. it is one of those deals where it is far better to have it in hand.
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Old 09-02-2010, 04:51 PM
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yea thats what i figured.
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