New guy clutch question cent. or T/C

[Jester]

Probably been discussed to death but ....... Centrifugal or T/C ...... Building off road kart for my 7 year old......... not interested in lighting speed at the moment but would like some torque off the line
Thanks for your opinions in advance.

 

[Hellion]

Torque Converter all the way, my friend. Accept no substitutes.

...to the forum, too!

 

[Poboy kartman]

Ditto....

 

[itsid]

I'd say : DEPENDS!

if you want the kart to be slow you need to gear really low already...
which will add the torque you want where a TC will still add to of course,
but isn't at all needed.

So you could get away with a centrifugal clutch.

the easy solution to add torque though is indeed a TorqueConverter,
with the benefit of a bit more speed thanks to slightly higher gearing.
but it's not necessarily the ONLY solution here.

'sid

 

[KartFab]

Yeah. I'm starting to think my torque converter I put on my mini bike is keeping the engine from revving past 4100 rpms. I'll be doing a test with a racing clutch later to see what the results are.

 

[Jester]

Thanks for the responses guys I appreciate your time

 

[Eric87]

TC for kids . unless you like pushing up hills.

 

[chancer]

TC.
You did say it was for a 7 yr old... So; many many guys have come here wanting
to limit the throttle for their young kids.
Doing so will burn up the a Cent. Clutch. But you can do that with a TC.
That is my main reason for voting TC.

 

[Poboy kartman]

TC.
You did say it was for a 7 yr old... So; many many guys have come here wanting
to limit the throttle for their young kids.
Doing so will burn up the a Cent. Clutch. But you can do that with a TC.
That is my main reason for voting TC.

But you STILL have to gear low....PERIOD!

 

[Jester]

Thank you all again for the responses I appreciate the input , I'm leaning towards T/C

 

[Hellion]

Eh, just because 7 years is a young age doesn't mean a child is or will remain inept or unseasoned--if you used a centrifugal clutch and the child was struggling to get the kart over some modest hills and terrain, they'd be complaining to you for some satisfaction.

*Especially as their skills grow and you're less concerned about gearing the kart as low as possible.

It won't go. More power, Daddy!

 

[itsid]

A TC can limit the speed (using a speed limiting weight set made for this exact occasion)

Otherwise gearing is indeed the only viable option..
not allowing to go full throttle (i.e. goverened 3600 rpms)
can end up in burned clutches (not allowing to fully lock)

With that limiter however you can use std. gearing the TC will stop shifting up at any set point
(so the overall gear ratio will be limiting the speed... the same as a huge axle sprocket would)

So that:

But you STILL have to gear low....PERIOD!

is not perfectly true!
it's true without the tc speed limiting weight,
NOT with it

'sid

 

[Poboy kartman]

True...but...a new AXLE SPROCKET is about half price...(and it's not like you don't have tear something apart to change either one...)

Apples and oranges....you say potawtoh...I say tomato...

 

[bob58o]

So am I understanding correctly?

Limiting the throttle when using an unmodified TC will burn belts similar to burning up CC's when limiting the throttle?

So cruising around at 2500 RPM with an unmodified TC on a heavy kart with big wheels is NOT healthy for the TC?

This was my understanding before. I never knew about the limiter sid linked.

 

[chancer]

Rumors I heard and believed was that with a stock TC you can limit throttle. As opposed to a cc you cannot. 'shrugs'

 

[JollyKarter]

I am assuming with an off road cart you are running big tires? Now this is info gleaned from the atv world, but one problem with throttle stops on youth atvs with a CVT drive is there is no way to limit the CVT shifting on them...so even though JR can't hit WOT, on a long enough stretch he can still have the CVT over driven and achieve some decent speed. I think the limiting weights would be the surest and easiest option on a kids cart. They can have WOT for enough power down low to conquer obstacles, but not hit blistering speeds. I am glad this came up...I had forgotten seeing those speed limiting weights...I may need to look into those once little girl gets long enough legs to reach the pedals...

 

[itsid]

you should never limit the throttle..

chances are you prevent whatever clutch (TC or cent) from fully engaging... and thus from burning through.

Yes, if done extremely carefully you can limit down to the exact point of full engagement...
but then there will be no pedal movement left to set a speed... it'll only be on and off (or burning clutches/belts)
keep in mind that a goverened engine only has ~1600 rpms from fully engaged clutch to max rpm.
So removing half of the top speed is NEVER going to work (since that's already below the speed for a fully locking clutch)

A TC speed limiter works differently.. it'll always allow the clutch to fully engage but it'll prevent the mechanism from shifting up.. so instead of a 0.9:1 final TC ratio you'll be stuck with say a 1.6 final TC ratio (adjustable all the way from 2.7:1 to 1:1 with the turn of a nut [two nuts])

and 1.6... means a 96 teeth rear axle sprocket (see where I'm going with this Doug? )
so in order to go as low you'll likely need a jackshaft anyways...
thus the weight is the best option you'll get.. it allows adjusting the top speed without risking to destroy the clutch (belt in case of a TC)
and since it IS adjustable you can not only set it higher and higher as the kid grows up;

you can also just replace it with the original weight (you wouldn't throw it away, would you?)
when the kid's old enough (or you want to have a go your own).

'sid

 

[Poboy kartman]

Throwing away? What's that?

Definitely got to call you out on this one, 'sid....

What exactly does the geared down rear wheel speed have to do with engine speed....(when it takes the same amount to engage the clutch? )

True...you can be limited by available rear wheel sprocket size...but....REFRESH MY MEMORY....Ummmmmm....just WHO was it playing devil's advocate against TC's?

 

[itsid]

Nonono.. you misunderstood..
I said, that limiting the throttle has adverse effects.

And mentioned that gearing lower could bring up a need to mount a jackshaft because of sprocket sizes. (especially if you want to gear as low as a TC could achieve)

Not related to each other, just two things to consider.

And true, I said that a TC is not the ONLY viable option,
especially if limiting the speed is on Jester's bill (I can't tell....)
just changing the gear ratio can do the trick.

But since I do know he's leaning towards a TC anyways ('cause he said so)..

I said, that instead of additionally changing the final ratio
the easier way of reducing the speed is the limiting weight.
especially since it's adjustable and reversible nearly hassle free*.

*one bolt, everything will be still aligned compared to
a potential need to remove the axle completely to change the sprocket...
yes split sprockets...
more bolts, diferent chain length -> still more work than changing the weight​

'sid

 

[Poboy kartman]

That's it....I try to help here....and all you wanna do is argue!!!!

I'm outta here....(JK!)