Adding weight? Kx125 shifter kart front end sliding thru turns..

[voided]

Some may know my build on the site.. I had a job opportunity that I had to take and I put everything on the back burner... Now that I'm comfortable I have been tweaking the kart I built.. I got the clutch, shifter, brakes, throttle, exhaust, and seat set the way I want. The only thing I got a problem with is steering.. The carts sliding thru the turns and I'm not talking about drifting the way I anticipated.. Cold or warm its sliding.. The cart also lifts the wheels when I dump clutch on warm tires..

Can I add weight to the front of the cart to even center of gravity of the cart ?

How could I measure such ?

 

[itsid]

that's odd.. you're in front of the rear axle, the engine is in front of the rear axle, basically everythink on your kart is in front of the rear axle...
And although that's a serious engine you have there it's gear ratio should be set for speed, not torque (it almost looks like 1:1)
So.. getting the front wheel up in the air is close to a miracle to be honest.

Well ideally the weight distribution is 50:50 on a kart.
To measure that precisely you should have a car/kart scale with four pads (one per wheel) but that's not a common household item, is it?

So, next best thing: get a bathroom scale and measure each wheel individually, take carefull notes and do it at least three or four times; kart facing north, kart facing south and west... (east just to make it complete )
take the average weight of each individual wheel and see what you come up with.

Oh, have a friend sitting in the kart while you measure, you're a significant part of the vehicle weightwise
(or sit for yourself, and let others take the measurements.)

there are kart weights, but they're rather small (I think up to 10kg maybe) I think that'll barely be enough to keep your frontwheels on the ground, not nearly enough to keep them from sliding.

Oh, sliding... have you checked that your wheels are not hardened out?

'sid

 

[Half-breeder]

This site has helped me alot in my last fabrication on my kart(finding CoG). I swapped my 2 seats to a solo seater and I wanted to know the CoG.

There's alotta measurements/calculations... but it seems accurate enough(for me). I selected the 'last' car option(Desert racer) as my 'plan to represent my vehicle'.

 

[OzFab]

Looking back through your build thread (not that there's many pics of the steering), I think the problem may be your steering, there's very little or no ackermann...

 

[voided]

My cart ran and drove fine with the 6.5hp motor it had on it.. Its is a older coyote race frame I simply removed a motor and replaced with a bigger motor, and added clutch, shifter and exhaust..

Would ackermann have to be addressed since its a company built frame and not a home made frame..

The tires are older, so I won't rule that out. I'll grab a pair from the local shop

 

[Half-breeder]

Would ackermann have to be addressed since its a company built frame and not a home made frame..

Manco is a company built frame... never seen one turn correctly off the line. I 'have' seen race karts w/ proper ackermann(after they fixed it).

... im just sayin...

 

[OzFab]

Not a lot of (if any) yard karts have ackermann. Yes, race karts usually do but, the main difference is in the spindles; do you know for a fact that you have the original spindles, tierods & steering column?

 

[voided]

Fabroman, everything appears stock, and local shop said his best knowledge he'd agree it was all stock.

only thing i can think of.

i needed alil extra height out of the steering.

i simply flipped the block that mounts my steering stem to the supports and it added 1 inch in height...

 

[itsid]

please add some pictures of your front end, showing the steering geometry,
best three (fully left, center, fully right) incl the wheels.

From the pictures in your other thread it appears that Fabroman's right with his assumption,
but it's hard to tell for sure.
Your pitman arm appears to be a "one hole" design, and the trailing arms of your spindles look rather straight for a good ackermann... but again; hard to tell for sure.

'sid

 

[voided]

let me know if you need any others for reference.

the one close up picture of the steering block that i simply flipped to add alil height to the steering stem

 

[voided]

um sorry but i dont know why they are upside down.

 

[itsid]

No big deal;
Well the images are not ideal to be honest,
but it looks okay, maybe not perfect, but definitely not too far off either.

There's just one thing that I'm curious about,
on full lock does the "outer" wheel move back again?
How do I say that...
say you want to turn left, does the right wheel go left and bounce back slightly to the right?
If so, your tie rods are in too big of an angle (ideally they're in a straight line from one wheel to the other)
Such bouncing can destabilize a kart;
easiest thing to prevent that is a restrictor to prevent hitting the critical angle.

If not this kart should handle at least good (if not great), you could try to improve the Ackermann angles if necessary
(you know, spindle kingpin to center of rear axle in a straight line with the hole where the tierod is connected to the spindle)
Make sure the outer wheels do not bounce back if you turn the wheel to full lock and check your tires (too hard, pressure etc)
And if that's all in order;
you should have a perfectly good steering (no understeering at all)

I'm sorry.. everything I see looks "normal" to me, you will have to wait and see what others say *shrugs*

'sid

PS the frame itself isn't bend, is it?

 

[voided]

the frame dosent look bent, i dont see anything out of the ordinary. and frame sits level on everything ive had it on while i was working on it.

oh. and when turned all the way to the left or right. i can let go of the wheel and it does not bounce back, not even a 1/16th of an inch

ive even measured floor to spindle. and any other possibility that may affect it. but still dont see anything that raises a concern even the slightest.

im planning on grabbing some new tires. anyone against some dirt/rain tires as i plan on using my kart in only parking lots / streets, that may have some sand or possibly puddles.

 

[itsid]

oh. and when turned all the way to the left or right. i can let go of the wheel and it does not bounce back, not even a 1/16th of an inch.

That's not what I meant, I'm sorry it's hard for me to find the correct terms here...
(I'd even had troubles describing that in german )

So, when you turn the steering wheel left, just before you hit the locking point the right wheel turns back right ever so slightly.
some sort of backlash in the wheel itself, caused by the tierods angle.

'sid

 

[OzFab]

Now that's just weird; looking at the individual pieces, it shouldn't have any ackermann (the steering arms on the spindles are almost square & the tierods are stacked at the steering column) & yet, it does

 

[voided]

Itsid I know what your talking about now... No it does not

The spindle mounts to a plate that's then mounted to the frame by 4 bolts that gives me adjustment but before touching any of that I'm gonna wait to get some new tires on and take it out for a spin with the gopro on paying attention to the front wheels

 

[itsid]

So, adjustable caster, that's a good thing...
camber adjustable too?

Anyways, I've read in a chassis set up manual (italkart.. different system same principle)
that for a understeering kart the amount of caster should be increased.
the italkart guide is here: http://www.italkart.com/files/pdf/chassis_setup_guide.pdf

So, the next step would be find a similar chassis setup manual for your front end system,
as a guide.

You can test your tires, scratch the sidewall of the tires with your fingernail, if it's still rubbery they should be okay (you can compare to your rear tires) if it feels more plastic like they're most likely too hard to make proper contact.
No need to buy new tires just yet (I think )

[EDIT]
So there you go a coyote chassis setup instruction..
unfortunately without images,
http://media.wix.com/ugd/b05594_042ec07045c6883189e58e63f46d446c.pdf
(caster setup.. page seven)

'sid

 

[jandj]

You can try the chassis/handling page at bobs4cycle forums. It's a racers page so you'll probably get some advice that helps.

 

[voided]

Thanks fellas... My tires are harder then my rears but not plastic like. So i am gonna grab a front set..

And I'll start reading thru those links for anything that can help me

 

[voided]

Scored some free used tires from the local kart shop. Some super Tackey tires the previous owner for some reason didn't like after 2 races..