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Lets talk center of gravity

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SteveV Avatar
SteveV Steve Vinson
Phoenix, AZ, USA   USA
1924 Ford Model T "Viscount Vinson Special"
1927 CycleKart American "Mono Wasp"
Hi all,

Here in Arizona we have had a couple of our new members get hurt when they flipped their karts on the track.

Its not my intention to air the 'dirty laundry', everyone wants gory details.....not going to happen. If the members who have had an accident want to share details, feel free.

Here are my thoughts on this subject.

First each driver/builder is responsible for his or her own safety. You need to decide what your kart is designed and build to do....race or putt around.

Both of the karts that had an issue where built with what I would consider a high center of gravity. The seat is level or close to level with the frame.

These karts can be driven fast on a track, however, if you have a high center or gravity....you will not be able to take a corner with the same speed as a kart that is built low to the ground.

Common sense goes out the window when you are on a track and trying to keep pace with the kart in front of you...we all get target fixation or an adrenaline rush......I just don't want anyone to get hurt.

CycleKarts are not shifter karts or even a go-kart. They are top heavy and can and will flip over if given enough force....I have had my kart on two wheels and it happens very fast.

If you are designing and building your kart and plan to race it at Tieton or any other event, please understand that where you place your seat and the weight of your kart will effect how quickly the laws of gravity, inertia and traction will come into play and ruin your day.

After these events I am planning to take these steps.
1) I am going to lower my seat down, now it is 3 inches below the frame. That is too high. I would like it to be about 3 or 4 inches off the ground.
2) I am going to install a removable roll bar and add harnesses that can be removed for 'Show'
3) I am going to look into whether I can lower my engine down between the frame rails, it sits on the frame now.

These mods may be extreme, but I plan to drive my kart fast and I don't want to flip it over.
I encourage each builder to give their karts a look over and decide if you want to make some modifications or just understand that you should not drive hard on a track.
Track racing can be very fun, you don't have to drive hard to have fun.

Be safe out there.
Steve



Steve Vinson
Arizona CycleKart Club

Design-Build-Race-Repeat

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tiopancho Avatar
tiopancho Silver Member David Dahl
Swansea Point, BC, Canada   CAN
Good post, common sense rules and safety first. We're all gettin' older and break easier!

1908Rick Avatar
1908Rick Rick Eggers
Cape Coral, FL, USA   USA
When I discovered cycle karts, my first reaction was they sit so high, I'd be hesitant to drive one hard.
That's why I designed mine the way I did.
The frame is 3.5 inches off the ground, the seat is as low as it can be and the seat back is reclined, and the track width is 40 inches.
The engine is also as low as I could mount it, with the crank height just slightly higher than the axle.
Hopefully all these things will work and it won't be tippy.

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CmdBentaxle Avatar
CmdBentaxle Dave D
Federal Way, WA, USA   USA
1950 CycleKart Italian "1950 Ferrari 166 F2"
Steve, thanks for bringing this up.
I drive a low slung cyclekart. Everything I did designing and building it focused on keeping the center of gravity low, because it was purpose built to race at Tieton. I could mention several others that have been similarly built, and these machines can be put literally sideways on good pavement without lifting a wheel. But many arrive at race events with karts that have much lower cornering limits. And naturally, on track the drivers of these cars want to keep pace. But I have seen them baited into turns at speeds their high C/G cars will not handle. And to make matters worse, theirs are the cars that have the most viscous behaviour at the limit.
If you are a fan of the earlier, taller cars, please treat them with the respect in the turns you would an actual car from the period. All of that said, ANY cyclekart can go over given the right circumstances.

carChips Avatar
carChips Victor Harnish
Kelowna, BC, Canada   CAN
1933 MG Magnette
1973 Triumph Spitfire 1500 "Chip"
1989 GMC Sierra 1500 "Bush Truck"
Ya, like if you hit something with the rear wheel while drifting. BTDT!


In reply to # 31774 by CmdBentaxle Steve, thanks for bringing this up.
I drive a low slung cyclekart. Everything I did designing and building it focused on keeping the center of gravity low, because it was purpose built to race at Tieton. I could mention several others that have been similarly built, and these machines can be put literally sideways on good pavement without lifting a wheel. But many arrive at race events with karts that have much lower cornering limits. And naturally, on track the drivers of these cars want to keep pace. But I have seen them baited into turns at speeds their high C/G cars will not handle. And to make matters worse, theirs are the cars that have the most viscous behaviour at the limit.
If you are a fan of the earlier, taller cars, please treat them with the respect in the turns you would an actual car from the period. All of that said, ANY cyclekart can go over given the right circumstances.



S'all for now!

Woodysrods Silver Member Brian Woods
Westbank B.C., Canada   CAN
Vic and Derrik can attest to that at the Tieton Grand Prix!
And we saw a number on two wheels at the Campbell Cup race.
All part of the thrill of driving one of the little machines!hot smiley
Woody

CmdBentaxle Avatar
CmdBentaxle Dave D
Federal Way, WA, USA   USA
1950 CycleKart Italian "1950 Ferrari 166 F2"
Vic's and Derrik's cars also have something distinctly in common;
A Chihuahua could walk under them without getting grease on his back!

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SteveV Avatar
SteveV Steve Vinson
Phoenix, AZ, USA   USA
1924 Ford Model T "Viscount Vinson Special"
1927 CycleKart American "Mono Wasp"
https://www.facebook.com/groups/1740072272984827/


Here is a link to our groups Facebook discussion.



Steve Vinson
Arizona CycleKart Club

Design-Build-Race-Repeat

SteveV Avatar
SteveV Steve Vinson
Phoenix, AZ, USA   USA
1924 Ford Model T "Viscount Vinson Special"
1927 CycleKart American "Mono Wasp"
Here is a good illustration of what we are talking about. Thanks Jon R.



Steve Vinson
Arizona CycleKart Club

Design-Build-Race-Repeat

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Attachments:
Center of Gravity.jpg    37 KB
Center of Gravity.jpg

Denny Graham Silver Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
You mean somethin' like this Steve?
dg


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RROLDSX Randy R
Delta, BC, Canada   CAN
I’ve been struggling with this one as well. My current inspiration kart is high and that’s obviously not good. I may just build the chassis low and see what develops from there. Probably a simpler design anyway. I may end up with thesamekart but a lower, sleeker look.

CmdBentaxle Avatar
CmdBentaxle Dave D
Federal Way, WA, USA   USA
1950 CycleKart Italian "1950 Ferrari 166 F2"
I don't want to feed the notion that all the higher c/g cars are deathrides and ought never be run in our events.
Most of the cars of the teens and twenties that inspire them, naturally had the same limitations. If you really love an old classic, build it to look the part and drive it accordingly. If you want to mix it up with cars inspired by later or lower designs, pick one of those to replicate. It is one of the reasons I'm an advocate of the post-war cars. Although there are plenty of low and sleek pre-war machines to choose from.

Martin HL Avatar
Martin HL Martin Hill Lonergan
Armstrong, BC, Canada   CAN
For straight framers (me included) Mounting the frame under the axle with pillow blocks will/should help somewhat. Puts the axle centre line 1 1/2" above the top of the frame. Just have to adjust front suspension accordingly I guess if you have parallel springs.
It's not actually anything that I have given or gave thought to during the build but now it's like, well duh of course low CofG.
I just kinda lucked out.
I'm definitely going to drop the seat down a bit more now that the subject has been raised. That should get my glutious cuticuss further below the axle centre line.


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1908Rick Avatar
1908Rick Rick Eggers
Cape Coral, FL, USA   USA
Low is fast.
The rear axle is mounted 3" above frame, which kicks up at the rear.
The horizontal part of the frame is 3.5 inches off the ground.
In order to do this, you have to design a front suspension that's above the frame rails. There's no room for leaf springs under the frame like a Stevenson design.
The transverse leaf spring will work, or you can go torsion bars like I did.


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CmdBentaxle Avatar
CmdBentaxle Dave D
Federal Way, WA, USA   USA
1950 CycleKart Italian "1950 Ferrari 166 F2"
It does complicate your build a little, which is probably why it isn't done as often.
Mine is dropped similar to Rick's, but I use a transverse leaf above independent control arms.


Actually, this isn't the best picture as I have long since replaced that spring with a reverse eye type.



Edited 1 time(s). Last edit at 2018-04-03 06:35 PM by CmdBentaxle.


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2017-03-01 17.52.50.jpg

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