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Quarter Elliptic Question

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Woodysrods Avatar
Woodysrods Silver Member Brian Woods
Westbank B.C., Canada   CAN
In all my years of building cars, I have never built or driven a car with quarter elliptic front suspension.
Thus, I have never paid too much attention to it.
As I am lazy, I will ask the question rather than doing my own research......"Is a Panhard Rod of some type required
to minimize or eliminate side travel"?
Brian



Edited 1 time(s). Last edit at 2019-01-07 12:59 PM by Woodysrods.

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RROLDSX Silver Member Randy R
Delta, BC, Canada   CAN
Brian:

I did some Googling and it led me to this site. https://www.cyclekartclub.com/member/gazanion Serge Gazanion built a beautiful French version of Bloody Mary. A kart I know you fell in love with.

Randy

Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
You will probably have about 12" of 1 1/2"x 3/16" steel on each side Woody.
I would think the critical feature would be that the mounting point be very ridged
with out any possibility of side movement. .
Try bending a 1 1/2"x 3/16" bar the long way and you will find it VERY ridged.
So....I don't see a need for any sort of sway control with this set up.
Denny G
Sandwich, IL

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carChips Avatar
carChips Victor Harnish
Kelowna, BC, Canada   CAN
1933 MG Magnette
1973 Triumph Spitfire 1500 "Chip"
1989 GMC Sierra 1500 "Bush Truck"
Check out this thread. https://www.cyclekartclub.com/phorum/read.php?2,693



S'all for now!

Woodysrods Avatar
Woodysrods Silver Member Brian Woods
Westbank B.C., Canada   CAN
Thanks Randy, Denny, and Vic.
General concepts is that no Panhard Rod os required!
Brian

Dave 46 Robert Davison
Toppenish, WA, USA   USA
Panhard bar shouldn't be needed as your radius rods should prevent any side sway. This is a little T modified that is in the Pacific Northwest

The thing to note in the first photo is that the radius rods (quarter eleptic has to have a radius rod that is mounted solid to the axle and pivots on the frame)

In the second you can see that it angles in slightly and that helps triangulate the front suspension. That rod is one side of a Model A wishbone or in hot rod parlance split wish bones.


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Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
I can see the need for radius rods with a 1500 to 1700 lb car with twisting forces from braking
and the leverage imposed from a dropped axle.
But with a 250 lb kart with only about 150 lb on the front end, driver on board, no brakes
and a 'straight axle' I don't believe there is any need for them. And parallel springs with
this size vehicle should be more than adequate to keep the axle in line.
Nor do I see a need to triangulate in Brian''s particular type of set up, but if that fits into the
design, it certainly will not hurt anything.
Tony Sanchez's kart in the link that Vic posted, utilizes a considerable drop in the axle,
which puts that large twisting force on the axle. Also he does not have a rigid attachment
at the front. He retained the spring eye and bushing at the front of the spring, allowing the
axle to rotate which necessitates the use of radius rods to stabilize the axle.
In a kart with a dropped axle, rigidly attached to the spring It may be necessary to
use radius rods to control the rotation if the axle if the spring pads are not large enough.
We must remember that we're not building a heavy, full size street going vehicle here,
that need to be designed to run 100 mph.
Denny Graham
Sandwich, IL

Carty McCartFace Robert J
Fresno, CA, USA   USA
In reply to # 37316 by RROLDSX Brian:

I did some Googling and it led me to this site. https://www.cyclekartclub.com/member/gazanion Serge Gazanion built a beautiful French version of Bloody Mary. A kart I know you fell in love with.

Randy

I THOUGHT I wanted to build a Peugeot as a kart... until I saw Bloody Mary. See, I’m not a car guy, so inspiration cars are EVERYWHERE! Haha.

Once I saw that little car, though, and looked at the 3horse “edger” motor I had, and emailed my wizard buddy about chaining two together, well I knew I had to build a Bloody Mary.

Which is why I’m really hustling on the pedal car. I want to be the terror of summer’s nights! Hahaha.

Peace,
Robert

Woodysrods Avatar
Woodysrods Silver Member Brian Woods
Westbank B.C., Canada   CAN
Way to go Roberthot smiley
Great choice!thumbs up
Brian


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Carty McCartFace Robert J
Fresno, CA, USA   USA
This picture haunts me.

Peace,
Robert


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Dave 46 Robert Davison
Toppenish, WA, USA   USA
Quarter eleptic springs on the front or rear axle won't work properly with the axle just clamped to the end of the spring. you won't be able to control caster as it will continually change with the weight load.

The car I posted actually needs a shackle on the axle to allow for a bit of movement up and down without binding according to some who saw the photos on another forum. They are my photos taken in 2005 though.

The drawing was my non artistic attempt to draw what is shown in the second photo with the spring eye connected to the axle with tabs on the axle and the rod controlling caster and alllowing suspension travel. over rougher ground

The third shows a shackle affixed to the axle that some say gives better handling and keeps the axle from getting in a bind.

I know we often try to cut a corner or two on these karts to save money, work or weight but the size or weight of the vehicle doesn't matter if you want the suspension to work properly.


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CmdBentaxle Avatar
CmdBentaxle Dave D
Federal Way, WA, USA   USA
1950 CycleKart Italian "1950 Ferrari 166 F2"
I'm with Robert.
I wouldn't do without some kind of radius rods to keep the caster under control.
Nothing huge or complex. Besides it's many laps around the Campbell orchard over the years, I have driven the Bloody Mary pictured above at speed on dirt and street and those little rods work great. You can also look at Kelly's Wood's Sargette as an example.

Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
And you're absolutely correct Robert.....but you've still got your head warped around a big car,
where the front and the rear are shifting, diving and rising when braking, accelerating and
in the turns.
These karts are very light and are especially lightly loaded at the front. In a panic stop the most
one would expect the nose to dip would be an inch or two, which would increase the caster,
which would keep it even straighter. The front does not lift as it would with a vehicle having
a lot of power and in a hard turn because of the solid rear axle you wouldn't see very much
weight transferred to the outside spring.
So.....for a simple. light ice racer, applying the KISS principle seems to be the most practical
way to spring it.
I'm not looking for a lengthy debate on the finer points of Grand Prex race car geometry,
and handling. We're simply building basic karts that will max out at 40 mph or so and get
banged around a parking lot or pasture.
Fin.
Denny G



Edited 1 time(s). Last edit at 2019-01-15 01:27 PM by Denny Graham.

Woodysrods Avatar
Woodysrods Silver Member Brian Woods
Westbank B.C., Canada   CAN
Thanks Robert
This is exactly how I envisioned it to work properly!
https://www.cyclekartclub.com/phile/2/15042/Shackle_on_quarter_eliptic.JPG
BUT, my thinking is the same as Denny. With the spring mounted under the axle,
the worst that happens is that your Caster is increased as you hit bumps or panic stop,
thus forcing the CK to go straighter at that moment.
Setting it up similar to Doug's Bloody Mary with a triangulated 4 bar and the shackle on the spring
is perfect and eliminates the need for any type of Panhard rod.
BUT, is it too complicated or necessary for one of these simple machines????confused smiley
Brian
Thanks Dave.... I will check out Kelly's

Rhysn Rhys Nolan
Tamworth, Staffordshire, UK   GBR
Or locate with these? Woody you might remember I donated you some of these bits!


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