Slow new quad build.

stormbird

stormbird

0
Hi all

So leaving the pedal cars behind [ https://chopzone.com/forum/index.php?threads/quad-pedal-car-2025-late-xmas-early-birthday-present.1367/ ]
j0733xricqgz.jpg

I still hanker after trying a quad for my leisure riding , so here are a few preliminary thoughts :-

better turning circle than the pedal car
lighter than the pedal car
lower seat than the pedal car
shorter than the pedal car

First up is to build a CAD [ Cellulose Aided Design ] general arrangement model full size , this should allow me to get the seat to pedals ok and shoulders/elbow room correct.

new-quad-car-45-DSCF9708.jpg

I saved the chassis shown on the left from my pre-pedal car age peripheral frame origins, it's a start :-
New Quad ----------------Pedal car
Front track 28" --------------34"
rear track 25" ---------------32"
W/B 40" ----------------------44"
new-quad-car-45-DSCF9710.jpg

So the front track perhaps 2" wider and rear track will need to be maybe 3" wider
new-quad-car-45-DSCF9712.jpg

However the chassis needs to be as wide as possible at the rear and as narrow as possible at the front - work in progress ;)
Once I have the packaging correct I shall build a proof of concept steel version , out of some old bed frame steel I picked up off the streets.

if I can get that all to work it will be off down to my engineers for some serious weight reduction.

458805354_10169501816885215_3306030547869298231_n.jpg

About this much body work for the summer easily removable [ current pedal car has just 6 bolts holding front bodywork on ] ...............
46167419_2009454145782444_7713252284221620224_n.jpg

and a main body continuation & tail like this attached for the winter.

I hope at the back will have a simple cage behind the seat to allow some grocery shopping etc etc

All for now Paul
 
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Give real CAD a try. Something like Librecad that I use is simple to pick up. It does allow ideas to be tried and discarded without cost or wasted effort.
 
Popshot said:
Give real CAD a try. Something like Librecad that I use is simple to pick up.
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I wish this were so, for me.
I have a really hard time with it - For whatever reason, it just is not intuitive to my thought process, although I've tried several versions.
Most people don't have this problem, so it must be a result of my childhood upbringing, or something :unsure:
 
undertoad said:
I wish this were so, for me.
I have a really hard time with it - For whatever reason, it just is not intuitive to my thought process, although I've tried several versions.
Most people don't have this problem, so it must be a result of my childhood upbringing, or something :unsure:
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Sorry but I fall into this camp as well :-
I need things real in front of me and in my hand
I am sure my body ' is not ' in any CAD program
I want to compare what I am building to other things i.e this quad to the pedal car I currently own
No reason to waste time putting the pedal car in CAD when it is for sale ?

Paul
 
stormbird said:
Sorry but I fall into this camp as well :-
I need things real in front of me and in my hand
I am sure my body ' is not ' in any CAD program
I want to compare what I am building to other things i.e this quad to the pedal car I currently own
No reason to waste time putting the pedal car in CAD when it is for sale ?

Paul
Click to expand...
Yes, God tried several versions of Paul and wasn't overly happy with any of them. At attempt 42 he gave up so we have what we have, it sort of works but isn't perfect by any means. ;)
 
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You might want that narrow Q-Factor BB cartridge thingy soon then?
BTW, I found a pair of steel straight cranks at 155mm in my office. ;)
 
So now that we've determined that God followed Mr. Churchill's advice, with Paul anyway, I have a question :

What is the reasoning behind sticking with a perimeter frame design for the new quad?
I'd think that a backbone type frame might be lighter, and for sure, would more easily yield a better turning circle.
Something along the lines of Brad's Street Fighter design, but shortened to fit your parking space, perhaps?
Is it because it would be more difficult to mount bodywork on something like that?
 
undertoad said:
What is the reasoning behind sticking with a perimeter frame design for the new quad?
I'd think that a backbone type frame might be lighter, and for sure, would more easily yield a better turning circle.
Something along the lines of Brad's Street Fighter design, but shortened to fit your parking space, perhaps?
Is it because it would be more difficult to mount bodywork on something like that?
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It was an option discussed [ and in fact CAD'ded ] in the second thread linked to above.

DSCF6585-sm.jpg

Whilst a mono boom frame makes sense if you only have a single rear wheel once you add a second wheel it becomes a different kettle of fish ?
Suddenly the central frame member is not in the right place for the rear wheel placement.
At the front it will require some complicated jinxing to get around the swept area the feet need
It becomes more and more difficult to make it shorter ?

Some of the French and Italian pedal cars have this problem as they are effectively a tadpole trike design/style turned into a quad. You end with with a very long nose [ not because of telling lies :D ] which does not help avoiding obstacles whilst turning.


You can see this here where on the back row 3 of the cars have very long fronts compared to the rest ?

Paul
 
There is a reason to have a long nose. It keeps the wheelbase short which means less chassis between the wheels where it is structural. The chassis in the nose is doing nothing but support the BB and body so can be light. The longer the wheelbase the longer the stressed part of the chassis where body weight wants to bend it and the heavier it needs to be. LWB also gives a poorer turning circle. The perimeter frame wants space the wheels want, needs crossmembers and still needs a central spar at the front for the BB. It's only plus is the ease of body mounting for simple shape bodywork.

The only time I see a perimeter frame being a good choice is if not using a BB. Ie having a pedal car style crank mounted at each side meaning a side drive. Still possible to have 2wd but more thought is needed there. There is still the issue of wheels wanting chassis space though.

If I were to make a body these days think I would choose fibreglass pole or aluminium frame and spandex cover. Spandex will weigh as close to nothing as possible
 
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I was not at my desktop when I posted so could not really show what I meant :-
Screenshot-at-2025-04-12-08-15-49.png

new-quad-car-45-DSCF9710.jpg

See that the position of all major components are different and it results in a very long quad.
Paul
 
But, if the seat on that black frame was moved back between the rear wheels, like yours, couldn't it be much shorter ?
 
undertoad said:
But, if the seat on that black frame was moved back between the rear wheels, like yours, couldn't it be much shorter ?
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Well yes and no.

Due to needing room for your legs to pedal AND them to miss the cross boom the pedals cannot go backwards.

So for your plan to work the rear wheels end up coming forward , with the resultant reduction in the wheel base. Whilst not building a pedal car ' per say ' they have some sensible rules for a quad including don't make the w/b to small it effects the handling.

Using there wise council we then run into the problem what is ' to small ' I did ask and no one would put a figure on it. Typically the Apollo cars prefer a long w/b and the Royce cars a much shorter one.

Paul
 
Popshot said:
The only time I see a perimeter frame being a good choice is if not using a BB. Ie having a pedal car style crank mounted at each side meaning a side drive. Still possible to have 2wd but more thought is needed there. There is still the issue of wheels wanting chassis space though.
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Yes I need to consider drive train once I have something I can sit in [ and dream ...]
The problem can be that drive train parts want to occupy the same space as the steering components [ another can of worms ]

Your suggestion I adopted in the pedal car was to have a removable piece of body work that allows you to plant your feet on the road inside the car WITHOUT standing on the seat. Standing on the seat NOT advisable if your shoes are wet or dirty , and of course to stand on the seat the seat and it's mounts need to be stronger/heavier than normal.

That only worked because the car had side stick steering , the Royce solution has a handle bar and steering column set up , this lives in the space needed to plant feet on road and so they stand on the seats
Popshot said:
If I were to make a body these days think I would choose fibreglass pole or aluminium frame and spandex cover. Spandex will weigh as close to nothing as possible
Click to expand...
482246515-10162291711289481-6148928246795285763-n.jpg


A BHPC member built this thin metal tubing and I believe Dacron material covering.
I suspect the trouble with Dacron or Spandex is the frame has to be over built to withstand the material stress when you shrink it to remove the wrinkles.
It is actually close to me and available free to anyone who wants to collect it.
DON'T go there !!!!!

Paul
 
stormbird said:
you shrink it to remove the wrinkles
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Dacron, you'd have to heat shrink it to de-wrinkle, as you say, but is airtight when done.
Dacron could be fitted to a frame, and not need shrinking, but would need to be elaborately seamed (and sewn, or glued), to lay flat.

Spandex, OTOH, would be just stretched over the frame, and fastened at the edges - No wrinkles, but will allow some air penetration.
2 different materials :)

I speak from having worked as a sailmaker, and in a sewing shop.
 
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So bit more done...
split-chassis-side-DSCF9716.jpg

New Quad --------Aiming for ----Pedal car
Front track --26.5"------30"-----------34"
rear track ---25" --------26"----------32"
W/B ---------40"---------40"-----------44"

So getting closer , I did risk sitting on it and it looked good.

split-chassis-front-DSCF9717.jpg


So next up :-
try dropping the seat from 7.5" to 6.5"
free the kingpins and widen the front track
find a way to increase the rear track - the axles have run out of thread !!!
458805354_10169501816885215_3306030547869298231_n.jpg

The board sized cross member is to trial mount a lay shaft on and get the chains on the outside of the car to the rear wheels.[ as shown in above picture ]

I will sketch out possible drive train configurations next , as always pro's and con's , no right or wrong answer just have you the parts and skills to make it work ?

Paul
 
I suspect the worry over too short a wheelbase may be overstated. The only issue is potential stability and that can be addressed by slowing the steering ratio down. Given swb can steer tighter turns slowing down the ratio is no problem and doesn't have to affect overall steering lock.

Many 20 / 20 taddies have been built that are quite short and a quad can only get about 8 inch shorter at most without sitting above the rear axle and even that amount gives you a big issue with the chain coming from under the seat at a massive angle to the rear cogs so reality is nearer 4 or 5 inch shorter than many tried and tested 20 / 20s maximum.
 
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