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Hi there

Background
This is my first venture into scratchbuild land. I'm really a collector of Formula 1 slot cars through the ages and am slowly (as budget allows) growing that.

However I did spend my youth modeling just about anything (I grew up without TV) but of recent years (that's about 16 years so not so recent maybe) have put all my modeling energies into my work as an architect.

Then after starting to collect the Scalextric retro car range, Vanwall, 250F, Cooper T53, Ferrari 156 and finding them impossible to drive I did my article on weights and somehow that got me back into the whole modeling thing.

Anyway, speaking with Graham Lane we decided we should mix our interests and enter the 'Early Birds' event in 2011 and on that basis I started to think about how I might tackle a scratch build.

Obviously being me I wanted to do something slightly different. I'm a huge F1 fan, especially of those '50's cars and have a particular passion for the Vanwall 56/7/8.

What strikes me about the things I see in your forums is that everyone is interested in building the body and then marrying that to a chassis which is usually very simple, might be even adapted from something purchased (Penelope pitlane etc.) and doesn't have much to do with the car that's being modeled.

This is not in any way intended as a criticism as I've seen some VERY beautiful things on the forum - way beyond my abilities, however for me scratch building is about another level of detail. Plus a simple chassis doesn't allow any notable 'performance' differentiation between the cars due to rigidity, suspension set up and geometry, weight distribution etc. etc.

Design
What I intend to do then is to build a car that faithfully reproduces the inside as well as the outside, paying attention to historic accuracy as much as is possible at 1/32.

There are two real problems here, access to historic information and access to parts. Then there is the problem of motors. Real cars don't have huge electrical motors in them and at scale an engine of 3 litres or so is smaller then most slot motors.

And then I hatched a plan. It so happens that I recently invested in a Lotus 79 from Ostorero, and in that is a very small motor. In fact way smaller then any other slot motor I've seen and since I love the Vanwall it occurred to me that I might just about fit the motor in the rear fuel tank, leaving all of the rest of the car free to model accurately.

I checked my records:



Having done my weight tests the rear weight didn't scare me since it will still be very close to the rear axle.

So I browsed the internet and through the Forum links found the excellent http://www.vsrnonline.com/Mags/MC/MC_Plans.html
With two different Vanwall plans. Then, using the scalextric car as a double check I redrew in Autocad the lines and the chassis to use as a 'jig'. I needed to correct the plans I found on the internet a fair bit to make correct it and ended up with this:



Construction
So to cut a long story short I took myself off to the local hobby shop here in Italy and bought some bits and spent much of Christmas building this:





The chassis came together fairly easily from solid 1.5mm brass rod and then I turned my attention to the rear drive train and motor mount. Here the Ostorero motor, axle and crown gear were used with Scalextric wheels and tyres off the Vanwall.

I decided to go for a swing arm affair since I wanted working suspension and the original (1957/8) car had coil springs with deDion tube and a Watts linkage, the concept of which I roughly translated as a slightly loose swing arm that allows each side to move up and down but as it begins to move, being rigidly connected via the axle the other side also starts to move just like the deDion.



Since I had limited materials I used some plastic tube over the axle as a spacer to keep everything apart and for the bearings I used some old Scalextric plastic bushes and soldered a thin brass strip around them to locate everything else to.

Obviously I had to connect the motor to the axle assembly. This makes un sprung weight quite high. I wanted to find a way to allow the rear axle to pivot around the centre of the motor so the motor could be stationary and the axle rotate but given the motor couldn't be flat this rotation would have had to happen on the axis of the motor, meaning the suspension springs would also have been at this strange inclination so I abandoned that idea.



The rear shock absorbers were made from various thicknesses of brass tube and some medium hardness Ninco shocks which was all I could find here in central Italy. Sorry for the hairs but my test track is real dirty and the model is all oiled up. I'll try to get some better photos soon!

This area needs some improvement for the next version and I've now got much thinner tubes to use and I've found a company in the UK which sell much smaller diameter springs.

Next I moved on to the front end and here since the springs were 4mm OD and I had thought I could find 2mm OD the front track ended up being about 2mm wider than the original which I will need to modify for the next version.

I struggled long with lots of ideas and finally opted for a front axle assembly which moves up and down on a fixed suspension central rod.

What I found was that due to the spring size I had to have the steering pivot centre on the same point as the suspension upright.



This failed since due to the centre of vertical load (tyre on road) being about 8mm to the side the suspension mount just jambs. I've now redesigned it all as a swing arm affair located on the chassis and the wheel will rotate about that pushing up on the spring. In this way nothing will jamb - I hope.

The slot was located simply by soldering a tube to the front of the chassis and this works fine. I have allowed plenty of vertical play to accommodate the suspension movement but sicne the suspension doesn't work this remains essentially untested.

The steering uses a simply fixed brass arm locating on lugs attached to the front axle.





Obvious things I learnt:
1. Fabricate as much as possible from single pieces since soldering more than one piece together (I had assemblies in the front steering/suspension of 5 minute pieces) is VERY frustrating.
2. Buy everything you need first. I'm very inpatient so realizing I had no front axle pins of the right diameter I made them by putting solder round a smaller brass rod and spinning it in a drill on a file to try to get it round and of the right diameter. - A total waste of time if I had the right rod!
3. Don't use a flame type soldering iron near suspension springs as they distort at 300°C if made of stainless steel!!!

Obviously now I need to clothe it and complete the body (where contrary to the norm in your forum I'm going to cut up and adapt the Scalextric body with many modifications of course), plus weight it etc. etc. Plus tidy up and spray the chassis...... there's a long way to go in fact but at least the car works......

Performance
So the million dollar question is 'how does it go?' and a further question is 'what can I do better next time?'.

It goes surprisingly well actually. Compared to the Scalextric Vanwall it is about 20% faster and compared to a modern, wide tyred, wide bodied F1 car its about 40% slower so all in all I reckon it's a success or rather, its pointing in the direction of a success.

What I have noted is that the steering geometry is incredibly sensitvive. I wanted the front wheels to turn, i.e. be on the track with the suspension taking up imperfections and allowing any necessary 'leaning' on the corners not to make the guide pop out of the slot. I set it up with slight toe in and a camber to simulate the real thing. All this remains untested to some degree givent he front suspension jambs, however to show the extreme accuracy needed to get it right I found that lifting the front right wheel by 0.25mm gave a 20% increase in lap time and meant the car didn't come off nearly so much!

Anyone else doing anything crazy like this???????

I'll show further progress as I make it.
 

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This is'nt crazy at all. I just love it!! Odd that the motor is at the rear however. But dont stop!

Regards, Graham.
 

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David Collins
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Wonderful work - although I guess you are aware that the chassis design probably flies in the face of most thinking about how to produce an efficient working slot car chassis...but as my club mates would say - what does he know!

I do wonder why you didn't want to put the motor at the front, where of course it was in the 121 car, with a propshaft. This would have been even more in keeping with a realistic approach, and would not have left you with the weight behind the rear wheels.

Anyway, please keep us up to date with the progress on your fantastic build!

David
 

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That is some seriously nifty work!!! Keep going!
 

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I imagine you put the motor at the back to get some detailed engine work under the bonnet. It's a shame that there aren't any really powerful motors that will fit inside a scale engine shell.
That's why my Austin Seven Ulster has its motor between the axle and the bellies of the drivers! I'm using a tiny model railway motor with belt drive, but if that isn't up to the job I'll use a cube motor for which there is JUST enough room, working as a sidewinder.

A great project and well worth the experimentation. Doing supension and steering has always been the holy grail, but the ngineering gets very tiny and ultimately a bit weak. In sixties Model Cars mags there were often attempts at doing both. Do I recall Alec Gee correctly, historians?
Martin
 

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A Very "Well Done" to Conti Rowland, Reminds me of all the photo,s we used to see of models in "Model Cars" all those years ago. A well thought out answer to the problem,s that come up when trying to re-create a working replica. This post certainly got my attension, mostly because i seem to be in the minority believing that car front wheels should turn when it arrives at a corner.Thank you for sharing this with us and for the photo,s.You certainly made the most of your Christmas holiday. I look forward to futher up-dates to your project. Best regards Peterjon
 

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mac pinches
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2,154 Posts
Conti what a wonderful piece of modeling !!
Its quite refreshing to see someone modeling for modeling sake and
getting away from the stereo type of chassis builds.
Today we are fortunate in having many meetings to keep us busy
but the down side of that is that your type of project tends to take
a back seat in the rush to get the next car to the grid on time.
Please keep us updated on the car, super stuff.
Mac P

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Senior Slot Car Mechanic
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Very nice job. I particularly like your efforts in ACAD to produce those very nice structural drawings.

The chassis came out quite nice, but, you need to get smaller materials yet to do the suspension bits. Always a problem.

Here's a few pics of something I'm working on, feel free to steel any ideas you might find interesting. Also, with properly designed steering, there is no need to attach it to the guide, so, that can eliminate a lot of fiddling.







 

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Senior Slot Car Mechanic
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No, no camber, it's just lenz distortion.

On slot car steering, it's VERY IMPORTANT to have the steering kingpin as perfectly vertical in both planes as possible. The change in geometry with angled king pins (either in camber or castor) will cause one wheel to lift (quite a lot) and the other to descend when the wheels turn, making handling somewhat awkward, and, probably has a lot to do with explaining this.

"I set it up with slight toe in and a camber to simulate the real thing. All this remains untested to some degree givent he front suspension jambs, however to show the extreme accuracy needed to get it right I found that lifting the front right wheel by 0.25mm gave a 20% increase in lap time and meant the car didn't come off nearly so much"

With perfectly vertical kingpins, this effect probably wouldn't happen.
 

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re member
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Well done Mr Conti...I like your fresh approach to things.
I too was apprehensive when I saw the motor behind the rear axle but I guess the weight in the rest of the chassis counterbalances things .
Keep going, I like it.

QUOTE Also, with properly designed steering, there is no need to attach it to the guide,
Al,are you saying that the steering will just float or follow along somehow?

regards
 

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Senior Slot Car Mechanic
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QUOTE Al,are you saying that the steering will just float or follow along somehow?
Yessir, ever ride a bike "no hands"?

Take a more careful look at the Maser suspension, it's all in the pictures (even though, it is actually backwards in those shots).
 

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Senior Slot Car Mechanic
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QUOTE Steering arms should be trailing?
Not necessarily, they can be front or rear, but, you are close.
 

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Senior Slot Car Mechanic
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Basically, except, it's not really Castor as such. Basically, the spindle trails behind the kingpin, which, is where the name "trail Steering" came from.
 
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