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· Registered
2,472 Posts
Hi guys, this was inspired by the post from Mophead Rider about Hornby supposedly intending on making a slot car rolling road or something...

In typical fashion I responded with a suggestion to make your own rather than buying something from Hornby... Here's my guide to building one for around £10 - £20. BTW: It's written for a complete newbie...


It is the easiest thing in the world to create a rolling road which will measure the relative speeds at the wheel of all your cars. This is the only thing that I could see me using a rolling road for.

You will need:
One cheap multimeter/voltmeter
Two slot car crystal boxes
One old chassis with motor fitted
Slot.It back axel system (big hubs)
Some copper tape
A 12v (or similar) power supply
On-Off switch x 2
100 Ohm Potentiometer
Some self adhesive velco

Firstly... cut out a slot at the front of one of the crystal boxes. It needs to be big enough to fit all of your guides into, but be around 2 or so inches long.. You should probably champher the edges too.
Next, cut out two holes at the back end of the same box which could easyily fit you biggest tyres through length ways. Also make them wide enough so that every car that you wish to test can sit with it's guide in the slot and it's wheels unsupported through the two holes in the back of the chassis.

Next, assemble the old chassis with motor and back axel system. Set the width so that the wheels will fit dead centre in the back two holes. PLace some wide rubber around them. Cut down the chassis to a reasonable size so that you still have a large contact patch to glue the chassis upside down inside the crystal box so that the wheels with tyres poke upwards through the holes.

Next lay some copper tape either side of the slot as you would to a routed track slot. Then lay some of the soft velco tape either side of the copper tape, running parallel to it.

Now to the wireing...

Wire the power supply through the potentiometer, the switch and the two copper strips. This is to provide adjustable power to the contact rails.

Next, canabalise the multimeter until it is set up solely to read volts, add some batteries and run the power circuit through the second switch. Wire up the motor from the old chassis to the voltage input on the meter.

Next, mount the meter into the second crystal box. Now you can tidy them up as you wish. I mounted the boxes next to each other on a bit of MDF, and used duck tape and felt to cover the boxes to hide the internal gubbings.

To use:

First turn on the meter using the second switch. Place the car on the first box with it's guide in the slot and it's wheels just infront of the top of the roller, but still resting on it. Take a piece of the spikey side of the velcro and place it against the guide perpendicular to the slot. This will prevent the car running forwards.

Next, turn on the power to the rails and adjust it using the pot. I suggest making a scale around the pot for furture reference and marking a point on the dial.

The voltage created by the scarificial motor running as a dyno will create a number on the meter, or move the needle to a certain point. This is a totally useless number, it means absolutely nothing... untill you chuck another car on the block. This one will obviously be either faster or slower, and you can see by how much in percentage terms (requires a GCSE maths course).

Obviously it can also be set up to check roundness of you wheels, in which case you don't need the meter on. You can also add a strip of sandpaper before the wheels for truein wheels and tyres.

A cheaper option would be to complete box one, but not bother with box two. You could have just rollers with no motor, or simply stick a 5mm wooden baton two thirds of the way down the box so that the wheels are suspended in mid air.

The whole thing is customisable, you don't even have to use crystal boxes, they just happen to be the right size. Maplins and RS do some great component boxes. Add lights to indicate On/off or the amount of power going to the rails. You could also add another slot to the meter box so that you can use it as a set up block.

To quote some Fisher-Price marketing exec...

QUOTE Oh, the possibilities...

I hope you all like this and make one yourself. They are very useful, and more importantly I spent ages writing this and I'm frickin knackered (thus the spelling mistakes)

Good night all, I expect to see pictures of your efforts soon...

McLaren (yawn...)

· Allan Wakefield
6,720 Posts
As clear as mud!

But it was late and the idea sounds pics?

They speak a thousand words and don't require a spell checker

· Registered
2,472 Posts
Discussion Starter · #3 ·
Na, I ripped mine apart 'cos I needed something from inside and never put it back together. Don't know where it is now...

I got free access to a Kelvin Light bench so I just use that. But to be honest, there are other ways of finding a quick motor and car without specialist equipment, so I don't really need one.

But someone asked so I posted it...


· Premium Member
432 Posts
thats great mclaren i have just finished building it (took long enough i know) and it is great, ideal for running in cars and it gives a reading not as complex as the kelvin light system, but for me it dosn't need to be! (the kelvin system confuses me!)
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