TUNING CARRERA CLASSIC NASCARS FOR PLASTIC TRACK WITH MAGNET
By Rupert Gaylord
G'day Guys, Just thought I'd share a few ideas with you about setting up Carrera Classic Nascars for racing on plastic track (Scalextric Sport in this instance) using magnetic downforce.
These excellent models are often unfairly maligned for poor on-track performance, but with a few basic modifications they can be made to perform very, very nicely.
Most of what I'm going to mention has been done before in one form or another, I've read many really great "How to" posts and articles over the years and adapted ideas for my own use. The Internet is a great way for enthusiasts to get together and share info on their latest projects!
Our Track…..
OK, out of the box these models are no Fireballs, on our home track performance ranges from 3.1 second laps (a really freakish Petty Superbird) to a lardy assed 3.7 seconds for a Petty Torino, these models can vary in basic performance (like any mass manufactured item). As a comparison a stock NSR Mosler Evo (with shimmed guide) will turn in laps in the 2.1 to 2.2 second range. A tuned NSR Mosler Evo will break into the 1.9 second lap range.
Anyway, first item that needs attention when tuning one of these models is the guide (and yes, you could be mistaken for thinking it was a yacht keel!).
The stock guide…
I like to dremel off the back of the guide, I find this helps in negotiating tight curves. Also check the depth of the blade in the slot to make sure it isn't touching anywhere. On these models I add 3X.25mm shims onto the guide shaft to take out slop. Alternatively if you are worried about ride height, I have found one .25mm shim below the chassis and one on top work well too (little bit tight to start with but will wear in ok).
The completed guide….
With that part out of the way lets move onto tyres and rims. Rims are trued as per usual tuning procedure, tyres are a little different.
The stock tyres (both front and back) are reduced in diameter by 1mm. You will end up with something looking like this….
Next you will need to "round off" your freshly ground down tyres. Rounding off the tyres greatly enhances handling in the corners, square un-rounded edges dig in on a corner causing all sorts of weirdy handling characteristics (hopping for one).
Mmmm, a nicely finished tyre!
OK, whack the wheels back on the axles and get them back in the chassis (remembering to leave some sideways "slop" in the front axle to account for the guide moving from side to side in the slot). I glue my axle bearings and motor into the chassis using superglue, although hot glue works as well. If you run a lot of competition laps its also good to put a trace of superglue on the front of the pinion and motor shaft and crown gear where it meets the rear axle shaft.
I don't know about you but this amount of wiring looks untidy to me and is a potential harbor for dry solder joints. Dremel off the heat welds, un-solder the wires and capacitors and run the guide wires straight to the motor, minimalist IS GOOD!
OK, now don't put away your Dremel just yet, its got a little more work to do! We need to look at body to chassis fit. Carrera really loves a tight fit in this regard, nice, but not conducive to quick lap times. We are looking to "de-couple" the body from the chassis, the aim is to get the rattly thing happening.
…A nice gap between body and chassis all the way around….
Firstly dremel off the heat welds on the exhausts, once we finish trimming back the chassis you can put them back on….
Dremel right around the chassis, a millimeter or two gap is what is required.
Next step is to grind off the lip on the body mounting post on the chassis to enable the body to move around a little when everything is re-assembled. Keeping this lip will negate any advantage in trimming the chassis (as per previous step).
The finished chassis mounting point for the body should look like this. Just use your Dremel with a small cylinder stone (use the flat end) to accomplish this). A little material removed at a time will give you uniform height on all four mounting points. The excess material will "flash" so just get an old axle or something to push through the screw hole to remove excess material (this is a really good way to gauge when you have fully removed the lip). You can also run a drill bit (ever so slightly larger than the hole diameter) through this hole during this stage to reduce the possibility of the screw thread binding in the hole once you get it all back together.
Finally test fit the chassis to body assembly, you will need to dremel off these do-dads on the bottom of the interior a bit to ensure the chassis sits flat in the body (its no good having the chassis bend upwards when tightening up the body screws, no tension is what we are looking for!).
I also would like to mention that in this build up, the only non-stock items used are the guide shims and I also used NSR tyre treatment (remember to Zippo off before running if you use this oil treatment). The tyre treatment on its own is no "silver bullet", it would be scratching to knock a tenth of lap times, but the stock Carrera rubber is a little hard so a bit of softening will help.
OK, time to put the beastie back together and see how it performs….
I set my body screws two turns of snug on the back, and between one and two turns on the front (depending on the chassis). The front slinding magnet was paced fully rearward, the mag assembly under the rear axle was allowed to "dangle" on its screws (between ¾ turn and 1 and ½ turns off snug, again depending on the individual chassis).
The front and rear bumper clips were hot glued in place, although super glue will work as well….
THE END RESULT
The final result of this tuning was absolutely stunning!!! Our #27 Torino turned in best laps in the 2.3 second range, our once sluggish Petty Torino managed best laps in the 2.4 second range…..
Please remember, this is with quite a whack of magnetic downforce. Reducing magnetic downforce (sliding magnet fully forward, rear magnet snugged up tight) will increase lap times into the 2.7-2.9 second range, but will give a lot more on-track feel to the "experience"….
I love these models regardless of how they perform, but its good to know that they can perform admirably if you spend a small amount of time tuning them.
