By Michael Ashton
Just about every slot car made has certain characteristics that are necessary for good performance on any track. Round, true wheels and tires; well matched, smooth meshing gears; a soft tire compound that provides adequate grip and a host of other design criteria that collectively define a "good" slot car. However, even though the general criteria may have been met, there are always issues that are unique to the specific track surface that must be dealt with in order to facilitate good performance and, therefore, a satisfying slot car experience. The differences presented between a routed wood track and sectional plastic track are obvious. But the differences between the major slot car manufacturers' plastic track surfaces are also significant. And it is common knowledge that these same manufacturers design and construct their cars to perform best on their own particular track surface.
Carrera has been producing some really nice 1/32nd scale cars lately, especially in the GT and DTM classes. I have acquired several of these cars and my impression is that Carrera has made significant strides in both performance and appearance, while maintaining a very reasonable price point. Remember though that these cars are optimized for Carrera 1/24 track. And the differences between Carrera and NINCO track are neither subtle nor trivial. To Summarize:
- Carrera 1/24 track has a smooth, rigid surface. The NINCO surface is rough and can be irregular in the sense of an actual paved surface.
- Carrera 1/24 track has a deep, wide slot. The NINCO slot is relatively deep but much narrower.
- Carrera 1/24 track rails are flush with the track surface and are made from low ferrous stainless steel which minimizes magnetic down force. The NINCO rails are raised above the track surface and are made from mild, high-ferrous steel which accentuates magnetic down force.
This means that it is unlikely that these cars will run really well out-of-the-box on NINCO track. In fact, the stock Carrera guide, made for that deep and wide Carrera slot, can prevent the car from running on NINCO track at all. So, here are some really attractive model cars, at a very good price and I want to run them on my NINCO home track. The questions for me are: can they be made to run well (really well) on NINCO track; and at what cost; and how much skill and effort will be required? In other words, will the affordability of the Carrera cars be eclipsed by the need for aftermarket parts or special tools? The rest of this article documents my efforts to tune a Carrera GT for NINCO track and hopefully answers those questions.
The Car
I have a number of GT cars from various manufacturers and I have to say that it is a slot car class that I really enjoy. The cars look good and usually handle very well as slot cars go. One car make that I did not have was an Aston Martin. So when I saw how attractive the Carrera release of the Aston Martin V12 Vantage GT3 looked I decided without hesitation to get it to run on my NINCO track. And hopefully not just run, but run well. Competitive with other GT cars in my collection.
My initial reaction to the Aston Martin Vantage V12's appearance is that Carrera is maintaining, and even enhancing, their commitment to quality and detail with each new model that they release.
Paint, Tampo printing, fit, finish and level of detail of this model are as good as any from a mainstream manufacturer in my collection.
The Carrera chassis is typical of their GT offerings that I have seen over the last year or so. It still uses their proprietary guide/braid system and the direction reversing switch circuit, however, it is much lighter and simpler overall than the typical Carrera chassis of just a few years ago. The motor is the tried and true (and consistent) E-200 which produces about 20,000 rpm and 100 gcm of torque at 12 volts. The motor is coupled to a nylon 27t/9t gear system that is remarkably smooth and quiet.
Out-of-the Box Evaluation
The Carrera Aston Martin V12 Vantage comes with the now familiar pair of bar magnets installed. One just in front of the motor mount and a second, narrower, just behind the motor mount underneath the pinion.
The Carrera Aston Martin V12 Vantage comes with the now familiar pair of bar magnets installed. One just in front of the motor mount and a second, narrower, just behind the motor mount underneath the pinion.
--- Mid-chassis --- -------- Rear --------
Both magnets come with a metal shim, or spacer, that allows the magnet to be raised a slight amount in its holder. This effectively provides eight distinct down force settings. The factory configuration has the spacer installed below the magnets, therefore, in the raised position.
I can't bring myself to remove a new car from the box, place it on the track and start running immediately. So, I lubricated the motor armature with a micro drop of oil at each end and ran the car with the rear wheels raised off the track at about four volts. Bushings and gears were already well lubricated. After about ten minutes of this simple break in procedure, I placed the car on the track and began running laps. Actually I should say lap. The car could not travel more than 24 inches with the long and thick stock Carrera guide in the narrow NINCO slot. Of course this was not a surprise, but in the interest of being thorough and methodical, it had to be attempted. Regardless, the solution to the problem was already in hand.
The black guide pictured below is the stock guide that is installed on virtually every Carrera car at the factory. It is designed for the deep, wide slot of Carrera 1/24 track. It also is very effective in routed wood tracks where a deep wide routing bit has been used. Unfortunately, cars equipped with this guide are virtually undriveable on NINCO, Scalextric [Classic] and SCX track due to binding in the narrower slots of these track systems.
The solution to the problem is the red alternative (replacement) guide, part number 85309 available from Carrera, pictured above and far right. This guide is shorter, thinner and slightly shallower than the stock guide. Installing this guide in the Aston Martin solved the problem immediately.
I feel that the two stock magnets in their raised position provide all the down force necessary to achieve the lowest lap times possible at a given voltage on NINCO track. I ran the car this way for about 100 laps. Although the car was quite "stuck down", it was still necessary to operate the throttle through turns, although the rear end would not slide prior to "snapping" out of the slot due to exceeding the narrow adhesion threshold characteristic of high down force racing. The motor became only mildly warm to the touch and I would say that the car was fun and interesting to run this way. My fastest lap was 6.388 seconds which I believe to be as fast as the laws of physics will allow on my track. Lap times were consistently in the mid 6 second range. I'm confident that most hardcore hair-on-fire magnet missile aficionados would be reasonably satisfied with this performance and could easily improve on it.
For this type of racing I don't think that there is any further tuning that would yield measurable improvements in performance. At this point I consider the Carrera Aston Martin V12 Vantage to be a very good running magnet racer on NINCO track. However, I would like the car to run just as well with much milder magnetic down force and/or no magnet at all. This fits with my personal goal of superior performance that is also realistic to watch and more subtle to achieve through the controller.
Tuning
First I removed the rear magnet and left the mid-chassis magnet in place in its raised position, running about 25 casual laps. Next I removed the mid-chassis magnet and ran another 25 laps. I didn't bother running with the rear magnet alone because the performance is not that much different than an LMP car. In any event, low mag and no mag performance were not inspiring to say the least. There was noticeable hop/chatter when powering through "S" turns and spontaneous desolating when accelerating out of some turns. But that wasn't surprising given the pedigree of the car. It is designed for magnet racing on a much smoother surface. Nevertheless, I sensed that better low/no mag performance was not only attainable, but not that far off.
At this point it would be easy to start chopping up the chassis and replacing parts. Install an aftermarket guide assembly, aluminum setscrew wheels, Slot.it drive train, etc. And there is no doubt that this would result in a much better performing slot car. But these are cars that are intended for the home racer and track. Casual slot car enthusiasts like myself who don't have a tire/wheel truer or a machine shop at their disposal. So my goal was to achieve the maximum improvement in performance possible without incurring additional expense and by relying solely on my limited but tenacious tuning talent.
From my standpoint, the basic foundation of a good running slot car was already in place: the tires and wheels are round and true; the tire compound provides more than adequate grip; the chassis and body, although characteristically on the heavy side, are straight and absent any distortion; all moving parts have adequate clearance with body/interior/chassis; and the drive train is sound. That being the case, in my experience the most important tuning opportunity lies in optimizing guide position relative to the rails and creating unrestricted float between the body and chassis.
The Carrera guide in their GT chassis' tends to ride a little high. This can be seen when the car sits in a slot on a flat surface such as a set up block. See the photo below:
However, the raised rails of the NINCO track tend to minimize this issue, especially when running with [even a mild] magnet. Also, the Carrera braids are relatively thick and stiff which tends to preclude the need for a truly planted guide. The photo below shows good braid-to-rail contact and a guide flag that sits reasonably low in the slot. This proved to be adequate for the low mag configuration, therefore, nothing was done to the guide for low mag operation.
Next is the issue of body float which, in my opinion, is the most important issue for low/no mag operation on NINCO track. This is because the rough track surface produces very high grip, especially during steep acceleration in turns. If the body is fastened tightly to the chassis or is in contact with the chassis edges, the inertia of the body is transferred to the chassis. This will result in wheel chatter during braking into or acceleration out of a corner, and/or de-slotting due to rolling or front end lifting when exiting a corner. Normally, loosening the body mount screws one or two turns will alleviate these problems. However, there are some design issues which require a little more effort for the Carrera cars.
A very common problem that can inhibit a free floating body is contact between the sides and/or ends of the body and the edges of the chassis. The Aston Martin side panels are a snug fit to the chassis and were definitely contacting, or catching on, the sides of the chassis, as pictured below.
Using a sanding or emery board, file the edge of the chassis along the area where the body panel is touching. The following photo shows the same area after sanding. Note the small, uniform gap that now exists between body and chassis.
The next issue, pictured below, are the rear body mounting post (left) and and the corresponding mounting base of the chassis. The base has a lip that surrounds the post and the post has two tabs (red arrows) that fit into slots in the base's lip. Presumably this is intended to maintain body/chassis alignment by preventing any horizontal play between body and chassis. The two front mounting post/base combinations are similar. This system of mounting is found in a number of slot cars. In the case of the Aston Martin, the combination of the lip and tabs creates a very tight virtual "snap" fit that effectively prevents any body float at all—even with the body mounting screws loosened.
One solution that has been used in the past is to grind/file away the mounting base's lip. But the mounting base's in this car are difficult to access for filing and this would still leave the tabs to possibly interfere with body float. So, I decided to deal with the mounting posts alone.
The following photo shows the modifications applied to all three mounting post(s). Approximately three millimeters of the tabs was removed at the end of the post, shown by the red arrow. Then the edge of the post's end was beveled (rounded) so that it no longer catches the mounting base lip when the body moves vertically or at an angle, indicated by the yellow arrow. The only tools required for this modification are a sharp hobby knife and a narrow emery board.
The body was reinstalled on the chassis and the three body mounting screws were loosened by two full turns from the tight position. The effect of introducing unrestricted body float was immediately positive and measurable. Lap times without a magnet were consistently in the 8.6 second range with a fast lap of 8.375. With the mid-chassis magnet installed lap times dropped to a 7.5 second average with a fast lap of 7.297. These are very respectable times on my track. More importantly, there was no chatter in the turns and the car exhibited no tendency to de-slot unless clearly overdriven in the turns.
The only remaining issue with body float was the mounting screws themselves. Carrera uses a relatively wide diameter screw with a deep thread. This was causing the screws to catch on the edges of the chassis mounting hole when the body moved vertically. Therefore, a 1/8" drill bit was used by hand to increase the chassis mounting hole size ever so slightly. Please note that I'm referring to the chassis mounting holes—not the body mounting posts. This eliminated the mounting screw rubbing problem. Now the body truly floated over the chassis, while still secured by the mounting screws.
The final action taken was to lower the guide flag. There are only two ways that I know of to lower the Carrera guide assembly. One is to lower the front ride height, either by installing lower profile tires or modifying the front axle bushing holders to allow the bushings to sit higher in the cradles. The other is to replace the entire guide assembly with an aftermarket assembly such as B-NOVA and a NINCO guide. Neither approach would fit with the goal of no additional expense and no significant surgery. Although I believe that the vertical position of the stock guide assembly is adequate, I decided to shim the guide flag to see if any advantage could be gained. The flag (or keel) of the Carrera guide is a separate piece that can be lowered with a properly configured shim. In this case, a #8 nylon washer with the sides trimmed to the same width as the guide flag's base. This allows the washer to fit snugly between the braids and keeps the vertical tab at the front of the flag positioned properly inside the slot of the guide assembly swivel plate.
The guide flag now sits about 1.5 mm lower in the slot as can be seen clearly in the following photo.
Lowering the guide flag in this fashion did not significantly reduce lap times, however, it did make them more consistent. Now there was a sense that the car could be driven a little harder into and out of the turns. I would consider lowering the guide flag to be less than critical to obtain better performance, but well worth trying, especially for no-mag running.
The following table lists lap times for all the various tuning steps and combinations of magnet placement. Lap times from the third row on were recorded after all tuning steps were taken. The final row times reflect the shimmed guide flag. These times are comparable to NINCO 1 PLUS GT's that run very well on my NINCO home track.
All testing was performed on my relatively twisty 61' NINCO home track:
- Power: Pyramid PS-26KX @ 12 volts.
- Throttle: NINCO 55 Plus.
- Timing: Lap Timer 2000 with homemade IR light bridge.
Tools required for all modifications:
- Hobby or utility knife with a sharp blade.
- Medium grit emery board or sandpaper.
- 1/8" drill bit (turned by hand).
Summary
The Carrera Aston Martin V12 Vantage is now, by far, the best running Carrera car on my analog NINCO track. And the only additional expense incurred was the cost of the smaller Carrera alternative guide flag which is obviously negligible. It's likely that performance could be enhanced even further with the aftermarket parts replacements previously mentioned. However, in my case the goal is not to compete with Slot.it and NSR. The goal is to optimize performance of a stock Carrera GT car on NINCO track. I believe that has been accomplished. The Carrera Aston Martin V12 Vantage is now fun to run. My preferred configuration is with the mid-chassis magnet installed over the spacer. This yields performance that is very similar to no-mag with just enough down force to allow moderately aggressive driving through the turns.
If you run on NINCO track and are contemplating the acquisition of a recent Carrera release, or already have one that is not performing as well as you would like, try these tuning actions. You will have virtually nothing to lose and I'm confident that you will be pleased with the result.
This article is a service to our slotting friends made possible by BRS Hobbies, who kindly provided the Carrera Aston Martin V12 Vantage "Young Driver" slot car reviewed here.
_Michael Ashton
