1/32 Sprint car
by Abarth Mike
For all you Python fans...
"and now for something completely different"
...Well, OK not completely, but different for me.
Some of the guys here have X-Slot so I thought hmm? A metal chassis car.
After some research I found some 1/32 Sprint car kits and I decided as this is my first one to get it "RTR" and the fully winged sprint as opposed to the Sportsman sprint. Why because the winged ones look so cool. I ordered one from Hotlapsracin, but one could also get one from Bryner's Slot cars and I am sure there are more. I should add here that there are resin sprint cars available from Startline in Australia, but my objective was metal chassis.
Alongside stock plastic cars this one does not look 1/32nd. It is bigger more like 1/30 but that is limited in this case as the chassis has a wheelbase of 3 inches and is not adjustable. Sprint car regulations vary and chassis are adjustable so a wheelbase of could vary. 84 is "std" but 96 inches could be good for some tracks and is not unreasonable. What are not scale are the tires, especially the rears. Scale sensitive guys read no further. (NB. From website photos the plastic Aus. ones look smaller)
I was worried about doing the decals and the painting but in retrospect the details are stickers and were applied after the clear coat. This does not distract from the appearance because real racing sprint cars can look less than perfect by the end of the night.
Painting the lexan body may require different paint than conventional plastic cars, but I do not know. It should be relatively easy though to anyone already painting cars. So ordering an unpainted one would be OK, as there are lots of decal/stickers available. No tampo here.
As this is a hand built car so do not look for perfection. On the whole the car looks very nice, it sits squat on the track. The roll cage is painted but the side rails are not. It is "ready-to-run" but needs a good clean and polish to bring it up to "showroom" condition. Purists may say that it is a race car so a few dirty bits doesn't really matter. The bottom of the rear section of the body was a little uneven so I trimmed it with some scissors and the numbers are not level on both sides.
One can order whatever gearing one wants and there is a motor choice although most seem to be Falcon, Little Ripper or Death Star. There is also some tire choices and I spent many anorak hours researching 1:1 tire sizes but in the end opted for "standard" ones. I also spent time analysing track length vs motor RPM, tire diameter etc. with Excel spreadsheet and decided on 8/41 ratio with an additional 7T pinion. What arrived was what looks like standard 9/27 with Cox plastic crown with a packet of metal 7, 8, 9 and10T pinions. I paid extra for Death Star but during some conversations about tire material somehow I got a Little Ripper and some extra tires. I wanted a high revving, low geared car so I am a little disappointed particularly also as Pattos' instructions say Ripper should be geared minimum 4:1 and I already have a Ripper. But swings and roundabouts. My neighbour was laughing saying that the builder got three things wrong, the colour, the motor and the gearing. Maybe Dana from Hotlapsracin figures as I live in Thailand I am not likely to go knocking on his door. Maybe the later livery is red and I'll change to 7/27 and remain disgruntled.
(Edit. I wish to add that the above paragraph in retrospect may have sounded a bit harsh. It was not a complaint it is simply a story. I did not address the issues above with Dana at the time, as I was simply happy to have something pretty and unusual for beer and laps. I am not really disgruntled for me it is a very different and unique car and as I got extra tires there was no financial penalty on my side.
I should also point out that Dana knows I run on Scalextric track and as the motor I clicked on the order is not suitable for home power supplies, the one I got may have been supplied with the best intention
Dana said he will kindly send me the Parma motor and the 8/41 I asked for. I will reimburse him, as I do not wish to get something for nothing.
He also pointed out that the guide needs to thinned for Scaley/plastic track and each car needs to set up as all tracks are different. So add weight as one would do on any other non mag car.)
The front wheels are very nice I have not heard of Pro-Track before. The rears are Parma? sponge but as I said I got some extras which are silicone. All the wheels are hubless. The front axle runs in simple holes in the chassis but then some plastic cars are very similar. There is no slop nor is there in the rear bushings. The roll cage is attached nicely with the uprights sliding firmly into two tubes on the chassis and the body is attached with some slick things called "womp clips" that fit almost invisibly through holes in the side of the chassis. The driver/seat is moulded into the body and the paint job is as good as I would do. The guide is huge compared to 1/32 plastic cars and somewhat disconcertingly sticks out in front of the car. Another different thing about the guide is that it is a leading guide and not a trailing guide like most if not all plastic cars. What difference this makes if any I do not know. Running on plastic track the braids are too wide and rest on the plastic not the rail.
I took the whole thing apart, changed the gearing and reset all the clearances and lubricated it. I broke in the motor following instructions on Pattos' website and ran the car with rear wheels off the track for a few minutes. As it is all pretty basic stuff I will let the pictures do the talking.
So on to the track
Well the first thing one notices is that the guide height is wrong. With the wheels touching the track the guide is only 4.5mm into the slot. The standard fix, I have now learner, is quite easy just an O ring under the guide. This is not a std. plastic car guide, it is 3/16" dia, is threaded and secured by a 3/I6 nut. I should add at this point that the braids are about the easiest ones to change, I have seen. Put the wire in a slot and slide the braid into the guide. Presto.
This is supposed to be a review but it might turn into a rant. Now the (expletive) guide is too wide for scaley track. Half an hour with a file and sand paper and it is thinned down enough. The braids themselves are very thick and too wide for plastic track. Simple fix. Twist the braids so the inside edge is lower. Sorted.
(Edit: the O ring swelled after absorbing the oil I put on it. I went to 3/16 phenolic washers "turned" down in a drill press now it is perfect for me)
After two evenings playing; for handling on this car, size and weight think Fly Truck. It is very wide, slightly wider than a truck but two will fit on scaley track, only just.
It is much faster than a truck in a straight line but still has a tendency to tip. Paradoxically under throttle is will slide a little as well. The gearing is a bit tall for our track so it never reaches its full potential. It overruns under braking, I am not sure if that is weight or characteristic of the motor , so brake very early then get back on the power, no deep braking here. This is a good car to heighten the senses and get finger eye coordination optimized! It is so solidly built that when it de-slots, usually by tipping, it comes back down to earth with an audible thud.
Initially I was thinking it should have the higher torque? Evo2 motor and 8/28 gearing of my truck but the more I ran it the better it or I got. Our track is reasonably large for plastic with two 12m straights and a magic R3 200 degree turn; the car just squats down under power and goes around. At 10v the car does not even reach full speed. That is why I wanted 8/41 but.. I tried it at 12v and it was actually smoother because there is more controller (25 ohm) to play with. In a straight line this is now my fastest car. Up till now it was my Fly Alfa 156 (10/27) which has the Fly Racing 27,500 Fk-130 motor. (Edit: On a SpeedChecker at 12v this car registered 41kph compared to 38 for my Alfa and 26kph for the Fly Truck
In the beginning the "standard' sponge tires gripped well enough on plastic track for the car to tip over on a trailing throttle in the tighter turns But the more I got used to it the more juice I would give it and then it was easy to overpower the tires. I changed to silicone as the grip is better.
(Edit: now I have got used to the silicones, I will "siliconize" the sponge set as the silicones are the way to go. They do not appear to upset the track and cause following rubber tired car problems with grip)
With the wings it is very top heavy. As has been said it has a tendency to tip in tight corners. With the wing removed at 108 gms it has less tendency to tip and turns into a missile. For a tight track maybe one should not get all the wings, i.e. get the Sportsman version. But for me the wings make it a proper Sprint car. My drinking buddy sat near the 180 R4 turn combination and said it lifts the inside front wheel just like a real one. It even partially wheelies. Magic.
For comparison at 10V with my abysmal driving skills. Ninco 934 (std but optimized) 10.2 secs; modified 115g Ninco Supra with NSR components 9.6sec; Sprint car 11.2 secs (sponge),
If anyone would like more info please feel free to PM.
|Lo-Fi Version||Time is now: 31st March 2015 - 02:02|