3 replies to this topic

[geardriven]

As I may have mentioned before, I race with a bunch of old timers down at the local hobby shop on a fair-sized four lane Scalextric Sport track. The track is on a layout of approximately 10' x 20' with four straightaways (approx. 16', 12,' 8' & 6' with a variety of connecting curves).
Many, if not all, of the cars are modified to one extent or another.
I have very successfully built a Scalextric Porsche 997 GT3 with Scalextric hop-up parts and I now have a Slot.it car to which I'd like to do the same.
It seems that the Slot.it car is a more technically built car and I don't want to error in my selection of parts.
I have a series of modifications I would like to do and have questions around these mods I am hoping that can be answered.

The car being used is a Slot.it SICA18b Ford GT40 with an Evo6 chassis/ sidewinder engine configuration.

1.) The engine selected is a 29K Slot.it motor. Does this chassis use the "S" can V12/29K plastic end bell type motor?
2.) Slot.it Rear tire (P6) designated for Scalextric track surfaces in a 19x10 size.....SIPT24s..?????
3.) This chassis shows provisions for the placement of two bar style magnets in the center of the chassis between the front axle and the motor. They appear to be a snap-in type like Scalextric and I understand their could be an additional provision for another magnet behind the engine. I see that the chassis is supplied with one magnet.
Can any one tell me by the Slot.it part number which is a matching magnet for the one supplied. And with two magnets, where on the chassis would be the preferred spots for placement????
4.)Lastly, gear ratios. The base set-up is an 11 tooth pinion/32 tooth spur. If I am running a motor with a wider and higher RPM band and range, can I gain more acceleration, with all other factors remaining the same by reducing the pinion diameter...say to 10t....? I can only suspect that top end speed would be reduced...?
Looking for some help here....thanks

[Michael Rigsby]

OK, I am presuming that you are using the Slot It SIMF-10 red endbell motor rated at 29K by Slot It? This should be a direct pop in replacement for the 21.5K motor that the car came with.

 

What kind of rules are you guys racing under.  Do you have a magnetic downforce limit on the car, and how are they measuring magnetic downforce?

 

The sidewinder motor pod should have two places for magnets in front of the motor, and one is at the rear of the car. Typically, when allowed to run two magnets, I placed one just in front of the motor, and used the magnet placement at the rear of gthe motor under the gear.  Again, this is going to depend on the rules you run under. The car comes stock with one SICN06 magnet.  You can either add another one of these to the rear under the axle, or if your rules allow it and you want more "stick", you can use the SICN07 Slot It race magnet. To keep these from coming out during a race during collisions, I always glue mine in very lightly with a hot glue gun, though some people use "Shoe-Goo".

 

As far as tires, the ones you mention are about right if you are limited to Slot It tires. If you are allowed any tires, I would suggest trying a set of Slot Car Corner's Yellow Dogs Urethane tires, or their own brand of Silicone tires. I know some track owners won't allow silicone tires, even though a few years ago Slot It gave you a really nice set of silicone slip ons with their cars. Despite what they say, silicone tires don't leave anything on the track, if anything they get dirtier quicker since they are so sticky. The track I run on which is a 105' Oglivie commercial track with Magnatech braid, I run Yellow Dogs on all my cars.  I also ran them on my home track before I sold it, and it was a 35foot Scalextric Sport track.

 

As far as gear ratio, that is something that you are going to have to play with.  I run nothing but the stock 21.5K motors in my Slot It's, and have great luck with them.  Most of my full race cars use the Orange endbell 21.5K motor with sidewinder pod, geared 12/29.  This gives me great top end and the cornering doesn't suffer. Once the motor is broken in, it will pull this ratio with no problem.  Now on your shorter track, you are going to have to experiment some. Maybe try and 11/30 or 11/29 and run it about 25 laps or so with each ratio and see where you stand as far as lap times. Going to a ten tooth pinion will make the car easier to drive in the turns, but I think you may lose more top end than what you want. So test, test, and then test some more.

 

Good luck, and hope my ramblings help some.

[Bob DeWoody]

We only run the 21.5k orange endbell motors in our slot.it classic GT and Can Am class here at DeBary Glen.  Basically the slot.It cars are so well made that the only change we make is rear tires.  

 

We use either yellow dogs or Paul Gage urethanes on the wood track and super tires silicones on the plastic track.  

 

We have a magnet marshall to check the magnet downforce and limit the maximum to 4X the actual weight of the car.  Example, an 80gm. car can have a max total downforce of 320gms.  This level helps with traction but is not so much as to prevent a car from deslotting if over driven.  

 

If none of your straights are more than about 15ft. long the stock gearing should be fine.  

 

The GT40 is a great car in the classic class and is a lot of fun to drive.  The new McLaren M8D is a blast too.

[pappyman]

We race in Apollo Pa. on a Carrera 4 lane track, 32' x 9' with lots of various turns and one stretch of chicane. The slot.it GT 40's are well liked and perform so very well. Our group runs 2 separate classes of the Can Am cars, Box stock and modified. Both classes are restricted to a maximum of 220 grams mag down force as measured by a magnet marshal. The box stock class only allows rear tire changes and chassis tuning as permitted by the stock chassis. In both classes, the tuning of the front axle height is critical to a great handling car. We prefer the Super Tires yellow dog urethanes for the best performance. The Silicone tires pick up too much dirt. Painting the front tires with clear nail polish also make a big improvement in handling.

 

The modified classes require stock chassis and no major body mods, and the tires must not extend beyond the body. Wheels and tires may be changed as desired. Motors must remain stock and are restricted to a max of 22,400 advertised RPM. That limits us to either a stock slot.it 21,500 motor, or an NSR shark 22,400 RPM motor. The shark has a bit of an advantage, but not as much as you might think. The majority of racers with the GT40's run the stock gears with good success, but as was stated before, test, test, and more test.

 

When it comes to gearing, keep this in mind about pinion gears; a 10 tooth pinion will improve the quickness out of the hole but will cause the car to use up the motor rpm towards the end of the longer straights. Also, keeping the same gear ratio while using a 10 tooth pinion versus an 11 or 12 will cause a noticeable increase in braking effect. I like to set my gear ratio first by listening to the motor where it peaks out the RPM. I will modify the gear ratio by changing the axle gear first until I get the motor peaking where I like it on the longest straight. If the braking effect is too strong, I then go up one tooth on the pinion and adjust the axle gear to get the same ratio as before, and try that out for a while to see if I like the amount of braking effect. Just remember, it is not just about the gear ratio that counts, it is the perfect mix of pinion and axle gears that get you to the, optimun fit.