Slot Car Drags

[Andy]

Tonight is the first Hellfire Hot Rods Slot Car Drag meet.

Back late last year I bought 2 Parma Edge slot car drag racing chassis off of Graham, the organiser of the Hellfire Hot Rods. Over the past couple of years he's been locked away in his garage building up a scaled drag strip, complete with Christmas tree, gantry, score boards and even a computer system that prints out RT, ET and a scale MPH.

After having a bash at it and setting the best RT and then ET of the day I thought I'd like to have a go at that. I did post up on here in the last eBay purchase thread that I had picked up a funny car model. As it turns out, that one died in a case of mistaking how strong thinners were when painting, cue the whole plastic body rejecting the paint and then going all gooey. Nevertheless I then went on to buy two further funny car bodies.

After a lot of procrastinating and having other stuff I finally got around to finishing off the building and the mounting of the body. As the funny car body is slightly longer wheel base than a standard 1/25 car, I needed to extend the front axle. This can be seen by the two junking great bits of Ally at the front with multiple axle holes to allow correct height adjustment.

So here it is in all it's glory, the Fruit of the Loom slot car funny car:











The body is held on with 1mm mild steel welding rods that have brass bushes to locate the body. All of them are soldered in place. The motor itself is a Super 16D which is apparently a very fast motor from stock. It's not meant to be hopped up but a few are looking at winding their own armatures, seeing as I do that for a job I'm also investigating it.

Have absolutely no idea if its any good, but will find out tonight. Ill try and take some photos and maybe even some videos.

[Roadkill]

Scaled-down coolness.

[Incursus]

Can't remember what happened to all my scalextric...probably still up in my parents loft

[Andy]

All ready to go after some final finishing touches at lunch. Trimmed the body rods so they sit flush with the outside. Using our granite test rig I set the front wheel heights and set the rear wheelie bar height. Took all the sideways motion of the rear axle and also wore in the rear bronze bushes, don't like them too much as they vibrate when spinning but that might just be because they have no load on them. Also wrapped the rears in masking tape and left them covered with the aim being when I pull it off some of the glue will stay on the tyres and they will be clean. For my own sake I also tipex'd on a white line on the walls just like the big cars do!

[Roadkill]

Quoting: Andy

I also tipex'd on a white line on the walls just like the big cars do!

[Andy]

Well that was fun, I thought I had it bad when I was up till 11pm last night putting transfers... one of the guys has a burnout procedure and everything.

Anyway, turns out straight out of the box it ran the fastest ET of the 'tune up' session. After that is started getting slower.

We ran three 16 car eliminations, unlike my dial in day I actually fared a bit better at this, not being first round fodder everytime! I even made it to the finals, which ended up being the closest race of the night, ok I lost to a 10 year old kid, he had me off the line, but from 1/8 track mine started pulling it back, the margin of victory being .002 of a second, which is scale size is f**k all!

There is obviously a lot of things to do to try and make the cars better, the track is nothing more than painted black wood which in the tyre area has lost its sheen, all the same my car wasn't able to hook up until the 1/8 mile when it really started motoring.

Heres the timing ticket from my last run of the night in the finals:



and heres the only video I got from when I was on car retrieval in the shut down area:

[Big Mouse]

lol, your scale speed is quicker than the Top Fuel range

What are the tyres made of? surface looks slick, but I'm guessing its not grippy?

[Andy]

Yeah, the scale speed is just a bit out! Was pretty interesting seeing how it varied depending on how well you got off the line and whether it picked up further up the track.

The tyres on the stock chassis are made from firm foam. I'm sure there is a technical term for it, but when it gets hot it melts and becomes a bit sticky. One of the guys was showing me during the testing time how it was just like a real rubber tyre and did leave a track on the track.

The surface was just painted wood to a gloss, there is no track prep apart from a dust pan and brush to get the crap off. Tyre compounds vary and one of the consistant fast cars of the night was running silicone tyres that he'd custom made himself with moulds and everything.

I think if I could nail getting going and making up for what is a poor 60' time I would stand a chance of having a fast car, as a lot of the races I ended up driving round them at the top end.

[Big Mouse]

On a real track the tyre compounds are designed to compliment the applied surface, ie VHT and the heat that builds up in the track - it can literally peel the shoes from your feet if you stay still too long. The stickier and hotter the track, the better the tyres will work and should keep you hooked up and straight (or so the theory goes, lol)

Given that the slot car runs in a slot there's not much chance of overpowering the track (or is there?) so I'm just wondering/interested in how important sticky is over weight distribution on a painted wooden track.

Do you get wheel spin?

Do you check the weight distribution over the drive wheels?

[Andy]

Oh yes you get wheel spin! The motors spin at 18k I can't remember what the exact ratio is from the motor to the axle, but I think the crown gear on the axle is 35 teeth, I imagine the pinion on the motor is somewhere in the region of 10 teeth. So if right, that's 3.5:1 = 18k = 5.1k rpm of the hit as these motors spin up so fast.

Weight over the axle is one thing I didn't really think about and can be something ill play with next I reckon. The wheelie bars don't really do anything as I think the front on mine is heavy enough.

What I need to do now is go away and figure out the best way to get the thing to hook up. There is likely to be no real track prep as really it's just a bit of fun but the guy said there is no limit to what you can do to the cars. He also showed me the SCRA (I think) rules and regulations that stretches to 14 pages in small print, he then showed me his appendix with said pages 1 thru 14 are deleted, instead just have fun.

Dave has gone away with the idea of playing with a DC to DC converter in the hope to get his motor to spin faster!