1239-Cc3 / Nothing Is Easy

[CMF3]

The next installment in the 1237 design progression, for all you scratchbuilding slot gar geek types, with the continuing album-oriented thematic nod to elder aficionados of music trivia.

It turns out I had more time to work on this chassis than I had thought I would. After my back got better, the following week Joey (“The World Famous Slot Car Dog”) had his back start giving him problems again; hey, I love playing with slot cars, but my pup-dog takes priority, you know? So, while I was taking care of him, I finished the 1239-Cc3.

The change from the predecessor 1238 to this 1239 chassis is the incorporation of front axle rails (FAR’s) along with their variable spring wire (VSW) adjustors. The left and right FAR’s each consist of two sets of rails (3x 0.032” wire each) flanking both sides and attaching at the rear of the buttress rails (4x 0.032” wire each). There are now two VSW tubes with adjusting screws, one for each left and right FAR, and are attached atop the buttress rails just forward of the bite bar’s articulation with the buttress rails.

This first picture is after completion of the 1239’s main framing (the FAR’s have not been added yet, as some superstructure components must be added before their installation). I added this photo as a matter of interest because at this point the frames of the 1238 and the 1239 chassis are exactly the same, so it helps to show the intended adaptability of the original 1237 design, and…




Okay, maybe it wasn’t all that interesting. But I’m easily amused…

Spacing considerations for the 1239 (and 1240) had to be given consideration before the finalization of any of the 1237-based designs. Of note, there had to be sufficient length for the front axle rails’ spring wires and their adjustment housings between the front axle and the articulations of the bite bar atop the buttress rails. Keeping all the components in relatively consistent locations, besides easing the construction process, helps to eliminate the variable of structural differences when comparing the differences in chassis characteristics from one chassis to the next (something I learned, the hard way, on the 1219-based designs/builds).

Yeah, I know, shut up and just put up the pics fer-cripes-sake…

The 1239-Cc3:












This one definitely starts to fill in the spaces. Comparing the mass of this chassis to the predecessor 1238-Cc3 at 93.6 grams RTR, with the addition of the FAR’s and their VSW’s on the 1239-Cc3 here came out 6.4 grams heavier to 100.0 grams. That number was purely accidental, and I had to weigh it a couple times to make sure I wasn’t imagining things (a necessary step I seem to perform more often as I get older…). As a matter of further comparison, the similarly component-oriented 1219-based design chassis, with the same dimensions and 0.032” wire framing, the 1229-Cc3, was 104.6 grams RTR; the 1239-Cc3 is 4.6 grams lighter, despite having the added mass of separate left and right VSW’s. Cool!

Okay, at this point some of you are no doubt aware I have built three chassis since the 1237-Cc2 that have not had any test runs. I know I was aware of it. If the 1237-Cc3 turned out to be another disaster (like the spectacular but nerve-wracking 1225-Ca3), it would mean I just wasted a lot of time on the 1238 and 1239… Yeah, right… Like I worry about slot cars… I enjoy slot cars immensely, especially designing and building them, but I’ll be danged if I’m gonna lose any sleep over them… Still, it was a possibility… “Failure is always an option.”

So, next up…

[CMF3]

It’s about friggin’ time. Huh?

Made it, finally, to Fast Eddie’s Raceway last night to try these cars out on the Hillclimb. (For those keeping track, pun intended, Joey, still not fully recuperated, did not go, some noting his absence.)

Let’s get right to this.

1237-Cc3 versus 1237-Cc2:

After running the previously tested 0.039” wire framed 1237-Cc2 for some laps, I put on the 0.032” wire framed sister chassis the 1237-Cc3. My recognition of the smoother handling and drivability from previous 0.032”-0.039” chassis comparisons on the 1237-Cc3 was immediate, like in the first lap. Slightly quicker, and more consistent, as well as being able to be pushed harder, and at the same time more forgiving. And happily, with some relief, it showed none of the bad traits I’d learned on the 1225-Ca3. Oddly enough, this pretty much relegates the predecessor 1237-Cc2 chassis to the role of dust collector. Slot car chassis life spans can be so short…

1238-Cc3 versus 1237-Cc3:

So now it is time to compare the effects on handling characteristics by isolating the guide mount and adding the indirect main rails (IMR’s). These two chassis are so similar on the track, the only difference being the ability to go a little deeper into a turn with the 1238-Cc3; in other words, it will save your behind when you screw up. I drove these two chassis more than all the others. It was a blast! I’d beat the time of one with the other, then top that time with the first one, and then… This went on for a while. But after many laps I had to give the nod to the 1238-Cc3, finally pushed to a 0.02-second quicker lap time, and for the aforementioned saving my behind numerous times. Really, that was some serious fun!

1239-Cc3 versus… uh… nothing, really…

So I put the 1237-Cc3 away, and began to test the 1238-Cc3 versus the newest in the progression, the 1239-Cc3. Okay, that was the plan. I put the 1239-Cc3 on and it ran like poop… the really stinky smelly kind… when it occurred to me I’d forgot to set any of the adjustment screws… duh… So, I went back to my boxes to set it up… at which point it occurred to me I had no idea how I should set the three adjustment screws (bite bar; right FAR; left FAR). Hunh? Okay, so I took a big WAG at it; I set the bite bar screw at minimal positive pressure, and for the FAR’s I turned them down about two-thirds, with the left screw slightly tighter (lead on, high bank deadman) than the right screw (180, kink, donut). And put it back on the track… Lights out! Without trying the 1239-Cc3 ran more than 0.07 second faster than the 1238-Cc3, whose best lap I was not able to better. And then, not even trying, running the 1239-Cc3 I turned even faster laps, eventually topping the 1238’s best lap by 0.15 second… Considering I’d been running the 1238 for quite some time and knew it well, and only ran a few laps on the 1239 with shot-in-the-dark settings, that was enough for me. There is no comparison. The 1239 is that much better. In a few laps it completely obsoleted the other three chassis.

Epilogue:

It should be noted, for those doubters out there, that for these test runs I set up all the cars as close to the same as possible; same bodies all set up the same (except for the color between the white and black), same guides, wiring, gearings… and motors, which are a bunch of mediocre but rather consistent PS-4002B’s in my inventory.

Unfortunately I was also trying a few set up changes last night on the 1229’s and 1233’s, all of which ranged from “pee-yew” to “won’t-do-that-again”. This meant I didn’t get any reasonable comparison of the 1239-Cc3 versus its similarly component-oriented 1229-Cc3 counterpart, or the 1233’s. Duh.

So more test runs are needed. I also need to play more with the 1239’s settings to get a better understanding of them before jumping into the 1240… in a perfect world. We’ll see.

Did I mention this was a lot of fun?






Later!

Rick