Last weekend I raced at TCM (German Touring Car Masters) and while I couldn't really score there, I made some new friends, met people I had only known online before, did a lot of screwing around (in verbatim sense) and had some serious fun. Among others I met Dai Sakaguchi and Ronald Völker, who turned out not only to be extremely cool (watch him racing...), but also an explicitely nice and openminded guy.
When I showed my little belt tensioner / battery post mod
to Dai - who also had a Raceberry Tamiya based on the 417X like me -, he soon came up with some ideas to improve it. So here we go, *** Raceberry mod V2 ***...
First, Dai found that there's a screwhole at the Yokomo motor arm that just seemed to fit for a belt tensioner. Also there's another screwhole at the servomount, which can be used for a second battery guide, so the battery is better held in place. A nice sideeffect of using the belt tensioner hole at the motor arm is, that the belt doesn't run as steep as with my first mod. So this eliminates the need to put shims under the steering assembly, which had some adverse effects on steering when the car leans to the outside of a corner. Instead the steering assembly can be put back directly onto the chassis, we just dremeled some material away from the bottom of the steering arm to have enough clearance for the belt.
When I discussed with Dai my uneasiness about having so many shims around the bulkheads (0.5mm under and 2mm above), he agreed that it would be desireable to have the bulkheads directly on the chassis again. He also thought that would make the car less prone to tweaking and he preferred a low center of gravity and low diffs anyway.
We tried the low COG at the race by putting the 0.5mm shims from under bulkheads on top instead and found the car to be a lot calmer and more controllable at once. It has to be said though that this was on high grip carpet. On low grip asphalt this might be a completely different story.
Anyway, we still both desired to eliminate as many shims as possible. So Dais final solution was to take away 2.5mm of material from the top of the motor arm and some material from the top of the spur gear holder (just enough for it not to touch the top deck) and mount the top deck directly on the bulkheads.
I found that a little too radical for my taste. Also, with the top deck coming down 2.5mm, there's less space for the pinion and the motor will touch the top deck earlier when being mounted in a back position. This both leads to less variability of spur / pinion combinations or less possible FDRs with the same spur. Also I guess thet the flex characteristics of the whole car may be altered in a measureable extent by reducing the height of the top deck by around 10% (from 28.5mm to 26mm).
So my light version of this mod goes like that: I removed 0.5mm from the top of the motor arm and replaced the 2mm shims under the top deck by 2mm thick pieces of carbon that I took from an old, broken top deck which just happened to fit my needs. I glued those pieces to the bottom of the Raceberry top deck and redrilled the holes, to regain that little amount of play that allows for detweaking the chassis. By glueing the carbon under the top deck, I hope to eliminate one place where the chassis can be tweaked.
Comments are welcome as always,