Sunday, December 30, 2007

Tamiya TB-02D DriftSpec chassis build

Although Tamiya's TT-01D chassis is very popular amongst r/c drifters (based on my WWW research), quite possibly due to it's general availability and the value for money it offers, I decided to go for the more expensive TB-02D as it has a number of features I wanted. Specifically, a metal prop shaft, oil-filled dampers, ball diffs and (perhaps most importantly) Tamiya's new "Super Driftech" tyres - more on those later.

As far as I can tell, the TB-02 (no 'D') is an end-of-life product. Tamiya apparently decided to modify it specifically for drifting, though, and use it as a launch platform for the abovementioned DrifTech tyres. The official product description and photos can be found at http://www.tamiya.com/english/products/49458tb_02d/index.htm

To the best of my knowledge this chassis is not sold in Australia. I purchased mine from an eBay store in Hong Kong (user ID hongkong_cowboy). As fate would have it, it arrived on Christmas eve. See the following photos, and note that the shrinkwrap is still in place on the first one - such self control :-)




























Part-time assembly ran from late on Boxing Day to Saturday morning 29th, when the electrics (including LEDs) were completed. As with other Tamiya products I've worked on, the assembly instructions were clear, but a little too concise in places where more detail would have helped. For example, fitting the tyres to the rims required that I soak the tyres in hot water (as hot as I could stand with bare hands) and use of a vice - which is a lot more than the "fit into grooves, apply instant cement" offered by the manual. The instant cement, by the way, is superfluous.

I deviated from the instructions in some other ways, too:
- ceramic grease was added to the motor pinion and propshaft spur gears
- the radio receiver antenna wire was run around the chassis rather than into a whip protruding from the body
- ball joints supplied with the TRF dampers replaced the standard chassis items
- the front body mounting posts were installed so the snap-pin holes ran north-south rather than east-west.

Additionally, impact absorption was added to the sides of the tub (to support the body), and padding around the battery bay.

The assembly instructions set the suspension geometry for drifting:
- negative camber on the rear wheels, none on the front
- toe out on the front wheels, none on the rear (without aftermarket mods, the rears have no toe adjustment anyway)
- wider track on the front than the back (by use of a spacer in wheel hubs)
- firmer spring settings on the rear than the front.

At first it displayed a strong tendency to understeer. I corrected this by tightening the rear diff. See the following photo for the section of the instructions that shows how the ball differentials are assembled. The amount of slip is controlled by the tightness of bolt & nut MA14/MA15. I found that less than half a turn did the trick.






















The resulting chassis is shown in the following photo. I've tried it with both the Type D (fitted for this photo) and DrifTech tyres and, trust me, it drifts! (especially with the latter) :-)))))

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Sunday, December 23, 2007

Tamiya NISMO R34 GT-R Z-tune body build

For the interest of other club members, and to prompt my memory should I build another, I thought I'd describe my experiences detailing this body. It's Tamiya part 1246, purchased from OZ-RC for $50. Note this is my first time working with polycarbonate, having previously only dealt with polystyrene scale models.

I found the included instructions easy enough to follow, but had I read them more thoroughly before starting, I could have bought 3 less cans of paint (& saved $30). Specifically, the black polycarbonate paint for the front spoiler, the black acrylic paint for the rear spoiler and the transparent smoke paint for the windows are all made redundant by decals. Yes, I knew there were outer window decals supplied, but I didn't realise that they were translucent until I started removing one from the backing paper... lesson learnt.

First step was, of course, to carefully wash the inside of the shell in preparation for painting.

The inner window/light mask shapes are printed on Tamiya's excellent masking material and, following the application steps described in XXX-Main's videos (available on utube), were easy to apply. The next two photos show the result. The miscellaneous bits of tape around the shell were to patch up small holes in the protective outer membrane, and other attachment holes - probably not required but I didn't want to take a chance with overspray.



















Next was spraying the main body colour - I used four coats of Tamiya's PS-12 (silver), starting with a very light 'dusting' as recommended. I found that it was not necessary to do the standard cleaning of the spray nozzle (holding the can upside down and spraying 'till there's no colour), in fact all this did was waste paint I would have liked to have for the final coat. There are areas around the roof/pillars that are too thinly covered for my liking.

I then removed the front spoiler mask and sprayed PS-5 (black). I covered the entire inside of the shell to make the silver more opaque. Then I removed the window masks (except the front window) and sprayed two light coats of PS-31 (smoke), removed the front window mask and did two more coats. This was intended to give the impression of the front window being less tinted than the rest, but it wasn't as large an effect as I'd hoped - this was corrected later by using the outer window decals. The remaining masks were removed, and I cut out the shell using scissors (one pair large, one pair small curved). The following photos illustrate. Note the rough edges to the cutouts. Also note that the rear spoiler and wing mirrors (not shown) were spraypainted at this time.



















I used a rotary tool with a course sanding attachment to better shape the wheel arch cutouts. I couldn't justify the price of a genuine Dremel, so I bought an Ozito brand from Bunnings - a bargain at $43 for everything including the table stand and flexible drive shaft. To finish off the cutouts, I used 320 grit wet-and-dry paper. Then I removed the protective membrane from the outside of the shell.

The outer decals were a bit of a challenge, being (strongly) self-adhesive and going onto a high gloss surface they want to 'grab'. I'm used to water-slide decals, which are much easier to apply because they allow for some movement after placement. However, I recognise that they would not be nearly as robust as the ones supplied. My original intention with the window decals was to place them, and then cutout the 'glass' sections so that the surrounds/trims remained. Although not obvious in the following two photos, I did this with the front window but not with the others. I'm happy enough with the result, but there are still some bubbles that remain to spoil the effect slightly. Overall, I recommend that the technique outlined in the XXX-Main videos be followed. Also, trust Tamiya when they say to place the decals in numerical order - this is particularly important with the tail-lights. On that subject, I was very impressed by how the they designed 2D decals to cover those complex, compound curves. You can also see in these photos that the rear spoiler and wing mirrors have been fitted. What you can't see is that the mirrors have had silver foil applied to them from an old sticker I had lying around.




















Finally, here's a detail shot of the headlight assemblies, the last thing I fitted to complete the body, a shot of the body sitting on my newly completed TB-02D chassis (a separate post details this chassis build) with Tamiya's Type D drift tyres fitted, and front/rear shots with the lights on (and Tamiya DrifTech tyres fitted):




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