Turbo Optima build - Project Barney: Finished

[Coelacanth]

I had an issue with too much positive camber on the front. The long control arm set I purchased came with its own C-carriers. I wanted to use these nice alloy purple ones (GPM #KF4019), however. They fit just fine and were otherwise an easy swap-in upgrade. I discovered that the design of the alloy C-carriers incorporated an angled region that acted as a camber block. Unfortunately the control arms prevented this region from moving within the outer notches of the arms to give me the slight negative camber I was looking for.

It was solved by doing a bit of grinding of the inner, upper edge of the foremost "notch". Fortunately, very little material had to be removed, so it shouldn't negatively affect the arm's structural integrity that much. The pics show where I had to Dremel a bit of the arms to allow the alloy carriers to rotate enough to resolve the camber situation.

The front swing shafts used are Kyosho 62.5mm units, the same length as the stock Optima dogbones. I had to switch the axles though, I wasn't getting enough axle thread to mount the front wheels. I believe I swapped the axles from LA258 60.5mm CVDs (which have 3 grooves in the axles) onto the bones of LA245 62.5mm CVDs (which have 2 grooves/shorter axles). The 62.5mm bones with the longer LA258 axles was perfect.

[Coelacanth]

I also got the steering linkage dialed in. I used HPI #93467 34mm titanium turnbuckles (which are actually 35mm) for the camber links and Schumacher #U1573 53mm titanium turnbuckles for the tie-rods.

I'm giving Barney some good clearance, I don't want this car knuckle-dragging and drooping in the dirt; I want it to stand tall and be solid-as-a-rock, for everyday bashing.

[Coelacanth]

I got a lot accomplished this afternoon! With the front end tweaking done, it was time to focus on the rear.

As mentioned before, the rear arms are el-cheapo $6 #DF2056 GPM arms (originally blue and were de-anodized, polished, and re-anodized purple.) They're almost exactly 5mm longer from pin-to-pin than stock Optima arms, which is great. I wanted to widen the track a bit to make a more stable ride. I found that 65.5mm Lazer universals were a tad too short, though; fortunately in anticipation of that possibility, I also purchased 68mm units, they were a perfect fit. I had to grind their flanges down like I described earlier with the 65.5mm joints.

The turnbuckles I used for the rear camber & stabilizer links are all 29mm titanium HPI #93464. The purple stab ball set is HPI #72302 with 4.8mm Delrin ball-ends. I used the top mounting hole in the rear Turbo Optima shock tower to mount the ball studs for the camber links so that they'd be more parallel with the arms & U-joints.

Rear stabilizer installed; had to drill & tap my own holes in the GPM arms for 3mm-threaded 4.8mm ball studs.

[Kayne]

That looks awesome. I love the colors .

[Jay Dub]

Currently doing something similar (axle/cvd install) on my pro radiant. The 62.5 mm bone, with the 3 ringed axle comes as a set for the original RB5. P/N UM 510. -Jeff

[Coelacanth]

For a change, I had some free time this evening and got around to fabricating a carbon fiber front shock tower so I could mount a pair of full-size Kyosho Gold shocks. Ideally, I would've liked the design to have a horizontal bridge on top to add strength, but the Optima body's front "nose" wouldn't have fit through the square hole. So, it was either cut off the Optima body's nose or use an open shock tower design. I'll see how this holds up, it's 3mm thick carbon fiber after all, it might be plenty strong. I can always re-fab another mount with a bridge and cut off the nose if need be.

As it is now, I like how trim it looks; the verticals are wider than the stock aluminum tower's are, and it's about 3 times as thick, and made from something a lot stronger than the thin aluminum front towers.

A couple other minor mods: these front arms had 3 holes for the shocks to mount into. I drilled & tapped my own holes about 5mm outboard of the outermost holes, to give the long shocks a flatter angle, allowing me to minimize my custom shock tower height. Next, my large-diameter springs & spring cups were binding with the control arms at the angles I was planning to mount the shocks. That was quite easily resolved by adding a purple spacer onto the shock shaft before screwing on the ball-cups. The outer diameter of the spacers fit perfectly inside the spring cup recesses and pushed the cups upward enough to clear the control arms...no more binding.

[EvolutionRevolution]

I hadn't noticed the spring color yet. Is that also custom-coated?

Where did you get the spacer?

[madmaxx]

Awesome work Mark !!!!!!

[Coelacanth]

I hadn't noticed the spring color yet. Is that also custom-coated?

Where did you get the spacer?

The spacers are 3Racing...search eBay for "3racing m3 washer" and you'll find 90 hits, washers of every color & thickness.

The springs, that's another story...I wish I could be more helpful but I was searching an online store that sold Integy stuff and was searching "green springs" or something and found these in their clearance section. I never saw any shiny green springs ANYWHERE on eBay, all the ones I saw were the plasti-coated kind, which I don't really like. These were 8 per set, the thickness & inside/outside diameter I was looking for, but the springs were all much longer than I needed...so I cut them to suit my needs.

[Diggley]

Looking forward to seeing this one when it's done.

That chassis is awesome!

[Coelacanth]

I got some suspension tweaking done tonight, it's more or less just as I was hoping to accomplish. Barney now has full-size front shocks like all the OTHER race cars out there! One weakness of the Optima series that I wanted to address were the aluminum shock towers, which are notorious for bending all to hell after some rough roof-top landings, especially the rear one. As mentioned before, the stock front tower (if you can call it a tower) was backed by a proper 3mm thick CF tower.

I had to figure out a way to fabricate a rear shock tower brace (of sorts), something just a bit wider, just a bit longer, and mounted directly behind the stock aluminum tower, to hopefully strengthen it. I used a piece of 2.5mm CF cut from a scrap I bought from eBay (carbonfibersuperstore, I think)...that arrived only gloss-finished on one side. (I positioned that side towards the stock tower so you can't see it.)

The CF towers themselves were finished by blacking the edges with a Sharpie marker before applying CA glue to prevent delamination. I had to use screws that were about 2 - 3mm longer than the manual-recommended screws to properly mount the CF towers (perhaps obvious but worth mentioning).

Some test-drops from 2' high onto a table, and 3' high onto my carpeted floor both with the car horizontal and dropping at weird angles seems to indicate the suspension is working great--not even a hint of rebound. I'll have to adjust some things once the chassis is complete and weighs quite a bit more, of course. Steering & suspension all seem free of any binding, at this time anyway.

[Coelacanth]

Why does it seem that with every project I work on, I run into the "missing part(s) roadblock"? I'm getting close to finishing off the chassis and--hardly surprising--I can't install the steering servo because the Optima's little square servo mount with the 4 posts has gone missing. Happens every single time!

Rather than spend hours of time searching for one, paying exhorbitantly for it, and waste time waiting for it to arrive, I figured I would try to fabricate my own from some carbon fiber scraps. We'll see how that turns out tonight.

[Mr. ED]

curious: I may have to copy that 'cause my optima seems to miss this part too...meaning I have no clue how and whre to mount a servo in the stock shape the car is momentarily still in

[Coelacanth]

curious: I may have to copy that 'cause my optima seems to miss this part too...meaning I have no clue how and whre to mount a servo in the stock shape the car is momentarily still in

I fabricated one from 2mm thick carbon fiber. 3mm thick would make drilling countersunk holes a bit easier. The dimensions of the stock piece are about 32mm by 30mm, and the hole spacing is approximately 28mm by 26mm. The original part has 4 screw standoffs. I figured 4 spacers approximately 5mm long would be an ideal switch...this was important as the servo mount also functions to affix the upper chain-guide to the radio plate. I'll update tomorrow with some pics, the custom mount installed great & with the purple alloy spacers, looks better than the original.

The only thing I don't care for is I had to use 4-40 flat-head screws & nuts, the screws threading up from the bottom through the servo mount, spacers & radio plate. The nuts on top kind of stand out and take away from the sleek look, they look a tad clunky compared to all the RCScrewz everywhere else on top. Nothing mounts there anyway so functionally it's not a problem, it just takes away from the aesthetics, IMHO.

[Jay Dub]

You could use threaded stand offs. Short screws from the top and bottom- That would look SWEET. -Jeff