Project OptiMutt - Finished

[Coelacanth]

I'm all about form, but never at the expense of function. And honestly, I didn't like the way the sheathing looked, either. Where things bulged, and at the ends, it looked terrible. So, IMHO, I got appearance and practicality together.

[jwscab]

I'd have to agree on ditching the split loom. a couple of well placed black tie wraps is all you really need. looming works best when you can make long runs of it.

as for the plastic braiding stuff, the trick with that is to use a ring of heat shrink at the ends to both secure and hide the frayed/melted edges. if it bulges in the middle for whatever reason, another heat shrink ring works well.

actually, just a few well placed heat shrink rings would also work as well as the tie wraps.

[Coelacanth]

Thanks for the heatshrink tip, I forgot all about that. I needed the reminder. I'll stick with the split loom though as I like the better protection it affords for moisture & dirt, and use heatshrink at the ends.

[Coelacanth]

Guys, how is the undertray mounted on the Optima Mids? I have a regular Mid manual as well as the Turbo SE, neither shows an undertray, so I'm thinking this was an aftermarket idea. I'm guessing some Velcro and maybe a few screws? I'd rather limit or avoid screws because the Turbo SE already has counter-sunk screws on the bottom; if I screwed on the undertray, I'd have to use normal screws which would protrude.

[Coelacanth]

Ahh, a free evening and some updates, I got some work done on the front end. I received some Kyosho Maxxum front arms from Jay Dub, I've used them on my Barney car and I love 'em! Thanks Jeff! They mount up exactly like an Optima/Turbo Optima arm does, they're a straight-across swap that requires no modding. Since the dimensions of the Optima Mid's front arms are pretty much the same, the Maxxum arms are a nice upgrade. Even the Mid's stabilizers can be reinstalled in the exact same locations.

That's not to say the front end was easy (so far)...I had to put a lot of work into thinking about this, with some trial-and-error for parts fitment.

I had to go with those stiffer blue springs because the stock Kyosho front springs weren't returning the arms all the way down after compression. The C-carriers are Kyosho Ultima SC/RB5 units from ST Racing. I'll be modding some 3Racing knuckles for the Lazer ZX-5 to fit (they'll need some filing top & bottom).

As the Ultima carriers have the hinge pins on the bottom inner corners, and the Maxxum arms are so long and intended to use carriers pinned on the bottom outer ends, mounting the Ultima units on the Maxxum arms would've pushed out the wheels too far, the front track would've looked too wide, and probably quite goofy. (Also, I don't think I have turnbuckles & tie-rods that would've been long enough.) So I carefully measured and drilled new 3mm holes in the arms to relocate the carriers approximately 14mm inboard, so the outer ends are pretty much flush with the ends of the arms.

Once the arms with carriers were installed with spacers wherever needed to eliminate any play, I had to find a way to install the camber links so that there won't be any bump-steer. I didn't have a lot of options but the links are parallel with the arms so I think the suspension will work quite well. I also hope I can manage to install the tie-rods parallel too.

[1300GT]

That's turned out reallly nice Coelacanth. The colour combo is great. Chris.

[Coelacanth]

I got my Lazer ZX-5 knuckles shaved down along with a bit of filing on the upper inside surface of the ST Racing carriers. I had to drill out the threaded holes in the Lazer knuckles as they're intended to work with screw-in kingpins, while the Ultima uses a hinge pin & e-clips. I liked the Ultima's simpler, lighter design so I had to drill out the threads enough that the hinge pin would pass through. The pic shows a comparison between the modded knuckle and an unshaved one.

With the parts lubed and reassembled, there's almost no resistance whatsoever, the knuckles flop easily back and forth; I think my brand-new Optima builds had even a little friction, but not this car. The steering with that bellcrank is soooo smooth! I installed some titanium turnbuckles for the tie-rods, turned on the radio and couldn't resist testing the steering. Let it center and adjusted the tie-rods.

I also tested the front suspension and it's smooth as well, no binding, and no dreaded bump-steer. I think with the slightly wider front track, this car should steer well and be very stable when cornering...we'll see. OptiMutt is finally starting to look like a car!

[j0pp3]

Wow! Creative solutions as always, Coelacanth. Your builds are always inspiring. For a 2WD it looks like a heavy tank. It would completely mangle any other 2WD in a battle

[Coelacanth]

Wow! Creative solutions as always, Coelacanth. Your builds are always inspiring. For a 2WD it looks like a heavy tank. It would completely mangle any other 2WD in a battle

Thanks, j0pp3! Although I'm not yet at the final weigh-in for this car, it might be surprising to some that this car doesn't weigh as much as one would think. The original box specs for the Mid states a weight of 3.31 pounds, or 1501 grams. I assume that's the weight of everything excluding the battery, because kits didn't come with batteries back then. If so, I'm aiming for this car to be in that neighborhood, even with all the alloy parts added on.

I got the body trimmed last night. I'll be re-mounting the Litesink on the opposite, inside surface of the motor plate instead of the "correct" location as I didn't want to have to cut large sections of the body away for it to clear the heatsink. I've come up with a cool idea for airflow to the heatsink, as putting a heatsink underneath a body isn't a great idea for cooling, less still if there's an undertray. Might have some update pics tonight. The body I chose looks wicked. This won't look like your everyday average Mid.

[Coelacanth]

FINALLY finished trimming, tweaking & modifying the body & wing! It's not a part of the build that I really enjoy much, actually--I'm paranoid of having the X-Acto knife skip and make a mess.

I liked this body from the moment I spotted it, a year or two ago, before I even had a Mid. I like it because the body itself is kind of like a wing. The way it's shaped--wide and flat with vertical side fins--should provide plenty of down-force as it kind of channels the air just like a wing would. Theoretically, anyway.

Anyway, as mentioned before, I re-mounted the heatsink inboard of the motor plate instead of outboard, so I wouldn't have to chop out a couple inches of Lexan just so the body would fit over it. Sure, it fits nice and snug in there, but with an undertray, this presents an airflow problem. That heatsink & motor wouldn't get much cooling unless I did some modding.

It was easy enough to cut out a rectangle windshield section, but that would only let air in. For cooling to be effective though, you need an exhaust outlet to release the heated air. I noticed just by luck that this particular body has a nice roof-line and a kind of louvered section at the rear, where the rear window would be. I cut out a little sickle-shaped exhaust window there that fortunately follows the body lines. I think this will work quite well.

[keithrc]

It's looking good Coelacanth, do you have colour sceme in mind for the body?


Keith

[jwscab]

what body is that?

[Coelacanth]

what body is that?

It's a body by JG Mfg. for the Mid, I saw it while going through all the items for sale by TBG.

http://www.ebay.ca/itm/150999689003?ru=http%3A%2F%2Fwww.ebay.ca%2Fsch%2Fi.html%3F_from%3DR40%26_nkw%3D150999689003%26_rdc%3D1

Keith, I have a paint scheme in mind...I just hope it turns out like I'm hoping it will. If so, it'll be a very dark metallic blue with red & orange pearl stripes and probably some gold accents.

[losiXXXman]

Cool project Marc! I'm excited to see what you lay down for paint, but even more so to hear how it runs. I'm a little concerned about the lack of caster on the front of a 2wd, BUT i think it may just be right - being a mid and all. Of course, I don't think your intention with the car was a hard core racer anyway.

[Coelacanth]

The front gearbox is angled to provide a small amount of kick-up, but maybe only a third of what typical RWD cars have. The way the front arms pin onto the gearbox/deck is simple enough, just an e-clip on either end of the pins, so if it doesn't handle well I can just bend up the front section of the chassis plate to give it more kick-up. Of course, with so much being modded & altered from the original chassis, only a few test-drives will tell how it handles.

What driving characteristics would I expect from a more neutral caster vs. a more positive "typical 2WD car" caster? From what I've read, it might be more twitchy without the kickup...?