Optima Mid Runner Budget Build to LWB conversion

[XLR8]

So, while Kyosho went with four-pack on the left, aftermarket went with four on the right. I think Schumacher also went with four on the left. Interesting.
Off-road in North America race clockwise (most turns are right), was this also true in Europe and Asia?

[XLR8]

Attaching the servo to the new main plate using the original mounting blocks will require a couple new screw holes (I don’t want to mount it with tape). Placing the servo and marking the holes isn’t too difficult but I guess there’s some risk of drilling the holes in the wrong spot. I have this cad model that I made a while back so, I reckon, why not use it.

BTW, I think the ESC fits very well on the right side, the cables will reach the motor okay, etc. I plan to extend the switch wires so it can be mounted back near the wing mount for easy access.

If I were to simply mirror the servo’s location to the left side (as shown here), this won’t provide much space for the RX. In fact, it’s really crowded in this model.

Simply moving the servo forward could cause it to collide with the bell crank and/or the undertray. There is ample space for the Rx on the right side ahead of the ESC. However, I remember back in the good ‘ole days of AM, I would never attempt to place these two components so near each other due to radio interference. With a modern 2.4ghz systems, would this still be a problem?

[GoMachV]

nice work on the cad model

Pretty sure you will have no interference issues with modern. Heck, they don’t even run caps anymore haha

[XLR8]

Thanks Jeff.
I think I'll switch to a Futaba 6g Rx. It's a little narrower and will fit easily in either location.

Anyway, I've updated the template to include my servo screw hole locations.

I'm ready to print the template and head to the drill press.

[matt1ptkn]

nice work on the cad model

What he said!

[XLR8]

Thanks Matt.

I don't know why Kyosho didn't add 2.84 mm and a threaded hole to the steering rack's pivot posts so they can also be secured to the upper deck. It seems that this could reduce or maybe even completely eliminate all deflection in the steering system and make steering inputs more precise. Anyway, I think I will go ahead and do this while I'm building the car. Also, I think I'll add a band (probably a tie strap) to the servo saver's plastic *spring* to further tighten things up.

[mikea96]

Any updates?

[XLR8]

Hi Mike,
I was about to ask you the same question.
Most of the chassis work is completed. I have the body, undertray and wing trimmed and painted white. I need to finish the body with black window paint and the matte black accent on the exterior at the back and apply decals like boxart. I didn't choose to do the sunroof so it won't be a perfect copy of boxart.
I also need to trim the belt covers then it will be ready to assemble.
At the moment, however, I want to progress the design work on the 91 Stealth car so I can order chassis materials. I have it drawn up but just discovered that it's too short so I'm trying to sort that out. Anyway, once those materials are on order, I can return to the LWB Mid project.
Where have you gotten to on your Mid projects?

[mikea96]

Still waiting on some parts most importantly a custom topshaft to run a b4 slipper. I am also working on 91 chassis and actually have already ordered a carbon panel with 30degree kickup.

[XLR8]

Cool. You are way ahead of me.

[XLR8]

Some progress....

I went ahead and fitted the re-release Optima/Javelin rear hub carriers and installed the 1 degree inserts. The inserts that are included with the carriers are zero, one and two degrees. You won't be able to see it in the photo but some small modifications to the arms are necessary at the carrier's slot to provide clearance for the new carriers.

[XLR8]

A previous owner removed (or probably broke off) the original wing mounting points from the tranny cases so I'll need to fabricate some replacements.
Some posterboard mockups. First attempt with the wing in factory location revealed that the wing will need to be removed before the body can come off. No good.

Second attempt with wing moved aft 20mm. It looks like the body will clear easily. Actually, maybe 15mm would have been far enough.

[XLR8]

Finished the wing mount today. Wing Stays are Kydex. Made some aluminum Wing Washers and Spacer Collars on the lathe.

[Lavigna]

Very cool build. Just to play devils advocate (looking at your previous layout drawing) what about swapping the esc and servo? It looks from your your layout, that the steering servo would be at a near perfect 90 degree angle to the steering arms if placed on the right hand side. And by moving the esc to the left side, you would have a shorter and cleaner run for your wires to the motor.

I am assuming there are reasons I don't know of for choosing the sides you have, but I just figured I would share what I see.

Keep it up!

[XLR8]

Thanks, I think the car will be a hoot when it's finished.
I agree that the locations for servo and ESC probably should be switched but the main chassis is slotted for individual cells and one of those slots coincides with where the rear servo mount would need to go. Also, the right side upper deck post would need to be moved to accommodate the servo. Ultimately, I've just accepted that the chassis was made for the servo to be located on the left.
The car is ready for electronics and the body and wing are ready for the decal set so it won't be long now.
Thanks for following the build.