A Tale of 1 3/4 Optimas

[markbt73]

The wheels are nylon, I've used Easy-Off oven cleaner (the one with the yellow cap) to remove paint, as well as the chrome finish that was offered on optional chrome wheels.

PM me if you need those parts, I have spares of all those items except the bumper brace. I could even sell you a hard final pinion if you're planning to build a runner, but those are a tad pricey and hard to come by.

I actually ordered a steel 5mm bore pinion gear that I'm going to try using as a final pinion. As far as the other parts, I'll PM you this afternoon when I'm in front of a real computer.

[Coelacanth]

Interesting, let me know how that pinion gear works out.

[markbt73]

So after a flurry of order-placing, I have a set of bearings, a Robinson steel 19 tooth 5mm pinion to use as a final drive gear, a stainless-steel screw set, and a reproduction body and tires from Marwan on the way. This stuff adds up quick... my poor credit card is reeling like a punch-drunk fighter.

Once those things get here, the plan is to build up the the car that was incomplete using the new bearings and gear, and the Duratrax gold shocks. This will be the runner. It will use the old black and gold body and a set of wheels and tires to be named later. At some later date, I have a really interesting idea for a replacement body for it.

The other car, the one the was complete, will also be run-able, but it will be the showpiece. (At least, in as much as I'm capable of building a showpiece.) I may even go crazy and polish up the chassis parts. It will be close to original, with the Option House side guards and period-ish electronics including a LeMans 360 Gold motor. White wheels (either they'll clean up or I'll shoot them with flat white), repro tires, and very much not a box-art paint job. (That's all I'm saying for now. If I can pull off what I want to do, it will be amazing, and if I can't, you guys will never see it.)

[markbt73]

Progress... got me a date with a bottle of Simple Green tonight...



...and after that, the fun begins.

[markbt73]

Progress: One chassis is back on its feet. Wheels were repainted white, with new Marwan tires.



LeMans 360 Gold motor tested and working fine, so we'll see how it does. May swap in a 540 for normal running.



Oh, and I solved the steering servo mounting problem:



As for that steel gear, it works great! You just have to add some spacers to take up the gap. I used one thin washer on the gearbox side, and one 5x8mm bronze bushing leftover from a Tamiya car on the chain side.



Hard to juggle all those parts blind, however. I slipped an allen wrench thru everything to keep it all aligned during assembly, and then slid the top shaft iin place of the allen wrench after the gearbox sides were on.



Still waiting on a few odds and ends for the other chassis...

[Coelacanth]

Nice alternative solution to the problem with the uber-rare hard final pinion gear. If I didn't have a few spares, I'd consider buying some. Got link?

That's also an interesting way to connect the steering assembly with the servo in that location. Looks solid. You'll find the 360 Gold has plenty of snort, even more with a LiPo battery or 8.4V NiMH battery feeding the juice.

[markbt73]

Here's the link to the pinion:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVCX4&P=7

By the way, I have a question for those with more Optima experience than I. The gear on the outside end of the top shaft... is it removeable/replaceable? It's really worn. I have what looks like a replacement gear, same dimensions, same tooth count, but with a slot for a cross-pin. I can't see how the old gear comes off the shaft, though. It almost looks like it was molded in place on the shaft. Am I missiing something?

[Bormac]

Hi Mark. Yeah the original gear was molded on I think. The extra gear you are referring to can be used with a different shaft. If you get stuck I might have a spare I could send you.

[markbt73]

I was afraid of that. I hate irreplaceable parts... still, all I need is a 5mm shaft that's cross-drilled at one end, cut to length, with a flat filed. I wonder if I still have an old TL01 driveshaft lying around? Could make two from that...

[markbt73]

HA! Tell me a replacement part doesn't exist, will you? Fine. I'll just make one. Found a 5mm shaft from some Tamiya gearbox or other that was about the right length, cross-drilled it right at the end (yes, it was a pain, and no, I didn't quite get it exactly centered, but close enough), and press in a roll pin.



The roll pin is black, so it's hard to see, but it's in there. The Sharpie marks on the shaft were so I knew where the flat should go.

[GoMachV]

Looks good!

[DennisM]

Did you remove the gear on the old shaft, to see if it had the hole for the crosspin?

[markbt73]

Did you remove the gear on the old shaft, to see if it had the hole for the crosspin?

Not yet. I only have two, so I didn't want to destroy it until I had a replacement figured out. I will check that eventually, however.

[keithrc]

I'm not sure if you're aware or not but there were 3 different versions of these counter gears.

The originals had the gear moulded or pressed onto the splined shaft which would eventually start to strip out and spin on the shaft, then there was the screw on type that the Turbo Optima's and I think also the Salute's had (both my Salute's have this version) which according to my Turbo Optima and Salute manuals consisted of 3 washers, a spring and a 3mm nylock nut. And the 3rd type was the one with the pin and slot.

I'm not sure if the pin/slot type versions actually came in any of the Optima kits though (possible the Optima Pro?). I do know that the Ultima Pro had the pin/slot type.

Having written all that, I just noticed that you gear is infact the slotted type. Your pic is very dark and hard to see.


Keith

[Coelacanth]

I'm not sure if you're aware or not but there were 3 different versions of these counter gears.

The originals had the gear moulded or pressed onto the splined shaft which would eventually start to strip out and spin on the shaft, then there was the screw on type that the Turbo Optima's and I think also the Salute's had (both my Salute's have this version) which according to my Turbo Optima and Salute manuals consisted of 3 washers, a spring and a 3mm nylock nut. And the 3rd type was the one with the pin and slot.

I'm not sure if the pin/slot type versions actually came in any of the Optima kits though (possible the Optima Pro?). I do know that the Ultima Pro had the pin/slot type.

Having written all that, I just noticed that you gear is infact the slotted type. Your pic is very dark and hard to see.


Keith

There's a fourth type of counter gear; well technically a third only, because the cross-pin gear wasn't really intended for the Optima series, it was for the Optima Mid/Ultima series, I believe.

The stock Optima gear was a solid, molded piece. The Turbo Optima/Salute could have either the gear you mentioned with the thin spring washers, or it could have the OT-74 Limiter Gear assembly, which had a beefy, thick spring. You can read all about it in this topic I started; the kind I use is the OT-74 thick spring variety, I've acquired a number of those over the years. They're getting pretty hard to find, at least separately.

http://www.rc10talk.com/viewtopic.php?f=30&t=17162