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I know this has been discussed before but besides the body, shocks and wheels where there any significant changes to the turbo. Upon doing a quick search I came up with answers like "The Turbo was beefed up to handle more power". What exactly was beefed up? The diffs? Drive shafts?
Many thanks in advance.

Diffs were the same, actually. The Turbo got taller shock towers to mount longer--and MUCH better--Kyosho Gold shocks; the Turbo's counter gear on the outside of the gearbox was upgraded to a primitive limiter gear using either a thick spring or 3 spring washers and reverse-threaded brass nut; that gear helped protect the gearbox from hard jump landings. The original Optima had a solid gear. The Turbo also got front & rear stabilizers and thicker, webbed control arms that offered multiple mounting points for the shocks instead of just one. The Turbo got a belly skidplate that ran most of the length beneath the car between the frame rails. And of course, 2" diameter wheels with low-profile tires. I almost forgot to mention different pinion gears were included, to work better with the much more powerful Le Mans 240S motor...I believe 9 or 10-tooth pinions were common with the Turbos, while the original Optima had 14 or 15-tooth pinions. I could be a bit off but that's pretty close to what I remember, give or take a tooth.

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One more small difference:
In Optima steering servo horn was facing up and servo rod was straight.
On Turbo Optima steering servo horn was facing down (in between chassis rail and lower chain tunnel) and servo rod was in Z shape.

Jirka

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Great info. Thank you , everyone. Can the optima's counter gear be upgraded easily to the turbo version? Is it even worth doing?

Grunger73 wrote:Great info. Thank you , everyone. Can the optima's counter gear be upgraded easily to the turbo version? Is it even worth doing?

Absolutely. It's as easy as swapping the gears. Problem is, they're getting hard to find and command ridiculous rip-off prices most of the time.

Everything you wanted to know about the Optima counter gear & OT-74 limiter gear upgrade:

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

This version is supposed to be the better of the two OT-74's:

http://www.rc10talk.com/viewtopic.php?f=30&t=17162&start=15#p167906

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tamiyadan wrote:oh horrible memories of the spring version,,, believe it or not the spring washer version was better long term.
you could also lock up the spring washer version much tighter. the spring used to collapse over time and the nut would keep getting loose because the gear would rock on the shaft more with the spring version.

the Spring was more tunable if you wanted some slipper setting that was in between loose and full lock.
however it was muted by the current limiter ESC, after that you went to the spring washer and ditched the spring.

So with the preferred version you only have the option to run loose or full lock? Now I'm really confused as to how it worked. Guess I have a lot of reading ahead of me.

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tamiyadan wrote:
there is also the slipper clutch kyosho pinion gear to confuse things further which is external.

Confusing because it was a centrifugal clutch and advertised to improve run time best part was the lexan gear cover!

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I never bought one of those clutch bells because I heard they were crap.

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tamiyadan wrote:also the clutch/pinion is made of butter, the clutch and the gear itself wear so fast you can actually watch it get smaller and smaller each run.

Thanks for posting this. I was just about to pull the trigger on one of these on eBay.