Yet another Customised Optima Mid Custom Special

[alcyon]

Phew What a awesome day ! I tested my Mid at SBS, and it handled the best it ever did ! I can say now the pinnacle has been reached. The 10 degrees of total caster made this car so easy to drive, it was so much more sure footed and had much much less tendency to swing the rear around on power. I was a lot quicker this time. The modern buggies didn't know what hit them. One funny thing though is I find myself driving this car faster with the Custom Special body, not as fast with the Turbo Special, I don't know why.



this pic shows my CS against a DEX410 V3.
I am uploading videos to youtube and will post links as soon as I can.

[alcyon]

Ok here are the videos.
This vid was taken at the end of the day. I raced against a DEX 410 V3. This is the guy that beat me in the July race, which I posted pics a few pages back. This time my Mid handled superbly and as you can see gave him a hard challenge.
[youtube]UootKXJO2hg[/youtube]

[youtube]GSp2Jgp8dVs[/youtube]

[rccars4sal]

Wow, I like that track! Its a rythm track for sure. Impressive speed in all sections. Good race!

[alcyon]

Pics of 9th nov bash captured from the video.






Short video on sunday on another track.
[youtube]5ptiddOVMIw[/youtube]

[alcyon]

Latest update. the last arm design is spot on, still no breakage after months of hard abuse, even when I ran it today.

On December the 6th, I told you guys I will be racing my Mids. I tried the SWB on practice day and found it to be amazingly good, so my plan is to run 1 heat with each car.
On race day, there were supposed to be 5 4WD buggies, but only 2 showed up, me and a modern caster S10b pro.
The 1/8 guys all showed up. Also one LOSI TLR 22 was in the mix too, but as he is 2WD, it itsnt really a fair fight. On race day, it was muddy, and this messed up every ones handling. The 1/8s ran first and that helped to distribute the mud for us 1/10ers.
After the 1/8 heat it was our turn. The LOSI 22 and caster S10b and my SWB mid, we ran a staggered start. To my horror, the mid was too bouncy, and I pushed it hard,there was just no grip and it spun at every throttle input. Both the Caster and the 22 was in front of me and putting a lot of real estate in between, I calmed my self down and went easy on the gas out of the corners.
Eventually I overtook the 22 near the 3 min mark, and then overtook the Caster S10b to the lead, and held it there. The Caster guy, was very careful and driving slowly so I caught up rather easily by just staying cool. So 1st heat , I won.

The track started to dry up with every run.
Heat 2, I switched over to my LWB mid. This time, I held the lead from the start to the finish, with clean driving lines, I did face some difficulties and crashes but no one beat me at any time throughout this heat, still the track condition was to blame and my dirty ball diffs.

Finals. Still with the LWB, at the start I screwd up big time and the Caster S10B guy picked up the lead. I was caught by surprise in the change in track condition, just within 1 hour.
For half of the race, I tried calming down and driving carefully, then I heard the Caster guy said he was having electronic problems, well eventually I caught up and overtook his car, the 22 was never a threat . I won the finals too.

In this pic, the TLR22 went home, so you don't see him.
after the race I took the car for a few packs spin, on one of the jumps, I cased badly and I saw my left front wheel disabled. It was a telltale sign of a broken arm. I was gutted and thought I have failed to design a strong arm yet again, when I picked up the car, I was pleasantly surprised the arm was still intact !. It was the ZX-5 C hub that broke in half. My CSI instincts tells me that the reason it broke was, the thread on the 3racing alloy knuckles on the lower side was stripped, so the lower kingpin screw fell off. This cause the knuckle to be supported only on the upper kingpin, causing a huge amount of load on the upper side only, which is supposed to be shared with the lower side too. So the C hub snapped.

So those of you who bet that my last design wont break, its time to collect .
I now use LA-219-10 , 10 degree c hubs, and the car feels even more planted. I switched to gear diffs lately since I did not want to keep cleaning the ball diffs, while it was good the first few packs the handling seem to have deteriorated, but this could be caused by the shocks losing its oil, since I have not serviced them in 3 months.
There will be a string of 1/10 races this year, and lets hope I will have more good results to report.

[alcyon]

After my successful race on the 8th of February, I tested my Lazer ZX along side my LWB optima Mid a few days ago. The lazer ZX failed me yet again, at the rear arm lock. The rear gearbox mount screws failed and cause the arm mounts to come off, then my rear arms dislodged it self. The surface condition at SBS has deteriorated rapidly since the race and the track owner has not maintained it at all. There are now many ruts and bumps throwing off my buggies.
However what surprised me about my ZX was how well it handled the bumps without washing out. There are a few differences on my ZX compared to my LWB mid even though both uses ZX suspension.
On the contrary, my LWB mid tended to roll a lot and then at its peak roll while attempting to change direction quickly on the bumpy surface, violently wash out at the rear, all of a sudden. I tried correcting it by countersteering and modulating the throttle and steering like a drift car, but to no avail, its just too unpredictable.
The ZX rear inner camber link is at it highest position, so the link is more parallel with the lower arm. I cannot achieve this camber link position on the Mid eventhough I am using the same ZXR shock tower, because the Mid motor is very far back, leaving no space to mount the camber link at that high position, because it will get in the way of the motor plate and gear cover. So I did the next best thing, I mounted it at the middle set of holes, second hole from outer.
The ZX is also much lighter than the Mid because of its FRP chassis. The mid is at least 80g heavier than lazer.
The final difference is the ZX has 2 degrees of rear toe in while My Mid has none.



This pic shows my newly designed modern bumper, that is meant to protect the undertray better. It does indeed do its job well.


Next modification is I noticed that the 3racing ZX5 knuckles has severely limited the steering angle of my buggies. So I grind off some areas of the knuckle that limit movement.

I also found that the inner steering plate also limits the steering movement in one direction , the right side. So I ground off a portion of the steering plate that interferes with the movement. Now I have full lock on both left and right turns.

Finally, I remembered that my new RC10 world car rere has an enormous amount of rear toe. And when I drove my friends Worlds car, I remembered it was very stable. So I rummaged through my Optima Mids parts bin and found some BITD rear toe in kit, I am unsure made by which company. I hear robinson racing made one.

So I took 2 hours of my time installing this and making sure it fit. I tried this before and I had lot of trouble fitting it and gave up, this time I KNEW I need more rear toe, so I did my best to file the edges of the outer mount and I managed to make it work.
Installing the outer e clips is a torture with this toe in kit, so I put some wheel clamps on the hingepins to prevent it from coming off.


Now my Optima Mid has I don't know how many degrees of rear toe.

I know my mid will perform great when the track is well groomed, even with zero toe, but I just cant rest on my laurels, I want it to handle great even when the track conditions is at its worst. I am hoping that with these changes I will be able to stop this sudden hooking of the rear at maximum roll and be able to put the power down on the rutty surface just like the Lazer ZX.

[Returning_Jim]

Thanks for sharing this stuff.

I hate that this forum moves so slow.

Every time one of us sells an old Kyosho part on Ebay, maybe we should be inviting the buyer to the forum.

[Coelacanth]

Thanks for sharing this stuff.

I hate that this forum moves so slow.

Every time one of us sells an old Kyosho part on Ebay, maybe we should be inviting the buyer to the forum.

That happens from time to time for all of the non-AE forum sections. The Kyosho forum was ripping along at a good pace a month or two ago, it just happened that a couple members were sharing their Optima scores & resto builds at that time. It'll pick up again.

[alcyon]

Thanks for sharing this stuff.

I hate that this forum moves so slow.

Every time one of us sells an old Kyosho part on Ebay, maybe we should be inviting the buyer to the forum.

Glad to help, its frustrating some times trying so many different things, some work some don't. I hope all my discoveries will help others who want to race their optima mid.
In a nutshell, what I discovered so far if you race on low grip.
1. Its very important to have lots of caster. I now use 10 degree ZX5 caster blocks, much more that the original optima or Mid.
2. Ball diffs are required, the gear diffs unload too easily. To make your ball diffs go longer between teardowns, use super lube synthetic grease, made in NY USA !
3. You have to find the right balance of springs, must not be too hard or too soft. Too soft your car will pitch in every direction, losing grip. Too hard it will get thrown off the surface.
4. Rear toe in is also very important, at least 2 degrees is required. I am now running 3..i think. Anyone know which company made those rear toe in blocks in the pic I showed ?
5. Proline M3s are great on dusty loose tracks.
6. A slipper clutch is very necessary!

[alcyon]

I had a really bad day on sunday the 12th of april, what was supposed to be a good showing on race day turned out to be a disaster of biblical proportions.
The organizer decided not to run any finals , so we had 5 heats and from those 3 best heats will be totaled for finals result.
I did not have time to practice for the new track layout.
1. Heat 1, since the track was really muddy, and the 1/8 guys ran first, I used hobbyking quonom vandal spike tyres to dig into the mud.
Well, these tyres gripped ok, but there was something wrong, I noticed that my car bounced a lot on every bump and when landing from jumps. it was difficult to drive and after some hard bumps, I suddenly lost power and the car just veered off the track. It was the ESC.
This has happened before, I traced it to the negative battery cable, and I resoldered a new one the night before, but this problem still persists. So I took out my ORCA Qspark ESC from my lazer ZX and soldered to the Mid's motor. Problem solved.
2. Heat 2, since I noticed the suspension bouncing so much with the HK tyres, I decided to use the ever trusty Proline M3s. While there was improvement in handling, the car was still a handful, especially on the table top jump, which it had a propensity to overturn upon chassis slap landing. I lost a lot of time trying to point the car in the right direction, and it was obvious my car was still under damped as it was still bouncing, though not as bad as with the HK tyres.
On one of the jumps, again I cased it and suddenly found my left side front suspension wont rebound. Pulling it off the track, I realized that the kyosho big bore shock shaft was bent. I removed the Durango big bores fronts from my Lazer ZX, and installed it on my mid..Problem solved right...
Heat 3, car was still bouncing everywhere,in fact far worse thatn with the kyosho big bores, it was obvious my Durango BBs were even more underdamped with 20wt oil. Suddenly the car felt like there was binding somewhere. Pulled the car off, and found a rear right wheel bearing was broken. Replaced the bearing, problem solved ?...
Heat 4. This time, again car was bouncy, I did manage to give a good fight in the corners until I crashed again, and broke a Durango wing mount, with a dislodged wing, the car was impossible to drive without losing it to oversteer, so rather than be a hindrance to others, I pulled out. I replaced the broken wing mount with the one I had from the lazer ZX.
Round 5. Still not handling very well, I gave the top drivers a tough fight through the turns, until I cased one of them, and the whole wing came off! I tried driving without the wing, but again, it was too twitchy. I pulled out yet again. This time the wing mounts were intact, but the wings sheared both screws clean off the threads..
So that was the end of my race day with a string of bad luck. Funny though, none of the usually expected components broke. arms, knuckles, c hubs all held up great. The track was exteremely punishing because there was a new huge triples jump added that launched the car 6 ft high. My optima mid could take that jump rather well, but on landing it would bounce and mess up handling.
My fighting spirit is still here, and I am now working on a come back.
1. I am in the process of making a super strong wing mount.
2. I will use the Fred Swain suspension tuning method, to balance the front and rear spring rates.
In case you don't know who is fred swain, he is an experienced racer on rctech forums, who developed a method to match suspension frequencies front and rear to get a balanced suspension.
I hope to make a comeback and kick a lot of Xray XB4 butts.
This is a video summary of the race.If you look closely you could see my car clumsily negotiating the track lanes.
[youtube]w7W8ujT3XC8[/youtube]

[alcyon]

After a very long hiatus due to my 1:1 car hobby, I am finally back. Some of you guys were waiting for my latest post about my RC10 worlds, but I still have not updated anyhting. iN short i lost all my imperial tools, so I cant do jack squat with my rc10 till i get new tools.
Back to my optima mid. on the 24th Of October there will be a 4 hr endurance 4WD 1/10 buggy race at this same track, seems there will be 18 cars competing.
Mine being the oldest, and the majority is X ray XB4s.
This is a video of my practice run last week, had some problems with the ESC switch turning off on the super hard landing, i have since moved the switch and done some setup changes.
[youtube]smOyh58Cej8[/youtube]


Just glued new panther Raptor tyres . Two tire choices for mthis race, Hobbyking Quonom Vandal tyres or this.

Modern wings are too steep in my opinion, what more in an endurance race. to reduce some drag, i drilled 5 -8mm holes on the vertical surface.

Will change this parts 1 week before the race to make sure of durability.

Rear repositioned Camber links with ZX5 rear hubs and zxR shock towers.

In order to have the inner camber link position where i want it to be, I had to use XRAY touring car open tie rod end with a slim ball stud, and space the shock tower 2mm from the gearbox.

ZX5 rear hubs with new yeah racing 5mm hexes. The original LA-28 rear hubs have too much slop in them after a short while.
If the track is dry tomorrow hopefully i have a better video to show you guys.

Oh yeah, i tuned the suspension according to the fred swain method, and got a 5hole front piston, 35wt oil, 6 hole rear piston with 37.5wt oil.
Front spring is durango BB 62g/mm, rear spring Durango BB 43g/mm.

[Coelacanth]

If I were to reduce drag from that wing, I would've just trimmed down the vertical section a quarter or half-inch instead of drilling holes.

[alcyon]

Ran my car for practice on sunday. The coming race is endurance 4 hr race, but this practice was still all out speed practice.
























and the video action !
[youtube]AvPeMactsG0[/youtube]