Narrow Front End, it works !

I spent a few hours setting up my front end to be narower. i tried the car today at the race track, and i am happy to report that the car has more steering now ! i went up againste a durango DEX410 which had a 7.5T motor, mine was a 10.5T, it was difficult to keep up with him, but at the corners, i was sometimes able to outcorner the durango, i literally was able to cut into his line at the corners! it was great. i also did not break anyhting on my MId, testament to kyosho old parts quality. I also tried the old mid special tyres, and they only work great in the extremely loose sand area, whern the spikes can really dig in. On the hard packed surfaces, the car was skating everywhere. i Swithced back to the Prolines M3 and i got a lot more traction on the hard packed surface, not to mention better bump absorption. The sealing i done on the gearbox and belt covers also paid off, my drive line is as smooth as the day i put it together.

Wheels to use on the Optima Mid and Lazer

I dont why, but  ifeel the old tyres look better than the new ones, the old ones really look like buggy tyres, but the new prolines look like truck tyres.

If you bought modern kyosho wheels like me becuase they were easily availabe at your hobby shop, you would have found a big problem that could affect handling.

The tyres above is the ZX-5 RTR (ZX-R) Rims and tyres, notic the front is wider than the reasr, thats the way ist supposed to be
The tyres below is the modern ZX-5 SP/FS2 rims with proline tyres, notice the rear trackwidth is wider than the fronts! a big no no. since i already bought them i might as well use them first.

The correct rims for your Optima Mid is W5026W front, and W5028W for rears. You can use any tires with them.
Ok i ran the car about 2 hours ago at alocal abandoned MTB track. Met 3 guys with HSP (china brand) SC trucks. When the saw my optima mid in the sand over the bumps, their comments was, ..the suspension really soaks up the bumps ! They said my car handled really well, when theirs bounce like hell !
The Mid jumped well and kicked a lot of sand, but i find the car understeered too much to my liking. Even though i slowed down for the turns, the car seems to push wide, only if the surface is sandy, when i gas it hard then rear will swing around and i have to countersteer to keep it in control. I did some reasearch on the internet about front and rear track width, and i found something odd. It seems having a rear track width wider than the front, you will get MORE steering, and front track width wider, less steering. The thing is my rears are now wider than my fronts, yet i still dont have enough steering ! I will still go ahead with the old ZX-R rims the next round , and keep the front hub on the outer hole. I will also try to put the front hub on the inner hole to reduce the front track width and see how it handles,  if I do indeed get more steeering.

NEWSFLASH, last night i took of the front LA-59 hubs and change the 3racing 65.5CVDs to Kyoshos LA245 62.5 CVDs. Placing the C hub using the outer hole reduces the front trackwidth, and also reduces the caster. These 2 changes alone should make my Optima Mid Steer better. The track width will increase grip, and the less caster will increase initial steering, something i am lacking right now. Becuase of that also i had to change the camber link location on the front, i had to use the outermost hole on the hub, so now my camber links are longer, this should give the front end more roll and more grip as well. This should work well on the optima mid becuase it is a rather rear heavy car unlik todays cars which only have small rear bias percentage. The Optima Mids rear is 200g heavier than the front ! The problem is my original Mid Rims cant fit in, unless i reduce some wahsers at the outer part of the upper link. Also another annoying problem is the new Kyosho front rims has lots of ribs in them, these ribs actually interfere with the outer hingepins! i Put in a 4mm washer in between the wheels and the hex and this spaces out the front wheel enough so that it wont touch the hingepins anymore, as a temporary solution. It seems kyosho is discontniuing the production of the ZX-R rims, so i will get them while stocks last.

How To seal the optima mid's drivetrain, and tips for easier maintenance

As many of you all know, th Optima Mid is not an easy car to work on, and maintenance work can be very difficult and time consuming. During my cteenage years , i spent alot of time taking apart the car and cleaing the gearboxes and diffs, i always followed everything in the manual and only used the car with original parts cause i couldnt really think for myself. Fast forward 20 years later, being and engineer designing machines, and applying my knowledge and experiments on touring cars, i managed to find a lot of ways to improve and lengthen time for teardowns and rebuilds on the optima mid.

I thought to myself, i must seal the gearbox properly and not allow any sand to get into the gearbox , and also must find someway that i dont neeed to take apart the diffs for maintenance.

Firstly look at the 1st pic, its selleys silicone sealent. The stuff works wonders, when its in it freshest state, its kind of jelly paste like, when it dries up, it becomes like a flexible rubber like substance,that can be removed by hand later by pulling it out, very good for sealing your optima mid's belt covers.

Buy this tube of sealent at your local hardware store, it fills and seals the gaps in between your belt cover joint areas.
To stick your beltcover on, use 3M high strength thin double sided tape.

The optima mids gearbox is made of high grade plastic, but the front gearbox is especially prone to stripping its threads after so many times removing and retightening the screws, and also form hard collisions. An easy way to remedy this is to drill through the mountin holes at the bottom. But it will expose the gearbox innards to sand. Drilling through with a 2.5mm drill bit will allow you to use longer screws ,in this case i used a 20mm screw to hole the bumper in the 1st front 2 holes, since there are 2 holes esposing the gearbox internals, use the silicon sealent to seal them, like shown in the picture. That T sysmbol is team Tanaplan.

Notice the silicon paste in between the belt cover and the front gearbox, and also in between the bottom of the gearbox to the chassis, also at the suspension mounts. I drilled a hole through the last 2 holes holding the gearbox to the chassis, so that i can place a nut to securely hold down the gearbox. You have to use a 14mm screw so that it will go beyong the suspension mounts. Since the drilling exposes the innards of the gearbox, you have to use silicon sealent to cover the hole back after tightening your nut. Dont forget to use sealent on the under belt cover under the upper deck.

See the 3M tape used to mount the upper belt cover, and the silicon sealent along the front seam of the belt cover to gearbox and top deck.

Sealent and thick double sided tape replaces the OT-103 sponge here to really seal the rear gearbox upper area.

Silicon sealent fills and closes the gap in between belt cover and rear lower gearbox.

Dirt can still get through one area , the diff side bearings, becuase ethere is asmall gap.

Use dishwashing sponge, cut up a thin slice, then cut up a hole in the middle with a curved scissors, the hole should be slightly smaller than the ball diffs output shaft. Yes i am using ball diffs again. Use silicon sealent to glue the sponge to the gearbox sides.To cut down times in between rebuilds, i bought ACER racing 3mm ceramic balls for my diffs, and greased the balls adequately. With the ceramic balls, and the side sponge sealing, you should not need to open the gearbox for at least 3 Months ! You only have to clean the wheel bearings and shocks, you dont have to touch the center part of the car! amazing isnt it?

The thrust bearings get dirty easily and contributes to the diffs gritty feeling. You can remove the diff outdrive like shown here, wihtout removing the gearbox ! Just unscrew the diff as shown, and pull out the output shaft, the bearings and spacers diff rings inside the gearbox will stay put becuse of the way kyosho designs them. Remove the thrust bearings, clean them then relube them, then simply place back the diff output shaft into the gearbox, voila, your diff is smooth again. If after you clean the thrust bearings the diff is still gritty, then you will have to open the gearbox and clean the main diff balls.But that should be a long long time before you need to that if you follow my tips ! Dont forget to put a small slab of sponge to cover up the thrust bearings to better protect your thrust bearings.

My latest additions and worry

I got myself a new wing for my Optima Mid, made by durango. Have look at it.

I finally used up the rest of the stickers that came with the Marwan Repro body kit.

i changed the rear springs to assocateds green springs, the softest, and the front to silvers, the second hardest. I also reduced the droop a little bit on the shocks. Waiting for the durango shock boots which i will buy from 1 Utama tommorow, then the car is ready to run again !

Then the little debacle with dirt getting in the tranny got me worried. OT86 gear is still easy to get, and the center gear is made by pargu2000 out of aluminium, and its excellent. But no one makes the SG-25 plastic sprocket set, and its getting verh hard to get hold off these days, and also very expensive at $25. I saw a seller selling the ball diff casing for only $5.99 which is cheap, but i dont want to use ball diffs anymore. So who will make the SG-25s? My current sprocket gear is very new, and i only have one more new extra sprocket, then thats it. i think these could last me perhaps 3-5 years, if i dont let dirt get into the gears. But after that what then? I got an idea to make a single belt conversion for the Optima Mid, which you will be able to use any worn out sprocket gear, cause there will no contact with the gears anymore. Unfortunately my idea will require some cutting on the rear gearbox, a little drilling on the top deck, and total removal of the upper deck belt cover. The good news is i beleive the belt cover will not be needed there because there will no need to have any grease inside the tranny anmore becuase of the single belt drive. I will work on it once i run out of gears !

Optima Mid Slipper Clutch

Firstly you might ask me, why do you need a slipper clutch on An Optima Mid? Doesnt it already run well? Well, i dont think the Stock Mid runs that well. On very rough tracks, the lack of a slipper places great strain on the tranny, and also makes the car very hard to drive. If the surface is too rough or rutty, the sudden jolt from the rut to the wheels , coupled with the power and torque still coming from the motor while your finger is on the throttle, will cause your car to bounce badly, and could even flip the car in another direction.

I decided i needed to do something. I did some research on Losi and Associated's slipper clutches, and i found some designs requires thrust bearings and some dont. I opted for the cheaper option, and chose Associated's B4 slipper clutch. I got one complete set from ebay for $20, comes with the top shaft which i need for measurements, the 2 slipper plates, slipper pads, spring, and the spur gear 81T.

My plan was simple, design a shaft that on the inside, matched perfectly to the Optima Mids gearbox, able to place OT-86 gear on the shaft. On the outer part, it will match with the B4 slipper parts.

Here is what i came up with.

The second protoype i got from my machinist. The first one was a failure.

The gear cover on, with a hole made. I ran it this way for a pack. On the second pack, a bit of stone went in and chipped the spur gear. So i devised a round tube cover, see picture below.

This is a chinese medicine plastic tube, it was cheap, and the right size to contain the spring and the nut. I sawed the tube, then siliconed it on the gear cover. The removable cap allows me to adjust the slipper setting ! NEAT !

I tested the car at titiwangsa track in Kuala Lumpur, and the car was much much MORE EASIER to drive. It felt like i was watching a Pro CAT in action. Yes it was that good. I gotta take video , if only someone could help me. The track is extermely rough, but for the first time ever, i could drive it around the track, without the car losing a lot of control. In fact it was the first time i could drive the car lap by lap by lap, until the battery dumped! I even took the huge jump, that launched the car 4ft high, over and over again, and landed hard ! On the second pack, the tranny was making some noise. So i stopped the car. It felt like the bearings were contaminated and some sand got into the tranny. So i went home and took the car apart, sure enough some sand did get in. So i did a total stripdown, relubed the bearings, put molybdenum grease on the gears, and put heavy lithium grease in the gear diffs. You might ask me why i am not using  the ball diffs. Well, they require too much maintenance. The will foul up after 2 packs only. And with the slipper, the gear diff works well. I also sealed all the joining areas of the belt cover near the gearboxes, with flexible silicone.

I also found that the gear diff outdrive bearings are placed a little bit nearer to each other causing a 0.5mm gap between the outer bearing and the gearbox. This is what allowed the sand to inside the gearbox.

So i devised a simple way to keep sand out from this area. I cut thin sponge, and placed it at the diff outdrives, and tighthned the setscrew. Now my whole tranny is dirt proof.

Next i am planning to buy durango shock dirt boots to place in my shocks to cut down on maintenance. Now the only part requiring maintenance on my car is the wheel bearings, but that is normal even for modern cars.

latest upgrades

i have now gone back to Kyosho LA-26 arms, and i modified the A & L bellcranks after i found their shortcomings. the problems was the plastic 4-40 nuts were not strong enough to hold the screws. after a few hard knocks it worked loose. so i replaced the 4-40 screws and nuts with M3x25L bolts.

Notice the missing bearing on the left, lost it on a bad day, waiting for the replacement to come. notice i flipped the graphite bar upside down from the instructions, this allowed me to place the ballstuds facing up and higher, thus enabling the steering link to be parallel with the lower arm, eliminating bump steer.

notice the amount of wahser under the pivot post to raise up the ballstuds.

The steering link is parallel to the lower arm, so no bump steer here !

View without body with modern electronics.

With modern tyres

Fibrelyte James Instone Lazer ZX shock towers.

Fibrelyte James Instone Lazer ZX rear shock towers

Top view, notice the A&L sticker

Car now sits low with reduced droop , thanks to the New shock towers.

I tested the car now it finally it had a LOT of steering, becuase the bellcranks now work they way they should, and also because i grinded the back of the c hubs protrusion so that the knuckles can turn more. I just have to stab full throttle, when i want to turn let go then turn, the car will slow down by itslef becuase of the friction and grip of the front wheels. i can now point it to whiceever direction i want it to go to. but i havent tested it off road yet though.

More modifications...

Ok, the ZX-5 suspension was a dissapointment, not that it didnt work, becuase the width of the area going in the hingepins is short, it caused the hingepins to bend easily. So i decided to go back to the lazer ZX arms. Installed MPP ZX arms , which was a lucky find, i found 8 at hobby haven, each bag costs me RM5 only. Coupled to LA-59 front c hubs, and LA-28 rear hubs, i managed to laser-lise my Mid suspension. I like the lazer's arms better, becuase they place the outer hingepins inside the wheel, which makes rough track handling much better. I used the inner hole on the C hub to push out the front track, and used 3 racing 65.5 CVD. At the back, i am still waiting for LA245 CVD to arrive from japan. My A & L steering bellcrank arrived and cured the sloppy steering problem. I also managed to use back the Mids original battery holder system to hold my Lipo Saddle packs in. With Proline M3 soft tyres all around, my Mid will surely handle better.