My Yokomo YZ10 94

[aip47-2008]

If not Jirka, I have two bumpers here without a car to put them on. I still owe you a bearing as well.

[Dual]

Very nice Yokomo Jirka. Very nice

I like the custom carbon parts and the lightweight machining throughout the buggy. This is the first time I have seen a carbon camber brace on the front of a 1994 YZ10 I remember seeing Craig Drescher experimenting with front camber positions on his own YZ10 but via a different method.

Were the bags/covers on the front bellcrank system to protect against dust or moisture?

Is the top deck on the right (photo 16a) custom made or purchased? Looks good.

Vin

[Jirka]

@Dual: All graphite parts in this car, except the main chassis, are "custom made". I and my friend Heikki Naulapää designed those. Heikki did also have import company (Yokomo, LRP etc.) and a hobby shop BITD, so he also sold these parts there.
- Rear shock tower is close to stock except different shape and alternative, more lower, rear wing mount holes
- Front shock tower is close to stock too, but it allow Losi shocks mounting maybe a little better than original
- We made three different ackerman plates. Those plates along with modified front hubs & steering blocks allowed inside tire to turn as much as driveshafts only allowed. The outside tyre also turned more than with stock YZ10 or Yokomo's modified steering system. We didn't follow Ackerman theory, since we believe it works only nicely when there is no tire slip e.g. in parking lots. When there are tire slip, like in offroad race cars there always is, less "steering toe out" made the car steer much better. With these mods, our Yokomos started to turn better, more like Schumacher CAT 2000's did those days.
- We also found that the rear camber location was maybe not the best possible, so we lowered the inside mounting holes like Yokomo did to following ZY10 Pavidis edition.
- Since we modified the rear camber geometry quite a lot, we also wanted to do the same to front to keep both ends about similar. Only by lowering inside mounting was not enough so we found an idea from Schumacher CAT 2000 to modify the outside mounting to kinpin
- The top deck was also modified so that receiver and antenna mount (I used one from Kyosho, small and light) were both on top deck. The antenna did come out from middle of "windshield" and not have anymore possibility to stuck under rear wing. Also the whole receiver&antenna was on different level on car than power wire so possibility to radio interference was much smaller. The rear belt tension adjustment possibility was removed, only "the correct" tension was left. With this mod we managed to remove the stock rod adjustment rod to get the a bit lighter and made room to rear camber plate.

Then two other major changes that we made, both to rear end to make it work better:
- Stock rear arms did have quite radical "swept forward" angle. This maybe worked well on Masami driving style, but my was totally opposite than his so I cut stuff from rear hub carriers so that rear drive shafts were no more pointing forward, now they are pointing at 90* angle. It is quite hard to explain how the stock rear end worked, but we felt that it did not work well while the car was cornering, the rear end wanted to slide (tires) and "stuck" (suspension) to it's state rather than keep traction. The drive shaft angle was also now what we wanted.
- Rear shock tower was moved about 3mm more back. This made rear shocks have more "antisquat" than rear arms did have antisquat. This allowed rear end to work more softer and allowed car to handle bumbs better. This also put a bit more weight to rear tires.

The "bags" around tie rods kept dirt, especially small stones, out, but also water if we raced in rainy weather. The major problem with Yokomos was open drive train. Small stones in rear diff pulley stuck the whole drive train and changing rear diff pulleys and belts, cleaning and replacing rear diff parts without those "bags" should have made about after every run, if the car even managed to work the whole 5-minutes.

Jirka

[Jirka]

Thanks to both Gentlemen Vin and Aaron, I got all parts to Yokomo's TCS. It is now installed to my YZ10. The thrust bearing is bushing style, I have never seen this kind of solution before, but since I will not drive my ZY10 no more, it is just fine. The slipper clutch is really smooth and I do not know what kind of grease is needed to such a thrust bearing, I keep it just dry. Maybe it is self lubricant.

Jirka

[Jirka]

Ah, some more mod:
- The front shock tower was "floating". The ZY10 94 didn't necessarily need this anymore, unlike all the aluminium and magnesum bulkhead version Yokomos that we used had this mod to prevent bulkheads (both front and rear) to break. There are O-rings between bulkhead and shock tower and in Yokomos before YZ10 94 also O-ring and a washer between shock tower and it's mounting screw (see an example here: http://www.rc10talk.com/viewtopic.php?f=29&t=33029 at bottom of the page pic "1989 Nordics 2.jpg". This also moved the front shocks a bit more forward so that they did not rub front drive shafts so much. Since mods in steering blocks and front hubs, the inside tire did have more steering, the inside driveshaft does move a bit forward during cornering and without this "more forward front shocks" it would have been not possible. Universal joint and the kingpin do not appear to have been in line.

Battery starps were changed to practically "no weight" versions.

Motor mount was drilled on motor area so that there are hole(s) that did match with motor can holes to make airflow possible inside motor. Also some random holes and material removes are here and there.

Also many small mods, like:
- removed material from rear wing mounts to make it still possible to use the most inside rear shock top mounting hole.
- removed material from rear lower arms to make room for drive shafts after rear hub mod.
- removed material from rear shock top mounting collars to move rear shock top mounting point more rearward.
- I used as many Losi part as possible

Jirka