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Project Locked UP (Fully adjustable caster RWD D4)
#1
Os-support 
I own a RWD Skaura D4 clone. Boo... Hisss.  Hold on, it aint that bad. Let's cover the basics first as far as the quality of the D4 clones.

Aluminum parts.
The aluminum parts are  decent. The aluminum itself is softer than what you'd find from 3Racing, or major aftermarket companies. It will gouge if you scrape it with hard tools, but it's not terrible. I have not seen any pitting or defects in the aluminum parts. The major problem with the clone aluminum parts is that they are not the same design as the 3racing aluminum parts. 

For example, the bulkheads. The 3Racing aluminum bulkhead looks completely different than the clone. The clone is simply an aluminum version of the stock plastic part. So if you're hoping to buy a different front castor mount and attach it to the front bulkhead cover, think again (it lacks the mounting holes). You'll have to buy the 3Racing bulkhead cover as well as the castor mount. You'll find several parts on the clone where this is the case.

The 12mm wheel hexes suck. They were too big they way they came. I had to sand down all the sides to actually make them fit my sets of wheels. I replaced them with some clamping 12mm hexes in different offsets.

Carbon Fiber parts.
These are actually pretty good. The weave isn't the tightest, but the finish is smooth, and the parts are rigid and strong. I was pleased with the countersunk holes in the main chassis, nice and uniform.


The Hardware
I have not had any problems with the M3 screws. I use Losi hex bit tools, so that may help. I did have a problem with the small screws that secure the bearing holders on the rear axle. The bearing holders that come on the clone are soft aluminum, and when I tightened the screws 1 of the threaded holes stripped out pretty easy. I replaced the bearing holders with the stock plastic units.

[Image: 20160325_201007.jpg]
[Image: 20160325_201955.jpg]

The Bearings
They suck, period. Replace them. I bought a set of Yeah Racing bearings and haven't had any problems. The clones don't have nylon shielding, and some bearings had no shielding at all. Garbage.

These bearing for the spur shaft were bad. Grease filled and very resistant on the motor.
[Image: 20160325_190704.jpg]

Everything was so much smoother after replacing the bearings.
[Image: 20160325_192418.jpg]
[Image: 20160325_192600.jpg]

Wheels & Tires
Junk. Replace them. But that was going to be a given whether you buy a clone or not (at least the tires). I bought some multi offset 3Racing wheels and few sets of MST tires.

Plastic Parts
The plastic is actually ok. It's got a similar density as the 3Racing parts. The ball cups I didn't trust, and I replaced them with a set of 3Racing ones. The clones seemed to be too tight or too sloppy.

Shocks & Springs
The springs are junk, throw them away. I purchased a set of every spring 3Racing makes for the D4 (5 or 6 pairs I think). This should be a given for all D4's. You will need spring options. 

The shocks seem so-so. The pistons were slightly too small for the bore, so I replaced them with 3Racing pistons. That made a big difference. There are no o-rings to secure the spring perch, so who knows how often I'll have to adjust the ride height (I adjust that kind thing often anyways). The shocks come dry, so you'll need shock oil. I may replace my shocks with better units down the road. I just don't know how much I trust the clones.

Misc Hardware
This is where you'll find the most issues. Stupid little things like the shock standoffs are soft aluminum and multi piece rather than a solid part. The smaller turnbuckles for the steering and servo have funky non M3 threads. You'll have to mess with a lot of parts, sanding, filing, trimming. 

The clones don't come with roll center shims, so I bought a set. This actually allowed me to stack shims in the rear and give my D4 1mm of anti-squat.


Was the clone a good deal ? Honestly, not really. With the amount of parts you'll want to replace, I don't think buying a clone makes for a good deal. You'd be better off buying a stock D4 and then buying the knock off carbon fiber parts on eBay. You'll never be able to get this many aluminum and CF parts for $180 (what I paid for my clone), so there is that.

Do I regret buying a clone ? Hell no. I love modifying RC cars. I do wonder how much money I would have spent on a stock D4 trying to make it aluminum and CF. Probably too much. The price of the clones teters right on the edge of being worth it or not. I guess that's why they sell at that price, rather than more or less.
¯\_(ツ)_/¯

Next step: looking at steering angle and caster.
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#2
Here is a shot of my max steering angle I was able to achieve on my D4.[Image: 20160409_175103.jpg]
[Image: 20160409_175118.jpg]

The steering is stock, the upper arms are 3Raicng aluminum, and the knuckles are 3Racing aluminum V2. My steering brace is in contact with the steering post, so this is the most angle this setup is going to ever have. Not bad, but there is a bigger issue here.

At full lock, suspension geometry goes wonky. Camber settings dictate caster, and caster settings ultimately dictate your lead tire camber.

Here's a shot of the induced positive camber on my lead tire at full lock.
[Image: 20160409_174611.jpg]

That is a very small contact patch. Not good. That limits my front grip and ultimately my control mid drift.


Here's a shot with the wheel off. You can see the caster angle (from the bottom ball cup to the top ball cup).
[Image: 20160409_174709.jpg]

I can dial out a bit more KPI angle, but ultimately the caster angle is the problem. Without the ability to adjust front caster this problem isn't fixable.


I set out to make my D4 fully adjustable. I searched for parts on the market and found a few. 

3Racing-
3Racing makes different front caster mounts, but no where near the angle I want. The lowest angle they offer is 10 degrees, which I think is stock. Nope.

Boom Racing-
BR offers a mono-shock setup that looks to have caster adjustment. It looks limited, and I'd rather not go mono-shock yet. Nope.

Oxygen-
Oxygen offers a really good setup. It's a whole different front bulkhead with caster adjustment spacers.
[Image: oxygen-41901BL1-13.jpg]

It appears you have to run a different center CF brace setup, which means more stuff to buy. The parts are out of stock everywhere and expensive. Nope.

Usukani-
Usukani offers a similar front bulkhead to Oxygen, without the need to change a bunch of other stuff. Promising...
[Image: US88102PK.jpg]

I checked out Usukani's upper arms, and they seem to be too wide. This means limited caster adjustment. But I liked the bulkhead, so bought one.

Out with the old.
[Image: 20160409_175916.jpg]

In with the new.
[Image: 20160409_181310.jpg]


Now I needed to find an upper arm on the market that would work with this bulkhead.

When reading Mod19RC's blog http://mod19rc.blogspot.com/, I saw him using Eagle Racing lower arms on his D4. They allowed greater steering angle due to better clearance. This got me thinking about other Eagle Racing parts I could fit on my D4. So shout out to Mod19RC for the inspiration !

I found these..
[Image: 20160409_181458.jpg]

TT02RWD upper arms. They are slim in width (good), and come with spacers (good). But upon measurement, I found that the arm fits a 4mm shaft. The Usukani shaft is 2.5mm. I modified the shafts that came with the EA arms, but ultimately that route was a dead end. The shafts are solid in the center, so you'd have to drill them out in order to fit them over the 2.5 shaft. I shortened some 2.5 pins I had to try to use it that way, no go. It was too difficult to adjust, pain in the butt.
[Image: 20160409_190744.jpg]

Fail.

So now I had to find a way to adapt a 4mm hole down to a 2.5mm shaft. McMaster-Carr to the rescue.

I found some tubing that got me close. http://www.mcmaster.com/#standard-metal-tubing/=120vls5

4mm OD, 3mm ID. Luckily I keep weird RC parts, and I had some 3mm to 2.5mm brass inserts. Some dremel and filing work, and TADA !
[Image: 20160414_200140.jpg]

These weird inserts come with every Solar servo. I happen to use Solar servos on all my RC, so I had a bunch of them.

And while I was at it, I bought some TT02 lower arms as well.
[Image: 20160409_204904.jpg]

The ball cups that come on the EA arms will not work with the D4 ball posts. They are a different size. The stock D4 upper cups are an easy swap, but the lowers won't work on the EA arms. I had to look in my parts bin and find some Axial ball cups and then grind them down to make them fit. You could swap out the ball posts instead, but I don't know the size needed, and I didn't want to go that route. So be aware of this if you do these mods.

Here is my front suspension setup as of now. Quite a bit different from stock. As far as I know, I'm the 1st person to use this set up (I could be wrong, but google searches came up with nothing).
[Image: 20160414_201253.jpg]


Here is the caster now.
[Image: 20160414_202737.jpg]


And at full lock.
[Image: 20160414_202751.jpg]

Contact patch now. Pancakes.
[Image: 20160414_202705.jpg]


[Image: 20160414_202440.jpg]
[Image: 20160414_202448.jpg]

Good amount of lock, and best part is I have close to zero toe out with this setup. I also flipped the steering brace to prevent contact with the post. The Usukani bulkhead allows this since it has greater clearance.
[Image: 20160414_202504.jpg]


But now I have a different issue. I can achieve so much lock now that I can pass the point of no return on the steering arms. That's where your knuckles pass the pivot point of the steering arms and get stuck at full lock. Not good. I adjusted my EPA on my servo, but ultimately I'm going to change the steering setup.


Next up, SLIDE RACK ! Bwaahahahaa

Stay tuned.
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#3
Also something to note.

I had to modify the front CF shock tower to allow room for the new upper arms to operate freely.

Here's a shot of the tower afterwards.
[Image: 20160409_193143.jpg]

I used my dremel to grind away material on either side of the bottom mount holes, and up a bit into the arms.

You can see in this before pic where the tower would interfere with the arms.
[Image: 20160409_181310.jpg]
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#4
very detailed, thanks for sharing
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#5
[Image: 20160423_135014.jpg]

Slide rack has arrived !

Build quality is great on 3Racing parts. Nice finish. Lots of pieces to this part. Not for beginners, that's for sure.

[Image: 20160423_135206.jpg]

I have noticed a design flaw in this slide rack. It relies on proper tension from 4 small ball bearings against the slide. The front 2 bearings in the pic below are mounted in slotted holes. It would be a piece of cake if you could adjust the tension and get the rack all set up, then mount it, but that's not possible.

[Image: 20160423_143154.jpg]

The whole unit must be assembled on the chassis. BOOOOO. Come on 3Racing. Rather than use the rear bearing posts to mount to the chassis they could have made the unit self contained, and it would have been so much easier to install.

Do yourself a favor and remove your entire front bulkhead if you install this rack.

[Image: 20160423_152828.jpg]

I had to fuss with the tension for quite a while before it all worked smoothly. It was a real PITA. I was quite disappointed with the design by the time I was done. =L 

[Image: 20160423_153655.jpg]


After it all was assembled I tweaked my caster settings, my knuckle settings, and messed with different steering arm mounting positions for a least an hour. This was my angle when all was said and done.


[Image: 20160423_213155.jpg]
[Image: 20160423_213209.jpg]

Everything spins freely. Almost no binding, almost no catching. Not bad, but I can do better.

I had a hell of a time setting up these 3Racing knuckles, so I bought a set of Usukani knuckles. They should arrive sometime this week.

Stay tuned.
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#6
Finally got around to installing my Usukani knuckles. Here they are layed out with all the included parts.
[Image: 20160506_194201.jpg]

The knuckles come with both AWD style stub axles, and RWD style. To use the RWD axles, you need to use the included inserts, pins, grub screws, and smaller inner bearings.
[Image: 20160506_201637.jpg]

I didn't really feel like depending on the tiny grub screw and extra crap to use the RWD axle, so I opted to use the AWD setup. It's what the D4 has already, so why not. Plus I can use the YR inner bearings I was using. (Note- The outer bearings are larger on the Usukani knuckles so you can't reuse your old outer bearings.)
[Image: 20160506_202136.jpg]

I ran into a weird snag while doing this install. Turns out there was a QC issue with one of my knuckles. The top holes never had the threads tapped. They were totally smooth. Luckily I have a nice tap & die set. I used a M3x0.5 tap and fixed the problem.
[Image: 20160506_203649.jpg]

All fixed. Yea !
[Image: 20160506_205842.jpg]


Here is a shot with the 3Racing V2 knuckle. It consists of the knuckle and the top plate/ steering arm. The top plate is the issue. 
[Image: 20160506_194713.jpg]

I found myself constantly having to remove it, shift it over a few holes, then reattaching it every time I need to adjust my steering. When you start to approach 90 degrees of lock, it's vitally important that the steering doesn't pass the pivot point and get locked out. Adjusting these knuckles started to get on my nerves. They work great in normal circumstances, but these aren't normal circumstances.

Here are the new Usukani knuckles installed. I had to adjust the steering a lot to find a setup that wouldn't lock out, and these babies were a breeze to work with. They also allowed me to kick the offset way out by using the rear most holes for the pivot points. This helped keep my front wheels off my lower arms at full lock.
[Image: 20160507_212917.jpg]


Now the moment of truth....

My steering angle stock(ish).
[Image: 20160409_175118.jpg]

And my steering angle now...
[Image: 20160507_185726.jpg]

[Image: 20160507_185740.jpg]

Project Locked UP has hit damn near 90 degrees of steering angle !

I'll capture some HD video of my car in action, as well as showcase my D4 in it's entirety (body on, etc).

Stay tuned.
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#7
This is awesome man, I plan to do an almost identical set up. I also used the MOD19RC blog and purchased some Eagle racing parts for my build, I have the lower arms and hubs. I'm picking up a slide rack today and now seeing your usukani bulkhead set up makes me want to do it myself too.
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#8
It's been a fun project. I'm happy that it may inspire people to try new things.

It would have been great if I had been able to find an upper arm that fit a 2.5mm pin, but my research was limited. Access to a 3D printer would have been perfect. I would print a 4mm OD 2.5mm ID sleeve, rather than a plastic arm.
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#9
why do you want your steering angle over 90 degree?, we only need 60-70 degree for drifting.
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#10
Why go to such lenghts.. i mean both Yokomo and MST has cars that are designed for drift - I know the D4 is too but it's basic at best, needs a lot of parts, upgrading with different brands and then you are left with a mixed build.

I know MST, just released their RMX 2.0 and Yokomo last year came with the YD-2 but those are 2 starter kit's you can't go wrong with for that price.

Sure i can buy 2 D4's for the price of 1 RMX, but the quality and perfection is so much better, since both MST and Yokomo are using Glassfiber reinforced plastic and 3Racing are using cheap plastics with a hell a lot of flex in it.

Just my 2 cents gents.
MST XXX-D VIP - CS 2.0 - Main

MST FMX-D PRO - RWD - Main

MST RMX-S 2.0 - RWD - Secondary
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