3Racing Sakura FGX F1 RC - Build Tips, Setup and Review
F1 RC Cars > 3 Racing Sakura FGX
14 Oct 2012: Best finish, 6th A-main. Setup at end of page.
9 Sept 2012: Track test day with Sakura FGX drivers. Results at end of page.
4 Sept 2012: Now down to 1090grams ready to race.
Update: It is getting faster and faster. Speed tips towards the end of this article.
This is one of the cheapest radio control f1 car you can buy at a sale price of around $120USD. Even cheaper if you buy from Hong Kong. Mine was bought at $77USD brand new from Andy Lam of Action Hobbies in Hong Kong by my friend Mark F. Thanks Mark! Let's take a closer look.
Photo: The 3Racing FGX kit ($80 USD) + Pardus F1 Rubber tires ($25 USD). Comes with an unpainted lexan F1 body.
Photo: 3Racing FGX with
electronics installed. Body is clear lexan waiting to be painted.
Building Tips - How to Assemble
Though simple in design, with not too many parts, I found it difficult to build the kit. Definitely adult help is needed. Here's a heads up to help you avoid my mistakes and make the build process as smooth as possible.
Let's start with opening the box. Inside you will find an unpainted and clear lexan Formula One body. Lower chassis looks like thick black fiberglass while upper deck is plastic. You have two oil filled shock absorbers for the independent rear suspension. In the front, two small coil springs in the kingpins act as the suspension.
This F1 rc car comes with wheels but no tires. You have to buy tires separately. Make sure the tires you buy fit the rims designed for the FGX.
Photo: Pardus Racing rubber tire set that fits well to the FGX.
There is also no motor. You will also have to buy the radio controller, battery and speed controller separately. In a way it is good as the kit can be sold very cheaply and you can select the right electronics.
The kit comes with full ball bearings, typical size of 5x10mm and 5x8mm. This is surprising given the cheap price. Ball bearing will ensure your r/c car runs smooth, fast and minimal wear to gears and parts.
Photo: The kit ball bearings are packed with grease. To reduce friction, soak the bearings overnight in WD40 to remove the grease. Then lubricate each bearing with a couple of drops of Mobile 1 synthetic oil.
Another bonus is the FGX comes with an oil filled gear differential. This is good as it requires less maintenance than a ball differential if built correctly. An oil filled gear diff gives more tuning options depending on thickness of oil used. The diff felt tight even without oil, so I decided on 30WT silicon shock oil. Take your time, it took me around 2 hours prepare and build the differential.
Photo: Top row are the untouched plastic gears. Below you can see the areas where I sanded flat with 600 grit sandpaper. This is to ensure smooth gear meshing and minimal oil leak.
Note the item on far right of photo above, mine was not 100% round on the part where the ball bearing mounts. This caused the diff to wobble. I took my time sanding that area to get it as round as possible.
The FGX has a lot of gears in the transmission. It is important to ensure these gears are 100% parallel to each other so that gear mesh will be smooth.
Photo: Make sure the aluminum motor mount is perpendicular to the chassis to ensure the spur gear shaft will be parallel to the ilder gear. I rebuilt my transmission a couple of times as I found I made some mistakes in assembly which caused some misalignment of the gears. I also coated the spur gear shaft with a light coating of superglue as the diameter was a little small for the ball bearings, causing the spur gear to wobble.
The kit also comes with a pair of small oil filled shock absorbers for the independent rear suspension. Out of the box the shocks came partially assembled on the o-ring side. The aluminum upper shock cap was also screwed on, you need to unscrew this befor putting oil.
First thing was to install a two hole piston on the long shock shaft and secure this with e-clips. However the pistons still wobbled on the shaft. I added a drop of superglue on the shaft/piston area to remove the wobbling.
Next I found that one of the shocks was binding when I moved the shock shaft up and down (this was before putting shock oil). Upon disassembling the o-ring side, I sanded excess plastic flashing on the black spacer.
Photo: Notice the black spacer has excess plastic that caused the shaft to bind. I removed this and voila, the shocks were silky smooth. I used the #700 oil that came with the kit.
Key to have a smooth shock is to make sure no air is trapped in the oil. Put the oil, pump the shaft a few times to get the air bubbles to rise to the surface. Wait a few minutes to get all the air out.
Photo: I used an old magnet to keep the shocks in an upright position while waiting for the air to rise to the surface.
Note in the photo I did not realize the pink/red aluminum upper shock collar was screwed on. I spent a lot of time looking for them in the box only to realize they were on the shock bodies. Unscrew them before adding the oil.
Important is slide the clear shock bladder at an angle so that air can escape. Then screw on the cap slowly and tightly.
If built correctly, both shocks should feel the same. There should be a smooth feel.
If it feels mushy, most likely there are air bubbles inside. This will lead to inconsistent dampening. Rebuild the shocks.
Tip: The shocks mount on 4mm aluminum ball ends. These use 1.5mm allen hex to screw to the chassis. I suggest you first tap the chassis with 2mm allen head button screws. Then it would be easier to screw the 4mm ball ends.
Speaking of screws, the FGX came with very nice quality 2mm button head hex screws found typically in expensive high end kits. Kudos to 3Racing for this.
However, assembling the wings makes use of very small philipps screws. You will need a small jewelers (+) screwdriver.
Now to the front end. Based on feedback on forums, the A-arms are very fragile. I decide to spend a couple of hours reinforcing the upper and lower arms.
Photo: I used 1.5mm allen wrenches to reinforce the arms. These were superglued, then with hot glue gun, then covered with a black shrink wrap.
The plastic upper deck is also a weak point. I reinforced with epoxy.
Photo: Strengthening the weak upper deck with epoxy.
Melted plastic from a parts tree was also used to reinforce the upper deck.
Another reported weak area is the kingpin. There is an area near the middle of the kingpin where it is thin in order to put an e-clip.
Photo: Install the kingpin upside down so that with weak part is enclosed inside the steering knuckle. That should help prevent breakage. Or simply replace with kingpins from a Tamiya F104 which is much stronger.
The front suspension design is the typical pan car and similar to the Tamiya F104. Small coil spring in the kingpin. The kit supplied spring felt very hard and I will replace it with a soft spring from my F104. Also try coating the kingpins with a light coat of Tamiya Anti Wear grease to provide the dampening.
Note: 3Racing is currently testing an independent front suspension design with inboard oil filled shocks. Can't wait for that upgrade.
As to tires, the FGX uses a different hex size, wheel diameter and offset than the popular Tamiya F104. What will fit are the Tamiya F201 rims and tires. Plus aftermarket wheels and tires such as those from Pardus Racing.
FGX (kit rims) = 39 mm
Curiously I tried to see what tires I had that fit.
Photo: Touring car tires easily fit. Though it looks weird. Width is 188mm rear and 183mm front. But note the FGX wheel hex is same as touring car tires. So maybe 26mm nitro TC foam tires on the rear and 24mm on front will give a decent look.
Photo: 3Racing FGX with Tamiya m-chassis tires. What do you think?
So in actuality, there is no shortage of rims and tires that will fit the FGX. But be sure to buy tires as the kit does not include any.
Electric Motor, Steering Servo, Receiver and Electronic Speed Control
F1 rc cars are a tight fit and it is recommended you buy the smallest size electronics.
Steering - I used a Bluebird BMS low profile servo, which is needed in order not to hit the plastic upper deck. Also a tight fit with the battery. Steering linkage might rub on a square battery pack, so I used an Orion rounded case Lipo battery.
Receiver - The space is tight. My regular sized Futaba receivers did not fit. I had to find a smaller one which was 40mm x 26mm, and it was an exact fit.
Electronic Speed Control - Here there is plenty of space. I used a Futaba TEU 104.
Motor - Used the common 540 Mabuchi / Johnson stock motor.
Gearing - With the 40T spur gear, maximum pinion size is 18T as motor will touch the battery holder. Removing the battery holder I was able to go to a maximum pinion size of 20T with an FDR of 5.4. To get a lower FDR (e.g. higher top speed) you need to buy the optional 35T spur gear.
Battery - Orion 4000 stick pack Lipo which was taped via slots in the chassis.
Total weight with electronics was 1195 grams. Around 110 grams heavier than a similarly equipped Tamiya F103.
FGX Setup Tips
This would depend on the surface, grip and size of the track. The higher the grip (e.g. carpet) the stiffer the setup. The lower the grip (e.g. asphalt) the softer the setup.
Out of the box the FGX comes with a soft chassis, soft rear springs and independent rear suspension design. This leads me to believe the designer might have parking lots or low grip tracks in mind. And fortunately that is the type of surface I race on. That means no need for hop up parts.
Before building I read thousands of posts on various forums on the FGX to learn as much as possible about good setups. Important is the oil used in the gear differential and shock absorbers. Here is what I will start with for low to medium grip surface.
Track test #1 (9 June 2012) - First few laps was enjoyable. The FGX felt more realistic to drive compared to the F103 and F104. The independent rear suspension allowed for body roll which gave more mechanical grip and confidence to push the throttle. Turn-in to the corner was surprisingly stronger and better compared to my F103.
Test Update (14 July 2012) - Determined to tune this car I did a lot of laps which helped break in the Parduxs racing tires. This significantly improved lap times. Key tuning tips was to reduce rear droop to 2.5mm which eliminated corner entry oversteer. I compared it with my Tamiya F104.Sakura FGX...49lap...15m14.282sec...17.738sec fastest lap
Tamiya F104...50lap...15m13.011sec...16.826sec fastest lap
Test Update (29 July 2012) - Felt very good especially with the new Pit Shimizu tires. Able to keep up with the direct drive cars on the same 50 lap.
It is getting faster. Will do some weight reduction (currently 1230gm) and try 0 deg rear toe in.
My F104 also weighed 1230gm but felt lighter (maybe due to efficient direct drive transmission).
Below is the carpet setup of Charles Lightfoot from UF1.com.1) Hard rear shock springs with 2000 weight stock lube
2) Stiff rear sway bar
3) Medium front springs with 10,000 lube
4) Titanium king pin with 8mm Pom Ball
5) 48 Pitch / 35 Spur / 26 - 28 Pinion
6) reinforce the front upper and lower arms with piano wire and shoe goo
7) 3 degree rear toe in/ 1 degree front toe out/ 2 degree rear camber / 1 degree front camber
8 ) 4mm ride height front and back
9) Shimizu 0565 and 0561 ... The rear insert foam I shave the thickness in half with a dremel...
Sauce full rears and 3/4 fronts
With the independent rear suspension providing better mechanical grip over the direct drive cars, lightening the car should lead to better performance (i.e. quicker cornering, acceleration and top speed).
Here is the painful process. Down to 1170gms by replacing the wings with lexan. Reduced by at least 20 grams! And no more saggy front wing. The dimensions of the FGX front wing are the same as a TC rear wing... hint hint.
Milled the chassis from 98 grams to 87grams. Battery and electronics will cover up the milled area anyways. A tiring way to reduce 11 grams.
Battery is already pretty light at 230gms. Can be reduced to maybe around 200gm with a FullyMax 3300 lipo. Waiting for local hobby shop to restock this battery.
4 September 2012 - Further reduced weight by lightening lower fiberglass chassis down to 66grams. Replaced rear wing with a TRG for 10 gram reduction. FullyMax 3300 lipo weighed only 209grams. Removed excess plastic from arms, hubs, steering knuckles.
Photo above: Down to 1090 grams. As comparison, my Tamiyas are 1030 to 1120 grams.
Photo above: Without the 50gram body. Still a box stock 3Racing FGX. Just removed excess materials from chassis, arms, hubs, upper deck, wings, etc. Also used lightweight electronics.
Now very excited to see how it will perform in the next race against the direct drive F1 rc cars.
9 September 2012 - Track test day with my fellow FGX drivers. With 5 cars we were able to gather meaningful test results and good setups. The lighweight FGX also felt much better and faster.
Main tuning item are tires. So far the Pit Shimizu are the best, though maybe with stronger sidewalls or thicker insert performance can be improved. I also liked the cheap Pardus tires and they were almost just as fast.
The silvercans provided good speed, but temp of over 200F after only 5 minutes. The 32T Formula tuned was perfect for 15 minutes but at the expense of slightly slower top speed.
Common issues we all had were severe oversteer during off throttle. For me the cure was to increase caster from 3 to 6 degrees. Other things to try are thick grease on front kingpins to slow down weight transfer.
Interesting is that at low grip conditions (similar to qualifying) the FGX is fast, if not faster, than direct drive. But in high grip (similar to mains) the direct drives are slightly faster.
14 October 2012 - Porsha, racing the FGX for the very first time, finishes a respectable 6th in the Amain. Only the F104 of Taka and Leo, very fast drivers, were faster. Plus a couple of F103 (200mm) wide cars were faster. But comparing to the 180mm direct drive, the FGX is competitive.
Weight: 1120 grams, Front: 4mm, 0.5 deg camber, Rear: 3.5mm, 1 deg camber. Diff has no oil, just lubricated the gears, oring and output shaft with teflon grease. Changed front and rear wings. Pit Shimizu tires all around. Kit is box stock, no upgraded parts.
Video of the FGX below. Fast forward to 1:57 to see it in action. It is the white car with black rims.
Review of the FGX
Overall the 3Racing FGX is good value if you want to take the time to reinforce the weak parts and build the kit properly. However, I do not think it is a good car for beginners given it is not as durable as other F1 rc cars and is very difficult to build. My hands have blisters.
During the build process I honestly started to dislike the kit. But after finally finishing the kit, it is beautiful. I guess it is like giving birth, the process is painful, but the result is worth it. Thumbs up 3Racing for making the FGX.
The end :)
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