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Speedy's F103GT Nissan GTR LM Nismo Build Thread

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For anyone who is not familiar with it, the F103GT chassis is a RWD touring car chassis based on the F103 F1 chassis. The F103 family had a long production run with several variants, including GT, LM, R, RM, RS, RX, Special Chassis, and TRF Special Chassis kits. It was introduced in 1993 and enjoyed a special 15th Anniversary model (F103R) in 2008.

The F103GT kits, 58367 F013GT Chassis Kit and 58376 Advan Courage LC70 Mugen, were introduced in 2006. While the GT chassis has many of the same components as a regular F1 kit, the 257 mm wheelbase and hex adapters for using standard touring car wheels are unique features.

About a year and half ago I was really intrigued by this chassis and did some research to find out more about it. I found Jang's review which did not sound very encouraging, but I also found a few rebuttals/counterpoints from others who claimed it was great. I also watched several YouTube videos and saw cases where the chassis seemed a little challenging to control, and in other cases it seemed to drive just fine. I even saw a video where someone was using it for RWD drifting successfully!

My attraction to the F103GT is simple construction, very low weight, efficient drivetrain, and usage of touring car wheels/tires. My desire is to meticulously and carefully build, test, and tune this chassis to find an optimum setup. My hope is for a pleasant and pure driving experience when running it in my cul-de-sac in front of the house. Setting up a makeshift track and running some satisfying laps during these summer evenings is all I'm after.

Box top.

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Feature list and chassis picture.

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Specifications and hopups.

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End panel.

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Box contents.

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Everything spread out. There are only a few plastic parts trees, some chassis plates, a bag of hardware, and the body/wheels/tires/inserts.

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Manual and stickers. The manual is a reprint from the 58367 chassis kit; there's a separate instruction sheet for the body.

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I'm looking forward to digging into this! I had been slowly accumulating spare parts and hopups with the intention of building a F103GT eventually, but the release of this kit makes it so easy now to just build and tinker with it. Thank you, Mr. Tamiya, for bringing this chassis back!

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This kit looks like a fun build for you, my friend. I'm looking forward to watching this bad boy come together. Are you gonna keep the silver can or put something in with a little more "hutzpa"?

Mike

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I like the F103GT too.

I had an original 58367 which I used for high-speed runs, but really struggled to find many places I could run it because of the ground clearance. Incredibly fast once the rear gets traction and it starts to get going, even with a standard silver can.

Unusually the 58367 I had came with an RS540 which had red and black motor wires (instead of green and yellow). I always wondered whether it was a different spec or just a different coloured wiring batch?

I built a second one of these back in 2008/9 with all the 3Racing back catalogue - the only Tamiya parts which remained were limited to...well the front bumper and not a lot else!!

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It's like tamiya was coming after me when they released this and the GT2 Porsche.

Subscribed because speedy is a bad influence.

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This kit looks like a fun build for you, my friend. I'm looking forward to watching this bad boy come together. Are you gonna keep the silver can or put something in with a little more "hutzpa"?

Actually, I plan to use the silver can. I've run RJ Speed pan cars with silver cans in the past, and with 3.5:1 FDR they really scoot nicely. The gearing provides a nice balance between acceleration and top speed. I have run the same RJ Speed with a 4200kV brushless system in the past, and it was just too much for the area I have.

I'm not sure how you can look at that shell and still want to put anything box-stock under it. The thing screams thoroughbred... With a Japanese accent...

I gave in and threw all of the hopups at mine. A fun build that doesn't take long, even when you go to the lengths that I did.

I hear what you're saying; I have several hopups for this chassis but I'm going stock for now. I really want to work with this chassis in its stock form first then selectively add hopups later if needed.

It's like tamiya was coming after me when they released this and the GT2 Porsche.

Subscribed because speedy is a bad influence.

:D

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After I posted last night I spent some time laying out the parts and checking them against the manual to make sure I had a full kit. I've never had a kit with missing parts, but I was surprised when I found the battery strap and top bumper brace were missing from the "B" parts tree. I was also surprised when I discovered there was no bumper either! I was checking against the 58367 manual first when I found these discrepancies, but later when I was reviewing the body set instructions I discovered the reason why. The body shell has such a low nose that there is no room for a urethane bumper. Therefore, there's no need to include these parts in the kit. I can understand not supplying the bumper, but I can't understand why Tamiya would go through the hassle of clipping B1 and B6 from the parts tree. After all, they have to mold a complete set of parts anyhow, so why remove the battery strap and top bumper brace from the tree? I hope they're at least grinding them down and mxing with fresh material to mold new parts instead of throwing them away! Ultimately what this means is if I want to use a different shell on this chassis in the future, I'll have to source the top bumper brace and a bumper. Bummer!

Anyhow, all the parts were found and the "missing" parts were explained away, so I had everything ready to go...

IMG_2099.JPG

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Time to start this build...

Step 1 is building the battery box and attaching the rear T-bar. You might notice there's a washer and an O-ring used in this first step. The washer fits between the front battery bracket and the T-bar; the O-ring fits between the rear battery bracket and the T-bar. The stiffness of the O-ring is controlled by how much the lower screw is turned into a locknut on the top of the battery bracket; this affects roll stiffness mostly.

Parts...

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FInished...

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Step 2 is building the rear motor pod that fits on top of the T-bar. I used a flat surface while assembling the pod parts to try to minimize tweak across the pod; it seemed to go together just fine.

Parts...

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Finished...

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I actually did step 4 before step 3. Step 4 is connecting all the electronics and centering the servo in preparation for installing the servo saver. I reset all the settings on my radio to defaults, bound the receiver to the radio, and let the servo find center position. I also took a moment to calibrate the ESC throttle endpoints and set the reverse (ON) and low-voltage cutoff (OFF) settings.

I've been using leftover TEU-104BK ESCs for my pan car builds, and I think they're fine for these applications. I know people complained about only having 50% braking and reverse compared to the older TEU-101BK, but in RWD pan cars the weaker brakes make it easier to control across the radio's trigger range. As mentioned earlier, I also tend to use silver cans in my pan cars as they have plenty of power for these lightweight vehicles. With the right gearing a silver can has no problem making a light car hit decent top speeds. I save the brushless systems for heavier touring cars and offroad vehicles.

Centering the servo...

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Step 3 is removing the mounting ears from the servo. The servo is actually held in place between two brackets with double-sided tape, then the brackets are attached to the chassis with screws. I used flush cutters to nip the mounting ears off and used a knife to trim some flash from the bottom edige.

Once I had the servo centered and the mounting ears removed, I worked on installing the servo saver. I found the base of the servo saver was a little loose on the splined shaft, so I wrapped the shaft with one layer of Scotch tape and then pressed the base on. It fit snugly with no slop. When I test fitted the servo saver spring and horn with the base as a complete assembly, I found the horn didn't have any slop via the spring, but the center hole in the horn floated a little on the base. I wrapped a single layer of Scotch tape on the part of the base where the horn rotates, and that removed all the slop from it. Finally I added the washer in front of the horn and installed a screw to hold it all together. Net result -- no slop in the servo or servo saver at all.

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After installing the servo saver, the rest of step 5 was attaching the servo mounts with double-stick tape and attaching the steering links.

Parts...

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FInished...

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Step 6 is installing the servo to the lower deck and installing the antenna tube holder.

Parts...

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Finished...

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Step 7 is installing the ESC and receiver on the lower deck. This is done with double-sided tape.

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Step 8 is building the upper deck with body post holders and damper post. EDIT: I figured out later that I'm using the wrong body posts; I was following the 58367 manual verbatim and forgot about the body instructions. See later posts.

Parts...

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Finished...

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Step 9 is where things start coming together. The lower deck, upper deck, and T-bar assemblies are all combined with six screws and nuts. Additionally, a damper bracket is added to the top deck.

Test fitting the assemblies and collecting the parts...

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Screws, nuts, and damper bracket installed...

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Wiring cleaned up. I'll worry about the battery and motor wires later. I just wanted to get the power switch, servo wires, and antenna routed cleanly for now...

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Another view...

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This is such a gentle build so far. The parts count is quite low for each step. I don't perceive any chassis tweak and I'm happy with the servo saver.

More to come...

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Looking good, but are you not sealing the edges of the FRP plates?

Dorvack.

I thought about it, but I'm planning to use a leaf blower to clean my cul-de-sac of pebbles and dirt first. The asphalt in front of my house is very smooth. I'm also planning on using some protective tape on the bottom of the chassis. From running the RJ Speed cars in the past I didn't have problems with the FRP chassis edges, although I got a few scars in the middle of the chassis plate. I'm hoping better street prep and some protective tape will keep things in good shape.

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Looking good so far, love the F103/F104 based cars, very fast on the right surface.

Really wish Tamiya would release a proper Toyota TS020 body, or possibly TS030 Hybrid body? :)

This going to be boxart? or is it to be the 1990's Nissan livery?

James

:)

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I meant to protect your hands... and add a little rigity. :)

Good point about protecting hands -- I caught a glass fiber in my right index finger and it was annoying for a day, but it has since gone away. As far as rigidity is concerned, most everything I read suggests more flex if there are traction problems, so I don't want to permanently make something too rigid with CA glue.

This going to be boxart? or is it to be the 1990's Nissan livery?

I'm shooting for 1990s Nissan livery with some extra enhancements to the body shell, but if some of these ideas don't pan out I'll default back to box art.

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Onward...

Step 10 is installing the rear axle. Ride height is adjustable by selecting one of a few different inserts from the "S" parts tree, and orienting the insert one way or another in the pod. I'm sticking with the default ride height for now. Note the kit comes with a complete set of ball bearings for everything.

Parts...

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FInished...

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Step 11 is installing the pitch/roll damper and the motor. The damper is basically a FRP piece compressed by two plates and springs. The upper nut can be adjusted to increase or decrease the friction between the FRP and plastic plates. There is a small amount of ball diff grease between the FRP and plates, although there used to be different grades of fricition damper grease that could be used as well. The motor is the standard silver can.

Parts...

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Finished...

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Step 12 is installing the pitch damper and connecting the motor wiring. The damper is purely a spring holder with no friction properties persay. The damper body has four grooves in it, and the spring clip can be installed in any of those four positions to change spring preload. The illustration in this step shows the clip installed in the second position closest to the front of the car.

The manual doesn't provide guidance on what to do with the motor wires other than connect them. Given the stiffness of the motor wires, I didn't want to secure them to the chassis too much as I didn't want to tweak or influence the rear motor pod, which is a moving part of the suspension. So, I connected the motor to the ESC and attached the ESC wires to the damper mount, but then the wires are simply floating.

Parts...

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Finished...

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Step 13 is installing the front suspension. The lower arms are rigid, but the upper arms pivot on hinge pins in a center block. There are two different sizes of aluminum balls to be pressed into the arms. The 7mm balls are pressed into the upper arms from below, and the 8mm balls are pressed into the lower arms from below. The 8mm balls also have a counterbore in them to accept the suspension springs, so while installing these parts it's good to orient the counterbores downward.

Parts...

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Finished...

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Step 14 is preparing the steering uprights. The uprights accept 850 ball bearings, and the axles are common with the M-chassis. Body clips are used to temporarily keep the axles from falling out.

Parts...

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Finished...

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Step 15 is installing the front uprights in the front suspension. In the parts picture below I forgot the upper set of T3 spacers, but they're in the final picture for the step.

Parts...

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Finished...

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Just a quick note to say everything about this kit moves smoothly and freely -- the upper arms drop under their own weight, the kingpins slide in the suspension balls well, the rear FRP damper plate slides smoothly between the plastic plates, etc. There's very little to no slop in most of these moving joints. It's a pleasure to build something and not have to trim a lot of plastic flash or ream holes or shim things to get the best results. There are certainly some small improvements to be made with the servo saver, but that just involved a little tape. The steering wires are probably the weakest aspect of this kit at the moment, but I have some turnbuckles to install later.

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Step 16 is building and installing the rear ball differential. The assembly process is straightforward -- grease the holes in the spur gear, install the balls, grease the diff plates, and assemble the complete diff. In place of a spring there are two cone washers; these work fine. A standard 1150 ball bearing is used as a thrust bearing; I think newer chassis use an actual thrust bearing instead. That's not to say there are any issues -- some of my other chassis do the same thing.

The instructions for this step suggest tightening the diff fully and then backing it off a quarter turn; I didn't do that. Instead, I gradually tightened the locknut and tested the diff for slipping by holding both ends of the axle and pushing forward on the spur with my thumb. I tightened the lock nut in small steps repeatedly until the spur was just on the edge of slipping. Note that the locknut is covered with a hex adapter in the next step, so spending some time setting and testing the diff here is a good thing to do.

Parts...

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Finished...

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Step 17 is installing the rear wheel hex adapter and motor pinion. The press nuts are shared in common with Tamiya's tank kits. I forgot to add the pinion in the parts photograph. The kit pinion is 14T, and with a 70T spur provides a 5:1 FDR. This is a little high for my taste, but I couldn't get a 20T pinion to fit. There is an extra paper included in the kit that mentions some different spur/pinion combinations; I may have to switch to a 0.4 mod spur later to fit a larger pinion.

Parts...

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Finished...

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Step 18 is assembling wheels and tires. The wheels are +2 mm offset. One thing that struck me was how nice the 53220 Super Slicks are compared to the usual kit tires -- the rubber is particularly supple and soft compared to some of the other touring car kits I've built in the past. The foams fit inside the tires properly and don't have any gaps between the ends; the instructions do indicate to glue the ends together.

I prepped the wheels and tires by partially filling the kitchen sink with hot water and dish washing soap. Then I dunked all the parts and scrubbed them with a toothbrush to remove any mold release. Then they were rinsed and set aside to dry. I had to run to the local hobby store and buy some new tire glue, so they had plenty of time to dry by the time I came home.

What a difference new tire glue makes! I think my old glue was going bad as it took forever to cure. The new glue cured in just a minute or two.

Parts...

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Finished...

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Step 19 is installing the rear body posts and all the wheels/tires. It was at this point I started thinking about the body post height settings for the shell and I consulted the body instructions. Whoops! I had installed the rear body posts per the 58367 instructions, but the body set instructions showed using a much smaller set of posts. The parts photo below was taken before I figured this out, but the finished photo shows the correct rear body posts.

Swapping out the body posts was easy. I just removed two of the rear battery bracket screws from the bottom of the chassis, pivoted the bracket out of the way, and removed the screws holding the rear posts in place. Once the posts were gone I rotated the bracket back in placed and reinstalled the screws and nuts. The proper body posts for the Nismo LM body use rubber O-rings and body clips to hold them in place.

At the rear of the chassis the wheels just slid over the hexes, and M4 locknuts were tightened. At the front of the chassis the temporary body clips were removed from the axles, and cross pins, hexes, wheels, and locknuts were installed.

Parts (not 100% correct)...

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Finished (with correct rear body posts)...

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Steps 20 and 21 involve prepping the front body posts and installing them on the lower bumper bracket, then installing it all to the front of the lower deck.

Parts...

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Finished...

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Step 22 shows how to install a battery, and step 23 shows how to install a body. I think I can handle this.

Step 23 is the final step of the formal instructions; the next page discusses adjusting the friction plate nut and setting the front steering toe. Up until this point I hadn't attached the steering wires to the uprights as I didn't want to cycle the ball connectors more than once. I powered up the car, centered the servo, made a few adjustments to the ball connectors, eyeballed the front toe, and popped them into place...

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I took this opportunity to break in the diff a little; holding one rear tire I'd run the motor at 10-20% throttle for 20-30 seconds, then hold the other rear tire and repeat. I did this a few times and checked the rear diff for slipping again, and it was still good. I will say the diff action itself improved; it went from a very fine graininess to butter smooth as a result of breaking it in a little on the bench.

Finished with the chassis!

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I couldn't resist taking the chassis outside and getting some first impressions! How would it respond? Would it feel telepathic, or would it be a total dog?

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With the NiMH, TEU-104BK, and silver can motor I feel like it could use a little more straight line speed. The FDR is 5:1 at the moment; I've been running my RJ Speeds at 3.5:1 with similar electronics and I like the resulting top speed more. This is easy to change later.

Straight line stability is good. I had no problems with wandering at speed, and I had no problems with returning to straight after turning. There's slop in the steering links, but the kit toe setting is minimally toed in, and it works fine.

With respect to steering, the car is more planted than I expected. Coming into a turn at full speed, I can cut the throttle, steer hard, and see the front end push a little while the rear end slides just a little. It doesn't spin out or act unpredictable at all. Mid-turn changes in throttle can affect steering some with transitions between understeer and oversteer.

The trickiest part of driving it is applying power after a turn. I found I could make the chassis oversteer coming out of a turn by applying too much throttle too early. A 4WD touring car would pull itself forward with a lot of throttle applied this early, and that's the driving habit I mostly have, so I had to make myself wait just a little longer than usual to hit the power again. It's better to roll on the throttle instead of trying to stab the throttle. That said, I can't condemn this chassis at all. I think adjusting my driving style, adjusting the T-bar screw, adjusting the friction damper, and possibly changing the front springs will help with exiting tight turns with more power. It's in this area that I feel like the car is 1/2 to 2/3 of the way there and just needs some tuning.

I feel like the chassis is pretty well balanced, as it behaves the same turning either right or left. The behaviors I mention above are consistent in either direction.

I do like how quiet the chassis is, and I do like how the tires progressively break away on the asphalt. Note I'm running on an unprepared street surface with dust/dirt/debris, not a track that's been cleaned and sugared, and I'm not using any traction compound. I don't have ultimate levels of grip, so I know that influences the impressions I'm reporting here.

Overall I would say this is a positive experience so far.

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Awesome build and initial impressions. You are tempting me to get one as I have many F1 cars but I have never had a GT chassis. Looking forward to more thoughts from you on this chassis and can't wait to see the finished body.

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Today has been a lazy day around the house. Just for fun I thought I'd break out some of the setup tools, take some readings, and tweak a few things.

First I wanted to see how heavy the chassis weighs without a battery in it. If you add the corner numbers in the photo below, the total is 741 grams. I was pretty impressed the front only had a 1.3 gram difference side to side, and the rear had a 16.9 gram difference. The cross weights are different by 15.6 grams. I compressed the suspension a few times and took readings, and the numbers were generally consistent.

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Then I installed the battery. Total weight was 1090.3 grams, almost 350 grams more with the battery. The front had a difference of 0.2 grams side to side, and the rear had a difference of 21.1 grams. The cross weights were different by 20.9 grams. With the battery the front-rear weight distribution is about 41% F / 59% rear. Right-left weight distribution is 51% R / 49% L.

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I found the battery could move a few millimeters side-to-side in the battery box, so I plan to install some weatherstripping foam in the right battery cup to keep the battery biased to the left side of the chassis. This will keep the setup consistent and prevent 350 grams from shifting side to side in each turn. In the future I might experiment with a shorty LiPo to drop the total weight and influence the cross weight a little more.

In addition to the scales, I also used some setup tools to check camber/caster/toe. Of course the rear of the car has no camber/caster/toe due to the solid axle, but in the front there was some value to checking the settings for symmetry. I found both sides of the front had 0 degrees of caster and -3 degrees of camber, but I found the left toe setting was not the same as the right toe setting, so I had to pop off the ball cup and twist it a few times to make the left match the right. I ended up with 0-3 degrees of toe in on each side depending if the steering wires were pulled or pushed against the servo horn. I did this with the servo active and centered to make sure both sides were matched. In general with the car moving forward the total toe should be 0 to 1 degrees of toe in.

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So with a little foam to bias the battery, and a few twists on the left ball cup, I think this chassis is fairly balanced now. The wear patterns of the tires are fairly even. The numbers are just a different view into the impressions I reported last night...

More to come...

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Awesome chassis setup equipment! Didn't know those were available for RC cars! I use this stuff regularly on my race cars. Where can I get it from and how much should I expect to pay?

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