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Speedy's FGX EVO 2018 Build Thread

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I haven't written about this model in quite awhile, but I ordered a new clear body to replace the original kit body I hacked up and sprayed black.  After careful trimming and fitting, it also has the same issue with rubbing against the rear shocks (lower spring holders).  The manual's recommended body post heights exacerbate the problem, but even running the body one notch higher is still not perfect.  I think part of the problem is the kit body is the same as the original FGX EVO body, but the wheelbase of the FGX EVO 2018 chassis has been stretched by 10 mm.  3Racing just recycled an existing body instead of designing something appropriate for the new release.

So there's some insanity for you, trying the same body twice and hoping for a different outcome.  I'm about ready to throw both bodies in the trash and go in a different direction.  Cool chassis, but frustrating body.

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As you can tell from the previous post, I was feeling a little frustrated with the body but ultimately I pressed on.  I have a decal strategically applied to cover up the eventual paint rub from the shock.  It's not *terrible*, but it's not perfect either.  Oh well.  I considered finishing it in a modern Renault livery, but got lazy and opted to use the 3Racing decals.




Eventually I'll get some electronics in it and take it for a drive; right now I'm busy with finishing bodies on a few more models.

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Short update on the FGX EVO 2018...

When I last put it on the shelf, I noticed the rear of the chassis seemed a little tweaked and the camber on the right rear wheel seemed wrong.  Also, the shock positions under compression weren't matched very well.  In the back of my mind I was thinking I should get this chassis on a setup stand soon and try to sort out the issues.

A few months ago I bought a used granite inspection block for about $40 locally.  Checking it with a height gauge in dozens of locations, it seemed to be very flat as the measured surface heights did not vary by even 0.01 mm.  So, it's the perfect setup board for chasing chassis tweak and checking the suspension.


Right away there was something odd about the left rear of the bottom chassis plate.  Holding the front of the chassis down, the right rear was touching the stone, but the left rear was elevated.  I could push down on the left rear and see the rear wing move, but the same didn't happen when pushing down on the right rear.

All of the screws on the bottom of the chassis plate are countersunk, so they are perfectly registered with the holes drilled in the chassis plate.  There's no simple opportunity to move them around.  So, I just inspected each one for tightness and did find a single screw in the rear that could take another half turn.  Nothing major on the bottom of the chassis, though, and the tweak was still present.

The top deck is secured to posts using button head screws instead of countersunk screws, so they have a little bit of opportunity to float in their holes.  I loosened them and saw a little improvement, but the tweak worsened as I tightened them down again.  I also tried lengthening the center rear turnbuckle that connects the top deck to the rear gearbox; the instructions call for 25.4 mm of length, but I had set it at 25.0 mm in the build because the adjusters didn't perfectly line up with the ball studs originally.  I did change the length to 25.4 mm and later to 25.6 mm, and that didn't seem to do much on its own either.

What seemed to make the biggest difference, though, was loosening the four top bulkhead screws in the rear.  These are the four screws that hold the two rear upper suspension arms in place as well.  Once I loosened those and set the center turnbuckle at 25.6 mm, the left rear of the chassis seemed to flatten.  I tightened the top rear bulkhead screws again and the flatness seemed to stay in place.  Pressing on the left rear, the wing almost didn't move at all, which was a huge improvement over how it was earlier.

With the chassis essentially flat I started checking the natural droop of each suspension arm.  With the droop screws set high and the shocks set at full extension, I found the front right pushrod and the left rear pushrod needed to be lengthened.  The front right needed to be loosened one turn, and the left rear turnbuckle needed about half a turn.  With those changes in place each pair of uprights floated above the stone the same amount to the nearest 0.1 mm.

Now with a flat chassis and the arms drooping in matched sets, I started looking at the dampers and their springs.  The front springs and spacers seemed pretty well matched, but I noticed the rear springs were not perfectly matched for length.  The right rear shock needed to have its lower spring retainer collar loosened and moved closer to the shock body by about 2 mm so the spring would just start to touch the retainer.  The left rear shock needed to have its collar loosened and moved closer to the shock body by about 0.5 mm.  Now the threaded adjusters were at the same starting position, and the lower collars were adjusted to compensate for spring length.

Rear changes:  Lengthened center turnbuckle, loosened and retorqued upper bulkhead screws, loosed and retorqued upper decks screws, left rear pushrod turnbuckle lengthened slightly, damper spring collars loosened and repositioned for actual spring lengths.


Front changes:  Front right pushrod lengthened by one turn, loosened and retorqued upper deck screws.


Flat chassis, equal droop, springs set to the same starting positions -- time to check the camber and toe.

The front was not bad -- about 2 degrees of negative camber on each side, and about 1 degree of toe-out on each side.  Perfectly fine as a starting point.

The rear was a little out of whack; the right rear actually had about 1 degree of positive camber and the left rear had about 1 degree of negative camber.  A few twists on the turnbuckles, and they were both at about 2 degrees of negative camber.  Each side has about 3 degrees of toe-in.

The ride height checked out all around the chassis plate.  In general the ride height was 8.3 mm with a minor variation of +/- 0.1 mm depending on where the measurement was taken.  This was without any electronics installed, but when I do I'll redo the ride height and check/tune the corner weights.  I'm thinking the corner weights won't be too bad as the battery and motor are along the center line of the chassis, so it'll be mostly a ride height adjustment later.


Anyhow, I feel a lot better about this.  Not sure when I'll get back to this car again, but at least I know it's not sitting on the shelf crooked and weird while it waits for me.

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