The new Exotek F1 car has been a source of intrigue for a few months now, having secured the ROAR national championship at the carpet nats. The car was kept under wraps for quite some time actually. It has been developed over several years' time. I saw an early prototype at a race in California a few summers ago, and I have heard about multiple iterations being tested out there.
One of the main design departures from typical F1 cars is the 3 shock pod arrangement, controlled by a panhard rod similar to a NASCAR or sprint car rear axle. This allows massive travel in comparison to a t-bar or link car with a center pivot. The entire pod can move up and down, without restraint from the center pivot. I like this concentration on maximizing travel, as I have felt that most pan car based designs don't have enough travel in the car. Rubber tires are heavier, and larger than foams. Greater travel, and also rear traction, should be a strength for a rubber tired F1 car. Counterintuitive to what you might think, this should be a huge asset for carpet racing. The dreaded traction roll, and it's little brother, the light inner rear tire, rear their heads when the car runs out of travel. Once the car can no longer roll in the suspension travel, it will hinge over and flip or at least pick up an inside tire.
The chassis is also different from almost every other car in that the main chassis is a 2 piece hybrid of carbon and aluminum. Different, but I can understand why this was chosen. I have had an aluminum chassis before, which I felt was too stiff. It seemed to kill the mid corner steering. Here the front of the car is allowed some flex without sacrificing too much rigidity in the rear.
The packaging of the kit has tremendous appeal visually, and everything fits nicely in the medium sized box. Beyond the chassis parts, a front and rear wing are included, leaving only the choice of a body, tires and electronics to the builder. Note that wing mounting is the standard Tamiya hole pattern, so nearly anything will fit. Bodies may be a little more restrictive as the links require some clearance. Most bodies introduced in the last few years should fit, and I think most Tamiya bodies could even work, though the "cut and fit" realistic side pods would probably have to be omitted in most cases. I chose a Bitty Design body, which fit just fine.
Assembly starts with the front end. As with any F1 kit, remember thread lock is essential, as the rubber tires will vibrate all the screws loose eventually. A sparing dab is all that's needed.
I included a picture of my trusty CRC pivot ball tool, which is a must have for any pan car owner. There are several different brands out there, but this prevents damage to the pivots during assembly. Using a pliers pretty much guarantees you will smush something eventually.
The pivots are secured in the arms with a large plastic C clip. It's recommended to add a dab of shoe goo to secure them, and that's wise. I also much prefer this arrangement to the o-ring securement which seems to be popular with other manufacturers. I've had the o-rings pop off before which at a minimum makes the suspension get sloppy during the run, if not fail. This seems very robust.
You may have to hold the grub screw in the bulkhead with a 1.5 mm driver while you spin the ball end down, as pictured. The grub screw wanted to rotate with the ball end unless I held it in place like this. You can snug it with a nut driver once it's in place.
Once you have the bulkhead and arms set up, the assembly is mounted to the chassis. You have the option here of two wheelbases. Long is recommended for large and high speed tracks. Short for smaller tracks and indoor. I went with a shorter car.
Just a tip, you can use a hex driver to hold the rear suspension mount as you tighten it...that's what the hole is for...
After you get all the suspension mounts and post for the steering on, the rear link mounts and chassis connections go on. It did seem like a lot of parts for this part of the car.
With the chassis bolted together, everything does seem solid. I was a little concerned there might be some tolerance once everything was built up, but the two parts came together nicely, matching up flush. Also pictured are the turnbuckles and ball cups, including a molded version of the now famous Exotek front end for full adjustability of caster and camber.
Again, the pivot ball tool comes in handy for the upper arm. It turns out the good old Tamiya cross wrench has the perfect size drive for the hex adjusters on the turnbuckles, making threading the ball cups a snap.
When securing the knuckle on the kingpin, be sure to squeeze the assembly together as you tighten the set screw. This will ensure even ride height and minimal slop.
Both Tuning Haus and Tamiya sell the same style of circlip which I prefer to e-clips for the kingpin. There is just more surface area and it's easier to pop them off for spring changes and maintenance.
I added some Tamiya hard grease on the kingpins for some dampening. Adding the grease above and below the arm, then working it in seems to be the best way to ensure it covers the whole area of travel on the kingpin. You can use any number of silicone lubes for gear diffs, greases, Tamiya Anti Wear grease (THICK) to slow down the action on the front end. This stuff has been working pretty well for me lately. Just remember, it has to be redone fairly regularly to be effective. Once a race day is the minimum in my book.
This is the front end finished with bellcrank steering. I found over time that leaving the screw in the upper arm connecting the caster control turnbuckle loose enough that it will still pivot ensures there's no binding. It's not hanging loose, but it's not locked down.
The rear pod is a little different from most cars, in that the lower plate is a single machined piece of aluminum. To me, it appears to serve to purposes. One, the rigidity is much better than most cars, and I hope this means there will be less bent left side pod plates. Two, it adds weight down low on the rear end, for an increase in traction. This is a rubber tire car, and it's never bad too have too much rear traction. "You can't fire a cannon from a canoe..."
This is the assembled pod, sans axle. 51.9 g, which is certainly heftier than the typical carbon lower type pod. Again, the weight is down low, so I feel it will be beneficial.
You can see the huge amount of travel afforded by the panhard rod arrangement when the shocks are off the car. Obviously, the car will have much less movement when the shocks limit things, but this is far more than anything I am aware of that out right now. You could go rock crawling with this setup...
Here's the center shock, which includes an internal limiting spring. I have never tried anything like this before, but the manual states using a softer spring improves rear traction. I can only assume that as the shock extends, it keeps an abrupt stop from disrupting the rear end of the car, versus solid shims more typically used to limit shock length.
The shock goes together pretty easily, and is designed in the Tamiya style. One thing I did do was to slightly sand the non shouldered guide, as it seemed to be overly compressing the o-ring once the bottom of the shock was assembled. The guide sands easily with something like 1200 grit paper, and you don't need to take much off. You might need to test it a couple times, but it's better to go slow and not remove too much material.
I punched a small hole in the top of the shock with a tiny drill bit. I have run a "dead" shock on my F1 cars for a long time, with almost no rebound. I think it makes the car more stable.
The rear end has a lot of well thought out features. The oversize bearings are nice to prevent wall shots from destroying the typical thin 1/4" I.D. bearings used in pan cars. Some might want an axle carrier that uses shims to set ride height instead of the cam adjusters on this car. I personally like shim adjustment, but I see the value in an easy to set and strong axle carrier. With rubber tires it's not as critical to have super fine adjustment, but I do like being able to dial in ride height more precisely when switching brands of tires.
The wing mount is the best out there in my opinion. The over the motor design is much better than the perimeter style mounts in that the parts count is vastly reduced, resulting in less weight. It also allows the body to rest on top, ensuring the body will never interfere with the pod.
A fan can be attached to the left side pod plate, again moving weight down on the pod since most other cars wind up with the fan above the motor.
One thing you may want to do is replace the upper ball studs for the micro shocks with something like Tamiya 42231 Damper Ball Connectors (that's what I used). There is an internal hex, making it easy to remove the shock without having to pop the top off the ball stud. This will be important when you set the droop on the micro shocks, which must be adjusted by shaft length.
Tamiya 42231
That's the main part of assembly. I chose to use an Xray gear diff in my car instead of the ball diff. I have not put my ball diff together, but I'm not worried about how it will build, having used Exotek diff parts on Tamiya cars in the past.
I just wanted to add a tip on wings. The car does come with what appears to be a Montech front wing, and a rear wing that is a copy of the old Ferrari wing that Tamiya first made, then copied by HPI for the old Super F1, and many others followed suit. I personally don't like how the Montech looks, but I know a lot of people use it. One reason it is a good wing is that it is far enough off the ground that it has far less "touch downs" where it contacts the track and disrupts the suspension.
The Tamiya 2017 wing set looks great and can be made to have a much better ride height very simply. With a lighter or butane torch, you can carefully heat the inner portion of the wing and make a Z bend with a needle nose pliers. Once allowed to cool while bent to shape, the wing will hold its form. The touch down problem is greatly reduced or eliminated.
Here's the car with electronics mounted. Admittedly, space is tight for the receiver and speed control. I used a Tekin RS Pro and a Futaba receiver. Tekin has one of the smaller ESCs out there, and you do need to stick with a small footprint to fit everything in. The servo is a low profile 9551 Futaba. Something full size might fit, but low profile is really what the car was designed for.
Setting Caster: I have found the easiest way to measure caster is just to keep track of the gap on the caster turnbuckle from side to side. So if your calipers measures 7.5 mm between the plastic rod ends, and both sides are the same, the caster is even. If you want a rough idea of the amount in degrees, you can line up a camber gauge next to the kingpin to estimate caster, and note it corresponding to the gap measurement. I just prefer the gap number, since it is much more accurate to track adjustments than eyeballing a camber gauge, and requires no special tools or setup gear. Caster and camber work together on this car, since adjusting either can change the other adjustment, especially if you make a big change. Generally, looking at the turnbuckle gap will keep you in the ballpark.
I wanted to show how I measured the micro shock droop on the car. The manual shows the use of a ride height gauge on the bottom of the chassis to check micro shock droop. This does work. I just felt that it was awkward to do the measurement in that way. I initially set it in that fashion and to ensure the shocks were drooping out, I was holding the car above me. I guess I could have simply flipped the car over, but I wasn't sure if that would correctly estimate the droop, especially seeing it should be 0.5 - 1 mm total.
I used a set of sedan droop gauge and droop blocks. The blocks can be set transverse across the main chassis. As you can see, the droop gauge can enter under the pod from the side, right where the link attaches. I repeated the measurement process many times once I found the best spot to ensure it corresponded with the measurement I got using the method recommended in the manual. This produces the same measurement, but I feel it's much easier to do, and it is consistent.
I think it's important as just setting the micro shock droop via shock length may cause a different setting side to side if you make both shocks the same length. I noticed I needed to be 0.3 mm different side to side on length to make droop even. That may sound miniscule, but the car has no center pivot, so droop imbalance side to side is exaggerated. Without the difference in shock length, droop was close to 1 mm off side to side. This is also where the Tamiya ball studs come in on the upper end of the shock. It's super easy to remove the upper ball still attached to the shock, and just pop the bottom off the pod. A ball end wrench is the easiest way to get the top off.
Pod droop as most refer to it is separate from the micro shocks. The center shock length sets the angle of the pod plate as seen from the side of the car as it unweights. Since there is no pivot, this acts different than a center pivot car (link or t-bar). To be honest, I'm not sure how all this interacts, as the microshock droop sets how far the pod can move down vertically. Hmmm....
