The car showed up and it was actually completely built.
The thing about the chassis is that it is F103 length. That is quite a bit shorter than an F104, and makes the car do strange stuff if you attempt to run it to the narrower F104 width (180-190mm). Unfortunately, this rules out using the link setup. However, the T bar setup, which the car comes built with, is able to be modified to a wheelbase closer to the F104. Moving the support posts for the upper deck and t bar connections to the extreme rear of the chassis plate will give a wheelbase about 4mm shorter than an F104, which is acceptable.
I used the upper deck as a template to re drill the holes in the chassis plate. Luckily, everything lined up almost perfectly without interfering with any holes already in the chassis. I also had to drill new holes to move the body mounts to the correct position for a modern body.
After setting up the rear end of the car to length, I wanted to put on the F104 front end with Exotek parts. I didn't really anticipate there being any problems with this, but the Yeah racing servo mounts are meant for an F103 front end. Normally this just means the mounts have to be replaced with F104 style servo mounts to work with the F104 front end parts. What's weird is that the Yeah racing parts are about 2mm shorter, requiring the chassis to be re drilled again to work with standard F104 parts. It's really weird since the F103 and F104 parts from Tamiya are totally interchangeable....
Once I was done drilling, here is the closer to finished product:
I did want to show the dual damper setup I was able to build. The motor pod parts support this for the link setup, but I was able to adapt it for the t bar configuration using the old body mount holes, and the plastic tubes from the F104V2 parts tree. I used the plastic damper tubes since I needed to cut them to fit, and I would not be making a mistake on the more expensive option roll damper tubes. Eventually I will replace the plastic tubes as the idea has proven itself on the track. The only reason I would replace the plastic tubes is that there will be more surface area on the option damper tubes once they are cut down.
Another small problem is the motor pod. It is like the F103 pod, set up for the smaller F103 tire. Ride height becomes excessive when F104 diameter tires are used. This was not a big deal as I was able to take a used F103 t bar and cut it down so only the pod area remained to make a spacer. This brought the ride height to about 4mm with the #2 axle cam.
To work with the modern bodies, a shorty pack fits perfectly. To secure the pack, I put two holes in the upper deck slightly wider than the pack to retain the battery. Tape is very hard to work with in this case, but the screws keep the pack from moving. The fit is pretty snug otherwise, so only the screws are really needed.
Those are the major changes needed to get the car running. I added a Tamiya axle and diff, along with a sedan shock. To mount the body using the separate side pods, a small slice needs to be made near the rear to clear the end of the upper deck where the tubes attach. If you use the body in one piece form, this probably is not necessary. I have not fitted it yet, but I think that the F104Pro body might be a nice choice in that the winglets on the side would hide the protruding parts.
As far as testing goes, once I finished the car, I turned it over to my buddy Kevin for testing. He brought it out to the carpet track on practice day. I wasn't able to drop by until later in the day, but he told me over the phone "You're not getting this car back unless you can find another one". It was pretty good out of the box. Initially it was set up with 2 o rings on the t bar and the tubes with 2000 wt diff oil. Kevin tried 30,000 wt oil in the tubes at the end of the day, but that was a bit much and the car wanted to traction roll from being too stiff.
The next week I took the car out and tried a few things as well. Kevin wanted to try the car with the F103 damper pucks just to see if it was any better. I ran it most of the day with the pucks and it was pretty good, but in the last couple runs I went back to the tubes, and for me anyway, the car seemed to drive better. I wound up with 7000 wt oil, and that was pretty good. I also changed the t bar setup to a .5mm spacer on the front screw and a stiff black Tamiya o ring on the back. We wanted to try to get the car a little flatter, and this worked well.
Overall, and with only a little time on the car, it is very good. You are limited on battery placement in the t bar configuration, but so far it has not been a big hindrance. On the plus side, the F103 style t bars are dirt cheap and offer a lot of options in setup (tilting the t bar, different types of o rings and spacers to control roll characteristics). I'm going to continue to work with the car as I think we have only scratched the surface.
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