Front Suspension

The good ol' f103 front end definitely has its fans and its worked pretty well for many years. There are a few variations on the theme, such as the one that comes with the F109, but not everyone considers them improvements.

The main disadvantage with the original F103 front suspension is lack of adjustment. While this ensures strength (which is obviously a good thing), serious racers tend to want a bit more of all the technical bits in search of that last 10th of a second. The F109 achieves some of this with the supplied front end allowing castor and camber adjustments, but the downside is the original plastics are soft or prone to easy breakage. There are some alloy hop-ups but these have their own issues and also seem to be getting harder to get.

Doing some reading online, I came across and American F1 blogger who makes up his own version of an Exotec F104 front end but wider to suit the 200mm width. It's actually VERY simple to make and most bits are probably in a serious racers spares box already. 

Minimum you will need - 

* F104 front suspension mount (plastic or alloy)

* 5mm ball ends

* 5mm ball studs

* 45mm turnbuckles (I used 42mm because I had them but longer would be better)

* original 3Racing upper ball mounts 

* Xpress Alloy upper arm joint set - part of their 1/10 4WD Mini. The plastic versions seem to be almost non-existent, but the alloy ones are still around in online shops etc, and they are cheap enough.

Ignore the big orange thing - its just a bumper

 I still use the original version though the the "creator" has since switched to a slightly different version which he says offers some advantages in ease of set-up. I didn't have any turnbuckles long enough but I also wanted to just test the concept. It takes a bit of fiddling to get it exactly right, as well as a bit of modifying. For example the original writer says that the F104 suspension mount fits straight on top of the F109 lower suspension, but I found that it needed about 3mm ground off one end to allow it to fit as the lower mount is "stepped" around the mounting holes.

Its surprisingly slop-free for a suspension with so many ball ends, but it seems to have less movement that the original 3Racing front end. It is totally different to adjust though as the rear turnbuckle affects camber and the front affects castor, but they also both affect each other so adjusting one changes the other (this is one area the newer version is supposed to be better). It is a little frustrating at first until you work out in which direction each one affects the other, but once that issue is sorted it comes together quite well.

I fitted this to my F109 that I use with a Le Mans body so its not directly comparable to my straight F1, but as both chassis did have a similar basic setup (castor, camber, springs) when I first started with them, I feel I can use the feedback with a fair bit of confidence. So far the LM hasn't seen as much track time as the F1, but this setup does seem to induce a little more high speed under-steer in the car but at the same time the car feels more stable throwing it into corners. Given that I use a 10T brushless set-up in the LM compared to a 17.5 in the F1, this is a actually good change, but since I use a higher down-force LM style body the induced under-steer is a bit puzzling, but I am sure with a bit more track time I can get on top of it

The original version of this suspension is here

Its all in the springs

The single largest area that needs work on a standard F109 is the side springs. It is also the area that seems to be the most contradictory when reading online information. Some seem to get the car to handle fine using the standard kit or option springs and others need to make serious modifications. The only pattern I can find to this is that most of the people making the standard springs work appear to run foams on carpet.

My view (and I've discussed this with others and they agree) is that the original side springs are simply too soft to support the pod when turning under power. The springs "collapse" for want of a better word. They are also too soft to make the pod return to center when rolling from side to side. This makes the car react as if it is tweaked and causes the car to spin out far to easily. I was able to use the hardest option spring and a bunch of shims to put a lot of tension on the springs when I started looking for a solution but in the end I knew I had to find different springs.

Most seem to do the CRC spring mod.

However, CRC parts are not the easiest to source for me as ordering from the U.S tends to be quite expensive if you want any form of express freight, and not ordering express can lead to waiting for months for an order to arrive. I was able to source Associated springs more easily, though this meant I had to devise my own mounting system. Unfortunately I didn't take any pictures at the time but its turned out to be quite simple involving 2 5mm ball studs and small amount of cutting to the original spring seats. This allows me to also adjust pre-tension and therefore tweak. It also doesn't require any modifications to items such as the upper chassis pivots.

I decided to go straight for the 6.25lbs springs which is the hardest spring Associated make for their 12R cars. This may have been a bit over over-kill as even the 5lbs spring is considerable harder than even the hardest of the 3Racing springs. However on-track performance is what counted and the hardest springs had worked thus far.

Follow the leader

The front suspension of the F109 is lifted almost completely from the F103, but with a 3Racing spin on it. compared to even the most advanced Tamiya front end the 3Racing one has more adjustment available. Now to some this is a good thing but to others in makes the front end fragile and a bit sloppy. Personally, I hover in the middle as far as my opinion of it.

As it's supplied in the box it is all plastic. I had read about that in advance so when I ordered my kit I ordered a few extra bits, mostly the alloy castor mount and the 3.5mm offset front uprights. The castor mount was well worth it as the kit one is rubbish. It flexes and moves pretty much as it wants and, according to others online, breaks pretty easy. The alloy one isn't perfect as it seems to induce even more slop into the front suspension but a few well placed shims seems to cure that for the most part. Remember, you don't want to remove all the slop because it will make the car darty and sensitive to bumps, but you don't want so much that it feels vague and unresponsive.

Hop-up castor block - numbers on it are relative to original castor not an absolute value

The 3.5mm uprights are something I used on my F1's in the 90's and they do the same job now. They calm the steering down and make it smoother and less aggressive. Because the F109 has a different chassis and battery arrangement, it has a LOT of steering and I've found anything that calms it down is a good thing. It's also unusual in pan car world not to use offset uprights and most big name 1/12 and 1/10 pan car chassis use offset uprights as standard. Tamiya have also recently released a new hop-up upright that allows either 0mm or 3mm, plus other options for the steering and ackermann. Not the cheapest so they might need to wait a while before I try them.

I also modify the upright so that I can create some ride height adjustment. I trim off some of the excess plastic and also use a slightly longer suspension pin. It doesn't give a lot of adjustment (3mm in this case) but it can be enough given the right situation. Right now I am running on a fairly bumpy track so I have it as high as possible.

Another simple mod to do is polishing the suspension pin. This gives smoother suspension movement. Combine this with using something like diff grease or AW grease to give a dampening affect on the front (not unlike damper tubes on pan cars). I also use Associated 1/12 springs instead of Tamiya or 3Racing springs but this is a personal preference thing.

Overall though, the original 3Racing front end doesn't have a lot of fans. Most people that express their opinions online seem to dislike it and switch back the carbon re-enforced suspension from the F103. They also say that they don't miss the adjust-ability from doing this. I say this is BS. In a world where, even at club level, people are looking for every last tenth of a second they car ring from their cars, the last thing you want to do is take away 2, pretty important, adjust-ability options! 

I also say to those that say they are fragile and break as soon as it hits something - don't hit things! I've used the original front suspension for over 6 months racing in both F1 classes and sometimes mixed classes as well due to numbers on the day. I've had my share or hits and crashes (one so hard it bent the motor shaft!) and yet the front end has withstood them all. Even now the only problem is wear as the pivot ball's in the suspension are starting to get loose, but 6 months of racing most weeks I am not going to complain, and at a bit over $15 for a complete front end its not hard to keep a few in the parts box.