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.

Tyres

And no, I don't spell them the American way :P

One of the biggest influences on how well my F109 performs has been finding the right tyre combination for the track I race on. Its a small club and still building up so things like track prep are fairly basic, but that just means a bit more of a challenge. 

There are masses of information regarding F1 tyres scattered over the various forums and sites on the 'Net, but I've struggled a little to make that information apply to my situation. Sometimes it's not always obvious the sort of surface or prep they use and that can make a big difference to tyre choice. One of the first things I had to get straight in my mind is that,to me, it appears some of the tyre manufacturers have started using the same reference number or compound name for their tyres but it is actually different front and rear. I believe this is particularly true of Shizimu who have labeled their tyres either R or F and then a number, but most seem to run the same numbers i.e. - F1 and R1 together or F3 and R3 together. Given that an F1/R1 combination gives the same grip balance as a Ride B/A combination (which are advertised as B=hard and A=soft) one has to assume that Shizimu have decided to simplify matter and just make their rear tyres softer/grippier than the fronts. 

However this idea is totally mine and may not be reality! It DOES however, reflect how the car performs on that brand compared to others.

So here is a list of the brands and types of tyres I've tried and my results and opinions of each.

Kit Tyres - Equate to Medium Front tyres and Soft Rears. According to various forums etc these tyres work on carpet. My experience was that they are too close together in compound to get any balance. Traction goop on the rears helped a little but they only became really driveable using the good ol' superglue ring around then outside of the fronts. However given how this wears off over the course of a race it's not ideal.

Zen – Another foam tyre brand – At first I was determined to go foam instead of rubber so I sourced 25 compound rears and 30 and 35 compound fronts. These are nice tyres and come pre-mounted and trued on nice strong rims. The 25  rears are very similar to the kit rears and the 35 fronts are very similar to the kit fronts, so delivered a similar balance. 40 and 45 fronts are available but I couldn't source them at the time I was experimenting with them.

After a brief flirt with foam tyres and having watched the other F1's at my track run around quite happily on rubber I decided rubber was the better option. However, as they were all running F104's I had to seek out my own combination.

Ride – Usually recommended as B(hard) fronts and A(soft) rears. This is an option recommended for F103 cars (and touted to work anywhere) so I tried it on the F109. With some tyre sauce for the rears this might have worked better than it did but I prefer not to bother with being that serious at club days. Its about fun after all. There was better balance than with the kit or Zen foams but given the typical conditions of my track they were still hard work to get around the track consistently.

Shizimu – Initially I could only get the R1 and F1 tyres to try. To be blunt this combo offered no improvement over the Ride tyres as far as balance front to rear, though they did appear to offer slightly higher grip overall. Using Shizimu R1 rears with Ride B fronts did make a car that was almost consistent and drivable but once pushed hard in a race situation it just becomes too easy to make a mistake, as the car feels on the limit of grip all the time. I've now sourced the R3/F3 combination which is supposed to be preferred but as I've found a different combination that works I haven't tried these yet.

TRG – TRG make a LOT of option parts (some breathtakingly expensive) for the F103 and F104, so a lot fit the F109. I read about the TRG Superion tyres being used in Asia when it rains. A VERY sticky tyre but so far proving to have surprising durability. So far these have done at around 25 runs, without any real loss of performance. They come pre-mounted on an excellent quality rim, though they aren't glued as they don't put the inserts in. I've only used the rears but there is now at least 1 other F109 and a Tamiya F103 (newer arrivals) using TRG Superion on the rear and TRG Hards on the front.

At present I am using a combination of TRG Superion on the rear and Shizimu F3 on the front. This is giving me an excellent and FAST combination with nice balance front to rear. Each end seems to have the grip it needs when it needs it. They also suit my driving style which is important. I also have this combo on my F109LM which also works very well despite having a much higher down-force body compared to a standard F1.

3Racing Out Tuned Ball Differential For F104

As the title suggested this hop-up is designed for the Tamiya F104, but like so many options parts for the Tamiya F cars it can be fitted to the F109.

Almost since day 1 Tamiya cars have had the simple but annoying diff setup of having the thrust washer in the wheel. Changing tyres meant disassembling the diff and then have to reassemble it once the new wheels/tyres had been fitted. If you are like me and consider diff settings very important to your overall setup and car balance (unlike those that simply do them up) then this soon becomes majorly inconvenient.

So when the I discovered the F104 Diff housing set, commonly referred to in these parts as the "Pro" diff, I though my problems had been solved. Unfortunately not, as the pro diff, while making wheel/tyre changing more convenient, actually makes adjusting the diff even more difficult by putting the adjusting nut in behind a little cap which has the stud for the wheel nut on it. I've also found this cap and stud to be a weak area, having broken the stud off on more than one occasion, and Tamiya being Tamiya you have to buy a whole new diff set to get a spare.

3Racing Diff as it comes out of the packet

The 3Racing diff takes the pro diff idea one step further by engineering an adjustment ring and thread behind the spur gear between it and the motor mount. This allows adjustment of the diff without removing the wheel at all and thus far holds the setting very well during the course of a race day. Building it is not that different from the F104 diff with the main differences being the threaded diff joint and the adjustment ring and o-ring and the removal of thrust washers to be replaced with a aluminium spacer. At first this concerned me more than the rest but once built makes for a VERY smooth diff action and very precise adjustment.

Installed on car

Cap in place

Cap removed showing main diff nut - Initial adjustment is still done with this nut

 Simply adjust the diff as per normal before fitting a wheel. Adjustment is then made by inserting a 1.5mm hex driver into one of the holes in the adjustment ring and turning the opposite side wheel. Adjustment done. So far, on the track it has worked very well, holding the setting without changing and being a very consistent diff generally. In my opinion this is a very worthy upgrade and given its less than $15, it is bargain bling as well.

Adjustment ring

A few things to be aware of. Firstly it does move the spur gear closer to the wheel in order to make room for the adjustment ring, though it doesn't change the width of the car or move the wheel etc. It's only a couple of millimeters but I've read that it can be enough to make it hard to mount pinions on some silvercan motors. There has been no issues fitting pinions to the brushless motors I use. Secondly - the first one I bought the diff joint (the long black bit in the picture) wasn't machined straight. This made the diff wobble and wasn't usable. Finally you WILL need the shorter F104 axle or (as I did) cut down the F109 axle.

Not the best day!

Not the best day for racing. Cold and wet until about 10:30 before the track dried enough to have a few runs. I focused on my 109LM as it had new suspension to try. I copied it from one I'd seen on another blog and it seems to work quite well, though I think the base settings suggested have induced too much mid to high speed under-steer, though low speed steering and balance still seems nice.

Most exciting part of the day was when the car, which just happens to run a 1/10 version of Mercedes CLR body, decided to emulate it's 1:1 cousin and decided to try turning into a plane (real life example here http://www.youtube.com/watch?v=Ow3rxq7U1mA ). In my case it was the location of a ill placed and unnoticed rock on the track that caused the front to jump up and then it just kept going as the wind got under the body.

This is the end result - 

Given some of the issues I've been having with high speed cornering maybe I should go in search of some more front downforce - just in case!

Also not a good day numbers wise. I've never been a supporter of the "race every weekend" style of club, and I think its starting to have a negative affect on this one. Also, there have been some strange comments about the time of year and the weather. I tend to just check the weather forecast and if it predicts dry/fine then I prepare to go racing. This silly thing about "wet winter" and not being conducive to on-road racing sounds like a pretty lame excuse in my book. If you want to go do something else just say so.

Intro

I've been racing RC cars for about 20 years now and I've decided that it might be fun to write about some of the stuff I am doing and racing. I probably should've started a couple of years ago when I was doing a bit more, whereas now I am focused mostly on F1, but I have raced pan car, 4wd tourers in most classes, mini and nitro (tourer and 235 2wd). I've done a lot of state level events but only one National level event. I could say I've managed to avoid most Australian Titles but the truth is I've just never had the budget, the time, and the location all match up at the same time. Even in 2011, I arrived in Perth just 1 day after the Australian Titles had been run.

So this basically this will be a bit of reminiscing and commenting on things I feel are important or interesting. I'll also write about my current racing activities (as much as they are).