Tamiya TRF419 Low profile Towers Part 1

Since the introduction of Tamiya's shorter TRF shocks I have been toying with the idea of making a set of shock towers that will be lower but still allow me to use proper 25mm touring car springs.

One of the negatives regarding short shocks is the range of springs that are available to use. If you me you have been racing for a long time you find an array of springs that you know work for different surfaces and conditions, so I am loathe to change those. Also there is much less choice when it comes to short springs.

Whist suffering from a dose of man-flu I had enough time to sit around and bring the low profile idea to life. It is quite a simple process. Initially I took measurements from the original TRF419 towers, and then looked at the applied suspension range that Tamiya had decided was ideal for the current car.

To do this I worked out the lower suspension mount point in relation to the front and rear shock towers and worked out the angles that you could mount the shocks.

Original sketch

Once this was done I plotted the new hole mount positions for the upper shock mounts. These would be in-line with Tamiya's original operational range, but would be 4mm lower to match the range of the Shorter TRF shocks.

Then it was simple, I checked the position of the mount screws to the bulkhead etc and I had my basic drawing for the shock tower.

Next up I translated these into CAD.

The old TRF419 tower on top and the low profile one below

Once finished I printed out the top views and cut them out to check they measured up and it all seemed to work well so I sent them off to the machinists.

Low profile on the left, normal on the right.

Here are the prototype towers next to the original ones. As you can see they are lower (4mm) and also slightly wider to compensate for the revised suspension geometry.

Here you can see the front shock tower in front of the original

The new rear tower on top of the original

They are made from 3mm thick carbon fibre like the originals and they are able to be mounted via 4 screws or you can use the Tamiya set-screws on the lower two holes for extra grip.

Why Lower Profile?

Put simply the lower the centre of gravity of the car and this will reduce the amount that the car will roll when cornering. This will give you more corner speed and quicker transitions in chicanes etc.

Fitting the parts

Yokomo Pinks at the front

I got the test parts back from Fibre Lyte. They had made a fantastic job and the parts looked great. The moment of truth was when I went to fit them on the car, I wanted to be sure that the bulkhead measurements were correct, otherwise they would cause tweak.

Yokomo Blues at the rear

Thankfully they fitted fine and I then had to install the shorter shocks ready for the test.

Set-up changes

As this car uses the same length springs I kept most things the same such as droop etc. As the car was lower profile I was expecting some changes, especially changing the roll centre shims as the centre of gravity will be slightly different.

Track Test

When I got to the track I was eager to get the car out for a run. I decided to run the older tyres that I had used the week before to have a better like for like comparison on lap-times and feel.

The first race went ok, although it was quite scrappy for all involved. The first thing I noticed was that the car was much quicker when at the slower part of a corner coming into the apex. It was almost unsettling at first, so I just started to see how the car could take the corner quicker. It felt ok, but not a large leap.

Unfortunately the second race did not give me a lot of time to learn the car. I was mauled by a back marker and that resulted in my GSF shell getting destroyed and I had to retire early.

By third race things were starting to get a bit better, I had got used to the increased response when entering the apex so I started to concentrate on the chicane that we had after the main straight. I had a relatively safe line that I would use to keep my lap times consistent, but I started to explore the extra transition speed by coming into the chicane quicker and flicking the stick left and right. Initially the extra turning speed caught me unaware and I found I was able to come into the chicane much quicker than I was used to. This sounds good but in reality I hit the corner early, just not expecting the amount of grip I was getting and I kept cutting the corner too much. When I did eventually hook it up I went 2 tenths quicker than before just because of the change of line in this one section.

Car all ready and ride height checked 

Despite these mishaps I managed to get into the A-final (Although at the back). It was a club night so we had a mixture of TC (Xray T415), and two GT10's (Both X-Ray). I was just pleased I had made it so I was ready to see if I could improve on my time in the last race.  Before this race I moved the rear shocks outward and I also took 0.5mm off the outer front camber mounts to lower the roll centre.

As the buzzer went we all launched into action. The car felt really good and I was able to quickly catch up to one of the GT10s. The course was very tight and whilst I was following close behind there was very few opportunities to pass. The main thing I was pleased with was how close I was able to stay behind on the corners, the wide foam tyres on the GT10's give a lot of grip and my car was staying close with my used Sorex. As luck would have it the GT10 clipped a corner on the chicane and I saw a gap so gave it more speed than normal to weave through. I managed to hold onto the move despite going wide on the exit. I worked  towards catching the second place man, again another GT10, I managed to catch him up and again chased closely behind. I had to maintain this for 15 or so laps, trying to pressure the driver into making a mistake and doing dummy lines, I knew I was faster but I just couldn't find a clean pass. Luckily after all of the laps following close behind, they clipped a corner and went wide so I could just sail past. Next up was the X-Ray in the lead. There was not long left for the race so I had to drive extra hard to try to make up the time I had lost. I managed to claw back a few tenths every lap and as I approached the driver clipped the corner and rolled so I could pass with ease. To be honest I was so pleased with this comeback and my comfortable lead I started to take slightly safer lines to consolidate the victory. Luckily I kept pretty similar speeds and I managed to take victory and also the overall F.T.D.

Summary

At the moment there are still some things that I want to tweak on these towers. I need more track time with them but I can see already that they will be useful for certain track scenarios.  Look out for another update soon.