42326 Tamiya TA07MS Race review

Another week and another niche Tamiya Chassis report.. ;)

The Tamiya TA07 MS arrived late in 2018 as with all MS versions of the TA series, it is a big step up from the TA07 Pro. Imagine if the TA07pro and a TRF419XR had a baby and you will be in the right ball park. 

When you look at the chassis the twin 2mm carbon vertical upper decks have a distinguishable hump. This is because of the chassis main party trick. You are able to swap between three motor positions quickly and simply. 

This is possible as the drivetrain uses a single belt (The optional Low friction Hop up (Part no 54798) is included). So all you have to do is remove the two lower motor mount screws and slide it to the required position and fastening them back up.. simplicity itself.  The motor position is also 1mm more inward on the TA07 MS to help improve corner transition speeds. 

The single belt drivetrain  has also been modified on the MS version of the TA07. The centre pulley has change from 18 teeth to 20 teeth, this changes the internal ratio to 1.85. The other big drivetrain change is that the 37t front spool and 37t rear differential are mounted 2mm lower in the beautifully machined aluminium bulkheads, this should give more traction on acceleration. The drivetrain is mounted on a 2.25mm carbon chassis.

Another TRF419XR similarity are the shorter SSBB dampers (Note I have upgraded the shocks with the 54878 Damper Upgrade set). Whilst they are quite tall compared to the latest TRF421 shocks, when they were released they were quite a big jump from the standard TRF shocks. 

The first thing that you notice when you have the chassis in your hands is how flexible the whole thing is. Even when compared to floppy chassis like the Mi9 this is another level of flex. So I was going be interested so see how it would fair on my local carpet track. 

Well the first week I can honestly say.. it wasn't good. The chassis had loads of steering but I just couldn't get the rear end to hold, even whilst holding off the throttle a good way away from the apex. It was a real battle to keep up with the other top level drivers.. I had to nurse the car around.  I could have easily just given up and popped it back in storage the rest of my fleet of quirky onroad Tamiyas. However the beauty of this car is that it can easily swap between different configurations. So I decided to give it another go with a different layout. 


Previously I had ran the car in the middle configuration, this time I moved the motor to the most forward position. This isn't quite like the mid-pulley layout that 99% of modern TC's use. Here the motor is ahead of the pulley so the weight distribution is quite different. 


When I changed this configuration, I also decided to made a small modification. Whilst I like the concept of a single belt, I did wonder about how to really tweak the belt tension. I wonder if the belt was a little too loose at the rear. this could also have contributed to the rear of the car feeling inconsistent when I applied the throttle.


Looking at the motor mount there was a hole that looked like it would accommodate a separate belt tensioner, so I found some small 630 bearings and added this to help avoid the any skipping at the rear.


Oh I had also made a couple of upper deck stiffeners to help minimise flex.. They have a U-shape to mount around the spur gear. They did add some extra stiffness, but it was not that significant. 

So it was with some trepidation that I was ready for another nights racing with the TA07MS.


Never one for practice, (That would require being early), the first time I managed to run was Q1 and I could instantly tell the chassis was transformed.. The rear stability was dramatically improved. So much so that I could really push the car straight away. A total transformation of the week before.

After Q1 I made no tweaks to the car other than I changed the springs. I had the classic Xray 2.5-2.8 front and 2.6 rear springs on the car. However I feel that with flexy chassis, it's better to run softer springs. So I went a bit rouge and mounted Tamiya Black Red front (2.29)  and  Black Green (2.09) rear. 

The car felt really good with the softer springs and it settled the car further. So I made no more changes other than just putting in my laps. The results speak for themselves. I was not running a modern 17.5 motor (An old SMC lowrider) and yet I managed take the car to Pole on the A.  The only thing that started to become a concern was that noticed the inner rear wheel rising on the end of the high speed sweeper. 

I didn't have much time to think about changes before the final. 

I just placed the car down waited for the tones to finish and slammed the stick forward, the car launched superbly from the line. 

The first few laps were great, I was making great progress with only second place anywhere near my pace. Unfortunately a few laps in I was clipped by a backmarker, span out and lost my position. I recovered, but at the back of the pack. Slowly I clawed myself back through the field, the car was really on a different level. I soon found myself chasing down the leader.. I was quicker, but the track was tight and it was hard to find a gap. I had taken a tighter line than I would normally into the high speed sweeper in an attempt to unsettle the leader.. this unsettled the car and sent my car rolling into the pits. Oh well... Game over...

These things happen.. importantly the pace was there.. I had the fastest lap and also the best 10 laps average... this shows that the car really has potential. There are a few areas that can easily be improved.. such as running the  22080 Lo-Mount Aluminium Retainers to bring a little of the weight down even lower, and maybe running a motor that isn't 6 years old. Importantly, this quirky Tamiya is actually surprisingly good. I would think it would really struggle on high grip carpet, but outdoors especially this car could really prove itself... 

I should get back to the TRF421 review now.. although I'm also getting a little distracted with a few more projects..;)