Ariel Atom 4 Carbon Brakes

We first approached Ariel Motor Company back in 2019 at the Autosports International which was being held at the NEC in Birmingham UK. Midland Brakes were exhibiting there for the second consecutive year and had the insane Skoda Yeti on our stand. We had produced a set of our carbon ceramic brake discs for what we think is the ultimate street sleeper!

Ariel had only released the Atom 4 around 6 months earlier at Goodwood Festival of Speed, so there was a lot of interest in the car. The new version was still very new and lots of people hadn’t seen it yet!


We had a great chat with Tom Siebert and Tom Ward from Ariel whilst at the NEC and we showed them one of our discs. They were very impressed with the quality and were shocked at how light it was, especially with the size of the disc they both held.


Tom S told us that they had a few of their customers interested in carbon ceramic brake discs for an option for the Atom that they had built. Which meant they were very interested in what we could offer them to meet their customers’ demands.

After the Autosports show we contacted Tom and were put in touch with the Ariel design team who provided us with a drawing of the steel discs that were being used on the car. The discs being used were 288 x 25mm so not a particularly big disc compared to some of the others we had made but we were sure we could produce a carbon ceramic disc to be a direct replacement for the steel disc. This meant the AP 4 pot cailper could still be used and no changes to the design of the brake set up had to be made. The same disc is used on all four corners of the car which made things a bit easier for all involved.


The first hurdle we encountered was the lack of brake pads being available in the correct material and pad shape to fit the AP brake caliper used on the Atom 4. We always recommend customers to use Pagid RS29 or RSC1 brake pads with our discs, so this was a problem! Simon made a few phone calls to a good contact he has at TMD explaining the situation and the problem that had already been encountered. We were delighted when TMD informed us they would make a special production run of the pads to produce 2 sets of pads; 16 brake pads were made, 8 in RS29 and 8 in RSC1. Thanks again TMD this helped us out no end!


Once we knew we had the correct pads to use we set about designing the carbon discs. With the Atom 4 being an opened wheeled car we knew we would need to bear that in mind with the design. Once the design had been completed, Ariel were happy and approved the go ahead. We then put the first set of discs into production for them.


With the Atom 4 being a vehicle that leaves no weight on the table, we thought "where else could a bit more weight be shaved off….. ah, the bells"! With this in mind 10 x 15mm holes were added into the 6082T6 aluminium bell to help further reduce the unsprung weight.

All of this resulted in the whole carbon disc assembly weight only 2.9kgs which was a saving of just under 50% of the original steel disc that had been replaced! This gave an overall saving of around 10kgs - a massive saving on an already light car! Not to mention the performance gains that will also be attributed to this with a lot less rotational mass, giving better acceleration times.

When we delivered the first set in May 2019 to Ariel for testing everyone who held the discs just couldn’t get over how light the discs were compared to the steel discs that they were used to holding.


In June 2019 Midland Brakes had booked a stand at Goodwood Festival of Speed to showcase our carbon discs to a different audience. Simon approached Ariel to see if they would loan MBL a car which they could use on the stand with another set of the discs fitted to that car. Tom agreed to loan us their original car for the show which was absolutely fantastic! We were very grateful to have the Atom 4 on our stand and it certainly got a lot of attention, especially with the carbon brakes fitted to it!

During the rest of 2019 Ariel conducted some on road test with the discs and the results they had were very good but they really wanted to get them on track to test them out properly. Winter was setting in, so this wasn’t the best time to go testing an Atom!


Heading into 2020 all was looking good and a test day was booked……. then I’m not sure if any of you remember but a small thing call COVID-19 happened!


The whole of the UK was on lockdown and a track day to test some discs was the last thing on people’s minds at that time. Fast forward to the summer of 2021 and restrictions were beginning to be lifted, which meant the whole country could start to get back to some form of normality that we were used to pre March 2020.


A new date was booked in to test the car with the carbon brakes on track. The aim of the test was to see what it took to make the discs fail in a non-real world situation with a lot more heavy braking, much more than any normal user would do. Well, let's just say that they certainly took all of the abuse from the test driver. The temperatures were up in the 500-600 degrees centigrade range, which is by no means an issue for the discs; you can keep pushing the discs over and above 1000 degrees centigrade before they start getting close to their limit!


With the test completed and all parties extremely pleased with the outcome, some more road miles were done on the car to see if the track day had had any effect on the ‘normal’ braking performance. All was as before, it was like the brakes had never been up to the temperature ranges that had been experienced on track.


Simon took a trip to see everyone again at the Ariel factory in November 2021 and a discussion was had with Tom who was really happy with all the testing that had been done. Tom was and is still pleased to be able to offer the carbon ceramic brake option to his customers in 2022 and beyond.


We then set about producing the first batch of discs and bells for the order that had been placed with us. A new supplier had to be found to produce the stainless steel bobbins, as the company we were using went into administration whilst they had our order. Fortunately, we found a new company who could make the bobbins for us to the tight tolerances that we were looking for, another crisis averted!


It was a couple of months until all the parts were ready for assembly; it is surprising at all the parts needed to go together to assemble such a disc. All of the parts were carefully assembled by hand and all the stainless steel fixings torqued up to the correct specification.

Simon set a date with Ariel to go and deliver the order directly to them, again everyone was super impressed with the discs and a lot of the staff there awestruck on just how light the discs were.

Within the first two weeks of the discs being at the Ariel factory, a customer who’s Atom 4 was in mid build had seen the discs and then had spec’d them onto his build. It’s safe to say we were super thrilled to see the first set going on a customer’s car, after the 3 years this project had been in the pipeline.

We hope that this customer and lots more customers have many happy and safe miles using our carbon ceramic brake disc option!

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