Dear 4C forum members,
I think we've done it...finally. The idea of adjustable ARB's started in 2018 and I started experimenting in 2019. It looked very promising with first prototypes, but then the challenges and issues just kept coming at us. The more we were trying, the less it seemed that it will be possible to achieve what we wanted - a lightweight and efficient ARB's.
For those not following our car development thread where we weekly post updates, let me tour you through a quick timeline how it all went. In 2019 we designed first protoype ARB's. Hollowed tube and blade type levers, CNC machined out of T6-6061 alu. The front ARB was piece of cake, so we quickly moved to the rear ARB and that's where the challenges really started. Rear ARB is bent in 3 planes and very difficult to fabricate. We couldn't make ARB blade levers to fit OEM suspension, it was a tight fit on aftermarket coilovers and due to its complex shape, the part was heavy - too heavy for my liking. So we ditched the blade lever type idea and started experimenting with CNC bending of ARB tubes. Front, again easy-peasy, rear, impossible. We wanted to keep hollowed tubing to save the weight, but large diameter and that's where the challenge started. It was impossible to bend rear ARB shape in 3 planes in large diameter without cracking the hollowed tubes. We were using a spring steel tubing, but none of the CNC bending companies were up to the task. They all accepted the project at first and had no second thoughts about it even though we provided all the technical drawings etc. However, once they started bending the rear ARB, the CrMo tubing just kept cracking as the radius for the rear ARB are very tight, it's bent in 3 planes and due to larger diameter and tight clearance in 4C, there was no room for error. Alternative was softer tubing or solid bar, but I insisted on having hollowed bars, otherwise there is no point. It would be just another aftermarket ARB way too heavy for the 4C. No way! So we tried different material hollowed tubing, made the shape using CNC bending for front and rear ARB, but the performance just wasn't there. After a few sessions the ARB's fatigued and dropped the stiffness noticeably. So were were again back at the start - finding a solution to use a spring steel tubing that we could bend and would perform as required. Now, I'm not gonna post every detail how many different materials, diameters and bending companies we tried to finally tackle this challenge, but at the end, I ran out of companies that wanted to further cooperate, even though we well paid all the work and samples. They just didn't want to bother anymore and I still have more than 15 sets of failed ARB's each with a problem and at least twice as much of different tubes and unfinished prototypes. I'm afraid to make a calculation of costs because it hurts. I was so close to giving up, but driving the car with some of the final prototypes which performed flawless in terms of performance, just looked bad (wrinkled bending), kept me going. I really didn't want to give up. Then one day, on the far end side of our country, I found another CNC bending company that specializes in CNC bending and makes parts for MB. They are big, so I knew they won't be interested in making 10 sets of ARB's for our testing. So I sent them e-mail and made a glorious presentation of what we do and who we are. Much bigger than we actually are, because I didn't wanted to get turned down. They called me a few days later and we scheduled a meeting. I gave them the technical drawings, the sample materials and didn't even ask for a price because I didn't really have any choice - no other company wanted to waste time with our project anymore. So in a few weeks they called and said that it is impossible to make a rear ARB bends without cracking in this material and sent me an invoice. That was the moment I really said to myself "Give it up, we can't do it, it's OK, you can't always make it". Being so close but so far, I just couldn't sleep. I went through all the material specs, certificates etc., and realized that we were right there on the edge of what we wanted to do and what actually can be done with given material (bending radius, fatigue, strength, heat treatment, etc.). So next days I gave them a call again and said: "I'm sure it can be done, I have all the CrMo tubing supplier certificates, tech specs., etc. and it can be done. Now you either don't know how to do it or you don't want to. I'm not asking you to do it for free. I already did cover all the expenses of fails, so at least listen to me and please try it one more time with different CNC bending machine specs, please, don't tell me it can't be done." I'm not sure whether I sound so desperate or so nasty, but they did give it another try. I got called 3 weeks later and they said "It's done". My first thought was: "They must have changed the material and it's gonna be shit". I don't believe they've done it". They explained it to me, that they've set-up the CNC bending machine parameters to a specs they haven't done before (speed, pushing force, clamping force, heat, etc.) and that they've nailed it. A bit skeptical and anxious I was waiting for the tubing to arrive. In a few days I got delivered a 10 pairs of front and rear ARB tubing. The bends looked immaculate, so I grabbed a pair of tubes and ran to a fellow company to make a material analyze and it truly was the material we insisted on - a hollowed 4140 CrMo in 25mm and 28mm diameter and it was bent to perfection. I haven't been so lucky for a long time. I've been running a "wrinkled" version of this 4140 assembly since 2021 and now in 2022 we finally made it to our standard. So, the long story short, it took us more than 3 years, to finally fabricate what I had in mind - lightest aftermarket ARB on the market, without compromises. It was painful and costful journey, but I'm happy now. My mind is set at peace and I can finally sleep tight now.
Forgive me for bothering you with such a story, but I had to let it out. It was one of the most exhausting projects I've encountered and I'm so happy to share the final project here with you. I'm honored to invite you to have a look at the pre-final assembly.
Idea and development since 2019:
I think we've done it...finally. The idea of adjustable ARB's started in 2018 and I started experimenting in 2019. It looked very promising with first prototypes, but then the challenges and issues just kept coming at us. The more we were trying, the less it seemed that it will be possible to achieve what we wanted - a lightweight and efficient ARB's.
For those not following our car development thread where we weekly post updates, let me tour you through a quick timeline how it all went. In 2019 we designed first protoype ARB's. Hollowed tube and blade type levers, CNC machined out of T6-6061 alu. The front ARB was piece of cake, so we quickly moved to the rear ARB and that's where the challenges really started. Rear ARB is bent in 3 planes and very difficult to fabricate. We couldn't make ARB blade levers to fit OEM suspension, it was a tight fit on aftermarket coilovers and due to its complex shape, the part was heavy - too heavy for my liking. So we ditched the blade lever type idea and started experimenting with CNC bending of ARB tubes. Front, again easy-peasy, rear, impossible. We wanted to keep hollowed tubing to save the weight, but large diameter and that's where the challenge started. It was impossible to bend rear ARB shape in 3 planes in large diameter without cracking the hollowed tubes. We were using a spring steel tubing, but none of the CNC bending companies were up to the task. They all accepted the project at first and had no second thoughts about it even though we provided all the technical drawings etc. However, once they started bending the rear ARB, the CrMo tubing just kept cracking as the radius for the rear ARB are very tight, it's bent in 3 planes and due to larger diameter and tight clearance in 4C, there was no room for error. Alternative was softer tubing or solid bar, but I insisted on having hollowed bars, otherwise there is no point. It would be just another aftermarket ARB way too heavy for the 4C. No way! So we tried different material hollowed tubing, made the shape using CNC bending for front and rear ARB, but the performance just wasn't there. After a few sessions the ARB's fatigued and dropped the stiffness noticeably. So were were again back at the start - finding a solution to use a spring steel tubing that we could bend and would perform as required. Now, I'm not gonna post every detail how many different materials, diameters and bending companies we tried to finally tackle this challenge, but at the end, I ran out of companies that wanted to further cooperate, even though we well paid all the work and samples. They just didn't want to bother anymore and I still have more than 15 sets of failed ARB's each with a problem and at least twice as much of different tubes and unfinished prototypes. I'm afraid to make a calculation of costs because it hurts. I was so close to giving up, but driving the car with some of the final prototypes which performed flawless in terms of performance, just looked bad (wrinkled bending), kept me going. I really didn't want to give up. Then one day, on the far end side of our country, I found another CNC bending company that specializes in CNC bending and makes parts for MB. They are big, so I knew they won't be interested in making 10 sets of ARB's for our testing. So I sent them e-mail and made a glorious presentation of what we do and who we are. Much bigger than we actually are, because I didn't wanted to get turned down. They called me a few days later and we scheduled a meeting. I gave them the technical drawings, the sample materials and didn't even ask for a price because I didn't really have any choice - no other company wanted to waste time with our project anymore. So in a few weeks they called and said that it is impossible to make a rear ARB bends without cracking in this material and sent me an invoice. That was the moment I really said to myself "Give it up, we can't do it, it's OK, you can't always make it". Being so close but so far, I just couldn't sleep. I went through all the material specs, certificates etc., and realized that we were right there on the edge of what we wanted to do and what actually can be done with given material (bending radius, fatigue, strength, heat treatment, etc.). So next days I gave them a call again and said: "I'm sure it can be done, I have all the CrMo tubing supplier certificates, tech specs., etc. and it can be done. Now you either don't know how to do it or you don't want to. I'm not asking you to do it for free. I already did cover all the expenses of fails, so at least listen to me and please try it one more time with different CNC bending machine specs, please, don't tell me it can't be done." I'm not sure whether I sound so desperate or so nasty, but they did give it another try. I got called 3 weeks later and they said "It's done". My first thought was: "They must have changed the material and it's gonna be shit". I don't believe they've done it". They explained it to me, that they've set-up the CNC bending machine parameters to a specs they haven't done before (speed, pushing force, clamping force, heat, etc.) and that they've nailed it. A bit skeptical and anxious I was waiting for the tubing to arrive. In a few days I got delivered a 10 pairs of front and rear ARB tubing. The bends looked immaculate, so I grabbed a pair of tubes and ran to a fellow company to make a material analyze and it truly was the material we insisted on - a hollowed 4140 CrMo in 25mm and 28mm diameter and it was bent to perfection. I haven't been so lucky for a long time. I've been running a "wrinkled" version of this 4140 assembly since 2021 and now in 2022 we finally made it to our standard. So, the long story short, it took us more than 3 years, to finally fabricate what I had in mind - lightest aftermarket ARB on the market, without compromises. It was painful and costful journey, but I'm happy now. My mind is set at peace and I can finally sleep tight now.
Forgive me for bothering you with such a story, but I had to let it out. It was one of the most exhausting projects I've encountered and I'm so happy to share the final project here with you. I'm honored to invite you to have a look at the pre-final assembly.
Idea and development since 2019: