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CMS Introduces Docol R8 Ultra-High Strength Steel Roll Bars!
After extensive research, consultation with testing engineers, and discussion with professional race car fabricators, Competition Motorsport is excited to be the first to transition fabrication of Porsche 991 GT3 and GT3RS Roll Bars from using 4130 CrMo (chrome-moly) to Docol R8. Docol is a modern, engineered Dual Phase Advanced High-Strength Steel (AHSS), replacing 4130 as the state-of-the-art material for race car chassis and safety cage manufacturing. 4130 has been the default tubing material for race car chassis since its introduction during WWII. However, racing fabricators have been switching to Docol R8; engineered specifically for motorsports applications, it is an improvement over 4130 in every way.
Docol is considerably stronger than 4130 CrMo. Tensile Strength of 116,000 psi vs 95,000 psi, Yield Strength of 100,000 psi vs. 75,000 psi.
Docol's heat-affected zone (HAZ) is much smaller, meaning TIG welded joints are much stronger, less brittle than with 4130.
Docol has a higher resistance to fatigue.
Docol is much more tolerant of heavy fabrication (such as tube bending and forming).
Docol is far more dimensionally consistent, with tube diameter variance of 0.3% vs. 10.0% in 4130 and wall thickness variance less than 1/3 that of 4130.
What that translates to in a CMS roll bar is higher strength, better protection, and more longevity. Docol can absorb greater impact energy while maintaining its structural integrity, remaining intact better than 4130 CrMo. Docol is the new state-of-the-art material in race car fabrication.
Is Docol more expensive than 4130? Yes, but our prices will remain unchanged -- the lowest in the industry. That's because we believe in delivering a superior product, with more choices, at a lower price. That's why we design and manufacture every roll bar in-house. It's why we professionally powder coat them, in your choice of color, on-site for free. It's why we use advanced materials like Docol. And why we ship every bar to your door for free.
The result is superior quality, service, and value. You can pay more for a roll bar, but you can only get the best from CMS. Check out all CMS Roll Bars here. Give us a call or drop us a PM if you want more info and to discuss what roll bar is right for you!
Thank you! It's not that 4130 CrMo is bad material, just that it is 75-year-old technology and has its drawbacks. Docol R8 takes advantage of modern advanced metallurgy to solve those drawbacks without any downside. Like a lot of chassis builders, we use it in racing chassis with excellent results in durability, strength, and fatigue resistance; it's time to transfer that experience to our Porsche bolt-in products.
Docol is far more dimensionally consistent, with tube diameter variance of 0.3% vs. 10.0% in 4130 and wall thickness variance less than 1/3 that of 4130.
Are you implying the incoming 4130 tube has a diameter variance of up to 10%? In my past career I've dealt with most of the major tubers as a supplier and have never seen a spec where the diameter on 1.5" - 2.0" tube could be off by 10%. A 2" tube at 2.2"? That would have ended up in the scrap hopper or on the secondary market.
Any pictures of the install points? What's the trimming needed for the install?
There is a little carpet trimming needed to install the main hoop, but it is not visible if/when the bar is removed from your car. I've attached a photo of the main hoop installation point to give you an idea.
Are you implying the incoming 4130 tube has a diameter variance of up to 10%? In my past career I've dealt with most of the major tubers as a supplier and have never seen a spec where the diameter on 1.5" - 2.0" tube could be off by 10%. A 2" tube at 2.2"? That would have ended up in the scrap hopper or on the secondary market.
Typically, the variance we see in 4130 is in wall thickness, which can be quite variable. Docol, on the other hand, is incredibly consistent in wall thickness, which is the more important spec when talking about safety cages and chassis. In terms of outside diameter, like you, we've seen much less variability than 10%. That is simply the allowable tolerance according to our ProMoly supplier. We've seen some minor variability in diameter with 4130 and absolutely zero with Docol.
Great question! The CMS 991 GT3 roll bar weighs 63 lbs made from 4130 CrMo; the Docol roll bar weighs 56.5 lbs. They are identical other than the metal used. We could save even more weight by using a thinner-walled Docol tube in some areas to maintain equal strength with 4130, but we chose to leave our tubing specs the same so the Docol roll bar is both lighter and stronger.
02-15-2018, 07:58 PM
CMS Introduces Docol R8 Ultra-High Strength Steel Roll Bars!
