A weld-in multipoint cage for the BMW E30 and E30 M3, built by Custom Cages in T45 to their International Multipoint pattern. Part number M3/99T. It is listed as FIA Approved.
Why this one and not the other E30 cages
The E30 is one of the better served shells in the Custom Cages range, which is a mixed blessing when you are trying to pick. There are three separate things going on:
- Pattern. This is the International Multipoint, the full competition cage. The Factory Style Historic kits (from 1515) copy the shape of the period works cages and exist for historic eligibility rather than for extra strength.
- Material. This kit is T45. The E30 Multipoint CDS at 1255.80 is the same idea in the cheaper steel. The 25CrMo4 cages at 1515 to 1895 are chrome-moly, a different material again.
- Fitment. Everything here is weld-in. There is no bolt-in E30 multipoint in the range.
If you are building a car to a period historic class, the Factory Style kits are the ones to look at. If you are building to a modern class and reading a rulebook, this is the one.
T45 against CDS, without the sales talk
Custom Cages publish figures for both. Their T45 is a high tensile carbon-manganese cold drawn seamless tube: minimum 620 N/mm2 yield, minimum 700 N/mm2 tensile, elongation around 15 per cent. Their high specification CDS (E355) is minimum 370 N/mm2 yield, minimum 510 N/mm2 tensile, elongation minimum 25 per cent.
Both clear the regulatory minimum comfortably. The FIA sets a minimum tensile strength of 350 N/mm2 in Appendix J Article 253, and Motorsport UK sets a minimum yield strength of 350 N/mm2 in NCR Chapter 7 Appendix 3. Those are two different measures, so do not compare them directly.
What T45 does not do is let you run thinner tube. On the build-to-specification route the minimum dimensions apply whatever the steel is. A lighter, thinner cage is only legal where that design itself is homologated or holds a certificate. What you are buying with T45 is strength for the same tube size, and a slightly stiffer car.
Fitting
This is a weld-in kit, so it goes in with the interior out and a competent motorsport welder doing the work. Budget for the shell preparation as well as the cage. A weld-in is stiffer than any bolt-in and it is what most closed-wheel competition classes expect, but it is not a weekend job on the drive.
Before you order
Approval wording is where people come unstuck. FIA Approved is trade shorthand. The rulebooks deal in homologation, or an ROPS certificate issued by your national authority, and your championship will name which of the two it wants. Check what your class needs before you commit, because a cage that suits one series can be ineligible in another.
Tell us the car and what you compete in and we will confirm the fit before you buy.
