Roll Cages MSA Blue Book; Section Safety C(c) Starting from page 173.
The roll cage fitted to Historic Rally Cars used for special stage events will be as shown on page 182. Drawing no 37. This shows a full roll cage, which consists of the following;
Main Rollbar. Structure consisting of a near-vertical frame or hoop located across the vehicle just behind the front seats. The backstays usually mount onto the inner wheel arch.
Front Rollbar. Similar to main rollbar but it’s shape follows the windscreen pillars and top screen edge.
Door Bars. These must be fitted in such a way as to protect the occupants in the event of a side impact. For this purpose they should not be mounted to low in the door aperture. The fitting of cross section door bars is allowed.
Additional Bars. These are shown as a cross bar between the front cage legs (Dash height) a bar between the main hoop, a diagonal across the main hoop and diagonal between the backstays. There is not a problem with mounting a cross bar between the back stays to mount the safety harnesses on.
The six main mountings of the cage may be Bolted or Welded.
The main and front rollbar must have at least a three bolt fixing. The rear backstays are usually mounted with two bolts (Drawing no19 Pg 177). The backstay can also be mounted as per drawing no 20. Pg 177.
These are the plates that the roll cage feet mount onto. The minimum mounting plate area for the main and front roll cage mountings are 120cm2. The mounting plates when welded inside the vehicle must make contact with the floor and the inner sill, this takes the shape of the letter L. The rear backstays minimum area of at least 60cm2. The minimum thickness is 3mm. They must be welded to the body shell as per (Drawing15 – 18. Pg 176/177. Plates must be secured with continuos good quality welds.
Additional mountings. The cage can have a total of 14 mounting points In addition to the main six mounting points an additional eight more can be attached to the body shell. These are usually two to the front screen pillars and two from the main rollbar to the body. Competitors should note that an installation to drawing 37 might contravene FIA appendix K regulations.
With this in mind I would suggest that the additional mounting points are bolted in and not welded. That way if a European event run to FIA Historic regulations is planned the bolts can be removed.
The additional mounting points if welded must be as short a welded area as possible. It is not acceptable to have gussets welded into windscreen pillars and main hoop area that are the length of the pillar.
Safari Spec Roll Cages.
A number of vehicles have been built with Safari specification roll cages. The cages usually have a number of extra bars fitted. These are not permitted for MSA sanctioned events. It is not acceptable to just put a hacksaw through each offending bar. They must be completely removed.
Anyone contemplating building a dual purpose cage should consider making the additional bars removeable. This is easily acchieved by the fitment of bolted saddle type fixings.
Important. Page 310. Safety 299. The roll cage bars must remain within the confines of the passenger compartment and not be used as a suspension pick-up point bracing unless the competitor can prove that this was done in period to the specific model. The fitment of extension sections up to either the front or rear bulkheads is not allowed. The practice has been to cut through these sections with a hack saw. This on safety grounds is not good enough. The thought of a section of pipe being exposed in the case of an incident does not bear thinking about. Needless to say it would make a very good hole punch!
Protective Padding. Where the driver’s or co-driver’s bodies or crash helmets could come into contact with the safety cage, non flammable padding must be provided for protection.