Differentials used in 1994-2005 Mazda Miata have a factory cut-outs designed as failure point in case of rear-end collision, which lead to diff housing failure in competition use or in cars with higher power.
Our brace fits tight inside the casting cavity and greatly increases strength of the differential arm. You can just bolt it on and you are good to go, no welding is required although we recommend it, as welding in the brace will reinforce your diff even more (please use 5356 filler rod for welding).
Differential has to be removed in order to install the plates. For bolt in installation you have to drill 4 holes into the diff and install it back. If welding the brace in, we recommend to remove rear aluminium case from the differential before welding and reassembling it afterwards.
Bolt holes are pre-drilled only. You will have to drill through in case you want to bolt in the brace. You don’t have to drill if welding (do not forget to drill small vent hole for hot gas to escape during welding). We decided for this solution as it would be difficult to drill holes in correct locations on differential itself, so all 3 holes would line up with bolts (front side plate, differential, rear side plate).
Fits all 1994-2005 models (cars with large diff housing). Can be fitted to earlier NA (Mk1) models if the diff is replaced with a 1994+ one.