This strap is used to give support and strengthen the centre main bearing cap on small-bore engines (850/998/1098cc). It helps counter the problems caused at higher rpm where crankshaft flex (‘whip’) causes the standard cap to move (‘shuffle’) leading to bearing failure and possible breakage of the main bearing caps. In particular, where higher rpm than standard will be the norm – i.e. in excess of 6,000rpm. Especially where this is for extended periods.
The standard centre main cap needs to be machined by a competent engineer or engineering shop, as the finished surface needs to be absolutely flat. The final finish being ground where practical.
The cap should be milled straight across along a central axis from one retaining bolt-hole to the other using a 1.03125”(1 1/32”) or 26mm cutter with as small a corner radius as possible, down to the original bolt head flat surfaces. This is necessary, as just milling the cap completely flat will remove the centre thrust washer locating slots.
Once machined, check the strap for fit to the cap, increasing the edge chamfers as necessary to clear the corner radius left.
When finally assembling the engine, ensure strap is fitted with adjusted chamfer edges to cap, fit new bolts supplied and torque down to standard setting (threads clean and dry, 65lb ft.). Higher torque settings are not necessary.