The MGB uses a rack and pinion steering system throughout its entire production life, a configuration that was ahead of many contemporary rivals and remains one of the car's most appreciated characteristics. While the basic operating principle remained unchanged from 1962 to 1980, there are four distinct rack variants which must be matched to the specific car when ordering.
Rack Identification
The key distinctions are bumper type and steering position. Chrome bumper cars use a different rack to rubber bumper cars, the rubber bumper rack has a longer input shaft to accommodate the raised crossmember, and RHD cars use a different rack to LHD cars.
This gives four combinations: chrome bumper RHD, chrome bumper LHD, rubber bumper RHD, and rubber bumper LHD. The two bumper types and their associated column universal joints are not interchangeable. Racks are available as new units, reconditioned exchange units, and in the case of LHD cars, on a customer's own unit basis. The rack requires EP90 gear oil as its lubricant, pumped in through both gaiters from the steering control arm side, approximately half a pint is needed, with the rack moved through its full range of travel to distribute the oil evenly.
A grease nipple was fitted to the pinion shaft on early roadsters up to 1965, but this was subsequently deleted.
Rack Components & Adjustment
Associated components include the pinion oil seal, solid support bush as a firmer alternative to the standard rubber type, cover plate shims for setting rack preload, the pinion bearing, and the sprung damper pad which maintains rack contact pressure on the pinion side. Mounting bolts, self-locking nuts, and packing shims for crossmember fitment are also listed.
When fitting a replacement rack, correct shim selection is important to achieve the proper preload adjustment, three shim thicknesses are available (0.0024", 0.005", and 0.010") and should be selected to achieve the specified rack feel without binding. Always mark the position of the column universal joint relative to the rack input shaft before disassembly, to ensure the column goes back together in the correct relationship to the rack. Track rod ends, tie rods, rack gaiters, gaiter clips, and track rod end boots are all available individually. The track rod end locknuts should be checked for security after any steering geometry adjustment