Follow the
kingpin.
The swivel axle now has a continuous bore around a separate kingpin, with two bush sections, lower dust tubes and a thrust washer. An offset upper trunnion connects to paired damper arms through its own bushes, pin and retainers. The old crossing solid cylinders are removed.
Two axes, distinct jobs
The earlier shared-front factory drawing separates the swivel pin, axle bushes, dust-excluder tubes, thrust washer and 2A4005 trunnion. Its damper drawing separates the 2A4028 horizontal pin, four upper bushes per car and arm-clamp screw. These supply component topology, not this car’s dimensions or a complete 1975 service procedure.
Rimmer’s own 2A4005 product photo and application listing show the offset orthogonal bores and include the Midget 1500. They do not identify this car’s trunnion. The construction places the horizontal axis 32 mm inboard of the retained kingpin line and 13 mm below its old top station along that line. The side, offset and height are estimates. The damper body stays at its prior stations; its arm ends move to this new comparison joint.
Source classes and limits
| Class | Applied or retained |
|---|---|
| Direct owner dimensions | None applied to these fitted joints. Available owner photos provide context without calibrated hidden sections. |
| Retained drawing datums | Kingpin line and approximately 37.25 mm shaft diameter, wheel/hub stations, stepped spindle sections, caliper-web endpoints. The old integral steering rods are now replaced by a separate lever/joint asset; its new lower eye height is explicitly estimated. |
| Supplier comparison | Y16 / 88G274 listing: tapered 23–29 mm OD and 12.7 mm bore. This is a Caterham replacement listing, not proof of a fitted Midget bush. Conflicting 16/17 mm axial readings are retained without application. |
| Estimated sections | Carrier bore, two 28 mm bushes, upper neck, dust tubes, 3 mm thrust washer, trunnion body/offset, upper bush half-length 20 mm with 3 mm lip, arm span and eye sections. An 8 mm-radius, 14 mm-long reduced kingpin terminal is added above the old shaft-top datum. |
| Nominal thread comparison | MGOC lists 3/8 UNF upper-pin nut and 5/16 arm-clamp screw. Nominal terminal diameters guide smooth envelopes only; no thread geometry or engagement is reconstructed. |
| Unknown | Actual shaft steps, reamed fits, wear, seals, lubrication drilling, shim stack, thrust end float, dust-spring 6K653, rubber compression and loaded geometry. |
The old shaft diameter is a coarse drawing value. The new matching sections do not validate it. Local open bores and nonintersecting pin/bush construction cannot establish running clearances, strength, steering travel, camber, caster or toe. The anti-roll attachment correction replaces the old horizontal pattern over the fork gap with a forward-wall plate. Its positions, sections and fitted relationships remain estimated.
Workshop use
Select the carrier, bushes, tubes, trunnion and retainers separately to study which components surround the kingpin. Their translations are inspection poses, without a verified release order or withdrawal path. The carrier, kingpin and some adjacent references share a display offset; that does not establish which pieces stay together during service.
MGOC catalogue p. 81 discusses reamed bushes, thrust shimming and suspension-unit removal. It is a supplier procedure, distinct from factory specifications and this car’s verified state. Its application, support conditions and surrounding connections have not been verified here. No shim combination, torque, spring-release instruction or safe removal path is applied to this model.
Native reference
Build the front-fulcrum reference first; this export reads its shaft axis and section. Validation covers valid STEP solids, local bores and pin/bush relationships, metric registration, retained spindle/web datums and independent viewer selection.
Separate steering lever, two-screw lock-tab mounting and tapered outer joint now replace the old carrier rod. Two blind carrier bores are construction references, not a fitted map or repair/drilling template.