Inside Collection: Lotus Seven S4 (Type 60): Design, Restoration, and Maintenance
The wheel bearings and stub axles for the Series 4 Lotus Seven were sourced from Triumph, in particular the Herald. While the wheel bearings are also common to the Triumph Spitfire, the axles are not the same. The Spitfire axles, which are also used in the Lotus Seven S3, are too long and if fitted in the upright insufficient thread extends out of the rear of the upright. The hubs are chosen to have a Ford bolt pattern (4 x 41/4”) to match the Ford sourced rear axle.
The stub axles were obtained from Redline Components, Ltd. Before sliding into the upright, a liberal amount of copper anti-seize (Permatex®) is used. The axle fits in from the outside (Figure 1). From the inner side a washer is placed over the stub (Figure 2) followed by a ½” thread nyloc nut (Figure 3). In order to torque the nyloc nut it is necessary to temporarily put a nut on the hub side.
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New bearings were sourced from Moss Motors. It is best to use a bearing race driver set (Figure 4) to install the bearing races. However, if not available using the old bearing race is acceptable, but care should be taken in ensuring the race is fitted correctly.
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First it is good practice to wipe the location where the bearing race will fit, to ensure no dirt will stop the race being inserted correctly. The outer bearing race is placed into location on the outer side of the hub (Figure 5). Then using the race driver set (Figure 6) the race is tapped in place with a hammer (Figure 7). It is best to support the disks on two pieces of wood to ensure that the inner side of the hub/disk combination is not damaged (see Figure 5).
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The inner bearing race is fitted in the same manner (Figure 8 and Figure 9); however, it is even more important to support the outer side of the hub on two pieces of wood so that the studs do not get damaged.
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The packing of the bearings is the messiest part of the overall process. It is important to wear suitable gloves while doing this. Disposable nitrile butyl rubber surgical gloves are the best; however, when these are not available the typical home washing up (dish washing) gloves will work, e.g., Marigold®. The easiest way to pack the bearing is to follow these steps:
With the hub/disk combination stud side down the grease packed inner bearing is gently pushed into position (Figure 10) ready to mount the hub/disk onto the stub axle.
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Before the hub/disk unit can be installed, the bearing grease seal is placed over the stub axle (Figure 11). This unit consists of a circular metal with a felt washer on one side. The felt fits up against the hub, and it locates into a grove on the face of the hub.
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While holding the inner bearing into its race, the hub/disk assembly is carefully slid over the stub axle until the inner bearing slides all the way to the dust washer. Care should be taken to ensure that the bearing is fitted on straight. With the inner bearing/hub/disk in place, the outer bearing is slid over the stub axle and while supporting the hub is pushed along the axle until it fits into its race (Figure 12).
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The entire hub assembly and the bearings are held in place on the stub axle by a washer that has a D-shaped hole such that it does not rotate on the axle (Figure 13A) and a crenellated nut (Figure 13B), which in turn is held in with a cotter (split) pin (Figure 13C). Once the hub is in place the D-washer is located (Figure 14) and the crenellated nut is screwed on. The crenellated nut is designed such that once suitably tightened the cotter pin will slide through the crenellations and through the hole in the axle (see Figure 11). In general, the nut is tightened until the hub will only turn with difficulty and then backed of to the last location at which the crenellations and hole align. The cotter pin is then pushed through (Figure 15) and then split by bending the ends over ((Reference)). Depending on the length of the pin it may be necessary to cut one arm on the pin so that the outer bearing grease cap can be installed (Figure 17).
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This work is licensed by Andrew R. Barron under a Creative Commons Attribution License (CC-BY 3.0), and is an Open Educational Resource.
Last edited by Andrew R. Barron on Sep 4, 2012 6:29 pm -0500.
