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The uprights, also used in the Europa are originally Triumph in origin, as used in the Herald and Spitfire. The brake disks and calipers are also Triumph, but the hubs are of Ford origin and have a 4 1 / 4 ” stud pitch matching the Ford sourced rear axle. [link] lists a summary of the nut and bolts used in the front suspension of the Lotus Seven S4.
| Application | Size |
| Upper wishbones, anti-roll (sway) bar link, and upper shock (damper) to chassis | 1 / 2 ” nyloc on threaded pivot pin |
| Lower wishbones to chassis | 1 / 2 ” nyloc |
| Lower wishbones to lower shock (damper) | 1 / 2 ” x 2 1 / 2 ”&nyloc |
| Lower wishbones to trunnion | 7 / 16 ” x 2 3 / 4 ”&nyloc |
One of the drawbacks of the Series 3 Lotus Seven was the design of the rear suspension. Although effective, the A-arm location of the rear axle in the S3 was a weakness that led to several failures (especially cracked differentials) and required the axle to be significantly reinforced. In order to overcome this Peter Lucas designed a much simpler system for the Series 4. The ends of the Ford Escort live axle were located by leading (lower) and trailing (upper) radius arms of the Watts linkage type, while the location of axle was achieved with an axle-locating link attached to the left hand side lower radius arm. The lower radius arms were mounted on big rubber bushes to compensate for the conflicted geometry as a result of bumps that is inherent on this geometry. Without the bushings the axle would act as an anti-roll (sway) bar. In this regard it was only partially successful since the inside wheel of the S4 is known to lift off the ground under hard cornering. [link] lists a summary of the nut and bolts used in the rear suspension of the Seven S4. The rear axle was given a 3.77:1 final drive ratio.
| Application | Size |
| Lower radius arm to bushing | 7 / 16 ” x 3” |
| Lower radius arm to axle | 1 / 2 ” x 5” |
| Axle locating link to bushing | 7 / 16 ” x 3” |
| Axle locating link to axle | 1 / 2 ” x 5” |
| Axle locating link to center chassis mounting | 1 / 2 ” x 5” |
| Upper radius arm to chassis | 1 / 2 ” x 4” (per side) |
| Upper radius arm to axle | 1 / 2 ” x 2 3 / 4 ” (per side) |
| Shock (damper) to axle | 1 / 2 ” x 2 3 / 4 ” (per side) |
| Shock (damper) to chassis | 1 / 2 ” x 3” with rounded nose (per side) |
The front brakes were unchanged from the S3 Seven and used Girling trailing calipers. These were used in a wide range of British cars of the era (including the Triumph Spitfire), as well as many low budget formula cars, such as the Formula Fords. The brakes were hydraulically operated with 9” solid discs. The rear brakes are hydraulically operated 8 1 / 2 ” drums incorporating a mechanical handbrake.
The Triumph Spitfire rack used in the Series 3 Seven was replaced with one sourced from Burman. The turning circle remained excellent with 2 3 / 4 turns lock-to-lock. For the first time, the steering column was collapsible in a front impact as a safety feature.
As with the preceding Series 3 Seven, the S4 was offered with a selection of engines. The 1558 cc Lotus Twin Cam was the performance choice while the budget (and consequently most common) choice was the 1600 cc Ford crossflow Kent motor. A third offering was the 1300 cc Ford crossflow Kent engine. Unfortunately, the sump for the latter engine had the oil pan at the rear of the sump, which forced one of the chassis cross members to be simply removed. A limited number of these were actually sold.
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