Lotus Seven S4 (Type 60) Restoration: Wheels and Tires *

Transcription

1 OpenStax-CNX module: m Lotus Seven S4 (Type 60) Restoration: Wheels and Tires * Andrew R. Barron This work is produced by OpenStax-CNX and licensed under the Creative Commons Attribution License 3.0 The Lotus Seven S4 (Type 60) was provided standard with 5 1 / 2 " x 13" pressed steel 'bolt-on' wheels with chromium plated hub-caps (Figure 1). As an upgrade 5 1 / 2 " x 13" light alloy 'bolt-on' Brand Lotus rims were available at extra cost (Figure 2). Both wheels were supplied with either 165 x 13 Dunlop SP Sport or Goodyear G800 radial tires as standard. Figure 1: A Seven S4 tted with the pressed steel 'bolt-on' wheels with chromium plated hub-caps. * Version 1.1: Apr 9, :11 pm

2 OpenStax-CNX module: m Figure 2: A view of the Brand Lotus wheels as tted to the Seven S4. 1 Wheel restoration Several of the tires on LBS4/2894/GT had burst as a result of re damage, and all of the road wheels showed smoke damage (Figure 3). No physical damage appears to have occurred as a consequence of the re; however, one of the wheels shows some indication of damage due to curbing. As a consequence of being mounted at the back of the car and hence the furthest from the re, the spare wheel showed only limited damage other than that expected for a wheel of its age (Figure 4). Figure 3: One of the re damaged Brand Lotus alloy wheels.

3 OpenStax-CNX module: m Figure 4: The Brand Lotus alloy wheel used as the spare. Each wheel was initially media blasted to clean of all the paint and re damage in order to determine whether any structural damage occurred; however, the wheels appear suitable to use for street applications. note: It is never advised to use original wheels for racing applications. New steel or alloy wheels should be used for any track, rally, or race uses. The wheels were cleaned, polished, painted, and clear coated by Wheel Wizard ( 1 ) in order to return them to the original style (Figure 5). One of the nished wheels is shown in Figure 6 and Figure

4 OpenStax-CNX module: m Figure 5: A copy of the original advertising for the Brand Lotus wheels (Lotus Cars, Ltd.). Figure 6: View of coated and nished wheels as nished by Wheel Wizard ( 2 ).

5 OpenStax-CNX module: m Figure 7: View of coated and nished wheels as nished by Wheel Wizard ( 3 ). 1.1 Lug nuts The original lug nuts were damaged by age and possibly the re. The stud has a right hand pitch of 7 / 16 x 20 and replacement items are available from Redline Components, Ltd (Figure 8)

6 OpenStax-CNX module: m Figure 8: One of the new lug nuts (A) with its collar in comparison with (B) two of the original items with and without the collar. 2 Tires The original size tires were 165/70 x 13. Unfortunately, in the US this size is not as readily obtained, and so an alternative size was chosen. However, it is important when choosing alternative tire sizes that the overall rolling diameter is kept as consistent so that the speedometer reads correctly. A useful tool for choosing alternative tire sizes is provided on the 4 web site. It allows for the calculation of diameter, circumference, and speedometer correction when comparing two dierent sizes of tire. Table 1 shows the comparison of the original size and potential sizes of available tires. Specication Sidewall (in) Diameter (in) Circumference (in) Dierence (%) 165/ n/a 175/ / Table 1: Comparison of original specication (165/70-13) versus potential alternative sizes. Note: a negative dierence results in the speedometer reading higher than with the stock tires. Based upon this program it was decided to use the 175/ Tire Rack ( 5 ) stocked a small selection of this size including the Kumho Solus KE21 (Figure 9) and 722 (Figure 10), the Michelin Defender (Figure 11), and the Sumitomo HTR T4 (Figure 12)

7 OpenStax-CNX module: m Figure 9: The tread pattern on the Kumho Solus KE21. Figure 10: The tread pattern on the Kumho 722.

8 OpenStax-CNX module: m Figure 11: View of the sidewall and tread pattern on the Michelin Defender. Figure 12: The tread pattern on the Sumitomo HTR T4. Since all the tires available have a similar tread pattern, and the tires will simply be used for storage during the restoration and for initial testing, it was decided to use a set of Sumitomo HTR T4. Figure 13 shows a view of one of the tires mounted on the restored wheel.

9 OpenStax-CNX module: m Figure 13: View of one of the restored Brand Lotus wheels with a Sumitomo HTR T4 mounted. 3 Resources Wheel Wizard, 3695 Longview Drive, Atlanta, GA 30341, USA. Tel: Moss Motors, Ltd. 440 Rutherford Street, Goleta, CA 93117, USA. Tel: or Tire Rack, 7101 Vorden Parkway, South Bend, IN Tel: Bibliography D. Ortenburger, Legend of the Lotus Seven, Mercian Press (1987). J. Coulter, Lotus Seven, Amadeus Press (1995). Miata.net Tire Size Calculator