Using MightyBoyEV - Adding light weight alloy wheels..... (part 2)


Adding light weight alloy wheels - fitting and wheel alignment....

Why play with the wheels?

Firstly, total wheel weight is reasonably important on such a light weight EV conversion. Each light alloy rim is about 600gm less then each pressed steel rim. This corresponds to a total weight saving of about 2.4 kgs. Keep in mind this is 2.4 kgs of "unsprung" weight. Thus 2.4 kgs of unsprung weight equals about 24kgs of vehicle weight! A factor of 10 times is general used in calculating the effective overall vehicle weight reduction when removing unsprung weight. Unsprung weight is the weight of everything basically hung off the shock absorber side of the vehicle (wheels, tyres, brakes etc). I am trying to reduce as such weight as possible to achieve the best watt-hours / km result - hopefully less then 80 w-h/km.

Note: I am aware of the various views about the 1:10 ratio mentioned above - other data supports ratios as low as 1:1.75. My personal experience indicates keeping wheel weights as low as possible and keeping tyre pressures as high as possible does have a measurable effect. Currently in the order of 2 w-h/km (gained with my lightest tyre/rim combination and 45 PSI tyre pressure). I would also like to find a source of LRR tyres but these seem impossible to find in my 145/70/R12 sizing.

Secondly (and not real very important at my speeds) these old school Suzuki factory alloys are nice and flat faced and the +45mm offset puts the narrow wheels (4.00B) inside the body as much as possible. All factors that help reduce wind drag - the best being a solid disc (or hub cap) as seen on many early EV's.

Every little bit helps.....

Beissbarth ML4600-8 wheel alignment now set to:

Toe = + 1.7mm(R) +1.7mm(L) - Total +3.5mm

KPI = 12 degrees 56 minutes (L) and 13 degrees 31 minutes (R)

Castor angle = 2 degrees 26 minutes (L) and 1 degrees 30 minutes (R)

Camber = 1 degrees 6 minutes (L) and 2 degrees 5 minutes (R)

For a complete log of faults and alterations please go to Project issues and resolutions.

Additional photographs showing the new rims installed can be found below......

Very flat design....

Front view....

Rear view....

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