Motorbikes are a great source for coil over shock absorbers!
Just be careful about spring rates.
The ’94 Yamaha R6 has some great shock absorbers but the spring rates are too high for a Locost or Haynes Roadster. Various sources suggest as low as 260lbs/in for smaller engine cars and 320lbs/in for larger capacity or competition cars.
- 554lbs/in spring.
- 38mm travel+12.5mm with bump-stop.
- 295mm eye to eye.
- They’re double adjustable with needle bearings in both eyes.
For a non-cantilever set-up, you’ll need some new lower rate springs
(300 – 320lbs/in) and to get reasonable travel cantilevers will be needed.
If a rising spring rate, cantilever system is used, then this high spring rate could effectively be lowered for small amounts of travel, rising as the car rolls into a bend.
Another option (the option I went for at the rear) is to use ‘off road’ style motorbike shock absorbers. They are much larger (typically 450mm eye to eye, with 120mm travel), but the spring rates are much closer to the required value (315lbs/in).
These shock absorbers are cheap and plentiful. I paid a total of £68 inc P&P for two secondhand, both are in excellent condition and only 4 years old. Off road bikes get hard use, but typically only have a fraction of the miles of a ‘sports’ bike. Another benefit of going for off-road shocks is that for serious ‘off road’ use, riders change them at nearly zero miles. The ones I have, still had clean paper labels on them.