The wipers on my 1967 +2 are playing up. The wipers only work on the second position of the switch and stop at about 45 degrees. If the wipers are given assistance by hand to about 90 degrees they then continue but stop again on the way back. I guess the motor is either worn out or the rack has too much resistance. I’ve disconnected the rack from the motor, which turns consistently but can be slowed by hand. The rack is pretty stiff to push and pull by hand without assistance from the blades. Does anyone have experience of similar problems and can suggest a solution? How hard is it normally to push and pull the rack by hand?
First is to determine if the problem is mechanical or electrical.
Check voltage drop between the brown/blue wire ignition feed on your voltage regulator and low speed (pin 5) and high speed (pin 3) of the wiper connector.
There are a lot of terminals between the charging system and the wipers, any of which are liable to create high resistance under load.
I have recently rebuilt my wiper system. The rack, if clean and lubricated should move back and forth easily by hand: best to test it after removing the wiper arms so there’s no resistance.Its easy to pull out the rack cable clean, lubricate with fresh grease and feed back in.
Other problems: the plastic park switch on the wiper motor body might be worn. The motor brushes might be worn. Both available as spares. Squirt some contact cleaner into the 5 wire connector as well..As with everything Lotus, check the earth on the block connector ( top one of the 5 on the block). It is unusual for the motor to fail as such..
The motor is the Lucas 14W model, there is a ton of stuff on the internet..Good luck..Tony