Agrace Posted February 26, 2019 Report Share Posted February 26, 2019 Hello all I have a nagging electrical problem with my overdrive (1967 TR4A). When the overdrive is engaged, after some time, I hear an electrical crackling noise and the overdrive disengages and re-engages constantly. Is there anyone in my local area (Market Harborough), commercial or otherwise, who I can have take a look? Electrics are not my thing. Many thanks for any help. Regards Andrew Quote Link to post Share on other sites
stuart Posted February 26, 2019 Report Share Posted February 26, 2019 Take it to TR Enterprises or Overdrive Repair services as your fairly close to either. Stuart. Quote Link to post Share on other sites
Agrace Posted February 26, 2019 Author Report Share Posted February 26, 2019 Thanks Stuart. I was hoping for something closer if possible. Quote Link to post Share on other sites
RogerH Posted February 26, 2019 Report Share Posted February 26, 2019 How about Racetorations in Gainborough. Roger Quote Link to post Share on other sites
TR 2100 Posted February 26, 2019 Report Share Posted February 26, 2019 You could save yourself a bit of cash (and time) if you removed the gearbox cover to allow quick easy access to the solenoid before taking it to any of the above. AlanR Quote Link to post Share on other sites
ianc Posted February 26, 2019 Report Share Posted February 26, 2019 Sounds as if there is an unsatisfactory solder connection to the hold-in coil, which starts to cause problems when the solenoid warms up. See my article on pages D49 & D50 of the Technicalities CD, and here's some additional information about the resistance of the pull-in and hold-in coils. The hold-in coil is a very fine wire, so making a solder repair is not easy - but it is possible because I did so on more than one occasion in the 1960s. Ian Cornish OVERDRIVE SOLENOID Today (25/05/09), I made some measurements on a brand new, spare, overdrive solenoid which I bought from Moss some time ago. I think it is fair to assume that it was built to the same specification as the original Lucas item. Pull-in (Pull-in and Hold-in coils in parallel) 0.8 ohms, drawing about 15-17 amps. Hold-in (pull-in circuit disconnected by plunger operating the switch within the top of the solenoid) 12.5 ohms, drawing about 1 amp. For the technically-minded, this means that the Pull-in coil has a resistance of about 0.85 ohms, and takes about 14-16 amps. The current drawn will depend upon the state of charge of the battery, which is usually between 12-13.4 volts. Quote Link to post Share on other sites
Swarf Posted February 26, 2019 Report Share Posted February 26, 2019 Hi Andrew, PM sent. Cheers Quote Link to post Share on other sites
Waldi Posted February 27, 2019 Report Share Posted February 27, 2019 12 hours ago, ianc said: Sounds as if there is an unsatisfactory solder connection to the hold-in coil, which starts to cause problems when the solenoid warms up. See my article on pages D49 & D50 of the Technicalities CD, and here's some additional information about the resistance of the pull-in and hold-in coils. The hold-in coil is a very fine wire, so making a solder repair is not easy - but it is possible because I did so on more than one occasion in the 1960s. Ian Cornish OVERDRIVE SOLENOID Today (25/05/09), I made some measurements on a brand new, spare, overdrive solenoid which I bought from Moss some time ago. I think it is fair to assume that it was built to the same specification as the original Lucas item. Pull-in (Pull-in and Hold-in coils in parallel) 0.8 ohms, drawing about 15-17 amps. Hold-in (pull-in circuit disconnected by plunger operating the switch within the top of the solenoid) 12.5 ohms, drawing about 1 amp. For the technically-minded, this means that the Pull-in coil has a resistance of about 0.85 ohms, and takes about 14-16 amps. The current drawn will depend upon the state of charge of the battery, which is usually between 12-13.4 volts. Thanks for sharing Ian, This is my learning for today, wish I had one like this every day;) Regards, Waldi Quote Link to post Share on other sites
Agrace Posted March 6, 2019 Author Report Share Posted March 6, 2019 Many thanks for all your responses. I have found a great resource in Mick at EJ Ward. Quote Link to post Share on other sites
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