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Agrace

Local LE16 Electrical

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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

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Take it to TR Enterprises or Overdrive Repair services as your fairly close to either.

Stuart.

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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

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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.

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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

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