Practically Classics Forum

Just had a "Lucas" rotor arm fail on me - slight misfire then failure to proceed, Blinkin nuisance
An old but good spare got sparks flowing again and I will give the distributor Doctor a call today for a new red rotor replacement.
Question for the wise sparky types: the two year old failed rotor was marked, made in England and was sold and boxed as a Lucas Part, could it be that the higher voltages generated by electronic ignition and higher rated coils are too much for the standard design rotor arm ( My Leyland E series has Hall ignition and an uprated coil)

On the "new" one, is the brass rotor arm part rivetted on, or bonded? If it's bonded that's good, but in my experience all the carp ones have a rivetted brass contact plate, and they are simply rubbish. Any decent quality part should be able to cope with the extra voltage no problem, but yes, the additional voltage could have speeded up or exacerbated the failure of the poor quality one.

I reckon these days you just have to get decent quality parts (I use Distributor Doctor too) as that's the only way you can be sure that whatever failure you've got is not due to that part. These days just because a part is new in no way means that it's good, sadly, a problem that applies to so many after-market classic car parts unfortunately.

All the best!

Yes both the failed arm and the replacement have a riveted brass segment

Wicksy wrote:Yes both the failed arm and the replacement have a riveted brass segment

No surprise there - the good quality one you will get from Distributor Doctor will be bonded - you'll see the difference in quality straight away.

Cheers!

Just to add to this, I seem to have a smoother idle using the dizzy dr rotor arm rather than a "Lucas" one. Whenever I go out despite having a red arm fitted I keep a spare in the glove box. They are so small and cheap keeping some spare ignition parts always seems to be a good idea to me

Here's an explanation of what probably happened to your "new" rotor arm. Like the other contributors I switched to the red rotor arms a few years ago. My Daimler 1969 V8 250 saloon is supposed to tick over at 450 rpm. With the Lucas rotor arm it was always a little irregular; with the red rotor arm it's really smooth.

http://www.distributordoctor.com/rotor_arms.html

Best wishes, Dave B

Thanks for your replies folks, I have now ordered a red rotor and had a very interesting conversation with the "Doctor".
Apparently the mechanism of failure on the old type rotors can be aggravated by erosion of the arm and cap segments, dimensional quality errors and tracking through the rivet
I note the comments about smooth running and will be interested to see the result when my new rotor is fitted along with a new dizzy cap

What happened...is there much joy? Is it running better?

Yup it's made a noticeable improvement to fuel consumption and engine smoothness. I've done about 300 miles since conking out and there has been no faltering, misfires or similar maladies.
Incidentally, I have noticed "red" rotor arms for sale on e-bay but I would avoid them; just because they are red gives no guarantee they will be any better than the other crap available out there.
Martin (the Doctor) has his arms made to his own high spec and has resorted to marking them with a DD on the inside to differentiate his genuine article from the fakes.
Sadly this probably will not stop the counterfeiters for long though as they will just stamp a DD into the mold

Correct- only order from the doc! Before I had one of his arms I resorted to using an old used rotor arm that i dug out of the shed meant for a 1275 A series that dated from the early eighties (when i last had a 1275 cc A series engine....) with the base ground down a little to sit at the same height as a 'proper' vitesse arm, and with the dizzy body rotated appropriately this was still better than the rivetted rubbish in lucas badged current production.