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MG Midget and Sprite Technical - Red Rotor Arms

Has anyone had any problems with the famed red rotor arms, ie shorting out? I have recently had my Dissy rebuilt by a well known refurbishment company and they said they don't use red rotors because of issues with them shorting out through the resin used to secure the brass insert. I was somewhat surprised at this statement because I've never heard of this problem and had been looking forward to having a red rotor because I thought they were bullet proof.

b higginson

I think there are red rotor arms and red rotor arms, if you know what I mean?! They don't all come from the same source.
Dave O'Neill 2

I'm a convert - but on a somewhat unscientific basis. The one I put in to replace a dead standard one some seven months ago has been faultless. But that doesn't mean it won't short out tomorrow, and it's quite possible that if I had used a standard replacement it might have lasted years and years. Who knows. We would best take advice from someone who has run several cars over a long period using both types - and be fully aware of the source. I assumed that because it cost a fair bit more it must be better, but that is the type of thinking that crooks would relish. I suppose when it comes down to nitty gritty, I bought it from a dealer I trust (Bill Reeves at Birchington)and if he had dozens of people come back with failed units he wouldn't be selling them. If he's confident enough to use them in his cars, then I'm happy to do the same.
But all that glitters is not gold - and there might well be red rotors available that are, simply, red. So to speak. And I wouldn't trust Mick Hucknall to sort my electrics.
I think I've just said the same as Dave O'Neill, but he managed it it in 20 words.
C Whiting

Oh, crap.

I thought the red rotor arms were the ones we could trust. There have been two sources making the black ones, one was trustworthy and the other one was not and because they were both black the vendors were selling both and it was a quality lottery.

Does this mean that there is now an equally disreputable red version out there too?

My advice to anyone looking for rotors, based on the ridiculous number of folks who've had trouble over the last 15 or so years, is to buy rotors only from the following sources:

In the UK:

In the USA:

Hah!, watch it turn out that Bernie bought his red one FROM one of them (it would be like, "Invasion of the Body Snatchers"; we wouldn't know who to trust anymore!).

Or, I guess one could switch over to a 123 distributor, which uses a Bosch rotor.

Back in the mid '90s, Popular Classics magazine had this happen to them (a bad rotor), which drove them nuts, replacing every other possible component, even replacing the rotor with another, new one, that also turned out to be a bad one. I laughed when I read it, thinking, "what are the odds?", only to see this story repeated by folks again and again, in the years since.

Always a bad rotor.

Norm Kerr

Norm. I haven't got a red rotor yet. It just surprised me that the company who did my rebuild,(H&H ignition solutions) don't use them and they gave the previously mentioned reason. I will shortly be visiting Peter Burgess and I know that he uses the genuine ones, so maybe I'll be able to buy one from him. The black one that I had got from Moss did indeed have the big rivet on it and it looked as if it was just waiting to short out. H&H supplied me with a black one with a much smaller rivet, but after all I had heard about how good the red ones are that's the one I want. Maybe H&H had experienced the spurious ones so stuck with what they trust.

b higginson

A quote from the Distributor Doctor website...

"Like most good ideas, we’ve suffered from low grade pirated copies being sold very cheaply, so BEWARE CHEAP COPIES OF RED ROTOR ARMS"
Dave O'Neill 2

Hi Bernie

We only stock the 'proper' red ones straight from 'The Doc'. I have known Martin for around 20 years and trust him implicitly.

To be honest we have not had problems with all black arms, we have, however, had serious failures with blue ones in cheap (read fall apart for that!)distributors which I am told trade for around £20!

Are you coming down for the power run sessions on the 10th?

P Burgess

My Aldon distributor came with a brown bosch rotor arm..rubbish! Changed to a red one from Distributor doctor with no further issues. Alson were great to deal with so no problems there, just their choice in rotor arms!
Robin Cohen

Hi Robin, we were hoping the brown ones would be ok :(

Never mind, I have a fair sized bag with early 4cyl. late 4 cyl and 6 cyl red rotor arms.

The new problem seems to be condeser/capacitor failure.

P Burgess

Hi Peter. Yes I'm coming with Les Robinson and some others from MASC N.West on the 10th June. Please reserve me a red rotor! H&H did a good job of rebuilding my dissy and I know I got mine back as I noted the number before I sent it. I was going to go to "The Doc" but I was bit strapped at the time and H&H were a bit cheaper. I have pertronix ignition, so condenser won't be an issue.

b higginson

PB forget points!
I know of and have fitted several magnetronic (simonbbc?!) units and and all are working fine.
Certainly better than the crappy points and condensers at almost the same price!

Just don't know how they do on the RR....
Onno Könemann

Hi Onno

I will wait to see how well the cheapy conversions work. The Aldon Ignitor/Pertronix are fine just more expensive than points and condensers. Also in some classes of racing...Bs so far, we have to use points. I am trying to source NOS lucas and the bosch type of condensers to build up a little stock of these. Some folk are selling v expensive items cobbled from HiFis, not sure these are vibration resistant though or properly compatible with 12v/8v.

P Burgess

Over the weekend I've had (I believe, yet to swap and confirm, but have tried everything else) a second condensor failure in my car now in the 2 weeks it's been on the road! Admittedly I have covered over 800km in that time, but there has been a rash of bad ones here in Aus the last month I am told. My father had what appears to be a failed condensor in his BGT yesterday as well.

Hi Andrew

Best dig a good condenser off a breakers yard dizzy! I have been looking out for the old Bosch type ones that have a little retaining screw to hold the condenser onto the dizzy and fir it to coil where it will run cooler than internally in dizzy. The new Lucas type ones seem to fail under heat.

As an aside, not wanting to teach Granny to suck eggs...make sure the condenser is tightly fitted and the earth wire in the dizzy is good.

P Burgess

This thread was discussed between 28/05/2011 and 31/05/2011

MG Midget and Sprite Technical index

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