Richard Farrant Posted May 22, 2006 Share Posted May 22, 2006 I have been asked to convert a GMC to 12 volts. The generator output is adequate to retain, what I need to know is, has anybody in the UK done this? Reason for specifically asking UK owners is the availabilty of the regulator used, ie a Lucas RB340 or similar, for example. If a commonly available regulator is used, it makes it easier to replace in event of problems. Thanks in anticipation. Richard Quote Link to comment Share on other sites More sharing options...
Jack Posted May 22, 2006 Share Posted May 22, 2006 I have been asked to convert a GMC to 12 volts. The generator output is adequate to retain, what I need to know is, has anybody in the UK done this? Reason for specifically asking UK owners is the availabilty of the regulator used, ie a Lucas RB340 or similar, for example. If a commonly available regulator is used, it makes it easier to replace in event of problems. Thanks in anticipation. Richard :shock: I was going to post the same question :shock: Nice one Richard and I think Degsy, Matt or Karoshi are your people. Looking forward to an answer 8) Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted May 22, 2006 Author Share Posted May 22, 2006 I was going to post the same question :shock: Nice one Richard and I think Degsy, Matt or Karoshi are your people. Looking forward to an answer 8) Thanks Jack, I was expecting one of those three to have an answer on this Richard Quote Link to comment Share on other sites More sharing options...
mick.wilson Posted May 22, 2006 Share Posted May 22, 2006 We have two 12v Jimmy's in our group but thats how they came :? . Jack you can have a look at the truck this weekend and see what you need to convert to 12v and I know one of our trucks is looking a converting it back to 6v from 12v. Mick. Quote Link to comment Share on other sites More sharing options...
Guest matt Posted May 22, 2006 Share Posted May 22, 2006 I'm afraid I'm not of much help,when I bought it mine was partly converted to 12V(just enough to bug&er everything up ) so I'm in the process of putting it back to 6 volts as per the original. Matt. Quote Link to comment Share on other sites More sharing options...
Karoshi Posted May 22, 2006 Share Posted May 22, 2006 Richard I'm not quite sure of the question here. Do I understand correctly that you want to retain the original 6volt GMC dynamo but use a modern 12 volt dynamo regulator with it, such as the RB 340, in the hope of achieving a 12 volt charge system ? Sorry but this makes no sense at all. If you've already realised the advantages in going to 12v, dont mess about..... get an alternator, you've already compromised the originality so do it properly. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted May 22, 2006 Author Share Posted May 22, 2006 Richard I'm not quite sure of the question here. Do I understand correctly that you want to retain the original 6volt GMC dynamo but use a modern 12 volt dynamo regulator with it, such as the RB 340, in the hope of achieving a 12 volt charge system ? Sorry but this makes no sense at all. Karoshi, It is quite a common practise to retain the 6v dynamo in conversions, many jeeps are done like this. The dynamo does not just generate 6 volts, it is probably in the region of 15, this is what the voltage regulator does, to bring the volts down to the requirement. All I was asking was if anyone had done this, what was the regulator they used, to save experimenting. Thanks for your reply. Richard Quote Link to comment Share on other sites More sharing options...
Karoshi Posted May 22, 2006 Share Posted May 22, 2006 As I said, it don't make sense to me. Flemming and his Left hand, and Right hand rules, agrees. It MAY work, but I guess there's efficiency and efficiency. The RB340 is a three bobbin, current, voltage regulation unit with a cut-out. It has an operating requirement of 13.7 - 15.1V. your 6 volt dynamo is not designed to give that as a constant output voltage. Your question may have been better posted on the Gee. If this is a common, and reliable conversion, someone there will have the answer. Such a conversion will make a nice underbonnet heater for the winter! If it lasts that long. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted May 22, 2006 Author Share Posted May 22, 2006 . The RB340 is a three bobbin, current, voltage regulation unit with a cut-out. It has an operating requirement of 13.7 - 15.1V. your 6 volt dynamo is not designed to give that as a constant output voltage. Your question may have been better posted on the Gee. If this is a common, and reliable conversion, someone there will have the answer. Thanks for your thoughts. I only mentioned a RB340 as an example of a possible unit to use. Reason I did not post on Gee, is that I did not want people from outside UK giving me examples of regulators than are not readily available in UK. A well respected jeep specialist in England advises that 6v jeep dynamos can be used for 12v, so I am basing my assumptions on that. I am open to any well founded advice from anyone who has actually done this. As to fitting an alternator, then you have the problem of fitting a wider pulley on it to suit the belt, sooner fit a C45 dynamo. Richard Quote Link to comment Share on other sites More sharing options...
Karoshi Posted May 22, 2006 Share Posted May 22, 2006 I ask you to consider one thought. IF a 6 volt jeep dynamo IS suitable for long term use....why do the manufactures make a 12 volt version ? I smell hot shellac !! Quote Link to comment Share on other sites More sharing options...
Degsy Posted May 23, 2006 Share Posted May 23, 2006 Got to agree with Karoshi on this one, I smell cooking. It is a simple conversion with an altrenator utilising the original reg as a connector block it doesn't look too non standard and the results are excellent. I know Frank Jolley does a kit but if you get a Bosch alternator off a scrap Mk4 escort it utilises a split pulley which is simple to space out to use a wider belt plus this type of alternator is particularly trouble free and very cheap and easy to repair with the one item that does ever seem to fail on it. Just my 5c worth but hope this helps. Quote Link to comment Share on other sites More sharing options...
Jack Posted May 23, 2006 Share Posted May 23, 2006 well I am going to get mine converted to 12v as soon as poss, I can really see the benefits of it. But does it cause problems with the dials etc etc in the cab? Quote Link to comment Share on other sites More sharing options...
Degsy Posted May 23, 2006 Share Posted May 23, 2006 Only affects the fuel gauge, you need to get aregulator to fit in the circuit, see recent comments on CCKW forum. Cheers Degsy Quote Link to comment Share on other sites More sharing options...
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