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TR4 fitting an alternator


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Most of the usual suppliers do a kit, e.g.

https://www.moss-europe.co.uk/alternator-conversion-tr2-4a.html

The complication is the fan-belt - does your car still have the original wide belt ? If so you either need to swap it for a narrow one which means changing the crank pulley and fan arrangement, or else keep the wide belt and re-use the pulley from the dynamo.

The latter will work OK but the alternator won't generate quite as well as it could at low speeds (though still better than a dynamo), since the dynamo pulley is a larger diameter than the usual size used with an alternator so it won't rotate as fast. 

What you do with the wiring depends on whether you wish to retain the case of the dynamo control box for 'original' looks or remove it entirely. You can keep it and use it as a convenient interconnection point, though you do need to remove the internals and just leave the connections. 

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Maggie, if you are a member of the TR Register you  have access to a technical article, explaining how to do just this conversion. Both mechanical and electrical explanations are fairly clear. TRaction 248 February 2011

james

Edited by james christie
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See my articles in TR Action 118 (November 1994) and the article which James and I published in TR Action 248 (March, not February, 2011 - I believe).

Conversion to narrow belt is not a necessity, but it makes life so much easier, as Rob has mentioned.  And if the belt should fail, replacement is so much easier.

Ian Cornish

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Maggie - if you are unable to access the articles which I listed, just send me a PM with your email address, and I'll send them as Word documents.

Ian Cornish

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Maggie - you could try one of these "Dynamators" which are basically an alternator inside a casing look like a dynamo - they only require minimal alterations:

https://www.ebay.co.uk/itm/391977196464?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338723872&toolid=20006&customid=OnvzIxcRAAAAS3t8Mh_tWGMJjc4FAAAAAA

this link is for a positive earth one but they also do negative earth ones

Cheers Rich

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9 minutes ago, rcreweread said:

Maggie - you could try one of these "Dynamators" which are basically an alternator inside a casing look like a dynamo - they only require minimal alterations:

https://www.ebay.co.uk/itm/391977196464?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338723872&toolid=20006&customid=OnvzIxcRAAAAS3t8Mh_tWGMJjc4FAAAAAA

this link is for a positive earth one but they also do negative earth ones

Cheers Rich

Personally I wouldnt, they do suffer from overheating and failure in service quite often, Alternators need a lot of cooling hence their open construction, fitting a dynamo full cover round them is a recipe for disaster

Stuart.

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1 minute ago, stuart said:

Personally I wouldnt, they do suffer from overheating and failure in service quite often, Alternators need a lot of cooling hence their open construction, fitting a dynamo full cover round them is a recipe for disaster

Stuart.

Stuart - fair comment - I've got a heat shield fitted and touch wood so far, in 8 years of use, admittedly not high mileage, it's been fine. I've also heard of some reliability issues but in fairness to the the supplier, the ones I heard about were quickly resolved with replacement units.

Cheers Rich

 

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4 minutes ago, stuart said:

Personally I wouldn't, they do suffer from overheating and failure in service quite often,

Plus it doesn't solve the fan-belt thing.  Because they are an alternator internally, they are supplied with a narrow-belt smaller diameter pulley.   The only thing it really achieves is that it looks like a dynamo - you still need to do the same wiring changes. 

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The heat and vibration of the four cylinder engined cars can lead to a short life for poor quality alternators.

Once you have done a thin belt conversion it's done. Much less likely to end up doing belt change at the roadside and easier with a thin belt.

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This is a good small alternator 

https://www.ebay.co.uk/itm/143548367716?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=aO0GUP9IQ0W&sssrc=2349624&ssuid=33-Tg7STSaq&var=&widget_ver=artemis&media=COPY

 

this is a great and effective fitting kit

https://www.racetorations.co.uk/product/alternator-fitting-kit-tr2-4a/

then, if not done already,  you do the narrow belt kit. 
 

then alter the wiring

 

if I can do it ANYONE can. 

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Why swap?

There is a reason modern cars run alternators. Greater output.

If our cars are regularly used a dynamo is enough to keep the battery charged.

Cars used occasionally with parasitic devices like alarms, modern radios and trackers will run go pretty flat between runs and an alternator may well charge that bit faster and allow more accessories to be use. High output stereos, electric fuel pumps and electric fans etc.

An essential swap? No. Bear in mind an alternator combines the roles of the dynamo and regulator so failure counts have to be compared with this in mind.

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+1 for your answer!

Triumph swaped to the alternator with the 6 cylinders - while the electric consumers remainded the same.

In my opinion the main reason was the lower price for the unit of alternator and regulator, more power was a win-win-situation.

With the new regulator was nothing to explain anymore - and nothing to do wrong.

My TR4A still has the C40 / RB 106 / type 20 belt and I never had any lack of current, electric power or voltage.

I drive the car occasionaly, about 3,000 - 4,000 km a year, the battery is 8 years old and still has 12,85 Volt.

It stays in the car during winter and got no attention at all.

Ciao, Marco

Edited by Z320
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Hi Marco,

hope you and yours are well?

I was running down the M6 Motorway, actually to an IWE, the last time it was at Stafford, in

heavy rain, I had wipers, fan, H4 Headlights on, and was running in overdrive.

Without warning the revs shot up, and then settled down about 500 revs higher than previously.

It took me a moment or two, to realise that overdrive had dropped out.

I touched no controls, but switched the wipers off, and the overdrive came back in.

I had the dynamo checked by teh local Lucas depot, they had a chian of depots the, and was told there was nothing wrong with it, just with all I had plus teh H4's it was asking too much of teh dynamo, thats when I changed to an alternator, never regretted for a moment.

John.

 

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Hi John,

thank you, yes, we are all fine here.

I know I‘m well known for often a different look on things, I hope the forum and its members can bear this :ph34r:

All I read about the overdrive, I‘m glad  not to have one. It can happen it drops out/in because of different problems „anytime“?

It is released by electrical voltage and current and to switch off I guess the voltage (means the voltage of the hole battery) has to drop down to 9 Volt?

And has to raise again to 12-13V?

This is the standard „on/off hysterese“ of a „2 point regulator“ (sorry, I don’t know the English terms),

btw this is why the RB 106 regulator (and all others) have a „reset coil“ for a fast switch off.

Perhaps you could measure.

The battery down to 9 Volt would have caused you also other real serious problems out there on the M6.

Just my thoughts, possibly it was not the missing power of the generator causing your OD problems.

As asked: perhaps you could measure the voltage your OD switches off.

Ciao, Marco 

Edited by Z320
My poor English
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Marco is quite correct on this -  if the dynamo was unable to supply enough current for all the loads, the worst that should happen is that the excess would be drawn from the battery and register as a discharge on the ammeter. For the voltage to fall low enough for the solenoid to drop out shows there must have been something else wrong - maybe a high-resistance connection somewhere. 

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Typical on/off characteristic of a "2-point regulator" - like a electrical relais.

  obEjxk880OIoimz7e3HLB5xEaNjkGe98Xd-x5ct4

13 V on, but off not before 9 Volt, off faster with a "reset coil",

From an article I wrote about the RB106-2 regulator in 2014 for our TR IG club magazin.

Edited by Z320
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We call that the cut-out contact Marco - that should only ever open when the engine is idling and is accompanied by the ignition light coming on.  Its function is to disconnect the dynamo when it is not generating sufficiently, to prevent the battery driving the dynamo as a motor. During all normal driving above idling speed, it should remain closed.

There has to be hysteresis in its action to prevent the contact 'chattering' as the engine revs go up and down. When it does open, all electrical loads are driven solely by the battery so should never fall much below 12V as you say. 

 

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Yes I know,

this is what I explained at the German article,

sitting out at the garden with my wife I just did not remember „cut-out“….

The OD solenoid very likely has no cut-out?

Edited by Z320
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The point is that an upgrade to an alternator (& narrow belt) is a good idea for any car used regularly or not, especialy if extra electrical loads are present, e.g. cooling fan, spotlights etc.

Bob

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Sorry Marco - I realise you know all this stuff but I am 'man-splaining'  things for the possible  benefit of others who don't and who may search the forum later. :rolleyes:

 

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