Alternator Conversion

[woodward]

Hello

 

Probably been covered somewhere else before, but can someone let me know what is required to replace my dynamo with a TR6 alternator or alternatively point me in the direction of a previous article?

 

Thanks

 

Myles

[John Morrison]

[Hi Myles.

 

yes subject has been mentioned several times here, use the search facility to track.

 

technicalities CD has the info, from a superb article by Ian Cornish in TR Action 118 Nov 1994.

 

If you cant find the info, mail me, happy to post you a hard copy.

 

John.

[RogerH]

Hi Myles,

If all else fails Revington do a nice kit with different sized alternators (get a big one)!!!

Dead easy to fit.

 

Roger

[TR 2100]

what is required to replace my dynamo with a TR6 alternator

Not a cheap option, but there is a Dynalite alternator - this is an alternator

built into a dynamo casing. £400 or something for the unit including an alloy

pulley. The pulley can be for thick or thin belt.

[BrianC]

Not a cheap option, but there is a Dynalite alternator - this is an alternator

built into a dynamo casing. £400 or something for the unit including an alloy

pulley. The pulley can be for thick or thin belt.

Does this require the usual electrical mods for converting from dynamo to a standard ACRxx alternator, or is it a straight swap?

I assume at least the ammeter will need upgrading to +/- 60 amps or replacing with a voltmeter (and in our case switch from positive to negative earth - yes our TR4A really is positive earth despite the majority apparently being negative earth).

[stuart]

Does this require the usual electrical mods for converting from dynamo to a standard ACRxx alternator, or is it a straight swap?

I assume at least the ammeter will need upgrading to +/- 60 amps or replacing with a voltmeter (and in our case switch from positive to negative earth - yes our TR4A really is positive earth despite the majority apparently being negative earth).

Brian I havent had anything to do with the Dynalites but I assume that they would need wiring up the same way as a standard Alternator and the other mods would also be needed. My TR4a was also originally positive earth as well which is also an odd one as its an ex USA car.

Stuart.

[BrianC]

My TR4a was also originally positive earth as well which is also an odd one as its an ex USA car.

I wonder if the positive earth TR4A syndrome is confined to cars originally delivered outside the UK mainland? Lynda's TR4A (CTC58xxx-O) spent its first three years in Jersey.

[stuart]

I wonder if the positive earth TR4A syndrome is confined to cars originally delivered outside the UK mainland? Lynda's TR4A (CTC58xxx-O) spent its first three years in Jersey.

Not sure but there was a thread running about this a while ago, but I cant remember wether it was an actual topic or if it came off something else.

Stuart

[TR 2100]

Does this require the usual electrical mods for converting from dynamo to a standard ACRxx alternator, or is it a straight swap?

I assume at least the ammeter will need upgrading to +/- 60 amps or replacing with a voltmeter (and in our case switch from positive to negative earth - yes our TR4A really is positive earth despite the majority apparently being negative earth).

Brian,

As far as I know, the conversion needs the same mods as for the normal alternator conversion,

change to pos earth and the voltage control box becomes superfluous (although I'm retaining

mine!). I'm not sure what options there are for the ammeter - maybe even disconnect, but it's

the same problem whichever alternator you use.

 

The advantage with the Dynalite is that it looks like the standard setup physically, although at a price.

 

There may be other pros and cons - one I can think of is that you retain the original, and undesirable,

feature of running very close to the exhaust manifold. It's bad enough cooking a dynamo, but you don't

want to cook a Dynalite at £400. I'm told they have been fitted to quite a few cars, and that includes

highly modified cars running 4-branch manifolds, and that they have performed well. I think it's designed

to push cooling air from front to back, but I'm not 100% convinced of that.

 

AlanR

[BrianC]

Not sure but there was a thread running about this a while ago, but I cant remember wether it was an actual topic or if it came off something else.

Yes - it was my thread, but proved inconclusive. I see Jon Marshall has responded in his registrar's report in the latest TRaction, but I'm still confused (not that it really matters, but I'm a configuration manager by profession and pedant by nature ).

 

Alan, Thanks for the info. I first saw the Dynalite a year or so ago and thought it ideal for the few concours cars which are actually used, since it preserves the look of originality. However, it's way too expensive for me - I don't really trust alternators anyway and will stick with the good old dynamo (which I sort of understand) and the heaviest duty battery I can find for winter/night driving

Edited April 13, 2007 by BrianC

[Ade-TR4]

Hi

 

re: gauge issue. As the alternator tends to be wired back to the battery directly, the gauge only has current flow on discharge, not charge.

 

It's a bit weird at first as the gauge only shows discharge, but I've had no problem with mine.

 

If you're running a non-standard exhaust manifold, either wrap it with thermo stuff, or heat sheild the alterntor as it's easy to cook the alterntor.

 

have fun!

Adey

[TR 2100]

re: gauge issue. As the alternator tends to be wired back to the battery directly,

the gauge only has current flow on discharge, not charge.

It's a bit weird at first as the gauge only shows discharge, but I've had no problem with mine.

Does anyone do an exchange ammeter that actually measures +/- 60 amps but shows this on

the standard +/- 30 amps scale?

That would be perfect.

If you're running a non-standard exhaust manifold, either wrap it with thermo stuff, or heat

sheild the alterntor as it's easy to cook the alterntor.

Does anyone make a heat shield or is it something you have to make up yourself?

[w_eden]

Does anyone do an exchange ammeter that actually measures +/- 60 amps but shows this on

the standard +/- 30 amps scale?

That would be perfect.

 

Does anyone make a heat shield or is it something you have to make up yourself?

 

To get +/- 60 from the 30A range you need to add a shunt across the ammeter terminals of comparable resistance to the ammeter itself. A piece of wire should do it. The ammeter will not be particularly accurate, but charge or discharge will show - as will abnormal operation. However, do realise that the original wiring to and from the ammeter is not rated for carrying 60A and some suitably rated wire should be run to replace it, or in parallel.

 

You can make a heat shield up fairly simply with a bent piece of thin steel or aluminium - attach it under a manifold stud nut.

[MikeF]

To get +/- 60 from the 30A range you need to add a shunt across the ammeter terminals of comparable resistance to the ammeter itself. A piece of wire should do it. The ammeter will not be particularly accurate, but charge or discharge will show - as will abnormal operation. However, do realise that the original wiring to and from the ammeter is not rated for carrying 60A and some suitably rated wire should be run to replace it, or in parallel.

 

You can make a heat shield up fairly simply with a bent piece of thin steel or aluminium - attach it under a manifold stud nut.

 

I did buy a 60 amp meter to use in my conversion, but didn't use it as has a shrouded needle so does not match the dials on my early 4, so thay are around.

I madeup a heatshield easily enough, and if I can anyone can

BTW. I followed a tip I picked up here or on register CD and lined it with the heat proof cloth you can get in the DIY sheds for protecting surfaces when soldering. I left it slightly oversize on the bottom edge and fixed it with a few pop rivets and large repair washers.

[Robin Powell]

Have a look at this web site http://www.s-v-c.co.uk/ under "other products" and you will see a 50-0-50 ammeter that looks like the TR4A 30-0-30 ammeter. I used one when rewiring my 4A to take an ACR18 alternator conversion. I wired an additional thick wire to the input and output of the ammeter to take the extra current.

[TR 2100]

Have a look at this web site http://www.s-v-c.co.uk/ under "other products" and you will see a 50-0-50 ammeter that looks like the TR4A 30-0-30 ammeter.

Hi Robin,

Thanks for the link.

I'll check out the possibility of combining the gubbins of the 50/50 ammeter with the casing and dial

of my (full face) 30/30. Just enough time to have the wiring amendments incorporated into the loom.

AlanR

[tr4af]

To get +/- 60 from the 30A range you need to add a shunt across the ammeter terminals of comparable resistance to the ammeter itself. A piece of wire should do it. The ammeter will not be particularly accurate, but charge or discharge will show - as will abnormal operation. However, do realise that the original wiring to and from the ammeter is not rated for carrying 60A and some suitably rated wire should be run to replace it, or in parallel.

 

You can make a heat shield up fairly simply with a bent piece of thin steel or aluminium - attach it under a manifold stud nut.

 

 

re ammeter: why would the original ammeter only show discharge whereas the bypassed also would indicate charge ?

i left the original instrument in place, the needle stays at 0 at all times unless lights or other energy consumtion activated, then it goes to minus something.

maybe you have an explanation for an electro-amateur ?

thanks

[ianc]

Beware putting "a really big" alternator in your TR. The wiring was sized for about 25-30 amps, and if you put an alternator rated at, say, 70 amps in place of your dynamo or more modest alternator, you risk setting fire to your pride and joy! If you really need that sort of output, then you need to consider the wires which will be carrying the extra current and uprate them accordingly. You can do this either by running extra cable in parallel on the relevant routes or by replacing those runs with heavier duty cable. Might be worth considering extra fusing, too, as the standard arrangements are pretty pathetic (two fuses in a TR2/3/4). If you are feeding, for example, a number of powerful head and spot lamps, it is worth running busbars (one being the positive feed, the other being an "earth" return, as relying on the bodywork is inadequate when the loads are large) to the front of the car and then supplying each lamp from the positive busbar through a relay and a fuse. That way, you will deliver as many volts as possible to each lamp and if you should get a short, you should blow only one fuse but still keep everything else running. The Works TR4s had separate fuses for each of the four headlamp filaments and yet more fuses for the spotlamps and all the other stuff - a total of 16 fuses in all.

My article from the early 90s, which is on the Technicalities CD, details how to carry out the conversion from dynamo to alternator - it is not difficult!

Ian Cornish (yes, I am a Chartered Electrical Engineer!)

[BrianC]

Ian,

What would the busbars actually consist of? Would insulated battery cable or jump leads be OK?

(I am definitely NOT a Chartered - or even unchartered - Electrical Engineer and only just scraped through O-level Physics at the second attempt )

Edited June 7, 2007 by BrianC

[Ade-TR4]

Hi

 

A TR6 alternator is incorrectly handed. You'll need an alternator for the correct side of the engine.

 

Search on the forum for previous posts - it's quite easy really.

 

Cheers

Ade

[jonlar]

What would the busbars actually consist of? Would insulated battery cable or jump leads be OK?

 

Hi Brian, no, nothing quite as heavy as that, 42A cable should be heavy enough but it's better to be too heavy than light especially when bundled with other cables. The current is unlikely to be much in excess of 25A, except for very short periods of time after cranking, available by the metre from

 

http://www.vehicle-wiring-products.co.uk/V...les.html#gen534 product nos. Ref 84 (42A), 97 (50A), 120 (60A), 80 (70A) the Ref Nos. correspond to number of strands of copper wire.

 

Battery cable and jump leads are generally much less flexible, have many fewer (but coarser) wires, these will flex and breakdown over a period of time, some of the cheaper ones are made of copper plated aluminium.

Edited June 7, 2007 by jonlar

[ianc]

Jonlar has the right idea, but you need to size for the load. If you hang 5 spots onto the front in addition to your headlamps, and put 100 watt bulbs in each, you could be burning 700 watts at the front alone! That is 58 amps, and things would get a bit warm if 40 amp cable were used. The simple rule is: decide what you want to install, calculate the load (watts), divide by 12 (volts) and you have the current. Choose cabling to suit, remembering that, for example, two 25 amp cables in parallel will carry 50 amps and will be more flexible than a single 50 amp cable. Use copper, not aluminium - it's the better conductor (and one can solder to it).

Ian