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Alternator choices for TR4


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My 4 has an alternator of indeterminate age (small belt kit). I'm looking to source a good quality fresh unit (and then carry the old one as a spare for endurance rallying - at least on the longer events).

Not actually sure what type/spec and pulley size I currently have fitted as the car is elsewhere right now.

What's the gen on the best quality/reliable units available? Rating: about 55 amps would be optimal for what I want to do with the car.

Grateful for any well-informed advice.

Nigel

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I used a compact 40amp from these guy on recommendation from the forum. 
I am sure you can find a higher rated one for your application

https://brise.co.uk/product-category/alternators/?v=79cba1185463

 

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Nigel

Denso make an 80 amp version, with spade connectors and a small 70mm pulled already peened on. I use these. Anything over 60 amp rating is sufficient. The 40 amp version won’t cope with lights, spots, heater, wiper etc all on at once. 

if you’re looking on the internet, make sure you buy an OE unit with ND embossed in the rear heat casing - the pattern units don’t tend to last long.

regards

Tony 

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Not all alternators have the same connections / connectors. If you want to use your old one as a spare, then you need to choose one with matching connections.

Bob

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Hi Nigel

Sounds like you have a Lucas TR6 conversion kit, pretty straight forward stuff and you probably need to replace like for like as, if you intend to carry the spare, you need to be able to use the same belt/ pully and connector block for your existing loom. Whilst I have replaced mine a couple of times due to the exhaust cooking the electrics, I'm not sure I'd carry one (we don't even on the Ten Countries) Providing the ignition light hasn't started to flicker you're normally OK for 2000 miles 

However, like Hamish, I have walked away from Lucas last year and fitted a lightweight compact 'racing' alternator rated at 40amps. Needs a different arm and, in my case, a longer belt, different connector etc. Further away from the exhaust heat and better made, I'm hope it's the long term fix and it's my recommendation. 

NB. My old Lucas was 65 amps, however, the new 40amp carries the load no problem, back from France last year in the rain, at night,  everything on, lights, wipers etc Newhaven to N. London, two hours +

20200806_152021_resized.jpg

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Excellent, many thanks chaps. I know I will definitely want more than 40 amps as on occasional night events I have found myself using all my lighting set including twin-element driving lamps/fogs... inevitably in the chucking rain! 55/60 amps is probably sufficient but Tony's suggestion of an 80 amp Denso might be the one. I'll have my hands on the car again this weekend so will check out pulleys and connectors.

(Mike you're of course right that you usually get some warning, however in January (in a different 1960s car) my alternator went from good to complete failure within half a mile (in the dark, pouring rain of course!). No doubt that was a voltage regulator gubbins issue rather than the generator itself but anyway I was fortunate to be carrying a spare. They are heavy buggers to be carting around of course!)

Quality intel as usual, thanks all.

Nigel

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Hi Nigel,

rather than worry too much about alternator power why not reduce your current needs - fit LED head lights ad you've saved nearly 10 amps at a stroke.

As you will have a spare in the boot why not buy the same as you have - you know it will fit and work.

And YES -they can die suddenly.

I have a Powerlite 60amp that has worked forever.I don;t need all those amps as I have LED lights.

 

Roger

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1 minute ago, RogerH said:

rather than worry too much about alternator power why not reduce your current needs - fit LED head lights ad you've saved nearly 10 amps at a stroke.

Good point Roger, however LED headlights/aux lamps not allowed in historic rallying unfortunately. (You can use them for sides, indicators etc). 

Nigel

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Nigel

There are a couple of other things to think about here.
 

Firstly the higher the rating, the shorter the life of the alternator in my experience so it’s a bit of a trade off - I’ve used most of the various ‘compact’ DENSO units and if you can live with it a 50 to 60 amp unit will give you a good 3 to 5 years depending on the treatment in the engine bay (repeated exposure to heat and water basically cook the diode set). They are also a lot easier to get hold of and the genuine ND stamped units are available in the UK. You can also buy a diode set to carry as a spare and if you use the one with the small pulley and modify the standard dynamo attachment arrangement on the engine block to suit,  the fan belt is the same as a Mk2 VW Golf so you can get them anywhere in a hurry.

Secondly, the bulb type as Roger says is relevant. We can’t use LED but we can use high efficiency bulbs such as the PIAA units which draw less current than most of the cheaper bulbs. They also seems brighter to me, so it’s a double win. Relaying helps with a voltage drop so they work better and are brighter as a result.

Thirdly, if you have a tired DR3a wiper motor or heater motor they do tend to draw more current and usually if it’s cold and wet these are both on, taking a good load themselves. A TR6 / Land Rover type wiper motor works better and is more efficient but needs to be wired differently. Similarly, getting rid of the old Smiths heater motor for something modern does a better job.

Lastly, a heated front screen drains a lot of current and to my mind is probably not worth the trouble. It’s great in snow and iced weather and at night, but if the heater and airflow is better and you run with the windows half down like I do mostly unless it’s pouring down, you don’t need to use it when the wheels are turning and the car has warmed up.

Its also worth noting that in the TR4 the first you seem to know about a failure is the red ignition light eventually coming on showing that the alternator is under charging / no charging. That’s fine. It’s much worse when it’s overcharging, which is in my experience how they actually tend to fail. This cooks the battery and if you are using a dry cell the battery expands dramatically in a short time and will explode. You might be lucky and the tripmeter and clock start to go crazy as the voltage spikes - this is how I spotted the last failure I had and it was only a minute of so before the battery started smoking and looked like it had been fat boothed. By the time I’d gingerly removed it all, both the battery and alternator were scrap. I’d suggest that you need to run a good voltmeter or a larger Ammeter and be familiar with what it’s saying. At least that way you get a little more notice of a failure and have a chance to fix it with what you can carry.

regards

Tony 

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Hi Nigel,

I have fitted both the TR6 14W wiper motor (slightly lower amps)  and the Spal 5.5 rad fan to the heater box (slightly less amps again)                                        read the attached

Both significant improvements.

Roger

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  • 2 weeks later...

Ironic/demonstrative follow-up to my original post two weeks ago...

On the Three Castles Trial this week, in the Welsh rain, my alternator started giving up. First warning was ammeter swinging jauntily, an hour or so later the battery was almost drained.

And I wasn't carrying a spare. Fortunately the event support team did have one (new in box). But when we put it on the car at the MTC, it was duff. Exactly same happened to another competitor, in a TR6. Extremely fortunately, the support guys managed to find functioning spares for both of us overnight.

It highlights how many absolutely cr@p alternators there are on the market.

Nigel

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8 hours ago, Andy Moltu said:

The location of the alternator on the 4 pots is also a factor in their failure.

Heat and vibration expose the crappy alternators.

Yes I'm going to have a heat shield when the replacement (actually, the replacement for the replacement for the replacement!) alternator goes on. Lots on the forum about that over many years, I'm persuaded it's worthwhile as something made from the 'waffle' ally sheet isn't going to add significant weight.

Nigel

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On 6/1/2022 at 9:44 AM, RogerH said:

Hi Nigel,

rather than worry too much about alternator power why not reduce your current needs - fit LED head lights ad you've saved nearly 10 amps at a stroke.

As you will have a spare in the boot why not buy the same as you have - you know it will fit and work.

And YES -they can die suddenly.

I have a Powerlite 60amp that has worked forever.I don;t need all those amps as I have LED lights.

 

Roger

Hi Roger, is this the one you have used, it states as a replacement for the Lucas LR100

https://www.gsparkplug.com/dynamos-starters/alternators/alternator-prestolite-20130142-replaces-lra100-lra102-lra103-lra106-lra226-12v.html

Rgds

David

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I recall asking a similar query on the forum many years ago and have found it (here)   On Tony's recommendation I eventually bought a Nippon Denso unit from someone but it originated with Bastuck and I believe its their E310Comp 40 Amp alternator.   I've had no problems with it so far, though my car is reasonably standard in terms of the engine and exhaust system, and I use the normal radiator shroud and have an electric fan.  

Paul

Just to add, I didn't fit a heat shield but many do.  A quick search reveals that there's 169 posts discussing alternator heat shields so plenty of views and suggestions to look at if needed.

Paul

Edited by PaulAnderson
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The location of the alternator does risk them being cooked as well as the impact of the 4 pots inherent vibrations does expose some poorer quality alternators.

Folk say the Nippon-Denso as fitted to one of the Nissan Micras is a good option but beware copies.

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So after a bit of consideration of the advice above, I have replaced my Lucas LR101 like for like; the ignition warning light was staying illuminated and the alternator wasn't charging; I have fitted a heat shield and placed the alternator wiring in some convoluted tubing wrapped with metal reflective tape. I discovered something I didn't know that the left or right hand alternator description doesn't refer to the side of the engine it is fitted, but the side to which the top bracket attaches, so for the 4a you need a LH model-confusing! I might in the future convert to a Nippon Denso alternator, but it wasn't clear from reading many posts both on here and sister sites in N America, exactly what work is required to fit and connect these alternatives. So in the interests of trying to get the car back on the road asap, I went for the path of least resistance - see how long this lasts!!

I found this helpful link on alternator troubleshooting for ref

https://images.borgautomotive.com/lucas/_supplementary/alternators/troubleshoot_alts.pdf 

Regards

David

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