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rcreweread

Ammeters and Alternator Upgrades

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I'm thinking of upgrading the dynamo on my 1962 TR4 ( converted to negative earth ) to a Stealth Dynamotor - a 45 amp alternator which looks like a dynamo. I'm carrying out a narrow belt conversion at the same time.

 

Will this "cook" my 30 amp ammeter and if so, can I get a larger amperage ammeter? If not, can I just connect the two large ammeter wires together behind the dash so appearances remain same.

 

Alternatively, I'm aware some people fit a voltmeter instead - can I get one of these similar in style to the other instruments so it doesn't stick out like a sore thumb?

 

Any help much appreciated

 

cheers

 

Rich

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Hi Rich,

if you wire the ammeter and alternator such that only charging current is going through the ammeter then you should have no problem.

The battery will take apprx 25amps max for a few moments after start up. After that there will be a few amps floating around.

 

The alternator will only give what is requested of it. So unless you have all the lights, heater, rad fan, wipers and radio on you should be fine.

 

You could link the brown wires at the ammeter but for why!!!

 

There is a voltmeter that looks the buisness bit can't remember who/what//where.

 

Roger

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The advice on this, when I was doing mine, was to bypass a lot of the current past the ammeter.

When I did this I found the thing didn't tell me what was going on.

I ended up wiring mine the same way as when it had a dynamo.

I have had no problems yet. But if I let the battery get flat the needle disappears out of sight for a while during startup and then comes back into the world again.

Edited by littlejim

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Thanks everyone - it doesn't look like I need to change it which is great and makes a change!

 

By the way, I got a great deal from Accuspark on this Dynamotor - £100 plus p&p ( Normally £125) - a lot of these are selling for £300-400+!

 

Cheers Rich

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I've just fitted a Smiths Voltmeter from a Scimitar GTE

It gives rock steady readings and is completely period - you can swap the chrome bezel from your ammeter to ensure a complete match

I put a search on EBay & paid a tenner - they crop up from time to time

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=161013577459&ssPageName=ADME:L:OC:GB:3160

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Don't forget that you will need to reverse the connections to the ammeter and also to the coil (but better to fit a modern coil made specifically for negative earth).

If the coil connections are not reversed, the engine is unlikely to perform well as the spark at the plug will be trying to jump in the wrong direction, thereby reducing efficiency and possibly causing misfiring.

 

45 amps is not a huge rating and, as has been stated above, only very infrequently are you likely to hit maximum and put the ammeter off-scale for a short period. I have an alternator rated at 34 amps, and I have never seen the ammeter read more than about 28, and that for a very short while.

 

Ian Cornish

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Did you think about converting (changing) the voltage stabilizer too?

 

Badfrog

Edited by Badfrog

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Hi Badfrog - apparently I don't need to change the regulator - I can leave it in situ to maintain originality as far as possible - there is a wiring diagram which comes with the kit ( don't ask me to put it on here as I don't know how! ) and basically it says you disconnect the cable going to the D terminal on the regulator (from the D+ terminal of the dynamo ) and connect it to the A terminal of the regulator, and you remove the cable from the F terminal of regulator and connect it direct to the cable to the "charge" warning light, having disconnected it from the D terminal as well. - You should end up with no cables on the F and D terminals of the regulator.

 

Hope this helps and makes sense - I haven't installed the kit yet so I'm not speaking from experience.

 

cheers

 

Rich

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That's it. The regulator becomes a connection point only. It serves no other purpose. I hid the cross connections inside the box on mine.

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Rich,

 

You got me wrong. I'm talking about the voltage stabilizer (VS) for water temp and fuel gauge. It's a diode. So if you invert polarity, you blow it. You need a negative polarity VS. Plenty of these on EBay, either classic make from Stags and MGs or solid state.

 

http://www.ebay.co.uk/sch/i.html?_trksid=p3984.m570.l1313.TR0.TRC0.Xtriumph+voltage+stabilizer&_nkw=triumph+voltage+stabilizer&_sacat=0&_from=R40

 

Badfrog

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Rich,

 

You got me wrong. I'm talking about the voltage stabilizer (VS) for water temp and fuel gauge. It's a diode. So if you invert polarity, you blow it. You need a negative polarity VS. Plenty of these on EBay, either classic make from Stags and MGs or solid state.

 

http://www.ebay.co.uk/sch/i.html?_trksid=p3984.m570.l1313.TR0.TRC0.Xtriumph+voltage+stabilizer&_nkw=triumph+voltage+stabilizer&_sacat=0&_from=R40

 

Badfrog

If its an original one then they arent polarity sensitive.

Stuart.

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Guys - thanks for all your inputs - it's great to know there is so much knowledge and experience out there.

 

I didn't know about the polarity issue on the VS's but haven't had a problem as it's an original one - fortunate from my point of view!

 

cheers

 

Rich

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Then, if it's an original '62 TR4 VS, it's now dead, lets out 12V instead of 10V and the gauges show wrong figures (in excess).

 

Badfrog

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Hi JF,

you silly french type person. :P

The Voltage stabilser of the original TRiumph TR4/4A variety use a bimetal contact switch with a combined heater.

When You turn on the electrics the heater heats the bimetal switch and it eventually pops open cutting the heater current.

where upon it cools and remakes its contact. To start all over again.

This should't be polarity sensitve as mentioned by Stuart.

This on/off chaos gives a sort of average 10V - actually very clever in the days when semi-conductors were part time clippies.

 

The modern variety as you say uses a diode of the Zenner styling. This polarity sensitive - it may not blow but it won;t work either.

 

Roger

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The modern variety as you say uses a diode of the Zenner styling.

 

 

Is that part of the Bauhaus movement in modern architecture?

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Hi JF,

you silly french type person. :P

Roger

 

 

Love it... :lol: ...(no disrespect meant JF).

 

Tony

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Roger, you nasty Redcoat ....

 

I acknowledge your remark. Indeed, this is getting really interesting as the tech info I had from various sources overhere called the stabiliser a "thyristor-based" circuit (means a diode in there somewhere).

Lady Anne ('63 TR4) had its original VS, which underwent pure neglect during my negative earth conversion. As a result, both gauges were wrong by excess and I assumed it was caused by the 12V current going thru the burnt diode unhampered.

 

So it seems I was oversimplifying and we have a thermal-based unit, a thyristor-based one, and then the modern solid-state repros. I'd like to know for the first two which is which, with ref. numbers and car applications. Can anybody help?

 

Badfrog

 

PS: The Zenner diodes were also used for psychic communication in some uncanny russian subs during the cold war. Didn't work either.

Edited by Badfrog

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If anyone wants the modified wiring connections diagram to the voltage regulator then please PM me your eMail address.

 

Tom.

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BadFrog,bring both VS to Malvern and we'll explain all at about 2am Sunday Morning,should make better sense about that Time :P .

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As Stuart says, the original VS is a bimetallic version and is not polarised.

Semiconductor versions use Zener diodes (and probably a MOSFET or power transistor), but I would be very surprised to have a Thyristor based stabiliser in a TR, these are more associated with heavy duty AC circuits.

 

Semiconductor versions, as Roger states, are polarised.

 

Good luck

 

TT

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Blimey guys, I thought I should read this thread as Richard is in my Group. All I can say is that it's a good job he didn't present me with his query. But hey, it looks like you've sorted him, the very best use of the forum.

 

By brain is overheating so I'm off for a lay down.

 

Cheers

Allan

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Just finished my alternatopr/narrow belt conversion:

 

Swap Ammeter connections over.

Original wiring can cope with about 30-40amps for a short burst but anything more and/or for longer will fry your wiring.[Example being a flat battery or starter motor jammed on causing huge current demand.]. Hence why an alternator with a huge rating isn't necessary. Downside of original ammeter is that it baerly registers any activity! Votlmeter could be used to replace ammeter or placed in line in the engine bay for instance!

 

Original VS is fine - no damage and no excess readings to fuel/temp gauge. Modern or thyristor diode - will be damaged.

 

Any auxilliary components such as radio etc need to be changed for -ve earth. Wipers OK.

 

I have instructions and wiring diagrams and pics of control box terminals if needed.

 

Use a heat shield to protect your new alternator rear end from frying.

 

[The good news about a narrow belt conversion is that you can now change the fan belt at the side of the road faster than the car's 0-60 speed!!!].

 

Enjoy.

 

WT

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Wayne - and did you swap your coil connections? (See my post #7 on the first page of this topic)

Ian Cornish

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