Changing from Dynamo to Alternator

[boggie]

Hi All,

 

The bearings on my dynamo are shot. Rather than reconditioning or sourcing a replacement I would rather change to an alternator and -ve earth. How easy is this to do and what components do I need?

 

Thanks, Ian

[Alec Pringle]

Hi Ian,

 

You need an alternator ! Try the search facility, you'll find some detailed stuff on changing polarity. It's no problem.

 

Cheers,

 

Alec

[Louis Metelko]

Bearing in front with bushing in rear would be about 10 / 20 Quid with start to finish job not over a good afternoon. Hardly worth the trouble to change to an alternator.

 

Lou Metelko

Auburn, Indiana

USA

[ianc]

Look at my article in Section J4 of the Technicalities CD, commencing at page J23 - this describes the whole process in great detail. There are many and smaller alternators available now, and even alternators hiding inside dynamo casings for those who insist on an original look! Be aware that your wiring loom was constructed for the sort of current likely to be taken by a car with a dynamo supplying lights and perhaps a couple of spotlamps - if you fit a 65 amp alternator and hang lots of ancillary devices on your system, you might overload your cables. In such cases, it is wise to double up the wiring in the critical areas.

 

At the same time as you swap toan alternator, I would suggest you make the change to a narrow, internally notched, drive belt - this necessitates a change of pulley on the crankshaft, water pump and alternator. You will find there's a lot more space at the front of the engine with a narrow belt and changing the belt is so much easier. Don't forget to buy two belts, the second to go in your boot as a spare.

Ian Cornish

[ianc]

I notice that this is the TR2/3 section of the Forum and that I forgot to mention that you MUST change to negative earth on a dynamo before then making a change to an alternator. The polarity change procedure is covered in Section J of the CD and elsewhere.

Ian Cornish

[jean]

In addition to the valuable advises I would suggest to fit a heat shield between alternator and manifold as the diodes in the rear of the alternator don't tolerate too much heat

[angelfj]

Bearing in front with bushing in rear would be about 10 / 20 Quid with start to finish job not over a good afternoon. Hardly worth the trouble to change to an alternator.

 

Lou Metelko

Auburn, Indiana

USA

 

I agree with Lou, this is a very straight forward repair and will probably give you another 40 - 50 years of service!

[boggie]

OK, fair point. For now, with so many other things on my plate, maybe a bearing change is the way to go. I can always fit an alternator at a later stage. Can anyone point me in the direction of a bearing supplier please?

 

Thanks, Ian

[Nick Webster]

OK, fair point. For now, with so many other things on my plate, maybe a bearing change is the way to go. I can always fit an alternator at a later stage. Can anyone point me in the direction of a bearing supplier please?

 

Thanks, Ian

 

Depending on whether the dynamo is the original one, the front bearing will likely be held in by a plate which is fastened in place by four hollow aluminium rivets. These are sacrificed in the bearing change, so really you need to find a proper Lucas agent (of which there are many) to get the proper rivets for you. You might even be able to get bearing and rivets in a kit. It may sound a bit daunting, but it really is a piece of cake to change the bearing. Drill the spread end of the old rivets so you can push them out and just spread the new ones using a small hammer and a centre punch.

 

Incidentally, shot bearings are nearly always an indication that the fan belt is too tight, so have a twizzle at the water pump while the belt is off for the dynamo, just in case that is rough too. It really is quite surprising how loose you can run that thick belt and still drive the auxiliaries more than adequately.

 

Nick

[Richardtr3a]

Try Classic and Vintage Dynamos Shirebrook Business Centre, Vernon Court, Shirebrook, Nottingham NG20 8SP 01623 747666

 

They supplied me with a very well rebuilt unit and we have had 30.000 miles without trouble. A loose fan belt is a must and occasional drops of oil help.

 

Good luck Richard

[boggie]

Thanks all - I will give Classic and Vintage a ring.

 

The fan belt is already very lose, possibly to take the pressure off the failing bearing but it 'aint half noisy. I thought the engine noise on the test drive was the rocker gear but it is definately coming from the front of the engine, doesn't sound like a cam chain and I can feel play in the dynamo front bearing. I guess the acid test will be to remove the belt an run the engine for a few seconds to see it the noise stops.

 

Cheers, Ian

[vivdownunder]

Hi Ian,

 

It's best to strip the old front bearing out before you order the new parts, as sometimes a worn bearing will start spinning in the housing. Obviously then the fit is too loose to grip a new bearing, and a new front plate will be needed.

 

While you have the generator apart, it's good to clean away all the copper dust from the brushes. A small paint brush does the trick.

 

Just another thing to check is that the thread is OK inside the pedestal that takes the generator front mount bolt. Occasionally the internal thread is stripped so badly that you can never properly tighten the generator. Any loose mounting at the front then can lead to snapping the rear flange off the engine mount bracket.

 

The bolts that hold the mount bracket to the engine are tapped right through the block, and being coarse threads, they eventually leak oil. Another job you can do is remove these bolts and return them with gasket cement or the like to seal them.

 

Just a few things so you don't have to revisit the same area later on.

 

Regards,

 

Viv.

[ianc]

Viv has mentioned sealing the threads on the bracket bolts to prevent leakage of oil from the engine. To ensure that these bolts do not become loose and fall out (happened on my brother's TR3, and an amazing amount of oil gets out as the holes are straight into the crankcase!), drill the head of each and wire them together.

The heat shield (mentioned above by another correspondent) is a very good idea. Can be made out of thin sheet metal, such as an old biscuit tin.

Ian Cornish

[Alec Pringle]

Hi Ian,

 

this may be of interest, dynamo on ebay item no. 200215620158

 

Cheers,

 

Alec

[boggie]

Thanks All,

 

Good advice, yet again!

 

Alex: This is listed as a TR4 dynamo, I assume it is the same design as the TR3a as they share the same engine?

 

Thanks, Ian

[Alec Pringle]

Hi Ian,

 

2,3,4,4A share the same dynamo but the terminals can differ - it's hardly a drama to change the spade connectors or whatever if needs be.

 

The unit on ebay I mentioned isn't that cheap, but I've found QH rotating electrics to be more reliable than some of the reconditioned units available elsewhere - hence my mentioning it.

 

Cheers,

 

Alec

[Dick]

I should check that the water pump pully is not loose on it's shaft.

 

Mine loosened off once and made an awful row.

 

Two of the best mods I made to my car was converting to an alternator and fitting one of those new starter motors.

 

I'd go for an alternator over a dynamo any day.

 

To connect the alternator I disconnected the copper bars under the regulator and re-soldered them to different terminals so that I could use it as a connector block......Cheap as it was there and redundant and causes some comments from those who think that I have an alternator with a regulator......

 

Dick.