Lotus Elan and Lotus Elan Plus 2 Forums

Just wanted to post my experience with fitting a nippon denso alternator.

Denso alternator 101211-1032 12 V 40 Amps.
Ford Pinto edge alternator tensioning bracket
Original dynamo bracket. Front hole enlarged to take M10 bolt.
1 x M10 bolt and nut.
1 x M8 set screw for the tensioning bracket (alternator end).
1 x 1/2 UNF bolt for fitting to the timing case front cover.

I fitted the alternator to the front face of the dynamo bracket. This lines up well for the belt. The pinto bracket was fitted to the rear of the timing case (there was already a vertical bracket and spacer there from the Lucas alternator fitment). The outboard end of the bracket clears the chassis but is very close to the body flange (about 1-2mm clearance).

Since taking the photos I have fitted a terminal boot over the output cable. Just waiting for a plug for the ignition
light.



I hope it’s of some use to folks. I must tip my hat to the guys who have done this before.

I have a similar one on my Plus 2. Doesn't charge super well at idle with a bit of load (cooling fan, headlights) according to the volt gauge, but works fine once over ~1500rpm. So little compared to the old Lucas AR17 type, and not that much lower in output.

Pete

Thank you for your very complete notes. These are most useful.

I'm all in favour of using economical parts from contemporary single seater manufacturers (John Deere, Kubota, New Holland...).

Several questions if I may...

- would it make sense to use a shorter fan belt for LHD cars using this alternator ?
- what is the real life length (without the pulley) / approximate diameter of the model ?
- area the mountings are 180° north/south ?
- does it really weigh 3.2 kg (7lb) ?
- I note the comment on power at idle. Is there a "rev limit" on this alternator (will the bearings go if it is used for race use ?)


Andrew

Many thanks!

thank you for your detailed post, useful to anyone considering a conversion.

I also would be interested in the confirmation of the weight when convenient, I've stuck with ACR17 for now which are a bit more period, but do not add much lightness that in turn induces stress on the brackets).

What would be the stock pulley dimension (shaft diameter and fastening method)?

Hi Pete,

Good to hear from you !

I'm interested to hear why you fitted the Denso alternator, I don't know anything about these.

I've never had any problems with my Lucas (apart from forgetting to reconnect the wiring after an engine out, and having EVERYTHING die in the middle lane of the M50 in heavy evening traffic ! )

Sean

I them on both the S2 and The Plus2. They are small and light and bullet proof. Used them on the former race car that saw 9000 rpm in each gear. Never had a failure. I use the one that came from a GM Metro Geo and a Suzuki Swift. Over kill at 55 amps.

Thanks for the replies. Thanks also to Rob. I think it was your conversion that had the ford pinto bracket. Sean, likewise. My Lucas alternator’s regulator is duff. I took the opportunity to change over. I’m going to get it looked at by Noel Carey up in Kilmacanoge (for those not familiar, it’s literally pronounced - kill mechanic!). I’ve used him before to rebuild a starter motor and he did an excellent job. I hope all is well with you.

As for the weight, it feels quite abit lighter than the Lucas unit. The diameter is smaller too. Let me get a ruler out and check. I shall return with the results. I’m not a racer so don’t mind about the upper rev limits too much! Sorry! The upper mounting hole is about 15mm deep and is tapped for an M8 set screw. I saw that someone, perhaps Rob again, using a rubber isolation mounting so that it will line up with a bracket mounted on the front face of the timing chest. The belt is the stock one.

Whilst researching the possibilities I noted that the lower mount is far thicker on the 24v ones. The 12v one is about 20-30mm thick. I suspect that the rdent alternator kit uses the internals of the 12v model in the 24v case. I’m only going by the photos online. They are parallel to the body of the alternator. The only thing I had to drill was the front dynamo bracket hole to accept the M10 bolt.

I shall check the pulley dimension but it’s secured by a nut with a smaller hex head on the shaft.

I liked the fact that these alternators have a great reputation and they were fitted in many, many cars, tractors and lawnmowers. The agricultural ones seem to have the v pulley as standard. I got mine for £80 off eBay. The bracket is available new from Burton power for £15. You could go to a scrappies and pull one from a Toyota, Suzuki etc.

I fitted one that looks pretty much exactly the same. I removed a ACR17 that wasn't charging at idle.

Mine was a rebuilt unit from DBElectrical(?) via amazon.

I measured the ACR17 (+ bracket i think at) ~7.5lb. The new one with new bracket was 3~3.5lb from memory. So ~3lb saving.

I made up the lower bracket from some 1/4" * 1/2" steel which picks up each side of the lower mount. The smaller alternator doesn't fit the (heavy) ACR17 bracket.

It does charge (no light) at idle but dash gauge register ~12v or just above, it picks up with a few revs. At some point I'll measure the output. I think I've looked for a small diameter pully for it and maybe found one or two slightly smaller but not actually investigated further.

The other thing worth mentioning is that mine needed a switched live to power it's regulator. So I had to run a new wire to the alternator.

Good point mbell! I’m awaiting the proper plug before I wire up the rest.

Thanks.

The real reason one puts a higher power alternator in a car is not so much the peak number[It is rare one uses 120 amps] but the idle number is a percentage of peak. One hates to have dimming headlights and such


I would consider using the slightly larger series of Denso alternator that is rated at 55 amps, I don't think they have idle charging issues.

I put a larger alternator than that in to power a larger stereo and it will charge an indicated 20 amps at idle. I changed to a 60 amp 'amp' gauge because it could cause the needle to disappear

Gus,

I agree that a larger capacity would not be a problem but...it would be a good idea to double check on the cable capacity and probably change this as a wise precautionary measure (I am not an auto electrician).

From what I could see on this subject, even an alternator of say 90 Ah would be fine to avoid dim headlights. For endurance racing (spots, headlamps, wipers etc), this would give a more confortable margin with a small weight penalty (about 300g I believe) for extra reliability.

Andrew

As mine is a rebuilt unit it came with a test plot showing rpm v output up to ~55A output. In theory I could do some maths to work out relative rpm and see what the output is at idle, but I don't care enough to do that.

I also connected mine using a fuseable link, but that is more protecting the car from an alternator short than the car from to high output from the alternator.

Nice writeup. Nippon Denso is a solid choice.

The other thing I like about the Nippon alternator in the USA is that its likely a lot easier to find than a ACR17.

If you happen to have failure while on the road in rural usa, its unlikely a rural local parts place will carry a acr17. However due to their very common use in agriculture vehicles it very likely you be able to pick one up of the nippon ones from a tractor parts suppliers that are pretty common in most towns.

mbell wrote:The other thing I like about the Nippon alternator in the USA is that its likely a lot easier to find than a ACR17.

If you happen to have failure while on the road in rural usa, its unlikely a rural local parts place will carry a acr17. However due to their very common use in agriculture vehicles it very likely you be able to pick one up of the nippon ones from a tractor parts suppliers that are pretty common in most towns.

+1 I must admit you have a good point there. Having been stuck on the North Circular in London during Friday night rush hour ( year 1982 approx). The only place i found with a new Generator only had a "C40" and not a "C40L" so i had to shim with washers on back Pivot. What had happened the Oillite Bush at back had decided to return to dust. It was a real nightmare.
Alan