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Discussion Starter · #1 ·
As most know, the Mondial has

As most know, the Mondial has had a reputation of having weird electrical things. And, as has been documented, often time the weird behaviors start mysteriously, and then are mysteriously cured by a new battery or fresh charge, even with a working charge system.
Here is the history of Mondial alternators and batteries:

M8: Bosch 65A alternator and 66Ah battery
QV: Bosch 80A alternator and 66 Ah battery
3.2: Bosch 85A alternator and 66 Ah battery
t: Delco 105A alternator and 66-70 Ah battery (same as 348)

reference example:
911 3.2: 92A alternator and 66Ah battery
911 3.4: 115A alternator and 72 Ah battery
So, what I think may be happening is a circuit load/battery/alternator mismatch. The electrical load is NOT that different between Mondials, and notice they kept going up every year while the real 'requirement' was about the same; Also, the drive train was engineered for the 2 seat 308/328 as well, with a bit lessor load potential Especially if a more powerful battery and/or stereo amplifier is installed, it may accentuate the condition.

Ergo, I think a basic solution to some of the Mondials weird electrical behavior may be solved by going to a bigger alternator and/or battery to better meet load requirements.

So, anyone have advice or a suggested a higher output replacement alternator and how to wire it up? I know the alternator is easy to get to through the starboard rear wheelwell.

Many thanks, and happy new year to all!

Discussion Starter · #2 ·
One thing I believe is that wh

One thing I believe is that when the Alts get wet they tend to go south shortly thereafter.

All the later Model Alts you mention are interchangeable up to the Mondial T, which is different.....and one giant source of problems is the Connections at the FUSE BOARD (the 2 Fat Red Wires with the phony rubber coating) , and the Relays under the AC Center Console!

Discussion Starter · #3 ·
Ok, if you're like me, you

Ok, if you're like me, you're wondering exactly why doesn't the alternator that came with my car work right. Most 308/Mondial came stock with the one wire alternator setup. That is, a heavy battery wire and the idiot light wire. This system creates current through the residual magnetism left in the alternator. This means that it has to spin in order for the voltage regulator to turn on. After it's on, it makes voltage until it reaches 12V-14V. It senses this voltage at the unit itself and self regulates based on it's own immediate output of 12-14V. The problem with this alternator is where the voltage regulator gets it's reference voltage to regulate itself, it basically tells itself to keep producing 12V-14V because it senses it's output--

Lost yet? So what's wrong with this system?
The problem is that after you start adding resistence such as lights, power windows, battery charging the voltage begins to drop. A good example is a row of lights...if you hooked up lights in DC series circuit, you would notice that when you look down the string of lights, the first one is much, much brighter than the last one.

This is called "line loss" or "voltage drop" by the time you take a voltage reading down the line from the Alternator you getting 10V instead of 14V which is what you should be reading anywhere in the system. This is because the Alternator is reading 12V from itself before these "resistive loads" and is perfectly happy. This explains why the windows and sunroofs usually move sooooo slow.

What they should have put in is a Three-wire alternator. The significant difference with this alternator is the Voltage Regulator, it requires a remote voltage sensing wire. This wire is also used to "flash" the field so you no longer need that "residual voltage" which means that the speed of the alternator is now insignificant in relation to voltage output.

Let me explain;
Remember when I said the 1-wire kept reading it's own immediate output and continued to regulate that output? Well a three wire requires a wire hooked up to an ignition hot wire, hopefully one that has a low voltage, The perfect wire would be the last wire after all the "resistive loads"

Remember that string of lights I was talking about? It would be like hooking it up to the last light.
These low volt wires are easily found in the outdated fuse box in most mondials/308's. What happens with this magical remote sensing is that the Alternator will sense 10V and adjust the voltage regulator accordingly to ensure that it's remote sensing wire has the required 14V.

Let me explain in easier terms;
1-wire= reads it's own immediate output before any resistance is added to the system, thus causing voltage loss down the line.
3-wire system= uses a remote sensing wire to adjust it's built in voltage regulator in order to maintain 14V throughout the entire electrical system.

So- why did Ferrari put a 1-wire system?
I don't know, why did they put those early style fuse boxes in either.
The way I see it, you can add a bunch of relays to make your system work as it should ensuring that the relays are fed with the 12-14V produced as it enters the fuse box or change the alternator for one that ensures the entire system maintains a proper working voltage. The problem now is none of the current 3-wire systems fit---that is until now.
I'm currently adapting my brackets to accept a 120 Amp Delco/Remy 3-wire alternator instead of my 65 Amp Bosch to my 82 Mondial- If it works I'll post on here the How-to (oh yeah, I guess I should mention it only cost me $85) The alternator is very, very, very close to the exsisting Bosch 0 120 469 537 unit I now have. If it doesn't work I just spent 30 minutes writing this for nothing... wish me luck.

Discussion Starter · #4 ·
If you go for the Delco a

If you go for the Delco alternator and tune it up with HD rectifiers and a 3 wire (sense) regulator, you can let it monitor battery voltage and you will have a fully charged battery in the future.
Went trough this with my T.

The parts are something like 20US$

Discussion Starter · #6 ·
Maybe this helps:


Maybe this helps:

The regulator is available in many different versions.

If you take (or already have) one with a "sense" input and route a thin wire to the battery, it will take the + terminal as a reverence. That’s all.
Maybe you have to get another connector for the alternator and connect it to the cars loom.

In the thread are some links to suppliers with good online catalogues. There you will find something that fits your requirements.

At these pages you find more basic information. They have some special hard to get parts too, even if they are a little expensive. Anyway, the info is great!

Many regulators have the sense input, but don’t use it. You only have to connect it, (maybe, better to fit a fuse near the battery)... yes, that easy!

IMO going for larger alternators is not the best way on a Ferrari!
Large, heavy parts rotating at high speed can create other problems, like broken supports or even worse things…
The 105 ampere of a CS130 should be more than enough, even a 65A unit should do the trick, but only if they reach the battery with the proper voltage.

Larger batteries give a much higher load if they are part empty, as often on our cars. The high charging current plus high rpm plus high engine bay temperatures kill the (often lousy assembled)stock units, that’s my theory.

I use a good 40AH battery on my T and don’t find any problems with it. Why carry a truck battery if you don’t need it?


Discussion Starter · #7 ·
A lot of what you wrote is ver

A lot of what you wrote is very good but your example is incorrect: "A good example is a row of lights...if you hooked up lights in DC series circuit, you would notice that when you look down the string of lights, the first one is much, much brighter than the last one."

If all the bulbs in the row are the same wattage they will all be equal in brightness. Remember the big old Christmas tree lights? They were wired in series (if one burned out the whole string would go dark) and each lit up with the same brightness.

Discussion Starter · #8 ·
Car electrics are wired in par

Car electrics are wired in parralel and not in series. So the resistance of the wire that supplies the voltage indeed lets the last bulb glow dimmer.

Discussion Starter · #9 ·
I am aware that car electrics

I am aware that car electrics are wired in parallel.

Again, if bulbs of equal wattage are wired in series they will all be equally bright. Brightness of ALL bulbs will decrease with each bulb added but all will remain equally bright.

If bulbs of equal wattage are wired in parallel they will be equally bright (full brightness).

IF, the wires to one particular bulb are much, much, much longer than the others you can get a voltage drop that can result in less brightness.

Discussion Starter · #10 ·
this is in fact the prob

this is in fact the problem with older cars. The resistance gets higher.
The Mondial has the battery far away from the alternator and the voltage at the point that the regulator sees is higher than the voltage at the battery + terminal.
So the battery is permanently undercharged, what causes problems.
Newer regulators don’t have the sense input because this is no usual problem!

The temperature compensation of the regulator makes things even worse, as it sees the high engine bay temperature and reduces the voltage even more when hot, while the battery in fact stays pretty cold... some regulators even sense the battery temperature in special applications to compensate for this.

Ferrari did not put one additional wire (only a thin one, as it does not transport current and so has no relevant voltage drop) from the alternator to the battery.

Copper is expensive and Italy is a poor country :)

Ferrari has not taken too much care about things that might happen when the cars get 15 years old!

So today the owner has to sort these problems, even if some see this questionable.

But it is a reality in 2007: In some points we can make these cars better than the Ferrari engineers in 1990 designed them.


Discussion Starter · #11 ·
I was using the "row of li

I was using the "row of lights" as an example. Christmas lights are not actually in series, more like series-paralel I think since there's usually a third wire.

I bought a Delco Alternator for an 85 Cadillac Deville I think, it's almost identicle to the Bosch 0120468537, except it's a three wire 120 amps. The original aluminum bracket that holds the alternator in place has two mounting points. I noticed that Ferrari had a problem with the bracket accepting the alternator and allowing it any adjustment because it looks like they had to grind down the rear mounting point to accept the Bosch alt. I'm posting a picture of it minus the grind job. I had to grind down the front to match the rear because the Delco one, although similar has more "girth" (material) and did not allow adjustment on the belt without grinding the front side a bit. I merely matched the rear as I was concerned about taking away too much material and weakening the hold points. I just ground down the front one to match so that I could actually tilt the alternator on the bolt as a pivot point and have some adjustment on the belt. So far so good.
Have not had time to wire it yet. I also had to adjust how deep the alternator sat in relation to the belt and crank pulley but that was easy enough. I measured the difference with a micrometer 5mm, I made up this distance with 3 washers between the front inside bracket and the alternator. Everything looks good so far. This alternator is huge compared to the stock one and the belt had very little adjustment. I wish I could get a slightly longer belt. 1 inch longer would give me plenty of adjustment. After the belt was on and all the bolts tightened I had about half inch up/down slack which is manufacturer suggested so I'm happy. Like I said I haven't wired it yet but I have 2 concerns; My first concern is that I couldn't put the rear heat shield back on the alternator and now the alternator, due to it's larger size (120 Amps remember) sits very close to the engine thus more heat. I bought exhaust wrap and to be honest this is the first time using it so who knows. I've heard that it will reduce engine compartment temp by 70% but I doubt that. I guess in a nutshell my concern is heat. Just in case anyone is wondering, I didn't just get up one day and decided to redo the cars charging system. I've been looking for a suitable substitute for some time but also for a permanent fix to the low voltage problems. I will post some info I've found next for anyone that needs it

Discussion Starter · #12 ·
While I'm at it I'm al

While I'm at it I'm also replacing the Starter with a new high torque starter. The starter unit is actually smaller than the actuator on the old one. It makes a serious difference in weight and space. I was able to omit the rear middle bracket of the original starter. This was in place to reduce vibration and force applied to the bolts which is no longer necessary due to the reduction in weight and size. Here's a pic of it...

Discussion Starter · #13 ·
Here's a pic of the back o

Here's a pic of the back of my new Alternator and how to hook it up...

1) This is the main power wire that goes directly to the battery. This is the heavy wire from the original Alt.

2) This is the NEW wire that energizes the alternator. It must be switched, or else it will drain the battery overnight. Do not wire this into the coil power wire that you use to switch the engine on and off since once the engine is running the alternator will feed power back through this wire, which will then power the coil, and you won't be able to shut your car off.
Find a different wire, preferably a Hot when ON wire that is currently running at a low voltage, something less than 12V is ideal since your alternator will use this as a reference for the voltage regulator.

3) This is the green wire originally hooked up to the OEM alt that goes to the idiot light in your instrument panel.


Discussion Starter · #14 ·
You can use the coil power wir

You can use the coil power wire if you fit a simple relay. So you can keep the wires short.

You can fool regulators if you put a cheap, standard 1 ampere 4001-4 diode in series with this wire, the output voltage will be 0.65 volts higher. This should make the relay unnecessary too.

Discussion Starter · #16 ·
Many thanks for t

Many thanks for the great discussion on /3 wire alternators. My engine is out being rebuilt at Norwoods in Dallas and I would like to take this opportunity to do a three wire upgrade. I also have a high torque starter ready to put in as well.
I am also a bit concerned about heat and size of the alternator. I am going to tubi headers without shielding ther than ceramic coating think size is an issue. I have heard that some alternator shops will rebuild your current alternator to a higher specification for large sound systems - could they also do a 3 wire conversion?
James - I will be in Dallas tomorrow (Friday 10 Aug) - will you be around to discuss this?

Chris - what specific recommendations would you have for a definitive 3 wire upgrade?

I think I am also going to replace my digital clock with a digital voltmeter.

Thanks all!

Discussion Starter · #17 ·
unfortunatly I'm not in Da

unfortunatly I'm not in Dallas for a while...doing that pesky bone marrow transplant in Little Rock AR, should be here about a month, then home for a month then back here so I wont be able to help.

Before I went about this alternator deal I found the place that rewires alternators all over the country, apparently they subcontract through mobile audio places and that have a need for higher amp applications.

They promissed me they could do it. But only if they could inspect mine first.

I went to a place in Alrington called
Dub Mobile Sound on North Cooper ave. They had this awesome display up with a before and after that was chrome and 150 AMPS! That got my attention. They guaranteed that they could rewire any alternator.. so back to the garage I went.

I took mine out, first came the "ballpark" estimate of $500 complete. I said ok, then I got a call that said the chrome was $100 more, again I said ok, ...2 days later (a week now) they call me and said that they took my alternator appart and did not have the capability or availability for parts because it was too old and no longer produced by bosch... duh! I knew that, that's why I was having it rewound instead of replaced..anyway. They said they couldn't get the VR or the brushes. I know yours (russ) is a newer one so it's very possible that they could do it, then again I think my whole entire job will be around $120 including the exhaust wrap for the heat issue.

So since your engine is out already I would probably go for an upgrade of the JR like(JR=me).
Some of the Pro's for me were;
Kept original incase something happens,
Did I mention cost?
Double the amperage,
Greater reliability
It's brand new,
Life time warranty through O'reilleys,
But the most important thing is that third reference wire that is not built into the alternator.

That alone was a make or break deal for me. I'm tired of dim lights, slow windows, well...slow everything, even my solenoids to open the gas and hoods are giving me a hard time. It's time to do it right.

The funny thing is I thought doing it right would mean it would cost more but now looking at how cheap that Hi Tork starter and this alt biz is, I think I'm going to start reconsidering my options from now on.

Did I ever tell you how much Norwood quoted me to rebuild my engine? twice what it cost me to do it except I got another 100hp our of it. Nothing against Norwood, I love them just wish I could afford them.

The cons to not rewiring my Alt?; No chrome.

I had to leave for the hospital before it could be finished so don't know when I'll have it running but electrically speaking this WILL work. I have 3 concerns still;
The heat issue,
my own measurements, which are always subject to interpretation depending on the time of day and liquor consumed..
lack of adjustment at the belt.

I really need to talk to someone about a longer belt, I really would like to pull the alternator further away from the block, as is now, I have about half inch clearance between the block and the alternator and I feel that maybe 2 inches would be more practical for airflow. I was also thinking about making an insulated heat shroud that would go around the concern parts.

There is however, a very easy and practical sollution to the heat issue and I believe Ferrari figured it out in the early 90's - There's two types of alternators, the fully enclosed that uses the push/fan at the front by the pulley to push air into the alternator (what I have and similar to the one pictured above) and out the back which does little to cool the main component...the VR, by the time the already hot air passes through the hot windings it hits the VR with it's maximum heat absobtion. It's like pounding it with a hair dryer.
The later Ferrari one, Pictured below, like the 348 for example , I believe it's a Hitachi type. Notice it has openings all around it and no fan at the front. Apperantly what it does is suck air through the body of the ALT and expells it out the front and back equally. To me this is precisely what mine needs because as is now the only air it pulls in is the heated air rising from the exhaust pipe directly beneath it, it's actually the collector so I get a significant hot air mixture up there. I'm working with a guy at O'rilleys auto parts who let me go through every single box of alternators they had until I found the one I needed. I found an exact dup. but exactly aneimic at 65Amps so I opted for a slightly beefeer knowing that I would have to make some modefications. As long as the bolt patterns were there I could adjust and it works.

So now that I have a delco part number, and all the brackets and spacing have been worked out,
it's a matter of having him order me one in the other "Hitachi style".

He said he'd even take the one I bought back in exchange even though I told him I just needed it to make the bracket-- hell of a guy! Any hoot, if anyone's willing to wait until I get home I'll post the numbers and you guys can do the same. I think the three wire is deffinately the way to go but many have been wrong on here before and I don't pretend to be the know it all In this company I consider myself the rookie wrench turner.

I was reading russ's other threads and was humbled at the fact that I know nothing about carburation for example...start throughing numbers at me and watch me cry.
Anyhoot, Russ, I bought 50' of fiberglass exhaust wrap on ebay for $25 and I'm about 25' short for the headers and 50' short if I wanted to wrap the entire system. Oh yeah had to get a bag of 3-4" hose clamps at the Depot. I don't really like them but they'll do for now. Once I get my strength back I think I'm going to pull the engine and detail it with some different stuff. All this while trying to sell it too. got about 50K invested in it selling for 20K and can't stop! I just love this car, it has so much potential now. I remember 3 years ago you couldn't get spark plugs now I see people making parts at home. I'm happy, oh yeah, if you meet my wife make sure you tell her the car's for sale...truth is I don't think I'm ever going to sell it.

I'm already looking for a decent 348 for my next one...that's if I make it home of course
gotta go, the chemo starting to kick my ass.

Now, I know I'm not very smart but I try not to nitpick too much at some of the silly threads on here but com'on, I was using the christmas lights as a metaphor... I know that christmas lights are hooked up in, but many moons ago they came in series, and what I was actually refering to was my own personal attempt to save wire by adding about 24 light sockets for a high school project using only one wire and that's really where my example came from. I also know that Ferrari as most auto manufacturers try to use parallel conections however there's more to just connections as you have to take into consideration resistance and many other things. I just didn't want to go overboard and loose the readers so I stayed with the easiest possible explanations. Like I said, I know there are smarter people than me on this post but don't judge me by my writing as I'm going by the easiest way to understand a concept that may be foreign to the non mechanically/electrically or electronical as I used to say it among us. Please forgive me but feel free to correct me if I'm wrong, that's where things are learned but if I'm talking about alternators let's keep it to alternators. If you want to talk about chritmas lights let me know and I'll open up a thread specifically dedicated to christmas lights .. the rest enjoy!

Discussion Starter · #18 ·
Chris Fricke (T

Chris Fricke (Tomdial)
New member
Username: Tomdial

Post Number: 46
Registered: 08-2005
Posted on Thursday, August 09, 2007 - 08:16 am:


You're absolutely right. I remember doing the diode biz back on an old MGB I used to have.... talk about weird elctrical systems. I couldn't figure out why my battery would go dead and couldn't shut the car off. Great catch however for me, I'm choosing to go for a wire that's already below the 12V. I found some wires under my dash that feed god knows what that have so much resistance at the fuse box that by the time they reach their intended source they're already 10V - I was thinking if I use this wire as a reference the great circuits will still receive the max of 14V while my low circuits will at least receive 12V. What I'm really looking for is maybe a return wire that would actually represent the entire electrical system, if anyone knows of such wire let me know. If the car had a factory volt meter that would probably be the wire although you can never be too sure. If you can think of it please let me know as I'm still undecided. The only reason I would concider the coil wire at this junction is location and asthetics. Fairly short wire that I could hide easy but I measured the coils and they're getting a respectible 11.45V - would like to find a wire with a lower voltage. The window wires for example are at 9.85 V from having to go through those switches unfortunatly they're always on for me from a previous mod to try and put relays in place to see if they would work faster... they did but still not what I'm happy with. Anyway, thanks, I'm saving this post incase I can't find another connection point.

Discussion Starter · #19 ·

George (Ff


George (Ff3)
New member
Username: Ff3

Post Number: 11
Registered: 11-2005

Posted on Thursday, August 09, 2007 - 04:57 pm:

It's a long story but the same place Russ got his, I think.. I found this company doing these conversions for brit cars when I was restoring MG's back about 10 years ago and became friends with someone there. Later on when he found out I bought a Ferrari he said he could make me one for my Ferrari if I gave him mine for a prototype, the deal was I could have the first one for cost since I was providing the template. It went great, I was so pleased that I asked him to let me source them out and sell them to my F friends (check out items for sale on this site) and that's when it got sticky, they wouldn't sell them to me for cost then they did what I was going to do and started advertising on eBay. No harm/no faul though, it's a great company and they deliver a great product. I mean business is business and I did get mine for like $275 but I think they're going for $400 on eBay. I think they once told me that if I could sell 10 of them they'd sell them to me for $350 each. I bought 5 and they sold in a week but I didn't make any money on the deal and they started doing what I was doing, except they already had a business account with eBay and well it was easier for them.
Tell them JR sent you see if they give you a discount but like I said, business is business. Here's the company's info...
They're always posted on ebay. Nicksforzaferrari also sells them but through me so no deal there. If you want the best price go straight to the source and talk to Martin. Or buy on eBay and hope you're lucky. I love Nicks Forza Ferrari and I buy what I can from him but he's not cheap so sometimes I have to go otherplaces. I love that people are finally making parts for these awesome parts. I'm keeping my eye on both supercharger deals going on within these pages to see who wins out... then we'll see
although I been told that with my 11:1 compression ratio it's not going to work well, I also got stainless steel valves which are not suitable ... at least that's what I've been told. This was an easy upgrade, you'll need to remove the alternator to get the old one out, remove the rear hold down bracket, loosen the four bolts and wiggle it out through the alternator opening. I took my AC completely out so no worries for me there. easy mounting but the electrical hook up took some doing for my fat fingers. good luck.

Discussion Starter · #20 ·
Chris Fricke (Tomdial)

Chris Fricke (Tomdial)
New member
Username: Tomdial

Post Number: 42
Registered: 08-2005
Posted on Monday, August 06, 2007 - 10:32 am:

Ok I get it now, Chris, I have a Mondial8 that's why your stuff didn't make sense to me. The alternator changed in late 83 or 84 when they went to the 3.2 - then yes, you could just make a dup delco substitution. My old bosch just didn't make the cut. That's why I couldn't get parts for a re-wire. I believe Russ has the newer style too so your suggestion will probably make more sense to him. Did you say when you rebuilt it you were able to get the third wire option? Also what would be the appropriate Delco number with the three wire that would actually fit your car? I'm wondering if perhaps it would be easier that way although I'm very happy with the 120A right out of the box deal I got. lifetime warr. etc.
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