F355 Alternator

At almost 15 volts, it would almost be an overcharge. I would see if the voltage regulator is working properly by loading the electrical system with a tester, and see about recovery.
That is assuming you took the measurement while the engine was running.

 

and with the charger disconnected, I presume?

Apparently it can be done in-situ (well, part of it, anyway)

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/522264-355-alternator-removal-help.html

 

Something is wrong if your static battery voltage is 14.75
It should be between 12 and 12.5

 

If your battery shows 14.75, there is probably something wrong with your multimeter. 12.75 would be about right. As suggested, check the voltage at the battery while the engine is running with the AC and lights switched on and make sure your multimeter is accurate. If you don't get 13+ (but less then 13), the alternator is bad.

Denso alternators are very easy to rebuild but you will have to take it out. I bought Denso parts from this company Nippondenso (Denso)Alternator Parts.

 

I repaired mine in the car both the regulator and the rectifier.

 

It does not appear in your picture of the back of the alternator that you have the update ground strap installed.

 

Probably why the alternator is dead.

 

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If you find the ground dangling, you'll owe these guys a beer for saving you $$$$$.

 

Where do you attach the ground strap to coming off the ALt housing post?? I've read suggestions to attach to battery negative terminal and chassis., Any better place to attach to chassis, how long of a ground strap is needed. I plan to use a battery cable with the post connector changed.

Thanks

Larry

 

The wire shown in post 10 is really too light a gauge.

Shorter the better. 8mm stud available right next to the alternator.

 

Lack of ground cable does not prevent it from charging. Ground cable prevents alternator from self destructing.

 

Thanks, Brian. Currently it's grounded like this...

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Connected to the block it seems? Why not to the frame?

 

Did you not read "The shorter, the better"? It needs to handle some current and the longer it is the bigger a cable that will need to be used. Do you really want to have to attach a full sized battery cable to the alternator housing? Do you really need to reinvent everything that has been a widely known fix for 20 years?

The problem is the alternator mounting is stupidly designed and does not provide a good ground path to the motor. The engine ground is just fine.

Lets fix problems, not make new ones.

 

Robbe, there is an engine to frame ground further back...

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@308 GTB, yes, I know, But thanks for showing.
My thought was that in case that cable is not 100%, then connecting to the block does not help (same ground).
The reason why I asked, is because there is a small hole in the frame (red oval), which might have had a bolt in it before , for this exact purpose.

@Rifledriver, I do not suggest to ground it to the battery or something stupid like that. I know you have lots of experience and knowledge, and I respect that, but you are a bit exaggerating the tone of your comment here.
I am trying to help, just like you.
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Robbe, I took that picture two years ago when I had that new alternator installed after an alternator failure at Daytona. The car was still in the shop and I was discussing the possibility of adding a second ground cable. My car is back from Watkins Glen and I'll be over there tomorrow. I'll ask my technician about this. We also discussed getting some extra air to the alternator by adding an extra NACA duct and hose to the undertray. I'll speak to him about that again.

The new alternator has done well these past two years. I think that the two days at Daytona where my car saw >8,000 RPM in 5th gear a good way around the track contributed to the alternator failure. Last year and this year I used 6th gear 5th and the alternator did well. Three other F355 Challenge cars had their alternators fail at that Daytona event two years ago. I now carry a spare alternator in my parts box to the track.

Barry

 

For that kind of use you need to change the pulley ratio. Alternators just don't take lots of high RPM. There might be a heat problem but I have had to change pulley ratio on a lot of cars used that way.

 

What about a clutching pulley?

 

Thank-you, Brian. I'll speak to him about that too!

A funny story. Last year at Lime Rock Park I suddenly started to get a bad vibration of my right front wheel at speed. I pitted in figuring I picked up some tire rubber. When the wheel came off, I saw that I threw a balancing weight. The techs brought out my spare front wheels and were going to put them on. The silver tape securing the lead was still there, but was partially peeled away. The imprint of the missing lead was visible so I knew I needed a single 1/4 ounce lead. I asked them if they had any leads on the trailer. They didn't so I ran from trailer to trailer until I found someone who did. I used the old tape to key where the lead should go and stuck it on. I covered it with a new piece of tape, had the wheel put back on and went back out. The was no vibration of the front wheel or the steering wheel. I now keep a strip of balancing weights in my box too.

I treated myself to a new hat when I got back from Lime Rock...

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That might be a bit too complicated for a race car. A slightly larger alternator pulley would be the answer. We'll have to check the specifications of the new alternator and see about a different pulley ratio.

Carrying a spare new alternator in my box provides some peace of mind. I was lucky at Daytona two years ago. My alternator went out during the next to last session on the second day. One by one, idiot lights lit up and the car started to break up. I made it back to the garage and checked the battery voltage. It was about 2V. I was finished for the day...








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