348 alternator removal & rebuild

Glad it’s working again.

Got the regulator from finditpart$$ and it at least seems to be a real Denso part (although counterfeiters have gotten pretty good these days).

 

Échange Denso Delco (348 1991)
https://www.theferrarista.com/forum-ferrari/topic/12219-alternateur-mort/

 

I'll post this on the various Alternator posts so it's everywhere.

For those of us who need the 103mm rectifier, I did confirm with Regitar earlier this week the only difference between the RN-02 and the RN-04 is the size of the stud.

RN-02 -- 6mm stud
RN-04 -- 8mm stud

Both are 103mm and have the 8-50Amp diodes

so they are both interchangeble by tapping out the stud and putting in the one from your old rectifier.

 

Interesting convo with an alternator rebuilder today. The 105amp version in my car was superseded to a 5071 for the last 4 digits of the part number Mike provided.

When looked at the BOM for parts...it did list the RN-04 as the rectifier but he found a different voltage regulator... 126000-1500.

I just put new brushes in, new rectifier new VR. It put out plenty of volts but only about 25 amps on his test bench.

Maybe his RPM werent high enough?

Stator looked good.

Thoughts?



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Anyone put their rebuilt alt on a test bench and see how many amps it was putting out?
mine with new Denso Reg, new Regitar rectifier and new brushes is only putting out about 20amps.

maybe a stator issue? anyone have that part number?
Also some mention in a thread about the windings.. but everything looks good with them at this time.
I'm half afraid to take her any distance as she'll leave me sitting.

I've checked all the grounds, even made a new ground wire from Alt to chassis as the other one had some corrosion. No parasitic draw either.

Help?

 

Having had long time problems with the alternator on my 355 spider including multiple recoveries when it left me on the side of the road I took the plunge and rebuilt my alternator insitu using the parts recommended by Ernie only to find that it was still only putting out just over 13 volts as previously so I then trawled through the site and found the thread on 355 alternators and earth straps, back under the car and lo and behold there is no earth strap fitted to my alternator so I made one up out of heavy duty cable and fitted it and bingo 14+ volts so maybe I didn't need to rebuild the alternator after all. Just a warning to other 355 owners to check the alternator earth straps before getting into alternator rebuilds.

 

Nice job, and good heads up.

 

So i never upated my thread on this?

Whoops. Will post deets soon but a new stator and rotor fixed me right up.

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Well get on it son!

 

wow... I'm a bit late.

303-52003 Rotor 80A-100A --- paid $49.87
340-52002 Stator 4 Lead -- paid 30.91

 

Better late than never

 

Thanks for the thread. It was very helpful.

That said, are there any special tricks for refitting the belt? I have the alternator back in but cannot get the belt back on for the life of me. I have the tensioner all the way loose and have tried to run the belt beside the tensioner for some extra slack without any luck. It is the correct belt (Dayco 199826).

First time I have been defeated by a belt
Help please!!

 

There where 2 different size belts. Take your old original belt with you to the parts store and just have them match it up. One belt is 774mm long while the other is 776mm long. Chances are you need the 776mm long belt.

 

Are you sure you're screwing the tensioner in the right direction? I've been told the adjustment is counter-intuitive.

 

Just an update. I ended up undoing the top bolt and pivoting the alternator a bit. I tried this earlier but was more forceful this time and the belt fit. It was then easier to get around the tensioner.

I would suggest refitting the belt this way for anyone else in the future. Car is running great again!

 

Thanks for the tip Sundeep.

 

Hey gents

Apparently my alternator is fried again according to my indy shop. He said its not putting out enough juice and looks pretty fried upon inspection.

I had rebuilt the entire thing last date of this post - every part in it.

How long are you guy's rebuilds lasting?

Is heat killing it?

Tia

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Heat for sure, and then high loads when the radiator fans kick on. I don’t think they are high enough amps to begin with anyway

 

Hey all... have all my new parts for the rebuild except for the voltage regulator and I can't find it anywhere.

126000-1500
Anyone have a cross reference for it or know where it can be sourced? I'm all googled out.

I also thought I used a different VR when I rebuilt it last time..... but I'm getting old and it was 3-4 years ago.

 

Interesting... doing some digging and it looks like a in434 from Transpo is a cross reference for the 126000-1500
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I'm doing my alternator as well
Thanks for all the info here! Helps a lot

I found this as today 2023

Specs and for sale Rectifier # INR736 https://store.alternatorparts.com/partnoin220.aspx
I bought everything here;
Denso Alternator Regulator https://www.finditparts.com/products/2379264/denso-126000-0400 - U$ 28,80
Rectifier INR736 https://www.finditparts.com/products/16977245/wai-inr736 - U$ 58,03
Brush Holder Assembly https://www.finditparts.com/products/2379112/denso-021620-2720 - U$24,35

 

dahveedem Is everything okay since your last rebuild? Did you use Transpo?

 

pn 155785 , 101211-5071 Smaller NipponDenso. Ferrari 348
Replacement parts used.
VRH2005-4A Regulator (Regitar)
INR739 Rectifier (Transpo)

Alternator is back up and running. 14.1 amps

Pro tip. Getting the belt on is easy if you deal with the tensioner last. Engage the larger pulley on the block first, then the smaller pulley on the Alt while bypassing the tensioner pulley. The tensioner is simple to get engaged at that point. The lack of groves makes sliding the belt into place much easier than the grooved Alt pulley.

I added an extra ground strap and made a carbon fiber oil shield. Dripping oil will damage these alts.
Be sure to double check the Sensor Wire that runs from the plug to the B+ terminal of the Alt. I had a ground fault short and was able to fix it.
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