While I find it hard to believe that an alternator pulley can actually slip on the shaft if it's torqued down properly, there is also the possibility that you could find a clutched pulley for a different application that has the same dimensions as the stock, solid Ford pulley. Clutched pulleys are threaded directly to the alternator shaft and have a one-way clutch inside of them that allows the alternator to be driven in the direction of engine rotation, but it will free wheel in the other direction. They are used extensively to help calm down the belt tensioner from dancing at idle. But for the purpose of this discussion using one will completely eliminate any chance of the pulley slipping because it's core is threaded directly upon the alternator shaft and not just having the core held down with a nut.
Here is a better explantion of how they work.
https://sprinter-source.com/forums/i...threads/63609/

 

Had I not seen it first hand and had my commercial parts manager and best friend right there watching all of it I wouldn't believe it either. After roasting the inside of the first pulley I got a new alternator and pulled the pulley from my 220k mile parts truck alternator and tried it on the new alternator. It has been working up till now with the lock washer as a spacer behind the pulley but seems to like 13-13.8V at idle. I presume this is due to the potential slipping. If I remove the washer from behind the pulley, the pulley will not ever stay tight. It tightens up good and then after idling for a little while the pulley slips backwards on the shaft and the pulley contacts the face of the alternator. Hence why I put a spacer behind the pulley to maintain proper clearance.

This happened to my bosses alternator exactly the same as mine. The pulley slipped down the shaft and scored up the face of the alternator casing. I can take pics when I get to the shop today for reference.

I installed my bosses new 320 amp mechman alternator this morning and will return the big black alternator to the parts store after I take pics. The amp sheet that came with the alternator states 200 amps at 600 RPM and 400 amps at 1800 RPM cruising. Really awesome alternator.

The idea of the clutched pulley sounds awesome for many reasons but, seems like it's going to be a bear to figure out which one I need. I feel that would be a perfect repair if I can figure that part out. Maybe I'll start with a caliper and the alternator shaft for dimensions.

 

Here is my bosses alternator that I returned to the store and here is the one I put on to replace that POS.

 

Looks a lot like mine!
Very happy with the Mechman product. I have the 240 amp model.

 

Wish I had put that Tag somewhere it didn't get lost....
I don't recall now, what the numbers were on my 320A MechMan..

Zero Regrets on the expense, IMO it is worth every farthing.....

the engine just "seems to start easier, and run smoother" by the seat of the pants ...

Headed out to Dawsonville, Georgia in two weeks, for spend Thanksgiving with my son, and hauling his Dump Trailer down to him... It is loaded to the gills with stuff....

 

In my experience, smoother running, better acceleration, and the butt dyno likes it too!

 

I always made my alternator pulleys "UGGA DUGGA" tight with the impact gun and never had a slipping problem. I too would like to have a clutched pulley on the truck, because technically it's a better way to drive the alternator. They work GREAT on a four cylinder diesel where the crankshaft speed is always going up and down at idle and if the pulley is locked up the belt tensioner wobbles horribly trying to keep the proper tension on the serpentine belt. You can even feel it in the power steering when it happens. Put a new clutched pulley on and the belt tensioner goes completely smooth.

 

I can't recommend the Mechman anymore...
I must have jinxed myself or something. Maybe it's because mine is a 400A and the lower amperage are fine, IDK.

I purchased and installed mine in Jan of this year. Yesterday I smelled something funny/ burning; I couldn't see anything obvious. Today I noticed my truck was only charging between 12-12.4v@idle but driving seemed to have normal charge. When I got to work I called Mechman. The lady i talked to was very nice, patient and doing what she could to help. She sent me a link to fill out the warranty form. I told her I would look into it more before sending it in.
Well, I go to leave work and it's not charging at all. I had to drive all the way across town to get the kids from school and drive back across town to get home...a 2 hr adventure. Wasn't sure we would make it, voltage was already down to 11.8 volts when we left the school. Luckily we made it home and only dropped to 11.5-11.6v.

Luckily, I had my tried and trued Bosch in the shed.

But now I feel like, even when I get a replacement or get it repaired, how long will it be before it fails again. I've had my bosch for around 12 yrs without issue. Mechman only made it 11 months.

here's what i found...Mechman are supposed to be some of the best

 

It can't be the alternator's fault because it's got billet. I'm pretty sure adding billet parts makes it more better.

I wonder what failed in there. Think maybe they'd tell you what they got wrong if you sent it in?

 

I've had my 230 amp alternator for a few months now. Unfortunately the pulley still slips on the shaft causing fluctuating.

When I was putting my new engine in I did all new battery cables and when I added this bigger alternator I added extra cables for charging.

Not sure what size alternator I technically need. I'm running a pretty decent sound setup. There is a little less than 20 ft of 1/0 running to the flush mounted plug in the bed of my truck. I plug my dump trailer into this for charging and extra go juice when dumping it.

I think I'm going to go back with a Bosch probably.

 

Dang. I wasnt too far from ordering one from them. Glad I waited. I hope they get you squared away quickly. Im thinking Bosch will be my best and most reliable bet.

 

Like to hear what failed there. Something got pretty warm there.

230a isn't that large if you're running a big system. Factory is what 110ish, and most alts don't put out full rated at hot. So with a 230a you're only maybe 100 amps over factory. At 12v that's 1200w sustained draw which only about 80% of which you can actually use with current amps (900w ish). Any more than that and you're pulling down the battery.

One of my vehicles, I'm running about 5kw worth of amps (been tested to make pretty close to rated power) so how big is big...

 

5kw would be awesome. I'm more around 3kw. Only so much room in a regular cab LOL

Not sure how much my dump trailer draws when I'm dumping a load.

Speaking of sound systems, since I blew my subs up again, I've got some new CT sounds subs coming and I'm hoping they will get here today!

 

FIFY. .

 

CT makes some good subs.

And my system pulls down my voltage pretty hard after a min or 2 of hitting hard. Running 170a alternator. Factory PPV (G8 Caprice) alt.