Add me to the list of failed alternators

[MVD]

we're discussing the rate at which a pulley spins based on the size of other ones and belt sizes?

This is why you are confiused. The alternator is only dependent on itself and the crank.......not the other pulleys or belt length.

You could change all idler pulleys add a snub idler and as long as the alternator and crank stay the same diameter, the alternator will spin the same as OEM.

 

[thelpb]

+1 belt length and upper pulley size have nothing at all to do with alternator rpm. Keep in mind that the stock pulley configuration overspins the Alt by almost 3000 rpm. If you change the lower pulley without changing the alternator pulley then the problem compounds itself.

With the stock Alt pulley 4lb lower and 7000 rpm redline your alternator will see more than 22000 shaft rpm.

These alts can physically grenade at as little as 16000 and your factory pullies will put the Alt at almost 19000 shaft rpm. I would suggest 3.2 Alt pullies for factory lowers, 3.5 alt for 2 lb lowers and 3.7 alt for 4lb lowers.

 

[MikeSop]

+1

The size of the crank pulley(since it drives the belt) is the only pulley that affects how fast the belt spins. If you increase the size of the upper, it doesnt change the speed of the belt, therefore the alt will not be affected.

I appoligize if I'm beating this to death... just my 2cents.

 

[About2bite]

Just reading this thread is confusing me:shrug:

I'm not going to say anything else, i'll just watch


op:

 

[djtyau]

Yeah, tell me about it. I was just reporting that my alternator went out. :shrug:

 

[pylecobra03]

I have stock lower, 2.8 upper, and stock alternator pulley and my original alternator went south after 25K miles. Then I got the one from Autozone with lifetime warranty. That was running well -generating 13.8 - 14.4 V at idle- for some time. Then, after like a 1K miles at the most, I noticed this weird vibrating/grinding noise from the engine bay. First, it was not too bad but it was felt inside and was annoying. Then it became worse. Well... I thought, something came loose and was vibrating and causing kind of like a resonanse. Then, I started reading posts here and decided to investigate.
I took the S/C belt off and started the car and the noise was gone. Hence, I got it down to either idlers -billetflow- or tensioner or the alternator. I spun all the idlers and pulleys and there were no problems. The alternator was making slight squelling while I was spinning it by hand. I also tested the thing while engine was running with the belt, using the screwdriver and it clearly was coming from the alternator and also idlers, but somehow weaker; therefore, I assumed it must be the bearings of the alternator.
So, I am in the situation where I think I will have to replace this alternator yet again. I will get it again from the Autozone. I am thinking putting the 3.2" pulley as well to be sure. Luckily, I can replace it myself, since I did that before using the how to instructions from this board - very helpful.
In addition, I have been researching this alternator issue with Cobras here and on ModularFords, but unfortunately, there is no solution to our problem.
I will list the possible solutions but not sure about most of them.

1. Get one from Autozone with lifetime warranty and replace it everytime it goes south.
2. PA alternators - not recommended, way too many going south even not making the 50mile barrier.
3. Stock alternator rebuild at a local shop with the voltage regulator made external. I think this should work if the shop can beef up the bearings and the rotors and other parts to resist heat and also protect from high rpm.
4. High Output Alternator - haven't heard anyone having them, but I called them and they told me they stand by it and assured me it would last. It is expensive at $600 dollars, but it is a 200 amp.
If someone has these, would be nice to hear about the experience.
5. Tuff Stuff. These guys have beefed up the original Ford alternators. Haven't heard too much about how long they last. Would be interesting to hear if someone has them.
6. Alterstart Systems. Some people mentioned these guys on ModularFords. Do not have more info.
7. PowerMaster. Dont have more info on this either.