Rebuild an alternator

[the_experience03]

It would depend on what exactly needs to be rebuilt. I certainly think you could do the brushes, etc yourself, but most rebuilders actually rewind the alternators, replace diodes, etc. I'm sure it's not as cheap now with copper prices what they are, but I had an alternator guy quote me $65 with the good guy discount to rewind a 10SI GM alternator up to 130 amps. I certainly would look into a remaned alternator. Most of what you buy at the parts store as "new" is remaned anyway.

[frank-id]

Rebuilding an alternator at home is a risky action. Rebuilders only replace what has tested bad, but after the reassembly, the unit is usually tested for performance. There is a great deal of difference between auto alternators and heavy duty units. On buses and large trucks, every part is bigger and stronger. Almost all alternators that have been rewound for a higher amp output do not have the same life expectancy of a factory rebuild. Alternator output makes more heat, and heat can destroy anything. To get higher amperage a larger frame alternator is required for longivity. The number one reason for alternator failures is.... poor battery terminal connections. The alternators connections are also very important. The components used to rebuild an alternator are vastly different. Most rebuilders want to satisfy the warranty period only. There are many different quality bearings used in all electrical components. If any part at a rebuilder is found to be OK, the part is reused. The profit in a rebuild shop is very very high. Quality components is the secret for good long lasting alternators and starters. Many offshore parts makers are flooding the US with very poor equipment. Always get a warranty on rebuilt parts. Many components have become throwaway with no rebuilding. Notable, many light duty truck and car brake shoes are not used as rebuildable cores. Bearings used in the rebuilding industry have become very poor quality. Keep the electrical connections clean and tight. Frank

[the_experience03]

Don't forget about the unit bearings used on most truck axles now, including the Dana 50's and 60's under those "heavy duty" trucks pulling fivers around. Throwaway parts that tend to break and take other stuff with them. Has society gotten that bad that we'd rather throw stuff away than perform very basic maintanance practices? I know I feel better driving on a set of kingpin bearings I installed and have serviced or on a set of wheel bearings I KNOW are greased and in good shape.

Sorry for the rant, but it seems like just about anything newer than a 1990 is just built....cheap

Oh yeah...and I never did have that 10SI rebuilt because I found a 12SI later on that was still in good shape (it wasn't for a car project anyway).

[abdabbs]

i had my 160 amp Leese-Neville alternator that came on my ford chassied bluebird rebuilt and am totally happy with it! Cost me 110 bucks. Although I find myself very handy and able to anything I put myself to I dont think I would want to try and do this myself considering the rewinding and all. I have it running to an isolator split to the starter battery and a bank of three others and have about 1500 miles on it so far without a hitch. I researched for a good replacement and found that I was saving 100-200 bucks easy on just having it rebuilt.

If you think you can do it yourself go for it. But for me there are some things on my rig that I would rather done by a 'pro'.

[lapeer20m]

Perhaps the problem is not your alternator? but the electrical wireing through the isolator ect....

another thing to try real quick is to rev your motor up. My newly rebuilt alternator does not start producing current until the motor reaches about 1K rpm. After it reaches that speed, i can let the motor idle and the alternator keeps charging. I forget the reason the alternator guy told me this happens.

try hooking things back to stock and see if it works then.

an alternator needs a source of 12 volt current (usually turned on and off with the ignition) to sense voltage so it can adjust the output through the large diameter "hot" wire. It also needs this source of current to create an electromagnectic field to produce current.

as a side note: If you energize this circiut on an alternator sitting on a bench, you can barely generate enough torque to turn the pulley by hand.

if you still can't get it working, drive your bus to the alternator shop and see if they can figure it out for ya.

[hoser]

Originally Posted by lapeer20m

Perhaps the problem is not your alternator? but the electrical wireing through the isolator ect....

another thing to try real quick is to rev your motor up. My newly rebuilt alternator does not start producing current until the motor reaches about 1K rpm. After it reaches that speed, i can let the motor idle and the alternator keeps charging. I forget the reason the alternator guy told me this happens.

try hooking things back to stock and see if it works then.

an alternator needs a source of 12 volt current (usually turned on and off with the ignition) to sense voltage so it can adjust the output through the large diameter "hot" wire. It also needs this source of current to create an electromagnectic field to produce current.

as a side note: If you energize this circiut on an alternator sitting on a bench, you can barely generate enough torque to turn the pulley by hand.

if you still can't get it working, drive your bus to the alternator shop and see if they can figure it out for ya.

Mine is the same way seems once you reach over 1k rpm then its triggered and the voltage goes up, I assume this is so you dont have a huge current draw soon as the engine fires up? So when I start my engine I tap the gas petal a few times and its good to go.