Alternator - Rebuild or Convert?

Mike8675309

Registered User
It's looking like I need to replace my alternator. Looking around at reman prices for these 110amp Mitsu alternators is sticker shock. $200 for a REMAN alternator?

I'm going to check with a couple local rebuilders to see what they think.

Of course, the other option is to go with the 3G alternator and modify the bracket to mount it on the SC. Are these a more common alternator, and thus a less expensive alternative over the long haul?

Or maybe better said. If to fix my Alternator issue it's going to cost $175-$200 in parts. Would I be better off, in the long run doing the effort and spending the money on a 3G unit to replace my existing unit?

Or is it just a wash so fix the stock unit?
 
The mods to install the 3G alternator are not that extensive and the Mitsu can be reinstalled at a future date.

I made the mods to the bracket while it was in the car. The alternator had to be taken in and out quite a few times, but it was easy to see what material needed to be ground away on the bracket. I just had the tensioner and the coil pack off and out of the way. Then with just a Dremel I was able to carve out enough clearance.

The 3G was used on several Fords including the 'Stang. It is also easy to get in different amperages, if you need that. It is much easier to find than the stock unit.

This post also has more info on the mods needed:

http://sccoa.com/forums/showthread.php?t=47464

The top hole also uses a different size mounting bolt. This is not a very difficult mod, only time consuming part is getting enough aluminum ground away. I also had to notch the tensioner for a little clearance as well.
 
Thanks George. I did the research last night here and found lots of info about it.

If 110amp is fine for me. Then the only thing that remains is price and availability. So the main question is what are the benefits of going to the 3G unit other than simply the ability to get more power?

If there are no other benefits and the price is the same I'll just stick with the stock unit. I just want to make sure that if I'm spending nearly $200 on an Alternator, I'm not missing an opportunity.
 
Mike8675309 said:
Looking around at reman prices for these 110amp Mitsu alternators is sticker shock. $200 for a REMAN alternator?
You can get a rebuilt one from Autozone for around $130 and take your chances.. they come with lifetime warranties, which admittedly does little for you when you're sitting on the side of the road, or you can try to locate a quality rebuilt one. I don't know what brand is good, but if you contact a garage or 2, they might tell you what brand from which supplier they use.
If you know a local shop that can do the work, a few questions about their warranty and how they load test the unit might give you more confidence. If they don't do a burn-in test, I'd look elsewhere. :)
 
Damon, how much more HP and why? Is this for the same amperage or more amperage in the 3g? What is the difference in RPM for full charge in the units?

It's a hard upgrade to bet for the $$ and availability of the 3g.
 
My unit came with a power (amperage * voltage) vs speed chart for constant voltage. It showed something like 6000 RPM for the rated power, but that is shaft speed, not engine speed. You can figure the reduction by taking the ratio of the crankshaft and alternator pulley diameters and multiplying by engine RPM. Just a rough guess of about 1:2.5 would mean that at engine RPM of roughly 2400, the alt should be making its rated power.
 
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i have always just had the stock one rebuilt cost me about $40-60 depending which shop i go to
i have always wanted to upgrade the alty about how much does the 3g go for and where can you get one
 
The one's I've looked at are around $200 for the 130amp version. More for fancier casings. Though I did focus on this site: http://www.pa-performance.com/

I took it to a local shop thus far and on their bench test it was putting out zero and isn't tripping the lead that is used to illuminate dash lights that there is a problem.

I'll get an estimate tomorrow. If it's reasonable I'll go with it. I figure having someone actually look for and solving an issue is more likely to provide me with a repair that will last. Rather than rebuilder shops that just swap parts and throw it on the shelf.

I noticed www.rockauto.com has some good prices on reman SC alts. But wow, those core charges can be steep. AC Delco has a unit for $165 with a $165 core charge!
 
PA Performance was making a "kit" at one time to install the 3g, not sure what happened.

Tom at Mr Alternator sold me my first 200AMP chrome unit and helped me with the plugs and info to wire it up. He also does rebuilds.

http://www.mralternator.com/
 
Check Ebay..I bought a 200amp 3g on their new for well under 200...Its in my stang and works mint.

Goerge.

Teh added rotating mass of the larger 3G is what makes it draw more HP. Why it charges at a lower RPM is beyond me. I have checked both a 3G and an SC alt on my stang and the SC with same size pulley is at full charge way before my 3G. At idle with UD pullies my 3G cant keep up...My SC alternator can
 
I thought you might have some specs from somewhere. I now have a 130AMP 3g unit on my 89 SC and it does fully charge at the idle speed with a stock pulley. I haven't tried the underdrive pulley on it. It was a brand new unit from Summit.

(p.s. the name is George! LOL)
 
I have an extra SC alt from a 91 sc, it worked when it was pulled. I bought an lx from the guy, and he was like here, have the other parts...

I am not using it, if you are interested in buying it, PM me.

I can snap pics of it too.
 
I'm not so good with the typing haha GEORGE!

I guess the only way to get written data is to bench test the units as faras actually charge vrs rpm data. Ilm just going from personal experience..However the HP thing goes without saying!
 
A sample

The last alt I got from AZone had this attached.. that alt has lasted for about 1-1/2 yrs so far.
 
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Just to follow up. My alternator ended up being not worth rebuilding. The Stator was shorted out, and the regulator diodes were fused together. The rebuilder sold me a new, rebuilt alternator for $100. Quite a bit better deal than the local auto parts stores.

I talked with the guy who took it apart and he feels that it burned itself up over a period of time, likely due to being used to recharge a bad battery, or possibly some wiring issue causing it to think it needed to be charging all the time.

I hadn't run it that way, but it is possible that since the car had been sitting for a while that the battery in it was very low on charge, and required the alternator to work very hard.

I'll make sure the new battery I purchased is fully charged before bolting it back in.
 
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