upgrade to 90 amp alternator

[wingthing88]

Well it finally happened my wing left me stranded (approx 300 miles from home) and I had to call my wife to bring the truck and trailer to get me. She was none to happy. I guess at some point in our marriage I should have taught her how to hook up a trailer and tow it LOL. I have an 88 with the original alternator and 160k on the clock and it has failed.I've searched the site til I'm bleary eyed and can't seem to find anything about upgrading to the 90amp alternator. Looking through the web everything I come across indicates the 90amp isn't compatible with the 88/ 89 wings. What is the difference between the 88/89 and 90/99? All the pics look the same are they interchangeable? If I can't install a 90a my plan is to get something cheap now and rebuild the factory alt as backup (and teach my better half to do trailers). Are there any realiable cheap alts out there?

[MikeB]

The old alternator may only need new brushes. Simple fix if you are someone that has mechanical abilities.

The '88/'89 alternator is only different in that the upper, inside mounting hole. I think the hole is slightly larger and a spacer is used to fill that hole. With a replacement alternator, you need to use the same bolt in the upper, inside mount hole as the rest of the bolts.

[wingthing88]

Yes the brushes are toast and so are the rotor rings they need to be turned down smooth but I don't know anyone with a lathe to do that for me. also the bearings are bad and if I have it apart I might as well replace the rectifier/regulator. All told for just a few more dollars I can get the one from Cycle Max so I will probably go that route I was hoping someone had a cheap alternative.

[Rambozo]

Are there any realiable cheap alts out there?

You can have cheap or reliable. Take your pick.

You can also find expensive and unreliable, if you want to go that route.

[Jonbarking3]

I replaced the original alternator on our 98 in May 2009 as it failed. You may have it if it can help you out.
I replaced it with a Compu-Fire. No troubles since.

[wingthing88]

Thanks I appreciate that. I've decided to order the compufire from Cyclemax and save the old one to rebuild and have on hand.

[MaineStreet]

Looks like you've already torn down bad alternator and ordered new, so this may not help, but I had my old alternator rebuilt recently for a tad less than a cheap Amazon alternator. Longevity on the rebuild is not known, but I think it's worth the risk. Good luck with the compufire. It's the only other way I'd go based on what I've read here, but it's a pricey item.