40amp alternator upgrade

Joined
Mar 24, 2017
Messages
12
Location
albany ny
Bike
ST1100
40 amp upgrade

I have a 1991 ST1100. I bought it for very little money with a known alternator problem. After replacing the VRR I got a not-so steady 15.4 volts from the old 28 amp alternator. Way too much, but it was enough to get me back and forth from work. On the recommendation of an electrical engineer here at work, I ran a wire from the VRR ground to one of lugs on the alternator to see if I was “floating†some voltage in there. In the process of tightening up grounding cable I snapped an arm off of the the 28 amp alternator. I was pretty f'ing annoyed.

I'd ridden the bike enough to know what a good touring bike it was, so I figured it was time to pony up and do the alternator upgrade. I ordered the parts and requested the kit from John. The kit arrived almost immediately, but the alternator shaft was on an indefinite backorder. Very frustrating. Customer service from Partzilla was pretty terrible as well. Once a week they'd send me an email saying my part should ship in 2-3 days, then I'd follow up to ask if that was true and they'd tell me that they automatically send that email once a week quoting the Honda stock time. Very annoying. I had to talk to a lot of people before someone actually talked to Honda and told me the what was going on. If they had told me the part was on back-order at the beginning I would have made other arrangements. I hate to lose a month of riding in the Northeast.

THE ACTUAL JOB:
Get the kit! Get the kit! Get the kit! It has all the weird little tools you need to do the job (swingarm lock nut tool, bearing driver, and a lot of extras people have thrown in along the way.) Without this kit, I'd have either used the wrong tools or spent a lot of money buying the right ones. Get the kit.

Pulling the swing arm is fairly easy. Park the bike, and hose all the nuts and bolts you'll be pulling with PB Blaster the day before you're going to do the job. I followed the manual everything came apart easily for me.

Assembling the new alternator shaft also went smoothly. It does take a little muscle to get the shaft locknut off of the shaft but that was about it. Between putting the new shaft in the freezer and the purpose made aluminum bearing driver everything went back together very smoothly.

I tried to install the 40 amp alternator shaft with the Lewis pin for hours. I got it to seat once but I was unable to pull the pin out. I pulled the alternator shaft again and I was not able to get it to seat. This process was extremely frustrating. I ultimately decided to follow the clymer manual and pull the exhaust and oil pan so I could actually reach up into the engine and seat the bearing in the motor by hand. It didn't take long to pull the exhaust and oil pan. Scraping the old gasket is annoying, but at least you can do it on the workbench. The alternator went in quickly as well. I tried to get it slip through the frame in one piece for about 5 minutes, and then I just split it and reassembled it in position. Don't be afraid to split the alternator. Just stick a socket in it to keep the brushes in position and put it together. It's easy. I didn't have a gasket at the time, so I used Right Stuff on the oil pan, put it together and tested it. 14.2vdc! FanF'ingTastic.
The next day I put the swingarm and rear wheel back on. Reassembly went smoothly. I have almost 1000 miles on it and still puts out a strong 14.2vdc. I ordered a gasket for the oil pan (I've haven't had a lot of luck with RTV gaskets in the past) but the Right Stuff gasket maker is holding up just fine on the oil pan. I'll put the gasket in the kit with all the other extras people have thrown in.

Ultimately, I was not able to use the lewis pin method, but I still got the job done. I guess sometimes it's better to take the long way around. It might take a little longer but it would have saved me some cursing on the garage floor. There's a gasket in the kit for the next person.

Thanks to John Oosterhuis and everyone else who made the kit and gave me advice along the way.

 

kiltman

Site Supporter
Joined
Apr 27, 2013
Messages
3,279
Age
68
Location
Stratford, Ontario Canada
Bike
2002,ST1100ABS
STOC #
8826
Congratulations. That 15.4V is a little high, the 28 amper likes to charge between 14.8 and 15.1. You made the right decision to upgrade, you will have many enjoyable miles in the future and very satisfying ones too as you got a good deal on the bike and you made it dependable again. Cheers
 
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