help required.

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I have just replaced the alternator on my st100 year 2000 and all was fine but I noticed a small oil leak and thought I had not seated the o ring properly but on closer inspection it looks as though the alternator housing has cracked. Is the housing part of the engine or just another component that can be replaced. Any help gratefully received.
 
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By 'alternator housing', do you mean a part of the alternator itself, or the aft engine casting the alternator is mounted to?
 
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91 ST1100/06 ST1300
If the circled pad is cracked, this is a feature machined into the crankcase.
1590233337224.png

If the cracked part is the mounting flange (#1 circled below), it can be replaced. Requires removal of the alternator and mount assembly.

1590233313567.png
 
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Thanks so much for the quick response. Looks very muck like part 1, the mounting flange. Don't suppose you know if this is an easy job to change. Changing the alternator was about my limit. Does the engine have to come out or is this fixable from outside the engine.
 
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91 ST1100/06 ST1300
Thanks so much for the quick response. Looks very muck like part 1, the mounting flange. Don't suppose you know if this is an easy job to change. Changing the alternator was about my limit. Does the engine have to come out or is this fixable from outside the engine.
Lots of work, none too difficult. The swing arm will need to be removed. There is a lot of discussion on this site about that. You will need a tool for removal of the swing arm bolts, there are four recessed slots around the perimeter of the bolt. Just a time consuming task.
 
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hi, I have just purchased an alternator drive unit to replace the cracked mount noted above. Don't suppose anyone knows how if there is any special knack to replacing the drive or is it a simple unbolt and replace. appreciate the alternator has to be removed but I have already done this. I want to know know how to replace the drive unit. picture of what's purchased attached. any help appreciated.
Regards
 

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ST1100Y

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I want to know know how to replace the drive unit.
Various methods on how to engage/match the two spring loaded gears are documented...
I found it very easy to just place the base into the engine case till I felt the slight resistance, then insert some handle into the shaft bore and give it a little twist while pressing inward... it slipped right in.

Hint on the O-rings though: keep all mating surfaces clean, apply lubricant (i.e. silicone grease) on the O-ring prior installation and ensure to insert the flanges parallel, aligned and with no force.
 
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