Wildguzzi.com
General Category => General Discussion => Topic started by: Huzo on January 14, 2026, 05:19:25 AM
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Today I was talking to Pete Roper about a V85 topic and he asked me if I had done the V85 mod yet on the swingarm.
Although I have changed mine a bit, I had not done this one.
At the rear of the swingarm on the right hand side where it bolts to the bevel box, there is a small drain hole bored and it’s function is to give an indication if you have blown a seal and hence will see oil seeping from the hole.
It seems that because of this hole, moisture can get into the swingarm and promote rust on the pinion shaft where the seal runs and consequently chop the seal out prematurely.
The remedy is to get a can of chain lube with the little tube still attached and spray some inside the hole, thus lubricating the shaft where it matters.
Then you run a suitable thread tap into the hole and wind in the appropriate bolt.
Remove this bolt at servicing to purge any swill that has accumulated… :thumb:
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And here I was considering drilling a little hole into both of my Guzzi small block swing arms due to the moisture that sometimes seeps in through the rubber bellow.
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Is it really an issue that a small weep hole would actually allow water and debris inside to foul the pinion shaft? No, I can’t see that as being a problem of any kind. The ‘remedy’ seems silly to me.
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According to Roper, and he would know, it is a problem if the bike gets ridden in the rain, and by that he means really ridden in the rain. I didn't really want to bother tapping a threads, so I made a small rubber patch from a bicycle inner tube and strapped it down over the whole using a slim black zip tie, works great and can't be seen unless getting very close and looking for it.
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Is it really an issue that a small weep hole would actually allow water and debris inside to foul the pinion shaft? No, I can’t see that as being a problem of any kind. The ‘remedy’ seems silly to me.
I have never seen this issue on the V85 yet but have certainly seen it on other Guzzi's with rusted splines and tubes so I am sure it could be an issue on the V85 as well, I expect water gets into damaged boots more than the weep holes though and the weep hole at least allows a bit of venting to help it dry out so I will leave it open.
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Besides riding in rain or through deep puddles, even just hosing off the underneath of the bike could get a little water in that hole. I found a small stainless cap bolt that was barely bigger than the hole so threaded right into the aluminum w/o having to even tap it.
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I don't recall the set up on my 03 v11 Lemans. Anyway, I went to replace the inner & outer seals on the rear drive due to a leak and found the pinion seal area was badly corroded. Although the pinion seal was not leaking, it was pulled out, seal replaced there too. I can definitely see seal problems occurring if left unchecked. IIRC, i sprayed a light coat of chain wax on the area to hopefully prevent corrosion in that area but it is now another caretakers potential problem. I guess I'll add "douche swing arm weep hole" to my To Do list. :thumb: