'17 GRiSO Rear Flange Festival

Greetings GRiSO Gurus,

While technically still under warranty (for a few more weeks anyway), I've taken my barely ridden '17 GRiSO SE down to bits to fix an annoying small oil leak. (Don't want my beloved hacked to shit by the local slack-jaws, plus, growing up wrenching on old German cars, this antiquated mechanical beast is right up my alley--it's relaxing to work on!)

Anyhow, it seems I've been struck by the 'ol rear bearing flange gag. The o-ring groove on mine was recessed a touch too deep (1.8 vs 1.5mm), plus improperly applied anaerobic cack which squished into the o-ring cavity, and the o-ring itself appears to have been of poor quality anyway (compression set failure), plus a few other little niggles. I've taken careful measurements and have procured quality, correctly sized o-rings that should remedy this specific issue.

Getting to the point(s):

1. I ordered a rear main seal from a well-known, Guzzi-only dealer here in the US. The OE seal is made by Corteco and is of very high quality, which essentially should last the life of the equipment (in fact, I should have left it alone!). Instead of the double-lip, Viton Corteco seal, I received a Timken branded part. While made in the US and of the correct size, it's only single lip, and made from nitrile.  IMHO this seal choice is a bit dubious for the application, mainly for the temperature handling capabilities of nitrile vs Viton, and the lack of a dust shield in a clutch environment, but I wanted to make sure I'm not being too fussy before ordering a seal from another dealer. I don't know enough about the "in practice" realities of the two seal types to make a reasoned choice--perhaps the nitrile seal will still provide a decent service life?

2. The small upper bearing cap: are these known to be a common source of leaks? The left side cap screw is weeping and can be easily resealed of course, but the cap itself will require some coercion to remove, and if it's not known to be a problem, perhaps it may be less risky overall to simply leave it alone?

Thanks for reading my ramblings, and in advance for any insight...

Damn, I had that issue on my old 09 but I thought they fixed that problem since then?
If I remember, the culprit was that the flange bolts were too long and didn't compress the O-ring properly.
I'm lucky that it was under warranty...happened at 5000 miles, in the first two months I own the bike! lol
I was a riding fool...

DO NOT use a nitrile seal! Who sent you such a thing! Name and shame! Make sure you get a Viton one or it will leak in a week!

As for the flange? I hadn't heard of any problems since early 2010! You just drew the short straw by the sound of it. The idler shaft bearing cap rarely leaks, it's sealed with an o'ring. If it's a screw weeping just put a bit of Loctite 243 on the screw. Should fix it!

Thanks Pete! According to the datasheet, this nitrile seal has a max temperature rating of only 120C! As far as the dealer, it definitely wasn't AF1 or Cadre Cycle (the latter sending me the correct part). I'll follow up pronto with the offending party before someone blindly installs the seal in good faith and has a problem. The service was prompt and otherwise outstanding, but clearly you have to closely analyze the specifics before substituting critical parts.

Grisonut, as Pete mentioned, and all of my research leads me to believe, my case is simply one of sheer bad luck. Overall, I'm really impressed with the quality and choice of suppliers. The driveshaft is made in Germany by Elbe, with INA bearings? Wow! Truly good stuff. Fortunately, this also gives me the opportunity to properly grease everything, check for other assembly errors, and install the shock I've had collecting dust since last summer.

Leone wrote:

Grisonut...................... The driveshaft is made in Germany by Elbe, with INA bearings? Wow! Truly good stuff......................

I don't know what to make of that. Because the BMW RTs and GSs had prone failures with their end drive assembly and I even witnessed it. Not pretty...

Got the correct seal fitted (thanks to Cadre Cycle who had the part to me in a day), and assembled enough to let it run for a bit, thankfully no leaks!

Aside from fretting about o-ring sizes and groove depths, the toughest part of this job was wrestling the engine back in by myself-- I'm definitely not 22 anymore! I also found the work to be very time consuming, but I'm much faster with a laptop than a wrench these days. Down to swapping the tires and a fork re-valve, so hopefully we'll enjoy some happier miles this year. This bike is absolutely worth the teething issues, so much class and character!

Grisonut:

Quote :

I don't know what to make of that. Because the BMW RTs and GSs had prone failures with their end drive assembly and I even witnessed it. Not pretty...

Yikes! That's unfortunate. No idea if that's a manufacturer issue (likely the same one I would guess) or a design fault, but sounds potentially catastrophic. I see many of the same parts suppliers between my Aprilia and now Guzzi as I do the MB's and BMW's I wrench on, which I suppose is only logical, though at least regarding their automotive applications, the Elbe shafts are long-lived.