• Ciao Guest - You’ve landed at the ultimate Guzzi site. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if you need help. New to the forum? For all new members, we require ONE post in the Introductions section at the bottom, in order to post in most of the other sections. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have, have likely been already answered. DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back in and reply within 24 hours, or your post will be deleted. Note there's decades of heavily experienced Guzzi professionals on this site, all whom happily give endless amounts of their VALUABLE time for free; BE COURTEOUS AND RESPECTFUL!
  • Be sure to see the GTM STORE link also above for our 700+ product inventory, including OEM parts and many of our 100% Made-in-SoCal-USA GTM products and engine kits. In SoCal? Click the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work, and don't miss our GT MotoCycles® (not) art on the BUILDS tab above. WE'RE HERE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED - DO NOT EMAIL AND ASK QUESTIONS OR ASK TO CALL YOU.
  • There is ZERO tolerance on personal attacks and ANY HYPERLINKS to PRODUCT(S) or other competing website(s), including personal pages, social media or other Forums. This ALSO INCLUDES ECU DIAGnostic software, questions and mapping. We work very hard to offer commercially supported products and to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. We don't have the time to chase repeat (and ignorant) offenders. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see the GTM STORE link above; ALL product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.

oil drip from lower brakeline attachment hole in swingarm, just fwd of CARC.

Daniel Kalal

Cruisin' Guzzisti
Oct 28, 2008
Stelvio NTX, 2013 [36,000 miles]

Just forward of the CARC-split with the swingarm is a small fitting meant to hold the brake line that is attached to the swingarm with threads into the bottom wall of the swingarm. Evidently, the hole runs all the way through the wall of the swingarm (perhaps that's a useful thing as it exposes any seal leaks). I've got oil dripping out of that hole.

It's either oil from the transmission (and a failure of that seal), or oil from the rear drive box (and a failure of that seal). The drips make a mess of things, but I've not lost enough oil to tell where it's coming from.

Question 1: Is this likely from a poor seal at the transmission or the drive box? Gravity would indicate it's coming from the transmission, but oil leaks can be sneaky things.

Question 2: If I pull the CARC off the swingarm, is it an easy thing to check and replace the driveshaft seal? The service manual indicates that it won't be trivial. Evidently there's a rubber bellows unit as well as a seal (which might require a special tool to get to)?

Sigh... The Stelvio is still under warrantee, but my local dealer is gone. If this is something I can take care of, I will; otherwise, I'll put aside a day or two to take a long ride to an authorized dealership. The leak isn't something that would prevent the ride.
Dan, it is likely from the final drive, often if it's overfilled (as would be from the factory spec'ed level IMO). Removing/re-installing the CARC drive is simple.
I've never been deeper as it is technically a sealed, non-serviceable unit outside of the wheel side seal. Post what you find.
Hi I had exactly the same oil leak a few months ago, I took the final drive off and shone a torch up to the gearbox seal to see if it had run down from there, fortunately It was clear, so that left the final drive. When I removed that small steel plate that hold the seal in place to inspect it, it had rusted, so I sanded it down and resprayed it. Refitted everything back to the bike and after doing about 2000K's it is all dry. I can only think the rust distorted the seal. I put a small amount of sealer on the face of the final drive just to stop water creeping in in the future. I can load photos when I get them off the camera if your interested.
Cheers Kevin
Daniel, Sometimes that larger rubber piece Kevin is referring to needs to be re-sealed. If it is the shaft seal, I think it requires special tools. Pete Roper did a write up on that seal a long time ago.
Thanks, guys. It sounds like this problem has been seen before. Tonym, I appreciate the link to Pete's much earlier post. So, in addition to the need for a special tool, this statement by Pete takes this task out of the shade-tree category:

to replace the seal you need to split the cases of the CARC to access the pinion seal holding mechanism
What an interesting way to seal off the CARC. It relies on the rubber boot to seal the periphery, and a conventional seal to take care of the pinion. It wouldn't seem possible that the pressure from just a couple of screws would be sufficient to make a good seal of the boot. Is the boot also attached using RTV of some kind? It seems more likely that the cause of any leaks that make it into the swing-arm would be from that boot and not the seal. If so, that's easy.
The steel ring is an exact size of the seal and when the 4 bolts on the carc are tightened it compresses the seal against the two surfaces, I think its there to keep a bit of pressure on the seal so when you remove the carc you don't get a floor full of final drive oil, although it will seep out if left laying down. Mine had no RTV on the seal.
By your description of the clamping forces on that bellows, it seems unlikely that that would be the leak path (with or without RTV)--back to the pinion seal, then.

As it's not as trivial a solution as I'd hoped, I'll put it to Moto Guzzi N.A. to be taken care of through the normal warrantee process. It should be a straight-forward approval...
Daniel, I had to re set the dam on my CARC. It wasn't positioned correctly at the factory. A little RTV, and carefully positioning that rubber, the leak is gone. It is relatively easy to drop the CARC. Once off you can tell if it is the rubber dam, or the pinion seal.
Hi all, not sure if opening an old thread is good use of the forum.....

I took a 2000 km trip the other day and now the final drive - swingarm connection is showing some signs of oil spil, see picture.

Is this something I should act upon and is the most likely candidate the drive seal?

regards, Jan


  • 20231011_061033987_iOS.jpg
    138.8 KB · Views: 13
Give it a good clean and monitor it, check your gearbox and CARC oil levels and the tightness of the CARC bolts. See if you can determine what type of oil it is, gearbox or final drive. I had a leak there on my Breva 1100 and it turned out to be the rubber boot seal between the CARC and the swinging arm, it just needed the surfaces cleaning, a tiny bit of rust had formed on the seal mounting plate. I was glad it wasn't the gearbox or the CARC oil seal. Its an easy job. Yours doesn't look too bad especially after 2000Kms
I've had a tiny amount of seepage for years. It is noticeable after I've driven on some dusty, dirt roads. I just clean it up, watch for any worsening and check the level occasionally.
Both oil levels are Ok, and yet when cleaning the CARC I found even more oil at the bottom of the swingarm. Could this be from the tubes also attached to the swingarm?
Both oil levels are Ok, and yet when cleaning the CARC I found even more oil at the bottom of the swingarm. Could this be from the tubes also attached to the swingarm?
Possible. Also if the air box drain line is leaking it can spray back to the swing arm.
Hi The Airbox drain line is still okay. I drain this tube every couple of months. This cannot be the reason. I’m suspecting the seal on the final shaft of the gearbox although the oil level in the gearbox is still okay.
A winter project.