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General Category => General Discussion => Topic started by: nwguy on October 15, 2025, 11:41:38 AM

Title: Rubber u-joint boot for EV1100
Post by: nwguy on October 15, 2025, 11:41:38 AM
The rubber u-joint boot on my 99' Bassa has a tear in it, possibly from me overtightening the forward hose clamp after installing the swing arm a while back. I noticed a small amount of oil on my garage floor below this. That's how I found it. Here's the part from MG Cycle:

https://www.mgcycle.com/index.php?main_page=product_info&products_id=829

Probably good to replace it based on its age regardless of the tear. I'm curious as to how oil is getting there. Seals prevent oil from the pumpkin flowing up there. Is it transmission oil that's coming out? Wondering what oil level to check to determine if significant amounts leaked out while riding.
Title: Re: Rubber u-joint boot for EV1100
Post by: Antietam Classic Cycle on October 15, 2025, 11:57:58 AM
The "pumpkin" is not sealed from the driveshaft, so oil/oil vapors can flow from it into the swingarm. It's also not uncommon for oil to leak from the output shaft of the transmission. Despite Guzzis best efforts it still happens on even the last of the five-speeds.
Title: Re: Rubber u-joint boot for EV1100
Post by: n3303j on October 15, 2025, 06:38:19 PM
The sealed (2RS) U-Joint carrier bearing keeps the transmission oil in the front section of the swingarm and the final drive oil in the rear.
I always get a bit of oil in both sections. I think this actually helps extend the life of all the internal components.
BMW had a reason for filling the /2 swingarm with oil.

I just finished replacing a torn boot on my T3 about an hour ago. Good chance to clean that whole area.
Title: Re: Rubber u-joint boot for EV1100
Post by: JoeB on October 16, 2025, 05:26:49 AM
While the swing arm is off take a good look at the carrier bearing. I had a few miles on unpaved roads at the time, and the tear on the boot must of let some dust through. No symptoms riding but didn't feel completely smooth when inspecting.  Replaced the bearing and u-joint for peace of mind. Had a copy of 90's Guzziology where he advised adding an ounce or two of fluid in it before clamping it down. Helps keep things moist and lubed in there and any further leakage should be spotted early on.
Title: Re: Rubber u-joint boot for EV1100
Post by: guzzisteve on October 16, 2025, 06:28:11 AM
The oil can transfer from front to back, my Cal2 does this! Even though the sealed bearing holds in it's lube the splines of ujoint & driveshaft let the oil pass. Level in my trans goes down & rear drive goes up.
Title: Re: Rubber u-joint boot for EV1100
Post by: Moparnut72 on October 16, 2025, 07:18:20 AM
The swing arms on the /5's also had oil in the swing arms. The final drive seal failed on mine which resulted in an over filled rear drive rather then the other way around. With the short framed bikes the swing arm pointed downhill quite a bit which also "helped" with the jacking effect. Anyone who complains about the jacking and torque reactions on a modern Guzzi should go ride an early Airhead. Sorry for the thread drift.
kk
Title: Re: Rubber u-joint boot for EV1100
Post by: n3303j on October 16, 2025, 07:52:34 AM
The oil can transfer from front to back, my Cal2 does this! Even though the sealed bearing holds in it's lube the splines of ujoint & driveshaft let the oil pass. Level in my trans goes down & rear drive goes up.
Last U-Joint I bought for T3 had blind spline holes. It was an intimate fit in the carrier bearing so there was no oil transfer. OTOH I overfill final drive. Oil is good. More oil is gooder. Doesn't leak past seals. Doesn't overheat. So I'm guaranteed full lubrication.
Title: Re: Rubber u-joint boot for EV1100
Post by: guzzisteve on October 16, 2025, 08:30:08 AM
believe as you wish.
Title: Re: Rubber u-joint boot for EV1100
Post by: n3303j on October 16, 2025, 09:11:48 AM
believe as you wish.
Believe nothing.
100,000 miles actual experience seem pretty conclusive.
Your results and your machines may vary.
Title: Re: Rubber u-joint boot for EV1100
Post by: nwguy on October 16, 2025, 09:20:44 AM
Interesting stuff. Good to know.

I've only put a few hundred miles on my Bassa after doing a lengthy restoration since April when I bought it. During that I did pull the shaft, clean everything, and reseated the main bearing after punching some divots in it with a metal punch so it wouldn't rotate. Guess I get to do that again.
Title: Re: Rubber u-joint boot for EV1100
Post by: n3303j on October 16, 2025, 09:23:16 AM
Interesting stuff. Good to know.

I've only put a few hundred miles on my Bassa after doing a lengthy restoration since April when I bought it. During that I did pull the shaft, clean everything, and reseated the main bearing after punching some divots in it with a metal punch so it wouldn't rotate. Guess I get to do that again.
What "main bearing" are you putting divots into with a punch?
Title: Re: Rubber u-joint boot for EV1100
Post by: guzzisteve on October 16, 2025, 09:51:50 AM
I'm not here to boast on my bio but some here know it.