• 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!
  • 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.
  • 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.
  • Like the new V100, GuzziTech is full throttle into the future! We're now running on an all-new server and we've updated our Forum software. The visual differences are obvious, but hopefully you'll notice the super-fast speed. If you notice any glitches or have any issues, please post on the Site Support section at the bottom. If you haven't yet, please upgrade your account which is covered in the Site Support section or via the DONATE tab above, which gives you full site access including the DOWNLOADS section. We really appreciate every $ and your support to keep this site ad-free. Create an account, sign in, upgrade your account, and enjoy. See you on the road in 2024.

97 Sport 1100i driveshaft vibration

S

Spaghetti Western

Just got it firing!
Joined
Jun 17, 2019
Messages
11
Location
the west
Greetings!

I am chasing a harmonic (i.e. periodic) vibration felt through the seat and foot pegs that is drive line related - feels just like a car/truck that has a bad u-joint that is allowing the drive shaft to oscillate. It only occurs from 70 mph and up.

After tear down I discovered that while the front u-joint is securely clamped to the trans output shaft the rear u-joint is not clamped down but is free to slide fore and aft on the rear drive input shaft. As such, it has a little play that allows it to rock on its axis.

Since this is the most likely cause of the issue (yes, the u-joint yokes are correctly aligned/phased/installed according to the FSM) I want to tighten it down but I can't budge the socket head screws with a long arm Allen wrench in either direction.

Does anyone know if the factory uses red Loctite on these?

TIA
 
All the exposed shafts I serviced had blue on them, many stuck allens. 1/2" breaker bar w/allen socket is the way to go.
 
V700Steve said:
All the exposed shafts I serviced had blue on them, many stuck allens. 1/2" breaker bar w/allen socket is the way to go.
Click to expand...

Ok, thanks. I'll give that a try.

Do you know if applying a little heat to the yoke would soften the blue? I know that is the trick for red.
 
V700Steve said:
Localized on the threaded coupler, careful there is a seal close by.
Click to expand...

Ok, got it apart using a 3/8" breaker bar, threads all cleaned up and test fit shows it gets real snug @39 NM (4 KGM) so might try a little tighter but am approaching the max.

Assuming it is supposed to be clamped down, is it supposed to be spaced a little bit away from the snap ring on the drive input shaft?
 
I can't remember if it's in that far against the snapring. You need to make sure the shaft has clearance to u-joint under all circumstances. The farther it is on shaft the closer the shaft is to rear u-joint.
 
V700Steve said:
I can't remember if it's in that far against the snapring. You need to make sure the shaft has clearance to u-joint under all circumstances. The farther it is on shaft the closer the shaft is to rear u-joint.
Click to expand...

Of course, the FSM says nothing about that, but with it slid up against the snap ring the drive shaft swings far enough that the yoke attached to the drive shaft contacts either the rear drive input yoke or the u-joint shroud. In other words, it does not contact the rear drive input shaft when swinging in either direction.

So that is where I positioned it. With fresh blue Loctite and clean threads when torqued to 39 Nm most of the slop was gone but it still would slide on the splines. Since the bolts are 12.9 I gritted my teeth and cranked the bolts down at 45 Nm and now it is tight.
 
Ok, finally got it all back together, did a test drive and the harmonic vibration is gone. Case closed.

For the record, the zerks are all pointing in the same direction, as shown in the FSM, as this ensures correct phasing of the u-joint yokes.

Thanks for the help!
 
You must log in or register to reply here.
Back
Top