vibrations

[baurcorp]

Hey guys,
Can anyone tell me what is happening with my LT? At approximately 80 to 90 mph. the front end or somewhere else it starts to vibrate. the other morning at 35 mph I let go of the handle bars and the front started to shimmey. Is this a front end thing or am I into something major? Jeff replaced my front tire 3-4 weeks ago. the tire had 4,000 miles on it, it had cupping down the center of the tire. He told me it was from low pressure so I have been watching this one to make sure I didn't make the same mistake. running 42 psi on a Metzler ME 880. I believe it is starting to cup thyis tire as well.

[Texas42]

It`s your tires. Mine wad doing the same. I changed the tires and it stoped.

[blouw]

Did you check the back tire??

[astuber]

At 80-90 MPH is the engine turning at 4500 RPM?

Engine vibration at about 4500 RPM is a common problem and I believe is related to the exhaust system. It is usually confined to a relatively small RPM range and doesn't cause any problem that I am aware of. Most people just stay out of that range and there are no problems.

The front end shimmy is also a common problem and seems to be tire dependent. BMW's response is to keep one hand on the handle bars at all times. Not much of an answer in my opinion.

[baurcorp]

At 80-90 MPH is the engine turning at 4500 RPM?

Engine vibration at about 4500 RPM is a common problem and I believe is related to the exhaust system. It is usually confined to a relatively small RPM range and doesn't cause any problem that I am aware of. Most people just stay out of that range and there are no problems.

The front end shimmy is also a common problem and seems to be tire dependent. BMW's response is to keep one hand on the handle bars at all times. Not much of an answer in my opinion.

It seems that Lone Star has the solution at hand, or my bike I should say. The rear bearing is apparently the problem. Seems it started vibrating at most speeds this weekend so when we went to Denise's thing they kept my bike. I'll suffer thru it by riding my Yamahammer Royal Star. I guess it could be worse, I could be penned up in a cage driving to work!
Thanks for the help to all!

[blouw]

It seems that Lone Star has the solution at hand, or my bike I should say. The rear bearing is apparently the problem. Seems it started vibrating at most speeds this weekend so when we went to Denise's thing they kept my bike. I'll suffer thru it by riding my Yamahammer Royal Star. I guess it could be worse, I could be penned up in a cage driving to work!
Thanks for the help to all!
Did they say which rear bearing? There are more than a few back there. Would be good to know for future reference.

[baurcorp]

Did they say which rear bearing? There are more than a few back there. Would be good to know for future reference.

Seems that Lonestar wasn't completely right. They got my bike in and the mechanic really looked into it and they checked out the bearings. They are all OK, seems it was just my tire......... those rubber rings sure can get a guy frustrated! I applaude Lonestar once again, excellent job and they didn't screw me buy doing something that didn't need to be done for the sake of a few extra dollars! AND .... They squeezed me in on an already overbooked schedule cause that's my daily driver!!!! KUDOS LONESTAR KUDOS!!!!!!

[davemoore]

At 80-90 MPH is the engine turning at 4500 RPM?

Engine vibration at about 4500 RPM is a common problem and I believe is related to the exhaust system. It is usually confined to a relatively small RPM range and doesn't cause any problem that I am aware of. Most people just stay out of that range and there are no problems.

In case you didn't see previous posts on this topic, you can greatly reduce this vibration by throwing away the exhaust hangar bracket that connects from center stand to mid-exhaust. The bracket exacerbates a resonance that eventually causes the cat converter-to-muffler weld joint to separate (happened to me and others). Eliminating the bracket may seem contraindicated, but there seems to be no bad juju when you do. Heck, Dick Largen's bike didn't come with a bracket there, and he has 100k+ miles on his original pipes.

[McRuss]

1. Baurcorp, was it the new front you just put on 3-4 weeks ago? That doesn't sound right, I got 14k out of my first 880, no cupping, got the same on the second plus a few, still no cupping. More info please.

2. Dave, is that a dog-bone shaped connector? Is it the same for the '05s? Ya know, our c-stands are a tad different (less work involved in deployment for one thing........)

[davemoore]

1. Baurcorp, was it the new front you just put on 3-4 weeks ago? That doesn't sound right, I got 14k out of my first 880, no cupping, got the same on the second plus a few, still no cupping. More info please.

2. Dave, is that a dog-bone shaped connector? Is it the same for the '05s? Ya know, our c-stands are a tad different (less work involved in deployment for one thing........)

Don't know, Russ - good point. I never looked at an '05 up close. I don't know if dogbone is the right description- it'a metal cylinderwith a heavy wire extension as I recall (on the '01).

[baurcorp]

[QUOTE=McRuss]1. Baurcorp, was it the new front you just put on 3-4 weeks ago? That doesn't sound right, I got 14k out of my first 880, no cupping, got the same on the second plus a few, still no cupping. More info please.



It was the rear tire I had to replace. The front is still ok. I was told that the "Factory" air pressures stated are way too low.
The front was at 36psi for 4K. Rear at 42 psi.
I'm now running 43psi in the front, and 48psi in the back. This should increase my handling and longevity of the tires. So far it's working. I talked with a brother from Canada and he runs 44 front, 49 rear. He said it keeps his tires good for over 12,000.
The vibration is not a sound, it is felt in the front end. I have been experimenting with the windshield height and have found that the taller I ride it at high speeds the less the vibration is. I'm still trying to figure that one out but it is better witht the windshield up!