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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: DaveyJ. on April 02, 2013, 01:49:15 PM

Title: K75 Gear whine
Post by: DaveyJ. on April 02, 2013, 01:49:15 PM
Hello fellow riders. I'm new to the forum. Why I'm posting is I just bought my first beemer. A beautiful and well maintained 95-K75 with 38,000 miles on her. I've ridden and owned alot of different bikes through the years but this is my first BMW. I was excited and could'nt wait to go for putt. After changing all fluids, plugs, wires, tires and filters, I hopped on and took off. The bike runs great. Plenty of power. Super smooth engine and shifting. Very comfortable riding position. Everything perfect for a 13 year old bike. EXCEPT- Man, When this bike reaches 3500 rpm there is a high pitch, ear drum ripping gear noise! I wear a full face helmet and the noise is so uncomfortable at that time, it is not enjoyable to ride. The reason I say gear noise is as soon as you let off the throttle the noise will quickly start to dissapaite. Throttle up to 3500 again and there it is. I've read a little on this problem with this specific bike and it seems some say this is a normal gear whine. Is it? Can I get this noise to go away by useing a different viscocity trans. oil? I'm hoping someone here can lead me in the right direction. I want to keep this bike but if I can't get this noise to calm down, I will sell the bike and try another model. I don't mean to whine about my whine, but please help!!!! Thanks
Title: Re: K75 Gear whine
Post by: johnny on April 02, 2013, 02:30:13 PM
greetings daveyj....

welcome to motobrick.com...

does it only do it in first gear at 3500 rpm...

j o
Title: Re: K75 Gear whine
Post by: DaveyJ. on April 02, 2013, 02:37:12 PM
Hey Johnny, Every gear. Seems more pronounced when your cruising in 5th. thanks
Title: Re: K75 Gear whine
Post by: johnny on April 02, 2013, 02:39:07 PM
greetings...

does it go away above 7,000 rpm...

j o
Title: Re: K75 Gear whine
Post by: DaveyJ. on April 02, 2013, 02:45:13 PM
I cant remember if the bike does 7000. but, as long as your appling the juice to it, its not there. Appling or letting off the throttle, the noise is not noticable so much. Almost like a tubo whine. It kind of sounds cool any other time untill 3500 then it is really high pitch.
Title: Re: K75 Gear whine
Post by: DaveyJ. on April 02, 2013, 02:54:31 PM
I am allmost sure that tere is a gear mesh problem. When I was a kid I rebuilt the rearend in my 83 duster and did not set the ring and pinion clearance properly and the car made a noise close to what I'm hearing on this bike. Any mesh problems with these bikes?
Title: Re: K75 Gear whine
Post by: TimTyler on April 02, 2013, 04:37:17 PM
1995...  ... perfect for a 13 year old bike.

She may look 13 but she's 18 for sure.  :yes

Put the bike on the center stand and rev the engine with the transmission engaged and then disengaged. You'll be able to  determine if the whine is really from the transmission.
Title: Re: K75 Gear whine
Post by: DaveyJ. on April 02, 2013, 04:44:07 PM
As soon as I get a chance, I'll give it a try. Thanks
Title: Re: K75 Gear whine
Post by: Kyle10 on April 02, 2013, 04:59:24 PM
DaveyJ, take a look at this attachment. A recommended revision issued by BMW re the output shaft.

Thinking of doing this myself.
Title: Re: K75 Gear whine
Post by: johnny on April 02, 2013, 05:11:41 PM
if it were me i would do this...

take it to the red line in every gear... hold it on the red line for at least one minute in each gear before shifting to the next gear... while on the red line in 5th after one minute turn it off by the kill switch and pull in the clutch simultaneously... once stopped reverse route and repeat... then i would ignore the whine and ride it till it wont move...

j o
Title: Re: K75 Gear whine
Post by: cy7878 on April 02, 2013, 07:46:31 PM
if it were me i would do this...

take it to the red line in every gear... hold it on the red line for at least one minute in each gear before shifting to the next gear... while on the red line in 5th after one minute turn it off by the kill switch and pull in the clutch simultaneously... once stopped reverse route and repeat... then i would ignore the whine and ride it till it wont move...

j o

I thought it's April 2nd....


Title: Re: K75 Gear whine
Post by: johnny on April 02, 2013, 11:28:02 PM
if you aints revving on the red line... you aints riding...

j o