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1991R100 GSPD Drive Train Problem

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david Swanson
 9515
(@9515)
Posts: 6
Active Member
Topic starter
 

I hope every one is having a great thanks giving today and you don't burn the turkey! 

 

My 91GSPD has a drive train problem I can not determine if it is related to drive shaft  or real differential axle. The transmission has been rebuilt by Ted Porter and when i put in the clutch the issue of clunking or vibration continues so i dont think the transmission is the problem.

One Clue, a month ago when i would get to work in SF and go to my parking space i coast down hill on the ramp. Now i noticed a kind of vibration when i turned to the left to get to the motorcycle parking (motor not in gear).   Later i went to sacramento to visit a friend an on the way i noticed some slop between gear changes when i re engaged.  Next on the way home that day i was just getting on to the freeway and it sounded like i was dragging something like a crushed can on the pavement.  I pulled over and  looked nothing was caught underneath.  Then when i restarted where was clunking sounds and i knew some problem existed that would prevent my journey home.  I returned to my friend's house who had a trailer to tow bikes and he returned me and the bike home.  I just checked the Clymer BMW manual and could not see any instructions for discovering whether my problem lays with the drive line or rear diff axle. I would like to know which is was or what to check to see which is the problem part.  I suspect the rear dif axle as it was in turning i first noticed the problem. any suggestions how to proceed appreciated. Swanny

 
Posted : 11/26/2020 14:01
Richard W
(@wobbly)
Posts: 2549
Member
 

I take it this is a single-sided rear end. Almost all the load is carried by a huge 6.5" ball bearing. The health of that bearing also determines the fit of the much smaller RS tapered roller bearing. With any combination of: age, mileage and/or lack of maintenance, that big bearing can/will go bad. The last one I replaced was an 1988 RS with 80K road-only miles.

In the beginning the wheel shows about 1/16" of play at the rear wheel rim. Sort of a clunk-clunk when the wheel is push-pulled from the side. When the bearing gives up, the balls pop out and then lodge between the pinion and ring gear, which instantly stops ALL forward motion for the entire bike... no matter how fast you are going at the time. 

A pal's Oilhead GS gave up at high speed in the "fast lane" on the interstate in Atlanta. That left a 30 foot black mark as he wrestled it to the center wall emergency lane. Then he spent 2 hours sitting atop the dividing wall with 6 lanes of traffic on each side, waiting on the local BMW rescue truck to arrive. He had to buy an entire final drive assembly.

All the best.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 11/26/2020 17:29
david Swanson
 9515
(@9515)
Posts: 6
Active Member
Topic starter
 

The tires Metzeler dual sport type so not aggressive tread.  No slop when moving the wheel side to side.  I will be getting to the GS in a couple of weeks thanks for the ideas. I am hearing noise in the drive line area when i move the wheel by hand while on the center stand.  

 
Posted : 11/28/2020 09:03
david Swanson
 9515
(@9515)
Posts: 6
Active Member
Topic starter
 

ok I found the problem was a toast ujoint in the non repairable drive line.  I decided to go with the Ted Porter Beemer Shop's upgraded repairable Drive line offering plus the upgraded bottom Pivot bolts that include Zerk fitting so you can lube this.  I dropped the drive train off at AirHead Adventures in  Redwood City CA with the new driveline and pivots  For Greg to do the the installation there.  By the way what a cool place! Greg is a Supporter of this Club has the Airmail club mag available and it is like a museum to see all the bikes he is restoring there.  So i am picking up the completed up dated drive train today.  It turns out that the 1990's BMW R100GS is noted to be prone to have drive line failure if driven two up loaded off pavement like mine was. Note there is a facebook group for the BMW R100GS owners only and i asked there for feed back on the new Drive line that Ted Porter offers and got very positive feed back from 5 people who had used it; so that was reassuring as it is $700+ with the upgraded Pivots and tax.  i would have posted a picture but the tool to add photo would not accept my photo which by the way is less than 10MB

 
Posted : 04/15/2021 10:14
Richard W
(@wobbly)
Posts: 2549
Member
 
Posted by: @9515

I would have posted a picture but the tool to add photo would not accept my photo which by the way is less than 10MB

Photos are always best hosted offsite. That makes it simple and easy, with no limitations.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 05/04/2021 13:08

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