Guibo Service

HEY GUIBO!
Gary Davidson
Roadrunner Chapter
Reprinted in the Windy City BREEZE
March 1996

Guibo Time: The guibo is a part that doesn't draw much attention, until it fails. If caught in time, it is a relatively simple 2-3 hour job for the average or even beginner BMW owner. No special tools are required other than simple metric hand tools.

The guibo is a rubber compound, doughnut-shaped device located between the output shaft of the transmission and the input of the driveshaft. Simply stated, it absorbs the shock of gear changing, acceleration, etc. Without it, other part should have to be much larger and heavier, and your bimmer would shake like a track.

Every BMW owner should make a point of examining the guibo periodically, especially if the car has more than 60,000 miles or is more than four years old. The symptom of a failing guibo is vibration from the transmission tunnel area. If you feel such a vibration, I recommend that you stop as soon as is practically possible. If the guibo is allowed to fail completely, serious damage can be done to the transmission and/or driveshaft.

When you purchase a new guibo, you'll notice that there is a metal band surrounding the outside of the guibo. This must be left in place to facilitate reassembly. The last step upon reassembly is removal of the strap.

Guibo replacement:

1) The car must be at least 10 to 12 inches off the ground using sturdy jackstands or a hydraulic lift. Take care to ensure that the jackstands are on a secure position on either the factory jack points or stable portions of the subframe. Never put a jack or jackstand under the floorpan or suspension pieces. These parts will bend under load.

2) Do a thorough survey of the driveshaft before beginning. Pay close attention to the center hanger bearing. It is located near the center of the two-piece driveshaft. Obvious cracking, distortion, or deterioration are what you are looking for. An obviously failing center hanger will allow the driveshaft to sag or otherwise assume a non-linear appearance.

If the center hanger bearing requires replacement, I generally recommend that the driveshaft be removed and taken to an experienced BMW mechanic for repair. The driveshaft must be marked, disassembled and reassembled exactly as it was balanced at the factory by methods usually unavailable elsewhere.

3) To remove the guibo or driveshaft, begin by disconnecting the exhaust at the junction between the downpipe and the center hanger mounting bolts to allow the driveshaft to flex for removal. The guibo is affixed to the driveshaft by four 2 3/4" 17mm bolts and in turn attached to the transmission flange by four of the same bolts. When purchasing a guibo, I recommend that you purchase eight new nuts. It is not recommended that you reuse the old nuts as they may back off in use. Remove the nuts that hold the driveshaft to the guibo. Pull the driveshaft rearward until free from the centering tab of the transmission output flange. Swing the driveshaft to the side and remove the nuts fixing the guibo to the transmission flange.

Reassembly is the reverse: everything snug and tight. Be sure to remember all washers, and Loctite or similar compounds aren't a bad idea either. Hard driving and hot climates are hard on rubber. I recommend that before you finish the job, take a small strip of rubber of cloth braided hose (fuel line hose is ideal), put just a little adhesive on it and put it inside the area where the center bearing will flex. This provides extra support for the rubber and should extend the usable life of the center bearing.