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Pelican Technical Article:

Replacing the 3-Series
Guibo / Flex Disc

Difficulty Level: 5
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

     This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.
 
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[click to enlarge]


Figure 1


Figure 2


Figure 3


Figure 4


Figure 5


Figure 6


Figure 7


Figure 8


Figure 9


Figure 10


Figure 11


Figure 12


Figure 13


Figure 14


Figure 15


Figure 16

     In-between the transmission output shaft and the driveshaft, there is a flexible coupler that joins the two together.  This rubber, reinforced coupler isolates vibration from the rest of the drivetrain, while transferring power from the engine and transmission to the rear differential and wheels.  As the car ages, and is exposed to the elements, these discs (or guibos, as they are sometimes called) develop cracks and begin to disintegrate.  The rubber shell is reinforced with rope cords on the inside, and it is not uncommon to see one completely fall apart with the cords flying everywhere.  I recommend inspecting this rubber joint about every 10,000 miles or so (about once a year) to make sure that it still looks okay.  If it fails, it does have the potential to leave you stranded.

     Replacement is not too difficult, but it does require that you take a few things apart to reach the flex disc.  Begin by raising the car off of the ground and supporting it on jack stands.  See the Pelican Technical Article on Jacking Up for more information.  The next step is to remove the muffler and catalytic converter.  I have found that it is best to disconnect the entire rear exhaust system from the forward flange and drop it as a single unit.  This actually sounds a lot harder than it really is - disconnecting the exhaust is really quite easy.   See the Pelican Technical Article on Muffler Replacement for more details.  Begin by unfastening the small exhaust retainer clamp from the bottom of the transmission.  Figure 1 shows the underside of the car with the small exhaust retainer bracket disconnected from the transmission.  Figure 2 shows a close up of the disconnected clamp.  Then, remove the six bolts from the exhaust flanges near the front of the transmission (Figure 3).  You may want to use some WD-40 or other penetrant on the bolts before you attempt to remove them.  If you have a later-model BMW, disconnect any oxygen sensor wires that may be attached to the exhaust pipes.  Now you should be able to undo the rear muffler clamps and drop the entire muffler/catalytic converter assembly.   Be aware though - this whole assembly weighs about 50 lbs, so exercise caution as you loosen clamps and bolts, and drop the entire system down.

     With the exhaust removed and out of the way, remove the light heat shield that covers and protects the underside of the car.  This heat shield is made out of an aluminum-foil type of material and can be easily unfastened from the underside of the chassis.  Although not 100% necessary, I recommend removing the lower transmission support bar at this stage - it will make access to the flex disc a lot easier (Figure 4).  See the Pelican Technical Article on Replacing your Transmission Mounts for more details.  By the way, it's also a great time to replace your transmission mounts while you have easy access to this area.

     Using some paint or white-out, mark the transmission output flange and the driveshaft to clearly indicate which flanges connect to each other when you reassemble the unit.  Place a mark at the point indicated by the arrow in Figure 5, and also another mark in the same place on the opposite side of the flex disc.  This will help you align the driveshaft with the transmission output flange later on.  Also in Figure 5, you can begin to see the flex disc start to fail - small surface cracks have appeared in the rubber.  Now, remove the bolts from the flex disc (Figure 6).  There should be six total, and they all might not be very easy to get to.  You will need a deep socket and open-ended wrench in order to get to them.  You will also need to rotate and lock the driveshaft as you work.  Release the parking brake and take the transmission out of gear, then use your hand to rotate the driveshaft so that you can reach the bolts and their corresponding nuts, and then re-engage the parking brake.  You will have to rotate the driveshaft three or four times in order to remove all of the bolts.

     Now, turn your attention to the rear end of the tunnel.  Remove the small cross-brace that spans the driveshaft tunnel (Figure 7 and Figure 8).  This will allow you to drop down the driveshaft and remove it from the transmission flange.  Turn your attention to the rear driveshaft bearing (Figure 9).  Remove the two nuts that secure the bearing to the chassis (Figure 10), while holding up the driveshaft with one hand.  When the nuts are removed, you should be able to drop down the driveshaft and remove the shaft from the transmission output flange.  Support the driveshaft using a jack stand.  On some cars, you may need to completely disconnect the center driveshaft in order to remove the flex disc.  If you can't seem to get enough clearance to remove the flex disc, then follow the procedures in our Pelican Technical Article: Rear Driveshaft Bearing Replacement.  Figure 11 shows the transmission output flange with the flex disc removed.

     Now that you have access to the flex disc, completely remove it from the driveshaft.  Figure 12 shows a flex disc that is getting very close to failure.  Since you have access to this area, now would be an excellent time to replace and replenish your shift bushings, or to install a short shift kit.

     Figure 13 shows a brand new flex disc along with new mounting hardware.  For important parts like these, I always try to use new hardware.  BMW recommends replacing the self-locking nuts, but I also like to replace the bolts if they happen to look like they have become slightly corroded.  Take your new flex disc and attach it onto the driveshaft.  If you look closely at Figure 14, you will see that the flex disc has an arrow that is cast into the side of the rubber disc.  This arrow points towards where the flanges are to be mounted.  In other words, the transmission or driveshaft flange will mate against the surface shown with the yellow arrow.  The rule of thumb is that the arrow shows which way the mounting bolts are pushed through the flex disc.

     Torque the bolts onto the driveshaft first, but only if you have enough clearance to get the entire assembly back into the transmission output flange.  Then, move the rubber disc back up to the transmission flange and insert the remaining three bolts, as shown in Figure 15.  Be sure to align the white mark you made on the driveshaft back up with the matching mark you made on the transmission output flange.  This figure also shows the arrow on the rubber flex disc, in this case clearly pointing towards the transmission output flange.  With the flex disc bolts loosely connected, reattach the rear driveshaft bearing.  Push it towards the front of the car as you tighten it down - you want the bearing to have no slack on the rearward side (Figure 16).  When the bearing is reattached, then tighten up the bolts on the flex disc.

     To complete the job, reattach the heat shield, the exhaust system, and any oxygen sensor connectors you may have disconnected.  If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

 

Torque Values

  Bolt Size Bolt Grade Torque Value

Flex Disc

M108.835 ft-lb (48 Nm)
M1010.947 ft-lb (64 Nm)
M128.860 ft-lb (81 Nm)
M1210.974 ft-lb (100 Nm)
M3 - M1210.985 ft-lb (115 Nm)
Driveshaft Center
Bearing Housing		  16 ft-lb (21 Nm)
Transmission Mount
Support		  16 ft-lb (21 Nm)
Exhaust Manifold NutsM10 22 ft-lb (30 Nm)

     This technical article is made possible solely through the support of Pelican Parts.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.

   
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Comments and Suggestions:
JCComments: Hi, thanks for a very informative guide, really appreciate the assistance it provides. Two questions: In the guide in Pic 5 above all the bolts point in the same direction. In Pic 15 the drive shaft bolts point one way and the transmission flange bolts point the other as per the arrows on the guibo. Which is correct? On the one I have just removed all the bolts faced the same direction - towards the transmission. Secondly - should I replace the locking nuts as a matter of course when fitting a new guibo? Thanks.
April 25, 2013
 Followup from the Pelican Staff: You want to bolts go back in how you removed them. Usually I find them all facing forward. - Nick at Pelican Parts
GlhxComments: This does cover some of the 3 series, but not all of them. My 2002 330ci and m3 are not like this.

They have a cv joint at the rear, one universal joint either befor or directly after the center support, and a bolt that goes through the center bearing inside the u joint housing. I would like to see a DIY on that.

There is no locking collar on mine
April 12, 2013
 Followup from the Pelican Staff: Thanks for the feedback. If we get our hands one to perform the repair on, we certainly will. - Nick at Pelican Parts
dr bobComments: Hi,
Not being at all mechanical I have had two quotes to replace the guibo. One mechanic said around 2 hours the other quote $1000 for labour, How long should this job take a m,echanic

Thanks

dr bob
April 1, 2013
 Followup from the Pelican Staff: This depends on many factors. BMW publishes labor guides, however it is only a guide. As a vehicle ages repairs become more difficult and can take longer. Soeak with a mechanic you trust and have them handle the repair. - Nick at Pelican Parts
JimmyComments: For those who have a vibration damper on their drive line:
After you get the exhaust system and heat shield out of the way, and have the entire drive line is exposed, you will see a collar nut right behind the center support, which holds the rear of the driveshaft down. You have to loosen that nut enough where you can slide the rear of the driveshaft forward, thus "shrinking it", this will give you enough space to get the flex joint guibo out of the damper. Of course you will first need to make sure that the nuts that hold the guibo onto the output shaft slip yolke flange of the transmission have been removed. All you need to do from this point is unbolt the center support, bend the driveshaft down from one end at a time starting with the front, and the driveshaft is out. Then, unbolt the remaining fasteners that hold the guibo onto to the front flange of the driveshaft and replace it.
December 29, 2012
 Followup from the Pelican Staff: Thanks for the great tip. - Nick at Pelican Parts
TimComments: Very Helpful Thanks Wayne, I am in the middle of doing this project and ordered parts through you guys. I am actually replacing whole drive shaft due to worn rearward universal joint. I might add that even with penetrating oil and heat the exhaust splined bolts shear off. I had good luck with an air cutoff wheel i fit up there and cut the remaining stud flush with the maifold flange, then drilled them out steping up bit sizes.......i think this may happen more often than not, just so folks are aware!!
July 29, 2012
W TullComments: I have a vibration between 40-50mph with 42mph being the worst, but only when cold. The guibos and center bearing have been replaced. This improved the vibration problem but did not eliminate it. My car is a 2007 328xi coupe, any ideas?
June 17, 2012
eunosComments: @ Delicron, I about to do change this on my 95 328, the guy in the parts shop specifically warned me to align the marks the same and ensure all 6 bolts are put in facing the same way as before, otherwise it's likely to cause a vibration just as you describe. It's also quite possible that a knackered giubo thanks dan s! has caused your center bearing to wear out, or vice versa! I reckon it depends how much time v's cash you have - it you can afford it you might as well change the bearing as you've got to take it apart again anyway and it's likely to be as old and worn as the giubo, or if you want to save a few quid n have the time just take it apart again, put it back together properly cross fingers and see if it's ok. Sounds like the CSB is a proper PITA so it's not just a case of 'doing it at the same time' either. I'm not keen on opening this can of worms myself so might just change my knackered giubo, and so long as the CSB and rear bearings look OK see how it goes for now. Best of luck - we might need it!
April 5, 2012
DelicronComments: Pardon my idiocy, but I followed this excellent guide to the T, but stupidly missed one very important step: I didn't mark the flanges before I rotated the driveshaft off the centering guide. I put it back together, cursing, hoping it would be fine and it mostly is, except for a vibration under load in second and third gear acceleration. Could this vibration be caused by this mismatching? Or can it be caused by and expired Center Support bearing? The Guibo I replaced was nearly in pieces when I replaced it, could the bearing be close to the same and I just didn't notice due to the guibo being in such poor shape? Could I have damaged it during Guibo replacement? Or did my idiocy result in misalignment since the flanges likely aren't lined up to the same holes as before? I purchased a new Center bearing from Pelican and intend to replace regardless, just hoping that I haven't caused additional problems. Thanks for any help you can provide.
April 5, 2012
danComments: HELP!! is there a guibo part that will cross with an 89 ford ranger? Mine says made in GERMANY on it, but I have had zero luck in locating one. ANY help would be GREATLY appreciated.
January 28, 2012
MikeComments: No Doubt your steps, explainations and instructions are very good, but it would be nice if you also include the short step in doing so rather than being so conservative. I replaced my Flex Disc for 1994 E36 without any of the steps above except 1. left the car 2. undo the bolts 3. bush back the rear driveshaft the replace the Flex Disc, the every back as it was without removing any ither thing.
January 12, 2012
goldenComments: Hi friends
I suffer from the problem of flex disk is not strong enough for my car Lumina SS 2006
I want the best and most powerful type... help me please...
January 12, 2012
geoh777Comments: @Char It sounds to me like you have a loose or missing flange nut 30mm wrench size for E30 manual trans. Since it takes a special 30mm socket or an ordinary one with the front outside diameter ground off a bit to tighten the nut properly, maybe the last backyard mechanic didn't get the nut tightened enough, and it came loose allowing the flange to slide on the output shaft splines. If the flange should slide far enough to the rear, the rear trans seal will become ineffective.
November 29, 2011
JonC04Comments: I have a 97 E36 328iC and the thumping noise that I'm getting has become progressively worse to the point that I can't drive it anymore. As I progress through the gears I get a very violent and rapid thump that continues until I let off the gas. I have purchased all of the parts required to do a full suspension overhaul because the noise sounded like it was coming from the rear passenger side. Now my tech thinks it may be a driveshaft issue but isn't very familiar with these. Does it sound like it could be something smaller like a Guibo or could I need the whole driveshaft?
October 23, 2011
CharComments: I recently replaced my Guibo. While everything was apart I noticed that the transmission flange slides front to rear on the shaft. Is this normal?
September 15, 2011
ntwrthyComments: I have a vibration damper on my 1985 e30, I was abel to remove the flex disc but can only acess three bolts because the damper is in the way. I am in the middel of a 1995 m50 engine swap, and this is really messing me up. please help.
June 21, 2011
BryanComments: First let me say, thank you Wayne - for putting all this info up on the web. Suggestion: place rearward facing bolts IN Guibo before installing unit on output shaft. Many times the bolts end up going in the wrong direction because techs or DIYs miss this step. As to whether this job can be done with car on front jacks only - yes it can, I just replaced the clutch in my '94 325ic using only front drive-up ramps - it can be done.
P.S. thanks Pelican, for all the parts and exceptional service and shipping.
February 26, 2011
 Followup from the Pelican Staff: Cool, thanks for the tip! - Wayne at Pelican Parts
1stantheman1Comments: Can this be done with just the front of the car on jacks? I just have 2 jacks. Guess I could remove the muffler end of the exhaust first, then move the jacks to the front?
Thanks for another superb article!
February 11, 2011
 Followup from the Pelican Staff: I suppose that it depends upon how skinny you are, and how high you jack up the front. I've never tried it, but I suppose it might be possible. - Wayne at Pelican Parts
andyComments: I'm having a a audible thump noise coming from below the shifter while the engine is cold . I can feel something hitting the tranny tunnel from underneath ,but when the engine warms up the funny idle goes away and the thump goes away. The noise is also there at times but sounds different like thudering with minimum vibration. I inspect the guibo ,and it looks normal with no crack. My last thought is it the tranny mount ?
January 31, 2011
 Followup from the Pelican Staff: I would normally agree that it sounds like a dissolving guibo. But, these tend to stay noisy when the car is warm or cold. The fact that the noise disappears when it's warm is suspect to me. It may be some type of problem with the transmission, and it just appears like something is hitting the top of the tunnel. If possible, I would put the car up on a lift / rack and see if you can run it cold and look at it underneath while it's making the noise. That might give you some additional clues. - Wayne at Pelican Parts
DiegoComments: any idea how to get guibo off a car equiped with vibration damper. the above mentioned is in the way and only allows me to get 3 of the 6 bolts off.....
June 23, 2010
 Followup from the Pelican Staff: Send me or post a picture here so that I can see what the issue is? - Wayne at Pelican Parts
SteveComments: What are the dimensions of these couplers or, are they universal on the 6 bolt ones? Maybe I can match one up? I have one on a 87 Ford ranger 2wd tk with a German 5spd built trans. and can't find one without buying a complete dual shaft assy. I see many I can buy for other German cars.
June 8, 2010
Dan S.Comments: It might be of interest to note that 'guibo' is actually a misspelling.

The proper term is 'giubo' - a contraction of "giunto" Italian for "joint" and Boschi the surname of the engineer who invented the flex disc.
May 4, 2010
 Followup from the Pelican Staff: Cool. I learned something new today! Thanks for sharing. - Wayne at Pelican Parts
SparkybpComments: Loud vibration under cupholder could be caused by worn drifeshaft center mount, which in turn causes the guibo to get damaged, or the other way around. Regardless, when such a problem occurs I would recomend replacing both from experience.
April 17, 2010
tcseadooComments: I am in the process of replacing the guibo coupling and noticed that the center support bearing is in need of replacement. I have removed the guibo and the front part of the rear driveshaft and left the rear part of rear driveshaft attached to the differential and supported ith a 4x4 sttod on end. Problem I'm having is getting the worn out bearing and the rubber thats stuck to it from the support to come off of the front part of the rear driveshaft. I did remove the threaded sleeve and the snap ring but the bearing does not want to come off. Any suggestions would be helpful as I still need to purchase the support and bearing if they are separate. Thank you.
T C
March 21, 2010
NikComments: @ Linda, the driveshaft is balanced in a certain way. If not installed properly like before, it would cause irregular vibration
January 10, 2010
TomComments: Hi. I recently bought a 1998 318TI and have a few maintenance/repairs to make. One I believe is the Guibo. Under hard acceleration from a stop there is a loud vibration/almost grinding noise from under the trans tunnel in the cup holder area. Does this sound like the Guibo?
December 25, 2009
LindaComments: Why is it so important to mark the flange position? what would happen if I put it back together in a different position?
You say "Be sure to align the white mark you made on the driveshaft back up with the matching mark you made on the transmission output flange."
November 22, 2009
mattComments: It would be awesome to be able to add all the parts to your cart from this page, or at least have links to the different parts. :)
April 21, 2009
 Followup from the Pelican Staff: That is a very good suggestion. This feature exists on the 101 Projects Website, we need to add it to here too. Here's the link: http://www.101projects.com/BMW/Projects/039/parts.htm - Wayne at Pelican Parts
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