How to Diagnose a Faulty Flex Disc/Guibo

Video tutorial on how to troubleshoot a faulty driveshaft flex disc. For this particular video, I will be using my 1997 BMW 540i. A flex disc, also known as a guibo is a rubber damper between the transmission flange and driveshaft flange which allows for a smoother driving experience. It dampens take offs, accelerations, changes between gears, and when you remove your foot off the throttle. As you can see this is the rubber flex disc. Over time with age the rubber will eventually deteriorate causing a failure. They will even dry out, become hard, crack, and fall apart in a worst case scenario. I’ll show you the old flex disc in a moment. A faulty or failing flex disc will cause a vibration, this can be found under acceleration at certain speeds or depending on how hard you are accelerating and at higher speeds. As the speed or acceleration increase, the vibration will become worse. At first I had a very mild vibration under hard acceleration and it became significantly worse within a few hundred kilometres. The vibration was noticeable in 2nd and 3rd gear at first, after that I wasn’t able to drive about 50km or 30mph without feeling a vibration. The vibration can be felt throughout the whole car, regardless if my foot was on the throttle or not and having the clutch in or out didn’t affect it either as the driveshaft is always turning. My car has about 260,000km or about 160,000 miles, so it’s hard to say if this is the original part or if it has been replaced at some point. Now here is the old flex disc. As you can see it’s still in somewhat good condition just glancing over, but upon closer inspection you can see cracking throughout the surface. The cracks cause a structural integrity issue which is why the vibrations happen. For replacement, it’s important to use an OEM part or if you know the manufacturer who made it for this vehicle, use that brand instead which may save money than directly buying a part from the dealer. For BMW, FEBI makes these flex disc, but this may vary between years and models. It’s virtually identical, the only real difference with the FEBI part is that the BMW emblem appears to be sanded off.