OK, perhaps not the type of donut you enjoy with a coffee but, the giubo AKA flex disk, flextor, Boschi joint or, rubber donut, is certainly something you should pay close attention to.
So what is it exactly? The giubo is made from flexible synthetic rubber and is designed to allow some angular misalignment and reduce driveline vibration. The giubo is not an exclusive Alfa Romeo part. Although it is believe to have been first used on an Alfa Romeo 1900, other European car manufacturers were quick to follow suit. One thing for sure, it is an Italian invention. In fact, the term giubo is a contraction of the Italian word giunto (‘joint’ or ‘coupling’) and the surname of the Italian engineer who designed and patented the first flex disc, Antonio Boschi.
You might be glad to learn that little bit of trivia but yet ask yourself “ Why should I care?”. I now invite you to watch the following video of a giubo disintegrating while driving.
And now you care. A lot. You can just imagine that the driver was likely wishing he had worn his brown trousers. A failed giubo could cause very serious damage to your car and perhaps even personal injury.
I always like to do a thorough inspection of my cars before storing them for winter. I then make a list of the work that needs to be done and hopefully have time to tackle the list over the winter months.
As you can see, my giubo was definitely showing some stress cracks and wear. I decided this was a high priority repair and added to my ever growing car part shopping list.
Installation is fairly straight forward and definitely within the capabilities of a backyard mechanic like myself. As you can see, brand new giubos come with a metal strapping that compresses the rubber. Whatever you do, DO NOT remove the strapping before installation!
After loosening the 6 bolts that attach the giubo to the drive line, I proceeded to detach the drive shaft from the differential after carefully marking the alignment with a bit of paint. I also unscrewed the drive shaft support bearing to allow the whole assembly to move towards the rear of the car to allow removal of the old giubo.
Don’t forget that this rubber is compressed. You can use a hose clamp to compress the old giubo to facilitate removal.
Installation is the exact reverse of removal. Once everything is torqued into place and driveline is all reassembled, you can then remove the metal strapping.
Here’s what my old giubo looked like. Caught it just in time. This would have definitely caused a breakdown likely in the most unfortunate moment.
In the end, no matter what you call it, keep close attention to your giubo. They are inexpensive, fairly easy to replace but could save you from a world of hurt.