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Peter Krause held an excellent tech session for nine very interested Alfisti on the subject of driveshafts—items unique to Alfas in their design with the cast rubber doughnut couplings known as “Giubos.” Peter started with the six cylinder models which are quite similar to the Alfetta and the Sport Sedan drive trains. The first usage of the De Dion suspension in Alfas was in the 8C 2900 and the tipo 159 race car, per Luigi Fusi. The De Dion axle arrangement dates back to the 1890’s, where it was used in cars to reduce unsprung weight, and to keep the driving wheels parallel with constant camber (usually zero) to keep them perpendicular to the road. The concept was patented in 1894 by Albert, Comte de Dion and Georges Bouton. Because of the geometry of the system, the flex-joints are required. Only some high performance cars used the De Dion arrangement, due to the high cost of the design.
The driveshaft is divided into two sections, coupled with a giubo in the center of the design, bolting both halves together. This is mounted behind the center support at the rear end of the front driveshaft section. At each end of the assembly there are giubos connecting to the driveshaft-to-clutch yoke in the rear and to the flywheel-to-front coupling at the engine.
The giubos are the usual items to fail. They are constantly stressed to transmit engine torque to the clutch flywheel in the rear mounted clutch/transmission/differential assembly. The giubos absorb rotational shock and allow the flexing of the driveshaft in other planes. They are made of cast rubber with inserts for the connecting bolts. The giubos have casting marks showing the date of manufacture and usually fail by loosing a chunk of rubber from between the mounting bolts, due to stress cracks developing over time. You can reasonably expect to have to replace giubos every three to five years. The failure is accelerated by usage and age. We all know that rubber hardens and looses resiliency with time, and it certainly has been true of Italian rubber. You should be able to inspect your couplings and note cracks, and certainly broken sections. The problems are usually evident from driveability clues, such as vibrations at different speeds. A very serious problem associated with partially broken giubos is accelerated wear of the nose ends of the driveshaft, causing support bearing wear and possible distortion of the bearing shaft end in the driveshaft nose or the end where the support bearings are. This wear can cause vibrations at certain speeds due to either (or both) worn bearing races or a bent end of the shaft. This causes an elliptical or off-center rotation, “whipping up” vibrations.
The best way to replace driveshaft giubos is to remove the entire driveshaft assembly and do the work “out of the car”. This also allows easy checking of the bearings at each end for wear and inspecting the center support bearing assembly. It is most important to mark the center giubo mountings so you can maintain the same relationship between the two driveshaft sections (use a punch AND white-out). Marking the front and rear giubos is not critical, since they are connected to the engine and clutch couplings, not to the other driveshaft. Removal of the driveshaft assembly is not easy, but with care it is within the home mechanic’s scope. The best way to do the job is to remove the rear muffler section the heat shield, unbolt the shift linkage rod from the bottom of the gearshift lever, and remove the cross member from under the driveline (only the Milano has a removable cross member). Loosen the nuts at the rear and forward giubos. It helps to have someone depress the brakes or put the car in a high gear to keep the driveshaft from turning.
Loosen the center support bearing bolts. Different giubos have bolts of different lengths, so keep them straight. Now, by jacking up the De Dion tube, the assembly is tilted forward and after finishing the giubo bolt removal you can slide the driveshaft assembly forward down and back for removal.
The center giubo, which you have marked for proper realignment, may be unbolted so the front shaft propeller assembly can be taken off to get to the center support. The yoke is held by two thin nuts which are very vulnerable to damage, so be very careful not to burr or damage the threads. Now the center support can be removed and inspected. The usual wear mode is not breaking of the rubber insert holding the bearing assembly but a sagging down so the bearing is not centered in the support. (A good time to probably replace it if the sag is evident). [To replace the center support bearing, you’ll need a gear puller or press and a 32mm deep-well socket. A 1-1/4 inch 1/2 inch drive deep-well socket will also work (available from Home Depot). The torque wrench setting for the 32mm nuts is 72 ft.lbs. Ed.]
The Milano and the GTV-6 use the same front and rear giubos, but different center ones. The giubos come with a band around the perimeter which allows for the bolt installation, and shouldn’t be removed until the final steps, after the bolts are secured.
Speaking of the giubo bolt and nut assemblies, Fred Di Matteo has written that he has seen different thickness washers and doubled up washers used in giubo assembly, for balancing purposes. Peter said that he has never run into this, so be aware of the possibility and note so if found. There is normally one washer per bolt under the nut. Keep the nuts and bolts together because of their different lengths front and rear. Note that the old giubos have dust shields to keep dirt and moisture out. Replace the seals for proper wear protection. New giubos do not come with seals, use the old ones or order new ones if necessary. After Checking for wear on the components and replacing any worn bearings, etc. its time for reassembly.
When reinstalling the driveshaft assembly, don’t bolt everything up tight at first. This allows for alignment of the bearing sleeves and center support, and checking for proper free play. Do not forget to lubricate the driveshaft bearings and sleeves on reassembly. Pay particular attention to the splined shaft at the engine end, it only goes together in one way due to a flat key, but it must be lubed. When you are certain components are aligned and properly placed, bolt everything up according to specs and be sure you removed the giubo metal assembly bands. Usually the bands come off easily by breaking off a special tab.
Be sure you are ready for the job if you plan to do it yourself. A competent Alfa mechanic will require five to seven hours to do a driveshaft rebuild and replacement. Also be aware that no Alfa manual gives complete instructions for this job. I have found decent instructions included in the following sources:
Special thanks to Peter Krause for a great tech session.
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