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European Car Magazine - GTV6 Project

 

 

Part 10 - Driveshaft rebuild

European Car Magazine - July 1996

Author - Paul Mitchell
Photos by the author

 

Your right foot presses the pedal into the carpet, and your GTV-6 responds by  accelerating hard, yet with a smoothness and aural accompaniment few automobiles can match.  You neatly grab third gear and revel in the smoothness of the torque and the combined screaming notes of intake and exhaust as you  approach 6000 rpm.  
 

The entire driveshaft assembly after removal from the car; on the left is the front flex coupling, followed by the center support.  Clearly visible are the indices we placed in white.

 
Then, out of nowhere, comes the loudest bang that your now speeding GTV-6 has ever produced.  It sounds and feels as if a grenade was planted just under your seat and has gone off.  That's immediately followed by the sound of some wayward but probably necessary part bouncing along between the car and the pavement and out the back.  A vicious new vibration replaces the ultra-smoothness of the 
engine.  

Recovering somewhat from the thoughts of imminent death that raced through your mind, your now perhaps mortally wounded GTV-6 vibrates and shudders, and you pull over to the shoulder.  Under the hood it looks the same as  it always has.  There is no connecting rod protruding out of the bottom of the pan or through the block, nor is a layshaft,  festooned with broken gears, hanging out the side of a shattered transaxle case in the rear.  Puzzled, broken in spirit and in car, you climb back in to what was once a source of pride and limp back home, vibrating worse than a coin-operated motel bed. 

If any of this sounds at all familiar, then you've probably spent enough miles in your GTV-6 to know that what just occurred was a failure of one or more flex couplings on the driveshaft.  Like most European cars, Alfas come with a large rubber coupling at the end of driveshaft, connecting it to the transmission. 
Actually, the GTV-6 comes with no less than three- the familiar front, with additional ones in the center and rear. Don’t feel too smug, Milano owners, your cars, being based on the same platform, are identically equipped, and so the tech procedure presented here applies to you as well.  Only the Spiders, Berlinas and early GTVs come with one at the front of the driveshaft.  

The layout of the 116 and 161 chassis cars, with engine in the front and the clutch located at the rear with the transaxle, requires the driveshaft to constantly rotate at engine speed.  Being a relatively stout and hence heavy piece, the driveshaft is comprised of two halves, joined in the center and fitted with a center support bearing.  These two halves when assembled at the factory are finely balanced, as they must be when rotating at engine rpm; otherwise they would produce extreme vibrations that would shorten the life of both engine and transaxle as well as be  uncomfortable.  The flex couplings, or "guibos" as Europeans choose to call them, serve several purposes: They join the engine to the driveshaft and the driveshaft to the transaxle; importantly, they dampen any vibrations that may occur during use, and they soften the blows delivered to the transaxle by hamfisted drivers.  
 
 

Front flex coupler - showing missing rubber section - no wonder the car vibrated!  The front pilot bushing is also visible in the center of the flex coupling; check it for play.  To the upper right of the flex coupler is the pinch bolt (minus bolt) area of the front yoke

The center support bearing assembly and center flex coupling.  Located between the two is the center yoke affixed to the rear of the front half of the driveshaft.  Again, our painted indices to facilitate reassembly are plainly visible

 
  

Considering their important roles, it's not surprising that they have a limited lifespan, they must be considered wear-related items, inspected on a regular basis.  They should be replaced upon seeing any signs of cracking or tearing, and of course if any pieces are missing.  Additionally,this is also the time to inspect the center support bearing for tearing, sag, or bearing wear, and replace if necessary.  Average life for GTV-6 flex couplings should be approximately 50,000 miles, less if the car has been abused, particularly if previously driven for extended periods with bad flex couplings.  Prices for individual flex couplings are in the seventy five dollar range, as are center support bearing assemblies. Inspection is the key, and replacing the coupling at the first sign of age or wear will not only ensure avoiding the experience described earlier but also keep the expense of maintenance down to reason- 
able levels.  

Neglectful drivers who continue to operate their cars with bad flex couplings eventually will have to purchase a new driveshaft.  Driving the car in this hobbled condition causes the bolts securing the remnants of the couplings to deform the holes in the driveshaft yokes, and this will definitely result in a massive increase in the expense required to put the car right.  

If it's a front or center coupling-the least likely one to go, the yoke itself can be replaced at some expense, but there's a chance that it will also throw the driveshaft out of balance because the new yoke isn't exactly the same as the original.  Try to find a shop which can truly balance a two-piece driveshaft.  If the neglected flex coupling is at the rear or center, again the special holes supporting the shoulder bolts connecting the coupling to the driveshaft and/or the transaxle will be damaged, requiring replacement of the entire driveshaft assembly. 
No simple take-your-chances yoke replacement here; your driveshaft is shot, and it's time to buy a new one.  

Don't take chances with a used driveshaft unless you can personally vouch for its balance.  It may have been serviced and reassembled incorrectly-out of balance.  Some shops and services, such as Alfa Performance Connection and Alfa Parts Exchange, will stand by used parts they provide, and these are the types of sources that you’ll want to use when looking for a used driveshaft or yoke.  To correctly remedy a damaged driveshaft the way Alfa intended and your car deserves, buy a new or factory reconditioned driveshaft; they are fitted with new flex couplings, pilot bearing and a center support bearing and then balanced as a unit.  Available through your dealer or AR Ricambi, the cost is approximately $500 to $600.  

As mentioned before, when servicing the   driveshaft-specifically, when replacing the center support bearing and/or the center flex coupling-proper disassembly and reassembly are key to ensuring the job is done right.  One mistake in any of these procedures, and your driveshaft becomes an expensive new doorstop at your mechanic's shop (in my case, an addition to his “Wall of Shame").  The two halves are joined together by the center flex coupling.  The center support, affixed to the rear of the front half, is secured by the front half rear yoke, which engages splines at the tear of the front half and held in place with a large nut.   It is here that the potential for trouble begins.  Alfa manufactured the shaft with splines that allow the yoke to be installed in any position of rotation on the shaft. As opposed to keyed or offset splines, which allow only one assembly position and thus maintains the factory-set balance. Additionally, the same is true for the rear driveshaft half, it can be assembled in any one of three rotational positions in relation to the front half, thereby increasing the odds that some mechanic, professional or otherwise, unfamiliar with such intricacies or plain incompetent, will reassemble the center yoke and two driveshaft halves out of phase.  Without proper indices or references placed on the driveshaft before disassembly (not likely to be thought of by the uninitiated), your driveshaft is ruined, as it is next to impossible to have it re-balanced, and you could spend a lifetime and a fortune trying all of the assembly combinations possible to regain the original balance. 

Try explaining all of this to the contemptible shop hand who just performed this service, and why because of his incompetence he should now buy you a new or reconditioned driveshaft and see what happens, 

 

Our left handed transaxle mount, showing signs of 13 years of use.  Now is the time to replace as necessary.

 
  

Remember, this is an affordable exotic, not be confused with lesser, more easily erviced proletarian cars.  In Europe, a good example GTV-6 is a very expensive purchase, reflecting more accurately the cars engineering and status.  If you wanted cheap performance, you should have bought an econo-box front-wheel-drive sport" sedan. In the final measure, your Alfa is relatively inexpensive to keep on the road when compared to similar cars, and in this country there are none.   Even the factory service manual is unclear on this procedure, apparently assuming that factory-trained technicians already know the drill.  That's why it's so important to use a reputable shop familiar with the subtleties of your Alfa or learn to do it yourself the right way.  
  

Tools Required 

  • Jack with jack stands 
  • Set of common hand tools 
  • Lever or pry bar 
  • Punches, with some type of permanent paint and brush 

Parts 

  • Flex couplings 
  • Center support bearing assembly 
  • Pilot bearing 

Tech Procedure 

  • After lifting the car and placing it on jack stands, remove the exhaust center-section from the car. Also remove the heat shield secured to the body above the catalytic converter. 
  • At either end of the driveshaft, release the three self-locking nuts securing the shaft to the flywheels.  They will be the nuts facing the center of the car.  Loosen and remove the two nuts securing the center support to the body work. 
  • After pulling down and free the center support, the driveshaft may be freed at either end.  This may require some levering with a pry bar.  Remove the driveshaft from the car. 
  • Clean thoroughly the entire driveshaft assembly and allow to dry before proceeding.  Once dean and dry, place the driveshaft on a bench and locate the center support bearing area, including the center yoke and rear half.  With permanent paint and/or a punch, on clean shaft surfaces, mark exact, in-line indices or references on the front half, center yoke, and rear half.  These must be very precise and exactly in line with each other.  I cannot over-emphasize this point.  It is preferable to use a punch to make deep, permanent indices if your driveshaft had good balance prior to requiring service.  If your driveshaft balance was in the least bit suspect, a temporary set of indices done with paint is preferable.  In either case they must be very precisely done and not removed easily if by paint.  Allow to dry. 
  • Loosen and remove the bolts securing the flex couplings to either end of the driveshaft, and remove the flex couplings.  Inspect the bolt holes for wear.  If found in the front, the yoke may be replaced, but if in rear, the entire driveshaft assembly must be replaced. 
  • Without removing or tampering with the metal bands around front and rear couplings, install the new couplings, insuring that the shoulders of the bolts pass through the yoke, not the Couplings. Tighten the self-locking nuts securely.  Prior to installing the front, inspect and replace the pilotbearing if needed. 
  • Unfasten the center flex coupling and separate the two halves.  With an appropriate wrench or socket, release the nut  securing the center yoke to the front driveshaft remove the yoke by lightly tapping with a soft-faced mallet if necessary.  Inspect the yoke for wear, replace if necessary.  Free and remove the center support bearing assembly, noting the direction of installation.  Install new bearing assembly and yoke with attention paid to yoke index and front have index. Use Loctite spline compound on splines. 
  • Install new center flex coupling while joining front and rear halves in proper alignment as per indices on both halves and the center yoke.  All should be in perfect alignment before final tightening.  Do not release bands around front and rear flex couplings yet. 
  • Working at either end, offer up the driveshaft assembly and lightly secure the center-facing self-locking nuts.  Position the center support assembly and loosely have fasteners in place.  At this point, with self-locking nuts at either end in place but not tight, as well as the center support in the same manner, remove the bands around the front and rear couplings. 
  • With the driveshaft in place but not tightened down as described in previous paragraph, allow car to idle for several minutes to allow the driveshaft to settle in. Do not rev.  Turn off car, and tighten 11 nuts securing the driveshaft.  Replace heat shield and center muffler.  The car may now be driven, and as more miles are put on the car, any  minute vibrations will usually work themselves out as the driveshaft further settles in. 

APC 
22692 Granite Way 
Laguna Hills 92653 
(714) 588-0500 

AR Ricambi 
6644 San Fernando Rd. 
Glendale, CA 91201 
(818) 956-7933 
(800) 225-2532 

Alfa Parts Exchange 
2436 Whipple Road #2 
Hayward, CA 94544 
(510) 471-7132