1966 275 GTS maintenance log and Gearbox question, help me please!

Discussion in 'Vintage (thru 365 GTC4)' started by The Josh, Nov 22, 2009.

  1. The Josh

    The Josh Rookie

    Nov 22, 2009
    Bucks County, Pa
    Full Name:
    Josh Jenny
    #1 The Josh, Nov 22, 2009
    Last edited by a moderator: Sep 7, 2017

    (to skip to the help! portion of this, please begin reading at paragraph 6)

    I am new to this forum and I come to you all seeking some insight on a dilemma I am currently amidst with a 1966 Ferrari 275 GTS. In preparation for the car to spend this upcoming winter season in Florida (instead of Pa), I have been going through it giving it a thorough maintenance and inspection. Upon an initial test drive to shake down the car in an effort to see what might be working properly, and what might not be I was unbelievably pleased with nearly every aspect of the car. In addition to its beautiful styling, I felt that the car handled superbly, its thunderous V12 echoed beautifully off everything in sight, and that its rear mounted gearbox was quite the pleasure to shift compared to an earlier 250GT front mounted gearbox. However, the only problem I was able to find outside of standard maintenance, did come from that brilliant cluster of gears in back end of this beautiful machine.

    While amidst the test drive, a noticeable clunk became apparent between 1-2 shifts, and sometimes 2-3 shifts. Localizing the sound was relatively easy and it was very obvious that it was coming from the rear of the cars drivetrain. A initial inspection yielded properly tightened front and rear mounts, tight connections at the driveshaft front and rear, and properly fastened output shafts as well. The rubber bushings that hold the front mounts in place are for the most part in great shape, and everything seemed to be accounted for.

    I continued on with my maintenance, which included basic things like fluid changes, spark plugs, carb tuning, etc and then when I got to the inspection of the exhaust and exhaust mounts, there was a bit of trouble. The exhaust was leaking at the junction of the down pipe to the mid pipes, and was becoming a bit rusty, and tired in general. It was deemed necessary to replace it and so a new Ansa exhaust system was fitted.

    A bit of topic, but, I was include a properly placed opinion here about that exhaust system. The decision was made to put on a non-stainless system onto the car (unfortunately) to replace the original pipes. I found the construction quality of the exhaust system to be nearly intolerable. The paint, which was unbelievably thin, could accidentally be removed by an eager finger nail. Also, they sprayed this one coat of paint on the pipe with the necessary tail pipe clamps loosely in place. This means that when you positioned them properly, you have a nice 1 inch wide ring of bare metal showing on your new exhaust. Being a dual exhaust system, with 4 tips, only two of them had the ANSA sticker on them, and those were heavily misaligned. There was also notable distortion to the inside of the bends on the metal tubing, implying that they were formed in less than an ideal manner. The fitment of the system was OK. Not horrible, but certainly not great. Most inexcusably, all of this came at the price of $4100. If I had bough an exhaust system for my BMW for $1000 and it was of this quality, I would NOT be happy.

    Right below the drivers feet, the bottom layer of the floor sheet metal had begun to rust notably, most probably from the moisture released from the tired exhaust system. I removed the bottom piece of sheet metal, or rather, what was left. I also removed the heat insulation and found that the upper piece too, had begun to rust. Unfortunately with the tight deadline that revolves around this car, there was not enough time right now to replace the top piece. I cleaned it vigorously and sealed it with a paint-over-rust primer. I added the proper fiberglass heat insulation sheet with was adhered via 3M high strength spray-glue. I then fabricated a new replacement bottom panel from 20 gauge sheet metal, and for the time being, secured it in their with metal fasteners. Upon proper replacement of the upper panel, the bottom one will be secured via welding. Once this was all sealed, I then installed the new exhaust system and ran the engine with the car in the air to check for exhaust leaks. This, is where things became interesting....

    I ran the engine with the transmission in neutral and began my inspection of the exhaust system. Since the car was in the air, the rear wheels kept the gearbox's momentum going and the wheels spun. At this point I noticed a disturbing amount of movement from the gearbox. I returned to the cockpit and selected first gear, then once again went back underneath the car to inspect my discovery. With the both rear wheels now spinning with purpose, I was in horror to find the gearbox rocking back and forth laterally, a solid 3-5 degrees of movement in each direction from center. I immediately silenced the engine and went back underneath, certain that I had overlooked a simple loose mount. The front two mounts have each have a bolt that go through a slotted hole on an extension that comes out of each side of the front of the gearbox. The rear mount is central, on the vertical face. The front mounts, which is comprised of each have two rubber puck mounts, on either side of the chassis mount. A bolt goes upward from the bottom, through the bottom of the unsupported rubber puck, through the chassis mount, through another rubber mount which is encapsulated by an aluminum cup, and then finally to rest in the gearbox arm. I cut the properly present safety wire from the front mounts and checked the tightness of those bolts. To my surprised, I found them to be rather loose. I would compare their tightness, to being roughly one full rotation shy of where you would tighten a bolt firmly to anything else. I grabbed my spanner and cranked down a bit, stopping short of any distortion of the rubber mounts. I fired her up again, and although there may have been a 10% improvement, the problem remained. I decided to explore tightening in more, and as per my suspicion, it became apparent that you could tighten that bolt all day, and just mushroom out the rubber mount. The hole in which the bolt passes through the chassis, is slotted side to side. Simply put, the rubber mounts can not offer enough friction to keep the gearbox firmly planted amidst all of its rotational glory. The mounts are in pretty good shape. They exhibit no cracking tears, dry-rotting, etc. Even after squeezing the proverbial hell out of them with that bolts, they only showed the slightest bit of hairline cracks. While it still may be wise, and in order to replace them, I feel that there is something going on beyond their condition.

    My feeling is that for obvious reasons, the gearbox should be as firmly mounted as possible, without compromising the integrity of any of other components on the car, including the gearbox itself, the chassis mounts, drivetrain, etc. Conversely, I have never seen any gearbox move around anywhere near the amount this one does. It seems as though the slotting of the chassis mounts might be in an effort to assure proper alignment of the gearbox to the driveshaft/engine. It is also rather apparent, that in its current state, all of the aforementioned components are perpetually misaligned because of the inherent slop of this mounting configuration. I believe that these holes are intentionally slotted from the factory, and are not a product of a loosely mounted gearbox that wore the holes out. The rear mount of the gearbox is perfectly placed to act as a pivot point to allow it to move in nearly any direction as the front mounts do their best to grasp for friction.

    My simple question to all of you, oh great Vintage Ferrari Guru's is this; What is the best and proper way to secure this transaxle to keep it firmly mounted to allow it to transfer power to the ground, helping the earth to keep spinning properly. Should these rubber mounts be made of delrin or something more firm? Should both of the top and bottom mounts be in aluminum cups to limit their movement? Should these holes not be slotted? Should the bolt be located in the slot, and then something machined and placed in there to keep them staying put? Should this car be sold and should I take up a profession in writing overly elaborate internet forum posts?

    Any input at all would be greatly appreciated. I can provide countless pictures if need be, and if necessary a brief video of the gearbox slopping around like

    Since they are readily available, here are some shots of the car including the repair work completed on the rusted out panel. It was quite the pleasure doing this project, I look forward to its formal completion.

    Thanks in advance! I am glad to have found this forum and look forward to spending some time here in the future.

    -The Josh
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  3. readplays

    readplays Formula 3

    Aug 22, 2008
    New York City
    Full Name:
    Dave Powers

    Welcome aboard. Some of the other guys can help you with the gearbox question and should be along shortly. In the meantime, I just had one comment- I would have thought the C6/CO would be out in Colorado these days..

    Best of luck with the 275,
  4. Napolis

    Napolis Three Time F1 World Champ
    Honorary Owner

    Oct 23, 2002
    Full Name:
    Jim Glickenhaus
    If you pm me I'll send you a link to my 275 Shop Manual which will start you down the right road.
  5. 2NA

    2NA F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 29, 2006
    Twin Cities
    Full Name:
    Tim Keseluk
    I wonder what the condition of your driveshaft enter bearing is with all that gearbox movement.

    The driveshaft on a 275 turns at engine speed and is rigidly (more or less) mounted between the clutch and gearbox. Alignment is pretty critical and there shouldn't be much movement at either end.

    It sounds like at very least some new mounts (correctly assembled and installed) are in order. I suspect there are other deferred maintenance items that need attention as well.
  6. ArtS

    ArtS F1 Veteran
    Rossa Subscribed Owner

    Nov 11, 2003
    Central NJ

    Welcome aboard!

    First, I cannot provide any direct comment or experience on the gearbox/driveshaft slop as my transmission is up front. However, you may want to cross post with Tom Yang's site a lot of the guys there do their own work and may have the experience you seek.

    Regarding the Ansa pipes; I completely agree. The Ansa pipes will last about 8 years and with today's exchange rate, a good stainless system is about the same price (or cheaper!).

    Good luck,

    Art S.
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