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Cam Gear Broken Teeth, aluminum gear 289

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  • A look at Dudley's gear book Table 7.39 suggests for a 1" wide medium precision gear the slope of the helix should be accurate within .0010".

    64Avanti's angle error of .3° on a 1" wide gear is more like .005".

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    • Well after some wait for the gear inspection CMM to get upgraded, the machine in Detroit area is functional. The gears I sent to be inspected arrived just when they started an upgrade to it. The machine costs about $1M and they spent about $100K on an upgrade. I may have inspection reports tomorrow. The next problem is to talk to whomever built these gears. Unfortunately there is no way to fix them.
      David L

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      • I am beginning to wonder at what step of the manufacturing process the error occurred. Having talked to some of the vendors selling the gears in question, the problem seems to
        be occasional and diverse. All it would take is a chip or bit of debris during one machining operation on the gear to bollix the whole thing. Having owned a machine shop for 40 years,
        I have learned that there are a tremendous amount of variables in any manufacturing process, and sometimes it depends on how many beers a key player had the night before.

        The capital investment in a modern machine shop is staggering in relation to the profits made. Vendors take risks financially, too (I have been there). The customer places
        trust in both enterprises. I have been there, too. That trust shouldn't be squandered.

        Statistically, there will be a certain number of bad parts. Every single one of the gears could be inspected, how much did you want them to cost again?

        On top of it all, the newest Studebaker V8 was made two generations ago, and many have been subjected to kinds of abuse that only the general public can conceive of and manifest.
        It is a good bet that many of the dimensions on the surviving engines are no longer the same as Studebaker made them.

        I am taking no sides in this issue. I understand them all. Ultimately it comes down to the engine builder being the final inspector, the vendor to back up their product, and the manufacturer to own up to their mistakes. It is a team effort. None of this is easy, and we are damn lucky to have people who will take the risk to provide parts for cars that
        haven't been made in nearly 60 years.

        Good luck to every one involved in this. I've ordered an extra tube of Prussian Blue.

        JT

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        • I have received the inspection report for the gears. The angle on the cam gear is a little worse than my measurement of about .3 degrees and turned out to be about .36 degrees which is a huge error. The crank gear angle was not perfect but should be ok but the gear tooth thickness was too high which reduces clearance and I would not use the crank gear for that reason. The angle error would have been caused by not setting the machine up correctly.

          The Studebaker drawing although it lists a desired clearance does not specifically tell the person building the gear what modification to make to get the correct clearance.

          What we don't know is how many batches of these gears have been built. If they were built in several batches then some may be good.
          David L

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          • Originally posted by 64Avanti View Post
            I have received the inspection report for the gears. The angle on the cam gear is a little worse than my measurement of about .3 degrees and turned out to be about .36 degrees which is a huge error. The crank gear angle was not perfect but should be ok but the gear tooth thickness was too high which reduces clearance and I would not use the crank gear for that reason. The angle error would have been caused by not setting the machine up correctly.

            The Studebaker drawing although it lists a desired clearance does not specifically tell the person building the gear what modification to make to get the correct clearance.

            What we don't know is how many batches of these gears have been built. If they were built in several batches then some may be good.
            Thank you very much. This is a tremendous help in putting some numbers on the thing.

            I have mine boxed up. I was just waiting for empirical confirmation. So, thank you again.

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            • I'm glad I've got my custom, timing gear set on my engines (2) now !

              Straight cut teeth, steel gears, adjustable cam timing. Some of you may remember a few years back when I had these made. Some of you may actually have a set.
              I have one set in my street 259 for my daily driver, stock 259 cam (for now). While the engine hasn't run yet, I did play with the cam timing while watching the cylinder pressure. It's been a while since I did this, as I recall, the cylinder pressure was the best with -3° on the cam to crank positioning.

              And yeah...the tooth backlash is good !

              Mike

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              • My understanding now is that there were about 4 batches of cam gears produced. So apparently some lots were good or at least not as bad as the ones that have been reported as bad and the one that I inspected and then had inspected on a gear inspection machine. A new batch has been produced and one will be inspected. I would suggest that in the future parts like this should be identified by lot number.
                David L

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                • Maybe a part number that signifies the manufacturer...and...the lot number stating the batch.

                  This is the way that the big manufacturers do it. Or at least the way that they "used" to do it.

                  Mike

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