2019 Gone Farmin' Fall Premier Auction

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Thread: D6 Pony Motor Pinion Issue

  1. #1
    Join Date
    May 2019
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    Shandon, California. Near the home of the Best of the West Tractor Show.
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    Default D6 Pony Motor Pinion Issue

    Hello everybody, I'm a new member who has been reading a great deal of posts on this forum. Thank you all for being a wealth of information. I am in the middle of rehabbing a pony motor and starting pinion assembly on a 4R D6. The motor is off with no surprises, just the typical wear/tear/dirt/grime that comes with a 70+ year old machine. We stopped using the pony years back because it was becoming difficult to start and we couldn't engage pinion to turn the flywheel. Pull start and roll start from then to now. After discovering Squatch253 on Youtube, I convinced myself that this would be an easy job to recommission the starting system.

    I removed the clutch and starter pinion to discover no sleeve assembly connected to the shaft, just the stop. I reached in and found the shaft with the locks connected and in great shape. The four cap screws mounting the sleeve to the shaft were gone. I thought that whoever last worked on the sleeve assembly didn't use the lock. Looking at the catalog, though, there is no lock. It calls for four capscrews (part no. 4B7273). Are these the old bolts that used safety wire to secure them?

    Other problem is that the pinion itself is very chewed up. Should I be concerned there are bolts and chunks of the pinion floating around the main bellhousing? Or are they resting quietly at the bottom? The 6 has been driven probably 40 hours since we stopped using the pony and, so far we don't see any bad results. Also, the oil I drained from the clutch assembly had gas in it - same as the pony motor oil when I drained it. Is there some crossover between the pony motor and the starting clutch housing? Finally, when I removed the assembly, there was some matted, fibrous material sticking to it. Looks like steel wool or shredded wheat but feels like some kind of fabric. Old shop rag? Are there any gaskets or surfaced pressure plates that would spin off something like that?

    Thank you in advance for help, advice, jeering, etc.

  2. #2
    Join Date
    Jan 2018
    Location
    Dungay NSW Australia
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    210

    Default

    Quote Originally Posted by sheddcanyon View Post
    HFinally, when I removed the assembly, there was some matted, fibrous material sticking to it. Looks like steel wool or shredded wheat but feels like some kind of fabric. Old shop rag? Are there any gaskets or surfaced pressure plates that would spin off something like that?
    Could be the links on the main clutch. They were originally canvas but later versions they used plastic of some form. I would check all the links on the clutch to make sure they have been replaced.
    Usually any thing that drops in the clutch will be thrown away from the clutch. If it is big enough then it can punch holes in the housing. There is a fair bit of clearance under neath the clutch and housing but I would still check with a torch to see if you can find anything. If you are really worried then it does not take too long to pull the top half of the clutch housing out.
    The small bolts do have a habit of falling out. One of my D6's had home made locking plates to help hold them in.
    D6-5R, D6-4R, D8 15A x 3, 955K Tracked Loader, 944A Wheel Loader, 305CE Excavator, XQE20 Generator

  3. #3
    Join Date
    Nov 2006
    Location
    Corralitos, Ca.
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    What's the s/n of this 4R?

  4. #4
    Join Date
    May 2019
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    Shandon, California. Near the home of the Best of the West Tractor Show.
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    Default D6 Serial

    4R1143. Great Machine!

  5. #5
    Join Date
    May 2019
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    Shandon, California. Near the home of the Best of the West Tractor Show.
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    Default D6 Pony Motor Pinion Issue

    Quote Originally Posted by PhilC View Post
    Could be the links on the main clutch. They were originally canvas but later versions they used plastic of some form. I would check all the links on the clutch to make sure they have been replaced.
    I just talked to our retired mechanic and he confirmed he replaced the clutch links. Mystery solved. Thanks for your feedback.

  6. #6
    Join Date
    Nov 2006
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    Corralitos, Ca.
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    Looking at the parts book for that s/n the starter pinion started out with neither lock wire or retainer on the cap screws so it's probably been through a few evolution changes. Unfortunately they are all doomed to fail due to the beating the sleeve, pinion, cap screws and locks get during operation. When they come apart it usually means the threads which are minimal at best are stripped and the sleeve holes hogged out meaning recovery is unlikely. A lot of them wind up resting in the flywheel clutch housing which doesn't seem to hurt anything although best removed.
    If you have to have pony start then renewal of the parts including original shoulder cap screws, lock tabs and permanent loc-tite are about all you can do and hope for the best.

  7. #7
    Join Date
    May 2019
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    Shandon, California. Near the home of the Best of the West Tractor Show.
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    Default

    Quote Originally Posted by Old Magnet View Post
    Looking at the parts book for that s/n the starter pinion started out with neither lock wire or retainer on the cap screws so it's probably been through a few evolution changes. Unfortunately they are all doomed to fail due to the beating the sleeve, pinion, cap screws and locks get during operation. When they come apart it usually means the threads which are minimal at best are stripped and the sleeve holes hogged out meaning recovery is unlikely. A lot of them wind up resting in the flywheel clutch housing which doesn't seem to hurt anything although best removed.
    If you have to have pony start then renewal of the parts including original shoulder cap screws, lock tabs and permanent loc-tite are about all you can do and hope for the best.
    Is it typical for the pinion gear to get chewed up as well? This one definitely needs replacing. I'm trying to figure out how to post pictures here. I'm a little slow on this technology... not that I'm much faster on the old technology.

  8. #8
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    Nov 2006
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    Corralitos, Ca.
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    A chewed up pinion gear and matching chewed up flywheel ring gear is usually the result of improper operation of the pony motor by not reducing rpm during engagement along with use of the pinion brake to avoid grinding of the gears. An overall smooth working system gives the engagement mechanism best chances of survival.

  9. #9
    Join Date
    Nov 2006
    Location
    Victoria Australia
    Posts
    328

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    Every time I open a compartment like clutch,gearbox crankcase ect I try fishing with a magnet to try and find any hiding spare parts.

  10. #10
    Join Date
    Jan 2007
    Location
    Moriches NY, Hancock Ma
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    2,355

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    Quote Originally Posted by sheddcanyon View Post
    Is it typical for the pinion gear to get chewed up as well? This one definitely needs replacing. I'm trying to figure out how to post pictures here. I'm a little slow on this technology... not that I'm much faster on the old technology.
    try this--scroll down and click on upload photos
    click on add file
    click on browse
    click on open
    click on upload
    click on insert inline
    click on done
    Attached Images Attached Images
    Cat 941B, Cat D2 4U, Cat D3B, Cat D4 7U, Cat D6 9U

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