crankshaft polishing belt grit
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 27
  1. #1
    Join Date
    Oct 2009
    Location
    Oregon
    Posts
    4,896
    Post Thanks / Like
    Likes (Given)
    5306
    Likes (Received)
    2520

    Default crankshaft polishing belt grit

    I have a couple crankshaft polishers. A big old electric one and a cheap small air one. I neglected to write down what grits the belts are that I like to use and cannot remember. The last belt finally went.

    I only work with forged diesel cranks that are fairly hard.

  2. #2
    Join Date
    Oct 2005
    Location
    dexter mich
    Posts
    300
    Post Thanks / Like
    Likes (Given)
    12
    Likes (Received)
    74

    Default

    I was in TK Atlas They make JD and Cat cranks There final polish was with what they were calling micron belts I believe 1500 grit

  3. Likes Garwood liked this post
  4. #3
    Join Date
    Nov 2007
    Location
    marysville ohio
    Posts
    9,888
    Post Thanks / Like
    Likes (Given)
    2820
    Likes (Received)
    6590

    Default

    Quote Originally Posted by Garwood View Post
    I have a couple crankshaft polishers. A big old electric one and a cheap small air one. I neglected to write down what grits the belts are that I like to use and cannot remember. The last belt finally went.

    I only work with forged diesel cranks that are fairly hard.
    Goodson has anything you might want in the way of polishing belts or anything else for engine machineing.

  5. Likes motion guru liked this post
  6. #4
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,907
    Post Thanks / Like
    Likes (Given)
    15345
    Likes (Received)
    15624

    Default

    I can ask my neighbours Tuesday - if that's any help.

  7. Likes Garwood liked this post
  8. #5
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,907
    Post Thanks / Like
    Likes (Given)
    15345
    Likes (Received)
    15624

    Default

    Quote Originally Posted by Limy Sami View Post
    I can ask my neighbours Tuesday - if that's any help.
    On Edit

    I have spoken with my neighbours ( a small ''country'' engine shop) and their crank guy (also the boss man - with over 40 years experience) uses 400 grit on their homebrew copy of the 1'' Goodson Polisher (like this 72" Portable Crankshaft Polishers | Goodson Tools & Supplies)

    They grind everything from small lawnmower to large diesels on Prinz crank grinders (as in if it can be got in the machine they will grind it) ………..and whether post grinding polishing, or just a polish, those are the only belts used.

  9. Likes Garwood liked this post
  10. #6
    Join Date
    Feb 2010
    Location
    ch
    Posts
    2,501
    Post Thanks / Like
    Likes (Given)
    215
    Likes (Received)
    329

    Default

    i guess you cant go too fine on a crank. micropolish.

  11. Likes Limy Sami liked this post
  12. #7
    Join Date
    Oct 2009
    Location
    Oregon
    Posts
    4,896
    Post Thanks / Like
    Likes (Given)
    5306
    Likes (Received)
    2520

    Default

    Thanks Sami, Much appreciated.

    Most times the cranks I deal with have no discernible wear. They are very hard and I could likely just drop them right back in and go, but I feel that a run through the caustic tank, a blast of all the oil passages and a quick polish ensures I don't miss anything.

    If there's even the tiniest imperfection in a journal you will see it as a spark when polishing.

  13. #8
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,907
    Post Thanks / Like
    Likes (Given)
    15345
    Likes (Received)
    15624

    Default

    Quote Originally Posted by Garwood View Post
    Thanks Sami, Much appreciated.

    Most times the cranks I deal with have no discernible wear. They are very hard and I could likely just drop them right back in and go, but I feel that a run through the caustic tank, a blast of all the oil passages and a quick polish ensures I don't miss anything.

    If there's even the tiniest imperfection in a journal you will see it as a spark when polishing.
    That's how next door treat them, ………...he keeps the old worn (and oil soaked) belts for the ''clean and polish jobs''

  14. #9
    Join Date
    Mar 2005
    Country
    UNITED STATES
    State/Province
    Indiana
    Posts
    4,791
    Post Thanks / Like
    Likes (Given)
    1266
    Likes (Received)
    1213

    Default

    Yep, I was gonna add that bit too. All the crankshaft polishing I've ever done was with worn out old belts. They polish up to a shine and finish much better than their actual grit would suggest. I think this has to do with the belt loading up with steel too. Sort of gives a burnishing effect. One case where you don't want to clean out the belt. The bad thing with the super high grit belts is that they load up instantly and then do next to no cutting at all. The 400ish grit still has room to do a little cutting if a high spot sticks out.

  15. Likes Limy Sami, Garwood liked this post
  16. #10
    Join Date
    Oct 2009
    Location
    Oregon
    Posts
    4,896
    Post Thanks / Like
    Likes (Given)
    5306
    Likes (Received)
    2520

    Default

    I haven't changed the belt in forever. I recall that it's best to run the belt in a little before hitting a journal. The crank I need to polish has hardened wear sleeves installed (that will be replacing) for the front and rear seals. I figure I'll run the belt a bit on those sleeves to knock it down a little then hit the journals.

  17. Likes Limy Sami liked this post
  18. #11
    Join Date
    Aug 2013
    Location
    stockton ca.
    Posts
    37
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    32

    Default

    8888b09b-8469-4fa5-9234-b82650a0cb4c.jpg53aa9ab6-8b64-4bdf-bbe7-71e1f16023f4.jpgcc46851b-469a-491d-b93e-85d6eec0ec55.jpg400 grit is just fine.

  19. #12
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,907
    Post Thanks / Like
    Likes (Given)
    15345
    Likes (Received)
    15624

    Default

    Quote Originally Posted by workin stiff View Post
    8888b09b-8469-4fa5-9234-b82650a0cb4c.jpg53aa9ab6-8b64-4bdf-bbe7-71e1f16023f4.jpgcc46851b-469a-491d-b93e-85d6eec0ec55.jpg400 grit is just fine.
    They're just how my neighbours look when he's finished with them

  20. #13
    Join Date
    Nov 2018
    Country
    ALAND ISLANDS
    Posts
    78
    Post Thanks / Like
    Likes (Given)
    77
    Likes (Received)
    39

    Default

    It makes a difference on hardness of the journal of course. But you knew that. I have a likening to the ultra fine scotchbrite type belts from goodson. I have had good results finishing with them. The worn out one are great too!
    Have used as lately some of the high tech 3 m structured abrasives some good , and not what i like results. On diesel cranks i like them. On softer cranks i have noticed marks on radius. Not a deal breaker but visible. Cant feel them. For radiius polishing i us a 3/8 wide well worn and use it just on the radius. Use some rouge on it come out like chrome. The polishing expert in my mind was the owner at ABS products, cant think of his name right now but he built and sold polishers and supplies and could make a turd look good. Lol He passed away couple years ago great guy.
    Their still in business look them up.


    Sent from my iPhone using Tapatalk

  21. #14
    Join Date
    Mar 2003
    Location
    Vermont
    Posts
    499
    Post Thanks / Like
    Likes (Given)
    122
    Likes (Received)
    132

    Default

    Clevite (now Mahle)published an excellence manual for plain bearing journal design and preparation. Was standard reference for OEM engine and transmission designers. PLEASE do yourself a huge favor an locate a copy. Much of the suggested information here is dead wrong.

  22. #15
    Join Date
    Nov 2007
    Location
    marysville ohio
    Posts
    9,888
    Post Thanks / Like
    Likes (Given)
    2820
    Likes (Received)
    6590

    Default

    Quote Originally Posted by 10 fingers View Post
    Clevite (now Mahle)published an excellence manual for plain bearing journal design and preparation. Was standard reference for OEM engine and transmission designers. PLEASE do yourself a huge favor an locate a copy. Much of the suggested information here is dead wrong.

    Such as?????

  23. #16
    Join Date
    Nov 2015
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    120
    Post Thanks / Like
    Likes (Given)
    11
    Likes (Received)
    8

    Default

    Mhale has been an OEM BMW supplier for years, there's 24 pistons sitting on my desk as typing. At work, we specializes in vintage BMW engines, and will say Mhale is on point.

    That being said, having been rebuilding these little I6 plants for a few years, 400 grit is perfect. We generally compete in 10-24hr races and monitor bearing/crank/cylinder wall wear patterns.

    The OP didn't specify the application, but as others' mentioned, Goodson is a great source. The wavy sided belts are nice for large fillets, and the ultimately the quality of the finished job boils down to operator. I personally pilot valve seat jobs manually with a Black & Decker seat grinder and Sioux facer. My local "cylinder head shop" is 5-8 tenths out of concentricity when comparing to my manual job, and the dude has a Serdi. SMH. Valves should bounce like jumping beans.

  24. #17
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,907
    Post Thanks / Like
    Likes (Given)
    15345
    Likes (Received)
    15624

    Default

    Plus another on that - although it's not my line I've rebuilt a good few engines over the years so I'm genuinely interested.

    On edit Please please don't let this thread turn in to an engine building fight as in ''my Harley beats your nascar'' shite.

  25. #18
    Join Date
    Oct 2009
    Location
    Oregon
    Posts
    4,896
    Post Thanks / Like
    Likes (Given)
    5306
    Likes (Received)
    2520

    Default

    Quote Originally Posted by 10 fingers View Post
    Clevite (now Mahle)published an excellence manual for plain bearing journal design and preparation. Was standard reference for OEM engine and transmission designers. PLEASE do yourself a huge favor an locate a copy. Much of the suggested information here is dead wrong.
    ?????

    Please explain.

  26. #19
    Join Date
    Nov 2015
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    120
    Post Thanks / Like
    Likes (Given)
    11
    Likes (Received)
    8

    Default

    Quote Originally Posted by Limy Sami View Post
    Plus another on that - although it's not my line I've rebuilt a good few engines over the years so I'm genuinely interested.

    On edit Please please don't let this thread turn in to an engine building fight as in ''my Harley beats your nascar'' shite.
    What if I put a NASCAR engine on my Harley? :P ...or compete in the Sebring 12hr with a v-twin VW beetle?

    Bottom line is: listen to the guys that consistently make 100+ hp/liter N/A, and live to tell about it.

    My machining birth came in production and got the opportunity to use those machines for parts in off time, as long as I didn't move any work vices etc. When going on my own, the first two items were an auto floor lift and a flow bench, 16yr later and the clients are on national podiums in various road racing circuits.

    BMW has been by far, the most stringent OEM engine we have worked with at work. They see a quarter to a million miles and even when totally neglected and/or with power adders, they show ridiculous promise. If you can keep the head down on a turbo engine, the m20b25 is capable if 500whp/tq from a single cam and 2.5l. In 1986 the piston to wall clearance is .02mm on 84mm, and many are well within stock spec this many years later.

    400 grit and 25rpm hasn't failed me in the last 18yr of competition, just adjust clearances with bearing size. Don't be afraid to use an oversized/undersized cap-side bearing shell on each journal, even with a main cap straightening.

    In all honesty, many people would be quite upset at the carnage upon disassembly of our engines after a season.

  27. Likes Garwood liked this post
  28. #20
    Join Date
    Oct 2009
    Location
    Oregon
    Posts
    4,896
    Post Thanks / Like
    Likes (Given)
    5306
    Likes (Received)
    2520

    Default

    I think the strength and minimization of stress risers is more important in a crankshaft than the finish on the journals.

    Never actually had a crank or rod failure on engine that I assembled (to my knowledge).

    Only engines I work on much anymore are Cummins 3.9/5.9/6.7. I make parts for other engines that some of you probably use though.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •