Xt350 crank bearings c3 or c4?

Discussion in 'The Garage' started by SHEP_5, Mar 6, 2014.

  1. SHEP_5

    SHEP_5 Been here awhile

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    It's an air cooled 350 4 stroke. Can't find call out on the oem parts site. It had c4 koyo 6036 in it. I ordered the all balls crank bearings for tge xt350 and got c3's. Now what. Specs say there is a .0007" axial clearance difference. Called all balls tech, he stated its an improvement. BS. To add to the mess, the steel insert cast into to the case that the bearing presses into is a tad loose, maybe couple thou play, Not replacing the case. Pondered cnc machining the ring out, pressing in new one and sizing, but seems like an incredible amount of work and a tight tolerance to hit for the proper press. Going to attempt to drive some shims in to tighten it up and lock tite in there. The play is minimal, just enought to know its there. Not sure if tighter bearings will help or hurt this condition
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  2. machinebuilder

    machinebuilder Long timer

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    c3/c4 is the internal clearances in the bearing.

    for the bearing fit into the case, look at some Loctite retaining compound (ask dirty sanchez in the loctite thread which one)


    P.S. you're probably better off going to a local industrial bearing supplier than most other places, it's a pretty standard bearing.
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  3. SHEP_5

    SHEP_5 Been here awhile

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    ya the fit on the press into the steel ring is fine, its the ring that is cast into the aluminum case that is a couple thousands loose.
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  4. andrewgore

    andrewgore Gôremā

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    Loctite Bearing Mount 620. It'll fill gaps up to 0.015".
    http://www.amazon.com/LOCTITE-38652...id=1394203824&sr=8-1&keywords=loctite+bearing

    We just used this on one of our CNC machines that the spindle bearings were a bit loose in the machine casting. I wouldn't hesitate to use this in an engine at all. Good stuff.

    Andrew
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  5. sailah

    sailah Lampin' it

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    I used 680 bearing retainer on a chain tensione assembly I built. Works awesome. Be fore warned, it sets up almost instantly. I cleaned both parts with acetone, ran a very thin line on both parts using clean fingers and inserted the bearing while rotating it about 90 degrees to ensure a good bond. Within seconds there was no adjusting it, locked solid.

    I don't know the oil resistant version but there are many kinds. Def check and ask dirty sanchez as suggested,, he's given me great advice before

    I'd go the loctite route over shims personally
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  6. SHEP_5

    SHEP_5 Been here awhile

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    i will use that loctite 680 o the other side where the press fit is loose, and the bearing spun, .0015/side will lilkly do the trick. this other side the actual steel ring that is cast in the aluminum is loose, i checked with shim and cant even get a .001 shim in the gap, i will see if some of that stuf will flow down in the crack and then put punch marks around the top to swell the aluminum back aroung the ring..

    eta. i see on loctites web site they have a 603 which is oil resistant and fills up to .005 gaps, would this be better?
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  7. H96669

    H96669 A proud pragmatist.

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    All Balls....I spent enough time sourcing bearings a few weeks ago. You are right BS.They sure make finding bearings easy don't they?fleebay is flooded with that on the motorcycle side of things.

    Even the local guys fed me BS and got me bearings that I returned.

    Stick with the specs. Darn mine were hard to find....took hours on fleabay and digging specs. Got what I wanted and less than OEM so that paid off for my "cheap time" spent digging them out. And my BMW is now sporting a Yamaha part......:clap

    You may want to check fleabay but in the industrial supplies side of things and add some of the better bearings brand names with the Koyo searches.Lets you avoid the No-name brands.....:wink:
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  8. SHEP_5

    SHEP_5 Been here awhile

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    I put them in, they are koyo like the original just c3 not c4. I'm going to run them. Also picked up some permeates sleeve retainer that looks to be the same as the loctite 680. Good to 400 degrease, oil proof and 300 psi gaps to .007". Nobody local carries the loctite stuff

    Eta: the loctite sight has a good chart for uses and the 680 is for oil resistant high temp press fits
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  9. H96669

    H96669 A proud pragmatist.

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    I can't tell you about the Loctite number, my stuff is so old it was still called "stud & bearing mount" but the 680 is specked somewhere on my bike, I tought I looked that up a few years ago and same as I have here. In any case we used it recently with confidence.

    Bearings....getting hard to find the good ones amongst the fleabay offerings and others. Koyo=good altough there has been a lot of bearing companies/plants bought and sold in the last few years. Even the Germans are now in Korea and many other places.Koyo....from their Canadian site are ISO certified and have been making bearings for a very long time.

    Bought 2 "same" SKFs within a week recently, from the same place and one is Argentina....the other Brazil??? Don't care much about country, my bike has mostly Fag bearings Polish...French and otherwise. Even an INA from Taiwan OEM. SKFs from ???? can't be worse than the Chinee they are replacing and not much more expensive considering the pita of replacing them on that lawnmower application.:cry

    Keep us posted on the going from c4 to c3, the factory specs may have to do with parts expansion when hot, I wouldn't know.:ear

    I know going from std to c3 is often recommended in bearing sites depending on applications and that may be a solution for me if I keep destroying the bearings on the mower spindles. But they lead a hard life.....:rofl

    There is one big c3 on my bike, the infamous BMW rear drive bearing.:eek1 Not recommended going down to std on that one but unlike yours that one has preload shims on it.

    And I still say BS about some of the allball products, I am very dubious of the correct fitment of my swingarm bearings they offer with the "generic pic". Same size bearings for sure and also used as swingarm bearings on other bikes but I doubt they have adopted the propriatory twist BMW/Fag put on them.:wink: I did buy such an alternative as recommended by others because it was easy to find and much cheaper. Didn't work out for me I removed it the next year.
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  10. SHEP_5

    SHEP_5 Been here awhile

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    So I have the cases assembled, and a mismatch on the cylinder mounting surface. Took back apart double checked tube dowels. There are 2 but 4 holes so tried both combinations same result. So either its warped or was like this from factory. Not much i can do about it. Hopefully the head bolts will pull it more even and permatex will fill imperfections. Any thoughts?
    [​IMG]

    [​IMG]
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  11. jfman

    jfman Long timer

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    For a crankshaft bearing one should never use a C0 bearing right?

    Reason I ask is I found a canadian made SKF C0 bearing for my klr crankshaft for a great price(18$) but it seems like what is in there right now a C3.

    OE bearing is 97$
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  12. Chad M

    Chad M A full head of air.

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    I would think C0 would be too precise / rigid for a used KLR engine. I would definitely go with the recommenced C3 if it were my engine.
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  13. jfman

    jfman Long timer

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    Yeah I bought a C3 bearing in the end. Waiting on it to show up
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  14. Beezer

    Beezer Long timer Supporter

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    my guess is somebody changed one half of the case.... it wasn't machined that way. there are too many mating surfaces that seem to match and yet there is some misalignment. that might explain the looseness in that case bearing shell too. maybe check the bottom flange of the jug to see if there is evidence of unusual wear.

    if the crank rotates free with the case torqued up I would surface the cylinder base pad. that is probably best done with the crank out
    #14