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Shielded bearing and bearing fits in a Briggs 18HP flat twin??

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  • Shielded bearing and bearing fits in a Briggs 18HP flat twin??

    I took the 18HP Briggs engine apart, and I was a little surprised to find a SHIELDED ball bearing on the PTO end of the crankshaft. The shield is on the side toward the innards, but the opening between the shield and the inner race is right next to the bottom of the teeth on the cam drive gear. I guess enough oil gets through the opening to keep the bearing and the crankshaft seal happy.

    The bearing was pretty tight on the shaft, but I was able to work it off by hand. The outer race is a slip fit in the housing, but there's no evidence that it's been spinning. I can easily turn the outer race in the housing by hand. Does that sound OK?

    The bearing in the engine is a 6307 R with one shield. It's got quite a bit of slop, but it turns smoothly. The local bearing house has a 6307ZC3 (35mm x 80mm x 21mm) for a reasonable price, so that's what I plan to put in.

    I don't know if the bearing in it is factory original, so I'm curious about the shield and the fit to the housing being OK. Anybody with experience on 18HP Briggs horizontal flat twins?

    Roger
    Last edited by winchman; 06-19-2008, 05:49 AM.
    Any products mentioned in my posts have been endorsed by their manufacturer.

  • #2
    Never seen a small engine with shield inside, maybe someone replaced it before and didn't bother to pry out the shield? That would be my assumption . . .

    Anyways, I'd install the new bearing(s) pop off the inner shield and stake the bearing in place to keep it from "possibly" rotating in the future in the side cover.

    I'm not a Briggs engine mechanic but have had my hands in a lot of Kohler cast iron ones
    "There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton

    http://www.flowbenchtech.com

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    • #3
      Hi Roger ("winchman").

      I have a good collection of B&S engine work-shop manuals. If you can post engine details - all of them (lots) - I will see what I can find and if I do find any I will post it/them.

      Comment


      • #4
        Pretty common to use a shield, especially one that fits relatively loosely, not "sealed" by any means.

        The inside of the engine has bits of metal circulating around in the sump, and they would be bad for ball bearings, denting the race, locking and causing skidding, etc.

        The shield tends to sling off the metal bits, and does let enough oil in

        A ball bearing does NOT require very much lube at all. It is really mostly for the ball-to-cage friction, not the rolling action itself.

        If the bearing were open, it would get "clogged" with slung oil, and that oil could carry metal chips in to damage it.

        DO NOT pop off the shield, unless you want to possibly have to replace the bearings, and maybe repair other damage.
        1601

        Keep eye on ball.
        Hashim Khan

        Comment


        • #5
          Originally posted by J Tiers
          If the bearing were open, it would get "clogged" with slung oil, and that oil could carry metal chips in to damage it.

          DO NOT pop off the shield, unless you want to possibly have to replace the bearings, and maybe repair other damage.
          Ah . . . if you got "metal chips" in your engine you have more problems to worry about on the rod/crank bearing surface than you do with a ball bearing. Lets see that's a few thousands clearance at most on the rod/crank.

          Just offered my opinion . . .
          "There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton

          http://www.flowbenchtech.com

          Comment


          • #6
            The engine is: Model 422437 Type 1266 01 Code 90102332

            I've worked on 2-stroke engines with open bearings, but this is my first experience inside a 4-stroke with a ball bearing. It's a splash-lube system, so having the shield makes sense.

            I'm still curious about the bearing fit to the housing. If the bearing is secured into the housing by stakes or Loctite bearing retainer, it's going to be a LOT harder to take the engine apart the next time.

            Roger
            Any products mentioned in my posts have been endorsed by their manufacturer.

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            • #7
              I just got a 422437 off of craigslist for cheap and have been looking into some things. Mine is missing the magnets off the flywheel and the stator is damaged so no charging for me. other than that it runs great. Here's some info from the service manual:
              First, the bearings are a press fit on the crank. The manual talks about using a bearing puller to get them off and heating them to reassemble. It also has this note - "Note: Engines manufactured after 1992 and service replacement ball bearings are not equipped with a bearing shield. If ball bearing is equipped with a bearing shild, install bearing so that shield faces crankshaft crankpin."

              I can't find any information about staking to the crankcase. Also can't find any specs on the fit. I imagine that if it is loose it you should loctite it or do something to keep it from spinning.

              Comment


              • #8
                also...

                This is a note on the oil slingers:

                Engines with a Top No-Load speed above 2400 RPM: Install only one oil dipper on #1 connection rod, Fig 18. Use ONLY dipper part #222480. Engine models 42100 and 422400 manufactured before code date 92072000 were not originally equipped with this dipper. It is recommended that the oil dipper be replaced with dipper part #222480 in all 421400 and 422400 engines at the time of servicing or overhaul. When installing dipper part #222480 in these engines, the oil trough must be removed (if so equipped).

                Engines with a top no-load speed below 2400 RPM: Engines with a top no-load speed below 2400 RPM require 2 oil dippers. Install ONLY oil dipper part #222480 on #1 connection rod. Install ONLY dipper part #223053 on #2 connection rod, Fig 18.

                Comment


                • #9
                  B&S parts list.

                  I did not have the OHV twin hand-book - only two for single cylinder OHV engines (plus others not applicable).

                  I went to the B&S web site and there are down-loadable (*.pdf) owners manuals and illustrated parts list - your parts list - which with help fropm other post(er)s is at:
                  http://www.briggsandstratton.com/mai...0Parts%20Lists

                  http://www.briggsandstratton.com/pdf...100/MS9492.pdf

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                  • #10
                    Mine is an L-head engine. Thanks for the parts info.

                    I remember seeing one dipper, but I didn't look further inside before I put the cover back on after getting the bearing info. I doubt I can do anything about them without taking the bottom off the block, which I don't want to do. I'm not going to be running the engine hard, so I'm not going to worry about that. I wouldn't have taken it apart at all except I need the crank to run reasonably true. At least it won't be wandering around any more.

                    I'll see how the new bearing fits in the housing before deciding what to do there.

                    Thanks again for the helpful info.
                    Roger
                    Any products mentioned in my posts have been endorsed by their manufacturer.

                    Comment


                    • #11
                      Originally posted by brucepts
                      Ah . . . if you got "metal chips" in your engine you have more problems to worry about on the rod/crank bearing surface than you do with a ball bearing. Lets see that's a few thousands clearance at most on the rod/crank.
                      Eh, sigh.......... THERE ARE GEARS...... where there are gears, there are chips. Small ones no doubt, but a ball bearing is a lot less forgiving of chips than most any sleeve bearing.....

                      A few thou clearance? Big as a house...... a ball bearing has zero clearance between parts under load...... the "clearance" in a bearing (built-in-looseness) may itself be only a thou or so.
                      1601

                      Keep eye on ball.
                      Hashim Khan

                      Comment


                      • #12
                        Magnet

                        Put a good strong magnet into the drain plug as it will catch a lot if not all ferrous material.

                        Comment


                        • #13
                          housing fits for a rotating shaft are typically H7 which would allow the outer race to rotate in the housing by hand, but as the bearing heats up, it will have a tighter fit that prevents rotation during operation. You should not stake the race in the housing, it is not necessary.

                          lubrication is necessary to keep the balls separated from the race during operation, if there is metal to metal contact, the bearing will fail quickly. The lubricant layer is very thin, but necessary for proper operation.

                          The shield on the inside does not make much sense, it will not allow much if any oil to reach the bearing. Is the shaft horizontal or vertical? If vertical, then I can see that to prevent too much oil in the bearing during operation, kind of like a slinger ring.

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                          • #14
                            sealed / Shielded bearings.

                            Many years ago I worked at an Amusement park. We were pretty careful to keep up the oil levels and grease as required. We has a gearbox cease driving one of our rides. On investigation we found that, though oil filled, it had sealed bearings inside it,and one of them had died and caused mayhem. We replaced shafts and gears as needed and fitted open bearings. This was 20 yrs ago and certainly until my last visit a couple of years ago the box had had no attention except for oil changes and occasional topping up. I later worked in the municipal sewage works that had hundreds of gearboxes driving machinery and never again saw a sealed or shielded bearing inside any. Regards David Powell.

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                            • #15
                              It's a horizontal flat opposed twin:


                              The bearing house is taking their time getting the replacement bearing (with one shield) I ordered, so I may look around for one without shields.

                              According to a previous post, the original bearing had one shield, but the current Briggs replacement (which costs 2X+ the one from the bearing house) doesn't have a shield. If the original lasted almost twenty years, I think enough oil was probably getting past the shield. The squirt from the meshing gears right next to the opening between the shield and the inner race must help.

                              Roger
                              Any products mentioned in my posts have been endorsed by their manufacturer.

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