No announcement yet.

Rear main seal and bearings

  • Filter
  • Time
  • Show
Clear All
new posts

  • Rear main seal and bearings

    I may be replacing my rear main seal, main bearings and rod bearings this weekend. Any tips other than take it slow and keep it clean?

    [img=left][/img=left]1951 Commander Starlight Coupe (aka "Stella")

  • #2
    Make sure you keep close attention on the way rod caps come off! I usually mark them with a punch or anything that will mark rod caps. they not only have to go back on the same journal they must go back on in the same direction as they came off. you also have to make sure you get the right rod bearings. When working with these old cars you never know if the crankshaft has been machined and you may need oversize rod bearings. If the motor has not been knocking and the rod caps feel tight when you get the pan off you might want to leave the rod bearings alone.



    • #3
      If you need to replace the bearings, so be it but a little plasti-gauge will give you an idea of the actual clearance. Unless you've had the car for a long time, you probably don't know if the bearings have been changed recently or ever changed. Rod bearings "usually" need to be replaced before main bearings, but don't take that as gospel. Many things determine how quickly bearings wear including the frequency of oil changes, whether your car has an oil filter or not and how often the car was started. More starts, more wear. The plasti-gauge is much easier to use on rod bearings since you need the journal free of oil to be accurate and getting the top side of the main bearings oil free will be mighty tough.

      On the main bearings, this is what I'd do, I'm not suggesting you do so, but just what I'd do. I'd remove the main bearing cap and inspect the bearing first. Gray colored is good but not a guarantee of being servicable. Any copper showing is "whew, good thing I checked it in time" and steel showing is "oh c**p, I'm too late!" Insert bearings have a steel back for strength with a copper coating over that which in turn is covered with babbit. Babbit is very soft and the purpose of such is if a hard chunk of crud happens to get in the oil space between the crank and the bearing, the hard crank will force the chunk into the soft babbit where it is effectively buried out of harms way. I'd dry the bottom half of the bearing, place the plasti-gauge, replace the cap and torque it, remove it and measure the clearance. If the clearance is well within tolerable limits, I wouldn't worry about it. If the clearance is right at the limit, I'd definately change it. The slight amount of oil on the top half of the bearing could make the clearance appear to be less than what the plasti-gauge says. You can dry both halves of the rod bearings off and get an accurate measurement, but unless the bearings were change very recently unbeknownst to you, I'd change them regardless since you have things apart that far. If you're going to wallow things around very much, consider slipping pieces of fuel line hose over the rod bolts to keep from scratching the crank. Just a suggestion. Good luck!


      • #4
        Just a reminder, don't forget to lube the bearings BEFORE you reassemble them regardless of whether they're new or old!!! I like STP.


        • #5
          Cleanliness, cleanliness, cleanliness! John covered the checking pretty well although I wouldn't use STP as it's too gooey, sticky, messy. I assemble engines with white grease. No drip, no gooey fingers[xx(].

          Miscreant adrift in
          the BerStuda Triangle!!

          1957 Transtar 1/2ton
          1960 Larkvertible V8
          1958 Provincial wagon
          1953 Commander coupe
          No deceptive flags to prove I'm patriotic - no biblical BS to impress - just ME and Studebakers - as it should be.