Topic: Engine Bearings

[bryanj]

OK, heres the bad news---they were fine to reuse!!!

Heres a hope

If you can get someone with a good touch and an accurate micrometer you can measure the thickness of the shells at the unworn part next to the locating tab, this would give you "pairs" of the same size and thicker ones would be tighter tolerance which means with the crank and case codes you might be able to work out which pair went where. Only problem is if there are a lot the same you wont know which journal they came off or which two together make a pair so wont be able to put them back where they came from. If you have the time and patience it might be worth a try but as you can't guarantee getting they back exactly where they came from its a long term risk

[Garage_guy_chris]

I do see a few shells i would want to replace in those photos. 

what are your crank and case codes?  If by chance you have like "BBBBB" cases and "AAAAA" main journals all the bearings **should** be the same If you have like "BBBBB" cases and "ABAAA" journals then you should have 8 shells one size and 2 shells another.  Keep in mind this is in a perfect world. if the engine has been previously opened who knows?!?!?

[theslayedsaint]

-bryanj thats what i said not to tell me!  maybe i'll talk to the guy rebidding my top end.

-Garage_guy_chris yeah I think our right on a few of them needing replaced, one looked like it had a good scratch on it
also with out looking at the lettering yet but seeing the back of the bearings it looks like they are all the same but two of them. i'm going to do some work this weekend and hopefully get a idea of what i need to do. sounds like I'll be just spending the money on new ones at this point.

[edwardmorris]

Those actually look alright, the one with the most wear isn't even close to one of mine with the least wear. I was advised to reuse mine, so you probably could do the same. The one close to the stator wear the most (or do I have this backwards?? check Mark's book) so I'd say use that as a reference point and plastigage.

[Jerry Rxman Griffin aka MuthaF'er]

They don't look too bad to me! I'd probably put them in and Plastigauge and hope they all squish out about the same so I wouldn't have to mix and match and mix and match and mix and match. I don't like to tighten it down more than once after Plastigauging IF NOT NECESSARY.

Of course you can always read the cases and the crank, determine the correct starting bearings, buy bearings, install with Plastigauge. Then possibly even order more bearings after you read the squish. Just out $$.   

[theslayedsaint]

OK a little update, My BMW R60/5 Broke the other day so now i have two bikes in the shop... anyways
here are the letters
-Crankcase bearings -BABBB
-CrankShaft Bearings - AAAAA
-Colors Green,Yellow,Green,Green,Green
Here is the bottom Clearances with the old bearings using green Plastigauge
.0015,.002,.0015,.001,.0015

Now i have two questions one how the hell do I Plastigauge the top half? trying to get the Plastigauge  on and then put the bolts on.
second question is the clearances good on the bottom? I'm having a hard time understanding this bearing deal it sounds simple but is kicking my butt for some reason. thanks for all the help so far.   

[bryanj]

You don't plastigauge both halves those readings will be the TOTAL clearance on the bearings, sorry don't got my book to hand at moment so can't comment on actual tolerances

[neevo]

Don't the bearings have codes on the back of them that relate to a colour code? I know my CB400F ones did and someone gave me a list of letter and their related colours.

[MiGhost]

Here is the bottom Clearances with the old bearings using green Plastigauge
.0015,.002,.0015,.001,.0015

clearance: 0.0008 - 0.0018 in  (0.02-0.046mm)
serviceable limit: 0.0032in (0.08mm)

From what I see.
Your measurements are within specs, but #2, and #4 look like they are possibly reversed, or mixed.
#'s 1, 3, & 5 are fine.

I would swap the bearings in #2, and $4. Then recheck.
If the clearances come in close to the others. You are in good shape.
If the clearances a still off. You can try swapping shells. Start with both bottoms, then one bottom with one top. Keep track of which ones you switch.

Worst case: You only need to replace the shells for the 2 odd journals.

[theslayedsaint]

Ok... So my head just went from i understated a little to WTF! so i only need to check one half of the engine case? and it doesn't matter if its the top or bottom? And are you saying that the shells have a top and bottom? This Bearing mess is kicking my ass.
ok i'm going to make sure I'm on the right page here. so here is what I've done and thought needed to be done.

-Put bearings back in case based on one being a different color and having one full bearing that was different.
-Plastigauge all bearings with Green Plastigauge.
-then closed the case with bottom on top.
-Torqued bolts
-Reopened and measured. 
-I thought I needed to Plastigauge the other half of case

And two other question do you guys think i should look at getting the crankshaft balanced? and as of right now my rods are still on the crank was wondering if i need to pull them and check bearings or if i should just leave them be. they move a "little" but not much. thanks for all the help guys.

[MiGhost]

And are you saying that the shells have a top and bottom?

All the shells are the same with just minor differences in thickness. They can fit in either the top half of the case, or bottom. My reference is to the location that you have them now. Top for shells in the top case. Bottom for shells in the bottom case.

ok i'm going to make sure I'm on the right page here. so here is what I've done and thought needed to be done.

-Put bearings back in case based on one being a different color and having one full bearing that was different. How did you determine that the one set was different?
-Plastigauge all bearings with Green Plastigauge. Correct
-then closed the case with bottom on top. Correct
-Torqued bolts  Correct
-Reopened and measured.   Correct
-I thought I needed to Plastigauge the other half of case  No. Once the case is bolted back together. The plastigauge gives the clearance between the crank journal, and the bearing shell. This measurement will be the same whether you measure the top, or the bottom.

And two other question do you guys think i should look at getting the crankshaft balanced?
The only reason to balance the crank would be for a change in the piston/rod weight. If you replaced the pistons, or rods with parts that were significantly different in weight for performance, or racing use. Otherwise the factory balance will be fine for an every day runner.

and as of right now my rods are still on the crank was wondering if i need to pull them and check bearings or if i should just leave them be. they move a "little" but not much.
The rods will have a little movement due to the bearing clearances. You can check them with the plastiguage to make sure they are still within spec on the clearances. But you should replace the rod bolts, and nuts if you do.
From your crank bearings. I would say to leave them alone.

 

Make sure you clean any old plastigauge of the bearing shells when you move, and recheck them.

[MCRider]

OK a little update, My BMW R60/5 Broke the other day so now i have two bikes in the shop... anyways
here are the letters
-Crankcase bearings -BABBB
-CrankShaft Bearings - AAAAA
-Colors Green,Yellow,Green,Green,Green
Here is the bottom Clearances with the old bearings using green Plastigauge
.0015,.002,.0015,.001,.0015

Now i have two questions one how the hell do I Plastigauge the top half? trying to get the Plastigauge  on and then put the bolts on.
second question is the clearances good on the bottom? I'm having a hard time understanding this bearing deal it sounds simple but is kicking my butt for some reason. thanks for all the help so far.

Bearing shells in top case; lay in the crank, lay onto the bare crank journals strips of PG per instructions; do not straddle an oil hole. Lay on bottom case with shells installed. Troque to spec; untorque, remove bottom case; measure PG.  Rinse and repeat.