crank bearings/binding (Page 1 of 2)

They should fitt tight ! How tight we talkin are you just trying to insert them in the case with out the crank ?
  I usually install them with out the crank shaft first ! Then I mark where they seat on the bearing with a sharpie ! Then I install them on the case .
  Use the number 3 bearing see if it fitt's all the way down in the saddle << You should be able to see it .
  As too bearing halves << They never do but try this out swapp them from one case side to the other look for the best fitt .
  Can Buy a Dial caliper made in China for 20 buck's at harbour freight !
  If it appear's that the bearing wont fitt you need a Smaller O.D. bearing !
  Also check the fitt on the crank !
  Whered case come from is it new ? New case would be a Standard bearing on the O.D. Box is usually marked !
  Realize here that there usually marked in metric and that most measurement's are takin in Standard thousandth's .
  Most Manual's have a reference comparison or translation size's cause my vocabulary isnt workin this mornin Arghhhh !
  Frikin tell's you Metric size then give's you the Standard size for that size >> The Equivalent etc.
                                          Sean

I have a gear puller to get the gear off the crank but I am NOT taking it back off again. 

The bearings to go all the way in, and fit fairly tightly without the crank.  The case is an old AS-41 from my 74 bug, align bored .50 over.

I'll try swapping the halved bearings tonight.  I'm going to try and get some bluing stuff and make sure that its not still a clearance issue with my crank.  I went and bought a Dremel moto-tool so I can clean up the ugly clearancing that I did with my big grinder.

Are you strokin ??
Dont understand clearanceing the case ?
If case is Lined bore 0.50 mm think that's .020 in. swipe from memory I dont build enough motor's to know off top of my head ?  think that's the right conversion ?
  Anyhow then you need a Bearing set that is 0.50 on the O.D. and then if crank has never been turned ??
  You need a a Standard I.D. Bearing what the bearing Box will say on it .
  0.50 - O.D.     STD - I.D.    <<< look somethin like this on the Bearing Box . Also look on top of the case for a stamped .020  << Indicateing the Guy who line Bored it might have stamped the case by the oil cooler usually .
     Sean

The ideal way ahead is to use a micrometer to measure the case and the bearings.  The bearings do need to be completely snug in the journals - any movement at all will quickly pound your case apart.

If you're concerned the bearings aren't seating properly, make sure the dowels are properly seated in the case, that nothing is preventing them from fully seating in the holes.  You also need to make sure your bearing/dowel alignment is bang on.  A lot of bearings have been trashed on assembly because of pinching.

As you're tightening the case halves together, you should be able to turn the crank easily (even by the distributor rotor...) the entire way, and still turn easily when fully torqued.  If you're getting binding then there is definitely something amiss.

The cheap tool at Harbor Freight (or House of Tools, Canadian Tire, etc) is a worthwhile expenditure.

I can understand your reluctance to pull the crank gear off again, but I'd hate to see your engine fail prematurely because you didn't pull it off.  I've found that heating the gear on a stove element makes for a real easy installation of it.  No pounding, cursing or sweating required.

Sean, Nick posted in another thread with a photo of how he had to clearance some inside his case to clear the counterweights on his crank.  I don't recall hearing of anyone having to do that for a stock stroke before, but who knows.

The reason I had to clearance the sides was because there was no end-play shim on the flywheel end, so the crank would slide around a bit.  Since I didnt know exactly where it would sit when shimmed and torqued, I decided to shave the case a bit to make sure that it wasn't an issue.  Even when I had the crank pushed all the way backwards, it was verrrry close to the sides of the middle journal.   

I have the correct bearings which are std inner diameter.  I went to another machinst last night with my brother and they both measured everything and said it looked good in theory and after fitting the rear main bearing into all of the journals they said that it felt as snug as it should be. The only thing they couldnt check was if the crank was bent. 

I know the half bearings are not perfectly round, and that this might cause a bit of resistance.  The guys mentioned that I should probably clean the case better since there was oil in behind the bearings and that is preventing the surfaces from mating properly. Also, they suggested using engine pre-lube instead of just motor oil because its thinner and more slippery than motor oil, which could be causing some of my issues.  Additionally, they said I should chamfer the tops of the journals slightly for the halve bearings because the material is mushrooming out when the case is tightened and has nowhere to go.

They also showed me what I can try to seat everything better, so I'm going to try all this stuff tonight and see what I can do.  Since two reputable machinists have said that the OD on the bearings measures correctly and that the journals also measure correctly when the case is tight, I'm not going to take the bearing off the crank just to check it.

... they also were of the opinion that I could probably build it, torque everything together, and then as long as I could rotate it with a small amount of leverage (ie: ratchet on a gland nut, NOT fingers), then it was probably fine and that things would seat themselves properly once I started the engine.  I'm pretty hesitant to take that advice.

All this leads me to believe that I have a slightly bent crank, which is a shame, but considering that I had let it sit on a table for a few days with the timing pulley still on it, I guess I shouldnt be surprised.  I had NO idea that a crank was that sensitive.

Ryan: whew!  crank is brand new, never been run and never left my shop.

been at it again all night....

Things I have done:

- I cleaned the case (again), washing out all of the bearing journals with degreaser.
- Chamfered the split bearing journals slightly so the case-half edges have a bit of room to mushroom.
- reseated the split bearings
- used assembly lube on the bearings instead of oil
- attached flywheel with correct shims to take out end-play and rule out if I had to do more clearancing or not

Results:  The crank definitely turns MUCH better now BUT when when I start torquing, it starts to get harder and harder to turn.  So I did a little more investigation... 

I just snugged all of the 6 studs and then, one by one, I started to ease them towards the torque specifications and I noticed something strange.  After trying a handful of combinations I noticed that the rear 4 bolts (closest to flywheel) could be torqued up to 20 lbs (I didnt want to go further..) but as soon as the front two (closest to pulley) got anywhere near 15lbs, the crank would bind.   It seems that the front main bearing (of course the one thats ON THE DAMN CRANK) is the cuplrit, but I'm not sure what its guilty of just yet.  I seated and reseated it, and it always seemed firmly in place.

I'll have to get a proper measurement of that front main journal bore when the case is torqued, to make sure its not tapered.   But I'm wondering if it's off-centre?  I took off the smaller bearing at the very tip of the crank to make sure that it wasnt the smaller hole that was off-centre and causing the crank to want to bend, but it made no difference. 

I feel like I've made a bit of progress, but I'm still not sure what I can do about it. 

To look at it from a spiritual point of view: the fact that I really didn't want to take that bearing off in the first place (because it was soooooo hard to get those damn gears on) seems to be a good indication that I'm avoiding something that I should do... so perhaps taking it off the crank, cleaning it, and putting it back on will set my mind (and my crank) at ease...

...wish me luck.

When you're torquing those bolts down, are you doing all the bolts on the case evenly, or just the ones in the area you're testing?

Make sure you follow proper torquing procedures for the larger studs first, then the perimeter nuts.

If you torque unevenly, or just in one area, you're probably flexing your case and causing more problems.