Setting Crank/Bearing depth when assembling

[CDBiker220]

Had some problems with the right side crank bearing on my 07 EC300. Having work done on the right case and getting a new bearing. However I was wondering how to correctly press the crank/bearing/case together to get the crank centered right. Does the bearing get pressed to the bottom of the case bore? or do you have to set that depth. Does the crank press all the way down on the bearing. The left side is easy since it is a roller. If anyone can explain this it would be helpful, any tips for the crank installation/case assembly would be helpful.

 

[gasgasman]

I haven't done one lately.
One thing to watch for. DO NOT allow the bearing to block the lube port from inside the crank case.

 

[GMP]

Its no problem, the bearing seats against the bottom of the bore, and should be approx flush with the inside of the case. Likewise, the seal is pressed in from the other side until flush, but NO MORE, or it can block the oil hole as gasgasman states.

If you have never done this before, use heat/cold and as little force as possible and never across the race of a bearing. Warm the cases to 250 deg or so slowly and freeze the bearings in dry ice, they should just drop in. I do most of my work in winter so I use the top of my pellet stove but an oven is even better. Post heat a bit to drive off condensation. Before you do this though, ask the shop that fixed the case with the sleeve if it will be a problem, and don't warm the case in a position that could allow the sleeve to fall out.

The crank should just drop in if the cases/bearing are still warm, its not as tight a fit as the bearings in the cases. Again, you could freeze the crank to make it very easy. Just let the crank seat on the bearing inner race.

The roller inner race is done the same way on the crank. The engine shop manual has the procedure, I'm not sure but I think it seats flush on the journal as well.

 

[elemetal]

Typically you have to adjust axial (long dimension on the crank) play by using small shims between the crank lobes and inner race. The manual should give a number for the allowed axial float (.3-.5mm I'm guessing) and you have to account for the center case gasket in there too. A good way to do this is take the old inner races off and hone out the inside so they slip rather than press on, then get the outers pressed into the cases. Do a dry asssembly with the old inners, center gasket and new inners and measure axial (side to side) play. Then you'll know if/how much shim to use between the lobes and the new inners for final re-assembly. Keep in mind if you put all the shims on one side it will move the crank off center so it's best to do it evenly to both sides.

I detailed this because the inner can be a real PITA to get off and usually you use a special tool (bearing iron) to get them off. You can't get a puller on them easily and you don't want to trash a new set of mains, they cost too much....This way you can hopefully put them on only once.

 

[GMP]

While your right and technically its a good plan, I've never seen a GG motor set up this way, and I've had a few apart. Keep in mind that the ignition side roller bearing is not a captured race type, so you can't apply this to the ignition side. I'll check the manual but I don't remember any adjustments for float.

 

[Neil E.]

End float is only important in an engine that has roller bearings on BOTH sides.

Assembly length is important so the crank doesn't get pinched when everything is put together.

Normally you would get the ball bearing located properly and install the crank snug to the ball bearing. The roller bearing just lets you put the other case half in place with no effort.

 

[GMP]

Exactly. I looked at the engine manual and it states procedure as Neil and I have.

 

[CDBiker220]

Thanks guys for all the help. Will probably be a week before I get to actually assemble. Is it a good idea to put new rings in while im at it? piston and rod bearings look good.

 

[elemetal]

Sorry for the confusion, most of the mains I have done use a roller on both sides rather than the GG way (which I hopefully won't have to do for a while). Disregard my info please.

 

[GMP]

No problem.

CDbiker,

How many hrs on the piston? I don't even do rings anymore, if I'm taking the trouble to tear it down a new piston is going in as well. Unless you know there are very low hrs on the part why not start fresh?

 

[CDBiker220]

Being poor is mostly the factor behind my decisions. It still had 185 psi cold before i tore it down. Probably doesnt even need it.