Drive side seal retainer

[hendy]

I'm trying and failing to fit a new crank (mazzochelli standard stroke and con rod length).

Every time I pull the crank through it catches on the bearing flange and won't rotate.

My crank main bearing is fully home (can't even get my thinnest feeler gauge) in the gap, therefore if there is a gap it's insignificant. I've also measured how far in it is sitting and it's pretty uniform all the way round - I can't be really accurate with this as I'm using a vernier depth gauge, but it's within 0.2mm all the way round and averages 2.4mm

I have now tried to tighten the plate down so hard that I've distorted it and need a new one.

The only thing I can think of is that my Halite gasket is thicker than it should be but it doesn't appear that different sizes are available. Is this likely or am I clutching at straws?

I've ordered a new halite gasket (from a different supplier) and a new bearing flange (again from a different supplier)

All my components are sourced from the likes of MB, scooter restorations or CamLam, so it's not Ebay syndrome

Any ideas?

[Tractorman]

Just I thought. I bought some seal housing screws with allen key fittings from Bridlington parts fair last year and when I fitted them they were proud of the countersunk holes and fouled the crank. Could this be you problem?

[mr series 2]

Try checking the thickness of the seal plate against another one if you can get hold of one I bought one from a well know reputable supplier last year it gave me the same problem turned out it was to thick

[corrado]

Does the drive seal plate sit proud of the face when fitted? It shouldn't do.

[corrado]

The MBbgm cranks come with 2 thickness of spacers that sit on the driveside shoulder of the crank to space it out [if needed, mine didn't need it] and they also come with thicker mag housing gaskets to fit if you need to fit the shims. I don't know if they sell these separately though.

[hendy]

Does the drive seal plate sit proud of the face when fitted? It shouldn't do.

No, it's flush with the engine casing

[hendy]

The MBbgm cranks come with 2 thickness of spacers that sit on the driveside shoulder of the crank to space it out [if needed, mine didn't need it] and they also come with thicker mag housing gaskets to fit if you need to fit the shims. I don't know if they sell these separately though.

They do sell them separately and I reckon I'll have to get the 0.5mm shim and thicker mag housing gasket. I have ordered the new bearing flange from MB which I believe is 0.7mm thinner. This would give me the clearance I need. I have just measured the shoulder on my Mazzochelli crank and it is 8.75mm. The distance from the face of the inner race to the top of the bearing flange with the Halite gasket compressed is 8.8 to 8.9mm so this is definitely a problem. I have measured the thickness of my new bearing flange against an original Innocenti one and my new one is slightly thinner at 6.9mm versus 7.0mm for the Innocenti, so this is not a problem.

This leaves me with two possible causes:

Halite gasket too thick - reasonably likely
crank shoulder too short - not very likely

using the thinner MB bearing flange should give me around 0.5mm of clearance, depending on the thickness (after compression) of the MB supplied Halite gasket. I won'y know until next weekend as I have to go visiting relatives for a week - I'd much rather be playing in the garage, but you have to be a husband sometimes.

[hendy]

Just I thought. I bought some seal housing screws with allen key fittings from Bridlington parts fair last year and when I fitted them they were proud of the countersunk holes and fouled the crank. Could this be you problem?

thanks, it could have been, but I checked and they were fine

[belly]

Halite washers do vary, had one that was too thick, crank wouldn't turn, replaced it with thinner one all OK

[hendy]

Halite washers do vary, had one that was too thick, crank wouldn't turn, replaced it with thinner one all OK

Thanks, that was what I was beginning to conclude, but the tricky bit is how/where to buy a thinner one without just buying random gaskets in the hope that one day I'll stumble across one of the correct thickness.