Crankshaft end float woes… no movement, just solid with no end play!

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The old bearing was C3 marked and not tight? I've forgotten if these are replacement bearings or not!
 
Fast Eddie said:
Sounds like you need to remove the bearing outers again, double check for extreme cleanliness and try again to refit them following the advice already given.

Also, did you freeze the bearing outers? Some say this is the thing to do, but there’s a counter view which is that the frozen bearing will cause issues by sucking too much heat too fast out of the heated case and then expand rapidly, causing tightness before being fully seated. Heated cases and room temp bearing outers are my own preference.

And what about Kommandos loctite question? His reason for asking is that loctite can cause a bearing to tighten too much when it hardens. So, unless your bearing housing are suspect, best to avoid loctite and simply aim for scrupulous cleanliness IMHO.
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I chilled the bearing outers in the fridge (avoided the freezer) and didn’t use any Loctite.
 
Looking at the 3C bearings that RGM sell, it should be very easy to tell if they are 3C or not...
Crankshaft end float woes… no movement, just solid with no end play!
 
Onder said:
The old bearing was C3 marked and not tight? I've forgotten if these are replacement bearings or not!
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The original (old) bearings do not show '3C' stamped. They do display: - 'FAG GERMANY F.D NU306E'. Plus, I originally checked the crank did have generous end float before I pulled the old bearings out.
 
Soundbite said:
The original (old) bearings do not show '3C' stamped. They do display: - 'FAG GERMANY F.D NU306E'
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Prior to the introduction of the ISO standards for rolling element bearing where the C was standardised you could see other forms of marking for bearing clearances.

All could be stamped or more likely etched, the old versions of C3 were 3 dots or 3 circles as it was by maker not a set standard. And for CN (N=normal) there were no clearance markings at all.
 
Once you sort out the correct bearings and ensure that they are seating well determine if the crank spins correctly with the cases fully torqued (no sealer). The last engine I built seemed to have no end float with the cases just stuck together but was fine once fully tightened.

Are you sure that there's no shim in either side of the cases. I had one that had two shims on the drive side case , super glued in, that I didn't notice because the normal machining looks like there is a shim. Once removed, everything was fine.

If there is zero end float but the crank turns freely, you will have end float when the engine is warm - the cases expand. IMHO, zero end-float is fine when the engine is cool as long as there is no binding. It may be difficult to feel the end float with the engine on the bench if it's only a couple of thou.

That said, I have replaced the bearings you had and older with the ones AN sells and have always had end float that I could feel and measure. The new one I'm looking at right now is marked: "FAG X-life NJ306-E-XL-M1-C3 India R301-180916" on both the inner and outer.
 
Echo what's stated by others, RGM sells both bearings, I had to return the non-C3's they sent me in exchange for the correct ones. Contact the vendor, they are easy enough to deal with and will exchange for you
 
acadian said:
Echo what's stated by others, RGM sells both bearings, I had to return the non-C3's they sent me in exchange for the correct ones. Contact the vendor, they are easy enough to deal with and will exchange for you
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Yes, they are being exchanged so no worries! Cheers.
 
The early bearings are NOT marked on the bearing and only on the box. Later fag bearings are marked on the bearings. Hard to measure 10-12 microns!
I saw no declaration of what NHT you are working on!
At some point, 71? maybe, the crank mains were eased a bit and LAB has posted the factory release many times.
I have NEVER frozen the bearing...I only heat the case to 350f and drop them in . Also I NEVER use case shims, cranks shims only for me but needing shims is very rare.
Soundbite said:
Likewise with the outer bearings to ensure the replacements were seated correctly at the bottom of each housing without any obstructions (like old shims)? – Yes and both went in smoothly after the casings were heated then driven down to the absolute bottom.
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UH oh!
How much evidence of the old bearing spinning in the bore? ( they always do)...
 
My engine is on the bench now. Bolted up the cases with the crank and nothing else in, no case sealant,
Case bolts nipped up but not full torque.
I got 9 thou side play. 60F temp in the garage.
Think Norman White says 11 thou is what you want. I cannot worry about 2 thou the engine has done 10k with these
bearings no problems.
When hot the cases are only going to grow and more than the crank.
 
Onder said:
My engine is on the bench now. Bolted up the cases with the crank and nothing else in, no case sealant,
Case bolts nipped up but not full torque.
I got 9 thou side play. 60F temp in the garage.
Think Norman White says 11 thou is what you want. I cannot worry about 2 thou the engine has done 10k with these
bearings no problems.
When hot the cases are only going to grow and more than the crank.
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I would not worry one bit at .009. Only if you are starting an engine from cold near or under 32f /0C, would I not like .005".
Reminds me of one trip ( 70 commando roadster) where I left Watertown, NY at around 9PM and the town Bank thermometer read +3f . :eek: Cases would have shrunk for sure...
 
Smartest part of that move was LEAVING Watertown. It is aptly named except they don't indicate the normal state of water in that town! |:)
 
dynodave said:
I would not worry one bit at .009. Only if you are starting an engine from cold near or under 32f /0C, would I not like .005".
Reminds me of one trip ( 70 commando roadster) where I left Watertown, NY at around 9PM and the town Bank thermometer read +3f . :eek: Cases would have shrunk for sure...
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I bet that wasn’t the only thing that shrunk that morning.
 
swooshdave said:
I bet that wasn’t the only thing that shrunk that morning.
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9PM is night and getting colder all the time. I only make 80-90 mile, out of approx 300 mile trip, and had to get a motel room. Most of it was NY thruway.
 
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