Superblends - Rumble, Which way round & sideplay?

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To do the frame alignment I needed empty cases so I stripped the engine and found zero crank end play. It was run at the lower limit but seems to have disappeared totally!
In addition to the high speed engine vibration I regularly felt what I can only describe as bearing rumble. Found the drive side bearing not as smooth as the timing side. I noticed there was some radial play with the crank in place in both bearings, ie with them dry the crank can be lifted 0.0015" measured at the centre of the flywheel. So 2 questions:

1. Is the play reasonable for 17000 mile bearings?
2. Is there a right and wrong way to install them? ie. smooth side of brass
cage facing crank or to outside.

Both bearings were from the original engine blowup so could they have got damaged from the hammering the crank gave them? Have done 10,000 miles since then. Crank is the same item and did not get bent and has minimal runout according to the guy who balanced last January.

Appreciate any help and opinions. Thanks.
 
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It certainly sounds as if the newness has worn off of your main bearings !

Could the lack of end float be a result of the tracks indenting? I have never been able to detect any up and down movement and I would think that any is too much. I have probably replaced a number of sets prematurely on the basis that the motor was apart and another cam had gone or something. That hardened steel has to go somewhere.

I think that bearing :oops: in mind the time, effort and cost involved in stripping down (those gaskets aren't cheap anymore) I would replace the mains if they had done anything more than a very limited mileage.

I have always placed my superblends with the markings on the inner and outer races on the same side on the basis that they were probably made that way and it wouldn't do any harm.
 
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Thanks 79. It was cheap of me to re-use 6500 mile old bearings but I'd already shelled out a grand for used cases, new barrels, pistons, rods, cam etc. The only experience I have of ball/roller mains rumble was an old T110 where the inner drive race would turn on the crank. It's a similar sound and sensation, just not as pronounced. Cheers.
 

L.A.B.

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Keith1069 said:
both bearings, ie with them dry the crank can be lifted 0.0015" measured at the centre of the flywheel. So 2 questions:

1. Is the play reasonable for 17000 mile bearings


When the factory changed to 'Superblends' they changed the specified clearance from 5-15 thou. to 10-24 thou., this is mentioned in the factory Service Release No. 68 (October 1971) that deals with the fitting of the new bearings, although that info didn't appear to filter through to the factory workshop manuals until 1975 (or '74?). The service release also mentions a new condition of crankshaft of "reduced overall width" that was also introduced at the same time to allow for the extra clearance, these new cranks being stamped with the letter 'R' on the timing side cheek. I think some people may consider 10-24 thou to be too much clearance?

2. Is there a right and wrong way to install them? ie. smooth side of brass cage facing crank or to outside.

According to the late John Hudson in the NOC Norton engine strip/rebuild video, the sides with the lettering should be kept together and fitted to the outside of the cases which would place the inner bearing race flange against the crank, most bearings now being of the 'NJ' type with the roller cage captive to the outer race, some earlier bearings being 'NF' type with the roller cage captive to the bearing inner race.
 
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LAB, appreciate that information which is completely new to me. I'll take a look at the timing cheek though with my engine I have no idea of the year. It was a 72 Combat but had suffered timing side damage to the cases. I believe that side was changed by the PO and when the crank was balanced in Jan it was pointed out the timing side was way out compared to the drive side.
Have installed new bearings the "correct" way round with a 010" shim on the crank giving 008" at first attempt. This is dry, bolted up in all holes. Usually this grows a little with sealer.
Side play is barely noticeable, is less than before and spinning the crank over sounds sweeter than with the old bearings. To be expected but they weren't on the point of collapse or anything, just lost their newness.
Thanks again.
 

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One thing I did notice is that this service sheet is marked as 'October 1971' (from the Kim Norton CD-ROM) although I don't think the factory started using Superblends until late 1972 as far as I know, so the date I mentioned could at least be wrong? The service release number (68) would seem to fall into line with the other service release numbers of that period though which is a bit odd?
 
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