Primary Side inner race

Jerry Doe · Apr 25, 2009

Hi All,

I have a dilema. Here it is -need advice:

I have crank case all cleaned up and ready to go back together with the new stock cam (taking megacycle 5600 out). Just about to put crank in and noticed the inner race of super blend is spinning on drive side. Obviously not good.

So what shall I do? First thing is I will have to order that special puller to get inner race off. I was not planning on replacing the bearings, perhaps I should?-- They look OK. I am assuming now I have to pull the crank to bits and take the drive side to a machine shop along with inner race and get it on right. Probably a good idea to inspect everything and clean the trap out anyway..

Any ideas from other welcome as I have never come across this issue before,

Cheers Jerry

Cookie · Apr 25, 2009

I'm sure you will get opinions on this one Jerry, nice work on the site by the way. I learned to inspect bearings in an aircraft shop and we have done the same in trucks, busses, and trains. I clean the bearing and stack it to allow it to air dry, spinning with air guns can chip a race or roller. then I hold the bearing up to the light while turning the rollers looking for chips or scratches in roller or race. Any marks and it's out. The race is easy to inspect, any chipping or scratching and it becomes a spacer for your press.
I'd inspect and measure the depth of spin on the case, if much material had been lost I'd have it welded up and machined to a press fit. If it wasn't bad and seemed well centered I'd just stake it a bit and Red Loctite it. I've used Red Loctite to hold greyhound bus wheel bearings and a few hundred thousand miles later when they are serviced we have to heat the bearing race to get it back out.

Jerry Doe · Apr 25, 2009

Yeah,

I think at this point it's all coming to bits for total inspection and new super blends -- even though I dont really think i need them---

Reggie · Apr 25, 2009

Jerry, from the Commando Service notes, that LAB kindly put a link to;

MAIN BEARINGS: What again I hear you groan? A small point, quite often with the super-blend, the inner
race, especially on the timing side, comes loose on the crankshaft; this does not seem to be detrimental
in any way, so do not worry about it. The next time things are apart down there a blob of Retainer Loctite
is recommended. Clean both surfaces with Carbon tetrachloride or similar (Evostick Cleaner) degreasant
(not petrol, it leaves a faint oily film) and use Loctite-601 green Retainer fit, this is some four times
stronger than the 641 yellow Bearing fit. Bearing fit 641 is for use up to four thou. gaps, 601 for use up to
six thou gaps. While the ultimate is Studlock 270, stronger than 601 but it needs a minimum gap of two
thou. and will fill up to 10 thou.

Funnily enough I found this on my MK3 crank but on the drive side, the inner race would turn with just finger pressure, and due to wanting it on the road ASAP, I took advice from loctite advice line, and loctited it with loctite 603 (I think), and to the best of my knowledge, all is OK, but I haven't split the cases to check. But I am no engineer (see my other post)

I may at a later stage get the crank metal sprayed, or some other fix like pegging the bearing inner, but I will take advice from the engineers when that day comes.

79x100 · Apr 25, 2009

I've always used red loctite as a preventative measure on my inners. As Cookie says, the crucial thing really is that the shaft isn't so worn that concentricity becomes a problem. If it's simply a sliding fit with no measurable play then I would loctite it.

I've replaced a number of Superblends over the years simply because the motor was apart and something like a cam lobe had done the usual disappearing trick but to be honest, I've never been able to observe any damage, even with a magnifying glass. Wear on Superblends is almost unheard of at normal mileages.

Jerry Doe · Apr 25, 2009

The inner is spinning with light pressue. There is not up/down play or wobble. I cannot get it off at this point since I dont have the puller, so need to order one to get it off and will report back then... The bearlings look good.

79x100 · Apr 25, 2009

If it needs a puller to remove then I reckon it's a clean-and-Loctite job.

The inner bearing puller is perhaps one of my least-used but at the same time most valuable tools. Damned difficult to do the job without it.

Cookie · Apr 25, 2009

From the further information I'm pretty sure I'd clean and Locktite it myself unless there was another pressing need for a complete disassembly. It can be truly amazing how well Loctite can hold.

splatt · Apr 25, 2009

loctite has come along way since stud lock was stronger than bearing retainers, if it was only a pull apart to replace the cam I would clean and loctite,keep the centre punch locked tightly away.

Jerry Doe · Apr 25, 2009

After much messing about I have the inner race off. It had shims behind it. Looks like ISO shims.. I am assuming that they were added to prevent end float. Any ideas? (I dont see them in the parts book). BTW what should crank end float be?

Cheers

CanukNortonNut · Apr 25, 2009

Jerry Doe said:
BTW what should crank end float be?

The International Norton Owners Tech Digest states 0.010-0.024" when fitting Superblends.
The Norton workshop Manual for 850 and 750 states Permissible end float: 0.005-0.015"
I set my tolerance at 0.008" somewhere in-between the extremes.
Regards
CNN

chris plant · Apr 25, 2009

hi jerry, it would have been a good idea to measure your endfloat before you stripped the motor(hindsight is a wonderfull thing)however shims are,nt added to prevent end float ,just to reduce it ,the main thing is that you,ve got it, i cant see why you cant refit the shims you took out unless they are damaged in any way,im not sure on the exact figures but i would,nt go for less than 20 thou

Cookie · Apr 25, 2009

The nice thing about something like this is it isn't all that critical. Somebody set it before and it worked fine didn't it? This is just a repair, Locktite it in and put it together. Just make sure you have a little float as being too tight is often what destroys bearings, the crank has to have room to expand and flex.

CanukNortonNut · Apr 26, 2009

Jerry
Just out of curiosity. Why are you pulling out the MegaCycle 56000? Are you not pleased with the performance?
CNN
:shock:

Reggie · Apr 26, 2009

Taken from the Old Britts site, under technical articles/engine.

This article shows the two types of crank shaft shims available. When placing two super blend roller bearings (06-4118) on the crank, you must fix the end play of the crank since the inner races are not held in place as in a ball bearing. The end play should be around .005" to .010". The end play will increase when the engine heats up, but .005" to .010" is a good end play to shoot for.

The factory part manuals show the shim, 06-7569 or NMT2196A, being placed between the outer race of the bearing and the crank case. However the factory shim, 06-7569, supplied by Andover Norton goes between the inner race of the bearing and the crank cheek. The factory shim is only available in .003".

We find it a lot easier and less destructive to the bearing to remove the bearing from the timing case than remove the inner race from the crank. Therefore, Old Britts has had some shim kits made up, 06-7569/A, and these shims go between the outer race and the crank case. Each kit comes with five shims and the sizes are: .002", .005", .008", .010" and .015", which should be sufficient for any engine rebuild.

I have not found that I needed any shims, as the play on my crank was within tolerances.

maylar · Apr 26, 2009

This is very timely for me, as I am about to disassemble the crankshaft for sludge trap cleaning and put the old girl back together this week. I have a few questions:

How do you measure end float?
Why did the factory not show shims in the books... is shimming not normally required?

Do the inner races get tapped on with a mallet and tubular drift?

At this stage, it'll be easier for me to shim behind the inner races if needed, since the old ones are still there and I can measure before removing them. The new bearings are installed in the cases.

chris plant · Apr 26, 2009

hi maylar,to measure end float you will need to install the crank in the casesand bolt everything up tight,then you need to rig up a dial gauge with the pointer on the end of the crank,by pushing and pulling on the crank the dial gauge will show you the deflection ,shimming is not usually required i,ve never used any,the inner races do get tapped on with a mallet and tube drift,heat them up in the oven and they will go on easier,it is easier to shim behind the inner races but i would,nt use the old inners in the new outers to measure with

Jerry Doe · Apr 26, 2009

Thanks for that... I will order some as I do need shims.

dave M · Apr 27, 2009

I always use an old inner race that I keep in my tool box for shimming crank-shaft end float. If you grind the inside of the old race a little with a dremmel it will slide on and off the crank for the purpose of fitting shims without having to use pullers and risk damaging the new bearing part. The end float will be close whichever inner you use. CAUTION this only works if you are replacing a superblend for another superblend.

Jerry Doe · Apr 27, 2009

Great idea--!! Thanks

Primary Side inner race

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