Simple main crankshaft bearing outer removal or not!

[Steveba10]

I’ve looked through past posts and think I may have something to add.
If it’s already been covered please ignore.

I read the instructions given in the posts and was glad I had read them prior to tackling the job of removing the old outer race of the roller bearing.
I did as was told, a) Wait for the wife to go out.
                          b) Remove my dinner and warm the case in the oven.
                          c) Put new bearing race in a plastic bag into the freezer.
                          d) Wait for dinner to cool and case to warm, I measured initially 120Deg C then, trying again 170Deg C with an infra-red gun.
                          c) Remove case, invert it and let the race fall out or tap it down onto a piece of wood to jar it out.

My problem is that it would not come out, either gravity was not paying attention and looking the other way, or inertia was weak and having a bad day.  It was still tight in there.

Having tried twice and not wanting to distort anything with higher temperature I resorted to a trick I used years ago on Jaguar IRS alloy hubs.
These held a pair of small taper roller bearings in the casting. The taper rollers come out easily but the small races are pressed in and buried deep.
You cannot get behind them or get a puller in the remove them.
The trick is to simply use an arc/stick welder and run a quick bead of weld around the inner tapered face of the race.
As the bead of weld cools it contracts and has the effect of shrinking the diameter of the race and out they fall.

So out with the stick welder, a bead of weld and the race dropped out.
Case back in the oven and out, bearing race out of the freezer. ( the bag stops ice forming on the surface.)
And in with the new race.

I didn’t make the mistake of installing the main bearing oil seal before using the oven.
But I did have to grind out the rivets and remove the g/box seal I stupidly installed yesterday.

So ‘Job done,’ nearly.
                             d) put dinner back in oven. ( turn thermostat down.)
                             f) deny all knowledge of hot oil smell in kitchen.
           

[BigJim]

Inertia and gravity? Gosh, lets not get into quantum mechanics. As a bear of little brain and even less tooling ie no welder would that plumber freezer spray have been of any use on the race to encourage it to shrink a little? Probably not but it would be something easy to hand. I'm glad you got it out without mishap. Good luck with the rest of the assembly.
 

[chaterlea25]

Hi All
Sitting in a box in my workshop is a Sachs two stroke engine in bits!! it came to me that way
Whoever took it to bits decided to use the weld the outer race to shrink it "method" 
The result was distorted bearing housings 
So be Warned

If the bearing race is reluctant to shift and you do not have an expanding puller to hook inside the race radius
try heating to 200c hol the temp there for 15min. and try again

John

[edboy]

wifes oven on max roast and  oily dinners for the rest of the week works for me. highs and lows.

[Black Sheep]

Not forgetting to thump the crankcase down hard on a solid piece of wood.

[Swarfcut]

 Steve. Just compared a plunger and S/A drive side castings.

 Plunger case AA7 series, scroll/no oilseal type  has a couple of holes conveniently placed to drift the race out. A later B series case (Seal type) does not have these holes, but the inner edge of the race is visible and actually supports the seal in an otherwise plain housing. There is enough of the race visible to enable a thin drift, typically a flat blade screwdriver, to assist removal from the heated case. This arrangement is identical on S/A Cases, C & D Series.

 Could be your bearing is not the right one, in which case what was locating the seal?

 Original bearing was Hoffman R130L, Skefco NFL30, Ransome LRJA.30 Data Published April 1960.


 Swarfy.

[Steveba10]

Hi Swarfy,
Thank you for doing the comparison.
My original bearing was marked only as R130 V3, I assume a Hoffman. It’s a ‘57 bike but plunger frame, originally as a side car mule.

My original seal and it’s replacement is a nice press fit into the crankcase half from the outside and additionally secured by three small centre punch deformations. It extends across the male collar left from the machining of the two recesses, one for the seal and the other for the outer bearing race. It seals against the engine shock absorber sleeve.
I’ve made a rough not to scale sketch attached below that might explain the layout better than words.

The outer main bearing race is pressed into the case with nothing protruding to aid removal.

Holes drilled in the case would allow for a pin punch to push the race out but would have to lie very close to the edge of the seals outer diameter or even across it for say 1/16mm and 1/8” pin punches.  Also perhaps allowing oil to creep through.
Thanks again and what do you think?
Steve.

[mugwump]

I have had success by plunging the crankcase in boiling water on several different bikes in the past, I can only think that it works well because on the sudden immersion as opposed to the lengthier warming up in an oven. Always worth a try.

[Swarfcut]

 Steve.  Your cross section diagram tells most of the story, but has an error which complicates matters.

 The correct roller bearing has a single lip on the outer race. As standard on a seal type case there is only one recess, for the outer race. The crankcase should only be machined to accept the outer race, lip side goes in first. The oilseal hole is just that, a hole. From the outside, the seal locates inwards, open side towards the crank, against the face of the outer race, and is retained by friction with the hole and by the peened in dots. As mentioned earlier, with the seal removed the lip of the bearing is visible and can be used to push the race out. As such there is no need or room for the earlier drilled pin punch holes.

 I hope you have either the wrong bearing or more likely have mistaken the lip on the race for part of the crankcase casting, and that some previous owner has not modified the case.

 Your diagram shows a bearing with axial movement both ways, with lateral outward movement controlled here by the aluminium crankcase. This is the error and if this is what you have its the wrong bearing and explains any nasty marks you may have where the crank cheek has been hitting the case, as there is nothing apart from this soft material to stop the crank moving outwards. This is the function of the lipped bearing race. Very early A7 Longstroke engines had a deep ball race, which effectively controls lateral movement, the later lipped roller bearing was added to cope with higher loadings as power output increased with the introduction of the A10 and redesigned A7.

 The choice, advantages and types of modern drive side bearings has been debated  on the Forum, the information is all there, plus some of the pitfalls and successes folks have had setting the correct crank end float with the correct single lipped roller bearing.

 Swarfy.

[Steveba10]

Hi Swarfy,
Thank you for taking the time to help me sort this bearing out.
Sorry my drawing came out upside down, it was right way up in my picture library.

I looked at my drawing again and see you are correct in that I omitted to include the outer race lip that the rollers thrust against.
I have redrawn it enlarging the area of concern and labelled the lip, see below and hopefully it’s up the right way.

You write that ‘the seal locates inwards, open side towards the crank, against the face of the outer race.’
But please see my drawings to see my seal butts against what I’ve labelled the ‘collar.’  The other side of which the outer race also butts up against.
The seal I bought from Dragonfly was the standard one and fits snugly against the collar.

Please also see that the ‘collar’ I’ve got protrudes inwards past the outer race making it invisible to any form persuasion to push it out.

The bearing I bought was NF206 by the Japanese company NSK. 13 rollers being better, I think, than the 10 or 12 offered and nearly the 15 of the original.
I bought it at a local bearing outlet to make sure it was genuine and not a cheap one repackaged.
It was a bit more expensive than on-line, but authentic.

The new bearing is a tight sliding fit on the crank so I assemble it and the crank cases to measure the end float at 0.018”
This compares well with the end float of 0.004” with a 0.010” shim = 0.014” of the original bearing.

You worried me when you mentioned damage to the inside of the drive-side crank-case as I can see some evidence of scoring but there was no metallic debris in the cases as I received it. The crank rotates cleanly with no contact in the case without any shims so with a shim in place it will be at least an extra 0.015” clear.

So in conclusion I feel confident that with thrust in both axial directions and a named bearing it should now be safe to assemble properly.
Thank you again for your input,
Steve.

[Swarfcut]

Steve. I can only report what I found on all the cases I have to hand. All  are machined in the same way, and none have a collar as you describe. So a conundrum, but it looks as if you have it sorted now and lucky to have a bearing that slides on and off to adjust the shims.

  Be interesting to see how your case compares to others out there.

 Swarfy.