Burning bridges

[concours]

So my moto bud and I are tearing down the old Limey last night, 30 years since we did it the last time. Figured we'd clean the sludge trap and replace the bearings (100,000 miles in it) and when we got to the right hand main bearing, the crank wouldn't slide, or tap out of the bearing. After lots of bright lights, several pair of reading glasses, we were both astounded to see that end of the crankshaft had been PEENED over with what looks like and air chisel to tighten the fit in the bearing. Because of the radius on the I.D. of the inner race, it's mushroomed over pretty good. Just fugging wow. I'm pretty sure the shop he had balance it 30 years ago did this... but it wasn't mentioned at the time. It's worked great for a long time, but now it's a bitch. I'm thinking a milling machine, an adjustable boring bar and plunge just enough to remove the crank material peened over into the radius. Any other thoughts??

[concours]

Abetter view:





And why the points and later the Boyer were damp...

[concours]

Aluminum rods with steel caps...

[anotherguy]

I port heads so my skill with a die grinder is high. I'd attempt using a die grinder w/carbide. Always the easy way first. The boring bar thing may work but what's you time worth? That's a bitch of a set up. If the mill is in your basement and the time is free sure. Paying someone else would make it a last ditch effort.

[chammyman]

like anotherguy said I would try the old die grinder.

Other options run a bit of weld on the bearing if you access it, hopefully get it brittle then crack it.

Heat it and then cool it to break but thats difficult.

or drill through the bearing in a lot of places remove it bit by bit.

[sporthog93]

can you gently heat on the case half itself enougth to expand ???? then maybe spray the end of the crank with some refrigerant. you could use a pipe to spary in and keep the refrigerant off the warmed up part.

[concours]

Originally Posted by chammyman

like anotherguy said I would try the old die grinder.

Other options run a bit of weld on the bearing if you access it, hopefully get it brittle then crack it.

Heat it and then cool it to break but thats difficult.

or drill through the bearing in a lot of places remove it bit by bit.

I've got a bunch of die grinders, different carbide bits, the sharpest point cone shape I have will still have a 1/64" radius that will be hard to get into the part line. It may be the only option. Anyone have a Rocklinizer? Tap removal device, maybe I could shatter the race..

[concours]

Originally Posted by anotherguy

I port heads so my skill with a die grinder is high. I'd attempt using a die grinder w/carbide. Always the easy way first. The boring bar thing may work but what's you time worth? That's a bitch of a set up. If the mill is in your basement and the time is free sure. Paying someone else would make it a last ditch effort.

You're right, the set-up would be lengthy. I have access to mills, for free, but probably need to buy the boring bar I need. Just trying to save this crankshaft, it's been a peach! SMOOTH and reliable. The custom balancing job was money well spent!

[Beezer]

I gotta go with cutting out a piece of the inner race & then nocking out the balls. It'll be a bitch to drill.... mebby a cut off wheel on a Moto tool/ Dremel. The other thing that would work if you have the stones is an oxy/acytlene torch... really. Do short burns & quench to maintain the temper of the other parts. I have burned broken studs out of aluminum cylinders more than a couple times... just takes a good aim. The heat transfer of aluminum is much higher than steel, so you can get the steel burning before the alu melts.


You dont have to cut the race all the way through... only enough to get the balls out.

[machinebuilder]

It's hard to see in the pics,

I agree with the die grinder idea, but instead of a carbide burr maybe a very small stone or diamond cutter. Carbide might have a tough time on the race.
If grinding the peening off doesn't work try cutting most of the way through the race.

Be carefull hitting things too hard, with the bearing being held to the case with a snap ring there is a possibility of breaking the case.

[anotherguy]

You could drill the bearing cage out,remove the balls,crank from the cases and then deal with the shaft. Easy.

[bomber60015]

Originally Posted by anotherguy

You could drill the bearing cage out,remove the balls,crank from the cases and then deal with the shaft. Easy.

Knowing what I do (from reading the thread) that'd be my course of action . . . .

In terms of purposeful bodges, you win by a country mile -- to think the engine ran well for all that time . . . . .phew!

[concours]

Ok, update, determined no retaining clip inside, heated the case and pushed the bearing out. I removed the peened on bearing with a die grinder. Great. The drive side, however... the inner race has been working on the pinion, it's now .004" UNDERSIZE. Ok, any ideas to restore this pinion? Is there a crank shaft house like Falicon that can spray weld it and then re-grind? Brainstorm time... all welcome!



Sludge trap out, it was partially filled..

[marchyman]

Chrome and regrind is a common repair to vintage BMW crank journals. Don't recall off hand who does it. Google says that folks who repair fork tubes do chrome and regrind.

[ttpete]

.004 isn't too bad. I'd be inclined to use something like Loctite 620. There's no axial load because everything's cinched down with the rotor nut. There's a whole bunch of different retaining compounds on the Loctite website. Have a look at the data sheets.

Saw your sig line. If you get out this way, stop by. I've got a complete take-out TX750 engine you can have for free.......