Question for a guru. Crankshaft reduction.


Information and questions on GL1100 Goldwings (1980-1983)
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Doniphan
Posts: 2
Joined: Thu Apr 26, 2012 11:40 am
Location: San Jose, San Jose, Costa Rica
Motorcycle: 1982 GL1100

Question for a guru. Crankshaft reduction.

Postby Doniphan » Tue Jul 15, 2014 8:13 pm



I just finished assembling my good old GL1100 after a crankshaft piston bearing problem caused by an overheat. It took me about a year because the spare parts are difficult to buy here in Costa Rica.

Now she is starting fine and sounds great.

An old mechanic (I think a wise one) told me that she will give me the same bearing problem in about two or three months because this Honda crankshafts have a thin hardening layer on his necks, and when I did grind it on the lathe, I damaged it forever.

It's that true?

:o



Old Fogey
Posts: 724
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Location: Glasgow Scotland
Motorcycle: 1976 GL1000
1979 GL1000
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Re: Question for a guru. Crankshaft reduction.

Postby Old Fogey » Tue Jul 15, 2014 9:09 pm

I have a GL1000 crankshaft here that has been ground 0.5mm on all journals. It had obviously done a lot of miles as the shells were worn, but the crank is fine. it must have been done some years ago as I cannot come up with new shells for it.

In theory, the crank will never wear. The idea is that the shells ride on a thin film of oil, supplied under pressure, that keeps the rotating parts apart. The oil is, to all intents, incompressible when supplied like this.

But it does, so why do we get wear?
Remember, the bearings are subject to huge pressures. If the oil is allowed to get 'dirty', filled with contaminants like carbon particles which get between the surfaces and break down the oil film, and acid condensate which attacks the bearing surfaces, then the the oil is no longer capable of keeping the two surfaces apart.
Oil changes are your friend! Yes, good oil is not cheap, but at the rate the NOS bearings are disappearing, neither is rebuilding your motor.
Also, on start up, the oil in the engine has had the chance to drain away from the bearings and in the first instance of starting there is no pressure, plus the oil is cold and doesn't want to flow. That is when you get the most wear.
Never, ever run a cold engine hard. Always let it get up to operating temperature before wielding the big stick!

As a tip, use the cut-out switch. Turn the engine over a few times with the cut-out off, to build oil pressure in the bearings before starting it.
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bigbugshurt
Posts: 12
Joined: Sat Jul 19, 2014 8:28 am
Location: Lawrenceville Va
Motorcycle: 1980 gl 1100 standard "patch" ;-)

Re: Question for a guru. Crankshaft reduction.

Postby bigbugshurt » Sat Jul 19, 2014 4:01 pm

I wouldn't worry about it...

Doniphan
Posts: 2
Joined: Thu Apr 26, 2012 11:40 am
Location: San Jose, San Jose, Costa Rica
Motorcycle: 1982 GL1100

Re: Question for a guru. Crankshaft reduction.

Postby Doniphan » Thu Jul 24, 2014 10:14 am

Thanks fir your replies guys. I feel more confident about it.




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