One piece crank.

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Feb 23, 2012 | 12:03 PM

#11

grbrown

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From: Bedford UK

Quote:

Originally Posted by str8jacket

There is nothing inherently bad about the multi piece crankshaft design. If you build them to the hilt, then the cranks should be welded and balanced. Snowmobile motors that turn 10k rpm and put out 150+ HP out of the box use multi piece cranks with 1 piece rods.

Never heard of sleeve bearings referred to as plane (or plain) bearings before. Curious where that term came from. A plane is flat and 2 dimensional. A sleeve bearing is curved and 3 dimensional.

Plain Jane bearings?

Multi-piece cranks have been used since the dawn of time and will probably be used for as long as there are reciprocating engines. I'm sure they have been successful in even higher power engines. Mercedes built in-line 8 cylinder engines with one piece rods and roller bearings throughout (seventeen of 'em!)

The modern plane bearing has a variety of names. You might notice we live on different Continents old chap!

Last edited by grbrown; Feb 23, 2012 at 12:39 PM.

Feb 23, 2012 | 12:47 PM

#12

str8jacket

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From: USA

Quote:

Originally Posted by grbrown

You might notice we live on different Continents old chap!

Ah, didn't notice that. Good point, a lot of different terminologies on the other side of the pond.

Feb 23, 2012 | 12:55 PM

#13

grbrown

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From: Bedford UK

Quote:

Originally Posted by str8jacket

Ah, didn't notice that. Good point, a lot of different terminologies on the other side of the pond.

Two Nations divided by a common language!

Feb 23, 2012 | 06:01 PM

#14

Hillsidecycle.com

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I'll let others, test the Fueling crank.
Scott

Jul 8, 2012 | 01:47 PM

#15

Trex

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From: Hawaii

I've thought a lot about this since I had my crank Trued, balanced, pluged and welded for a big H.P build. I don't think this would be any more costly than what Harley builds right now either. The crank would be a forged steel one piece crank. The rod journal being the width of one flywheel too long. Machine and balance the crank as it is still one piece and machine in 2 or 3 key ways into one flywheel and rod journal while one piece. Then cut the keyed flywheel loose from the rod journal flush with the inside of the flywheel pin side. Machine a tight fit hole for the rod journal on the loose flywheel and thread the rod journal for a big bolt to tighten everything down. Now you have a crank that was forged to zero runout tolerances that accomdates male-female traditional HD rods and bearings and is able to come apart for rebuilding.

Jul 8, 2012 | 03:01 PM

#16

grbrown

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From: Bedford UK

Trex, I'm a Production Engineer by profession, started my working life devising ways of manufacturing aircraft engine components. I don't see anything wrong with the three-piece Harley crank, except possible inadequate quality control and suitable tolerances on components, prior to installation. What you suggest wouldn't be easy to make and would introduce other problems.

BSA made a more suitable crank for their single cylinder engines (250s and 441/500s). They used a car-style crank, with bolt-on flywheels, using side-by-side plain/shell style big-end bearings. That has the disadvantage of requiring a wider crankcase, to get the longer crank in. Harley's set-up is very elegant!

Jul 8, 2012 | 06:16 PM

#17

Trex

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From: Hawaii

I don't think your envisioning what I'm saying. The crank would be the same size not any bigger. The only difference in manufacture is it would be forged as one piece not 3. It would be machined just like curent parts need to be machined but just as one piece to get run out perfect,.0000. The keyways would be cut while it is one piece then the flywheel on the side the keyways were cut would be cut off. no more difficult than any other machining step. Then the hole cut through the flywheel where it was cut off so the rod journal can now go through it. Still be able to run the traditional HD male-female rod setup and be rebuildable, but no runout issues. The keyways and a bolt in the end of the rod journal holding everyting good.

Jul 9, 2012 | 03:41 AM

#18

grbrown

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From: Bedford UK

Quote:

Originally Posted by Trex

Your final crankshaft would not be one-piece! The keyways you talk of will not guarantee a perfect alignment, as we can't achieve that degree of perfection in making them, or when assembling the final crank. If Harley applied themselves to aligning their current set-up accurately (just requires a little more time and skill) they would be as accurate as your suggestion and easier to make.

The 'problems' we read about with TC crankshafts are entirely Harley's making. The design is fine, it is only their execution of it that is poor. I also suspect that the number of actual problems is very few. Unfortunately things get magnified out of all proportion here on the internet!