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Old 12-10-2012, 09:43 AM   #8
XL-erate OP
Gnarly Adventurer
Joined: Mar 2008
Oddometer: 154
Fly Sniper, I am talking about a motorcycle 2WD. I mentioned the massive Dana 70-80 type limited slip as a simple reference to cluch plate & driven disc surface area. You couldn't get it in the understanding.

The Dana 70-80 is massive for a reason: the relative load. The Dana 70-80 is designed for a 7,000-9,000 lb vehicle. That design also references, or is relative to, the possible coefficients of traction, with possibly huge, wide, aggressive tread 4WD tires. The Dana 70-80 is designed to keep the pinion from snapping or walking up the ring gear when 400-500 HP or 400-500 ft/lbs of torque is applied. The carrier housing is designed to cope with extremely large rotational and dynamic forces. It is also designed to stay straight instead of wrinkled like a pretzel when all these combinations of forces are present at the same time, which calls for massive axle tubes, full floating axles, a monstrous carrier housing and sometimes even extra reinforcing ribs cast into carrier.

Despite all those huge forces at work trying to disintegrate metal in all directions, the Dana 70-80 uses clutch frictions and steel driven discs of about 5.5" diameter and 1/8" and 1/16" thickness respectively. That was the point of reference: the RELATIVE diameter and thickness of friction materials used in successfully applying force from engine to wheels.

A motorcycle sidecar rig does not weigh 7,000-9,000 lbs. It does not have 400-500 diesel HP or 500-600 ft/lbs of diesel torque applied to rear wheels. A diesel's low speed torque occurs at very close to off-idle rpm's so that the shock to drive system is much greater due to mass of vehicle not yet being accelerated: more inherent resistance to applied force. A sidecar rig does not have 42" tall x 13" wide extreme traction 4WD tires either.

A motorcycle sidecar rig doesn't need a Dana 70-80 sized rear carrier or drive system because it is RELATIVELY tiny compared to the described Dana 70-80 equipped truck. Additionally, it has 1/10 -1/4 the amount of applied horsepower and torque. The applied force is far lower.

I never described an unsupported clutch in any way, shape or form. You may have imagined it or interpreted that from what was written. Did you read the part about clutch hubs and bearing carriers/supports and spline shafts? Unsupported? Flex? How? Where?

My original post was not perfect and I expected some folks to have questions about the areas of the design that were confusing because of wording or individual understanding of it. I would happily answer any questions the best I can.


XL-erate screwed with this post 12-20-2012 at 11:41 PM
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