Wildguzzi.com
General Category => General Discussion => Topic started by: Doppelgaenger on August 16, 2015, 01:49:26 AM
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Has this been done?
My car has a carbon fiber drive shaft, I was wondering if anyone has done this for a guzzi to try and reduce sprung weight. you could probably lose a few pounds by going to a carbon CARC support strut (whatever you call the top piece that joins the carc to the frame) and a carbon drive shaft.
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You are kidding, I hope.....
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What kind of car do you have?
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mazda rx8. lots of cars use CF drive shafts now
I don't see why it couldn't be done, and I don't see why they don't already do it.
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Plenty of reasons- onesey twosey production like Guzzis would mean no economy of scale in doing the composite work. Never having done it before would mean a huge investment in engineering. As there is no real testing program (the first buyrs are the test program)- any design glitches would be bone by the consumer. Although improved, the indifferent assembly line work does not mate well with high tech. I'd be willing to bet that you cannot just swap out existing dshafts witha composite- it would mean altering trans output as well as the final drive. The brand hardly promotes itself as bleeding tech - why wedge a carbon shaft in a bike that's already 550 lbs?
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mazda rx8. lots of cars use CF drive shafts now
I don't see why it couldn't be done, and I don't see why they don't already do it.
It can't be done.
It works on a car because the car is a large hollow tube. It has a large diameter and the loading is low. The Guzzi drive shaft is about an inch across and solid, for a reason. The torque on that small diameter is many times what the torque on a fat car drive shaft is. So you would need to go to a really narrow rim and tire to make room for a fat driveshaft. And unless it is a spine framer, you would need to increase the diameter and weight of the swingarm. Sounds like a lose lose, just to save a 1/2 a pound.
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A car can easily have a shaft that is 6-8 feet long. With that length a CF replacement will save enough weight to make a difference and still be very strong since the shaft can have a large diameter. On our CARC bikes the actual shaft is only around one foot long and of a fairly small diameter. The Cardan joint and splines probably weigh as much as the shaft. Thus you have two problems, heavy metal bits to make it all work and a small diameter which will limit the strength of a CF replacement. It's just not worth the effort. You'd be much better off to somehow reduce the weight of the swingarm and the actual CARC.
(https://peteryoungblood.smugmug.com/Motorcycles/12-Stelvio-NTX/i-CWQJh6x/0/S/IMG_0410-S.jpg)
Peter Y.
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If I can twist the splines off of the steel shafts & couplers, carbon fiber wouldn't hold up.
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If they were to replace everything that is bulky, like say the CARC housing, might be some unsprung weight savings there.
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If you've ever had a CARC housing stripped, you'd appreciate how light it really is. I can't see you making a casting any lighter. The next step would be a complex welded swingarm like I've seen on Aprilia race bikes.
No matter what you do, wight savings and shaft drive do not mix. If you wanted to save weight- go to a chain.
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For me
The Best,Cheapest and Healthiest way to lose sprung/unsprung weight is for me to quit eating Pizza!!! :grin:
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I'd say if you want a quick and dirty way to up the responsiveness of the bike, go down a profile size on your rear wheels. 90 > 80 or 80 > 70, and leave the vital parts factory for best reliability.