Author Topic: Just asking, where does the torque go?  (Read 1459 times)

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Offline Tour1

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Just asking, where does the torque go?
« on: December 08, 2018, 02:40:27 pm »
Sitting here before work, near freezing outside, thinking about stuff.
Like, torque is 2 equal and opposite forces separated by a distance.  So if somebody tries to pull a wheelie on a C10, most of the weight of the bike is on the rear wheel, and as the front fork extends less weight is on the front wheel.
Does the torque tube transmits fore-and-aft torque forward to its pivot point near the transmission?  If so, those 4 bolts are doing a lot more than squishing the gasket.  I don't recall anything else back there that would take torque off the wheel.  And since it is torque, it would mean that only the 2 bolts in tension are trying to lift the bike from the back end.
 ::) So now I'll look at a parts book and discover how silly my question is (probably).
 
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Offline RWulf

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Re: Just asking, where does the torque go?
« Reply #1 on: December 08, 2018, 04:23:26 pm »
If I understand this correctly. The torque applied to the rear wheel is trying to rotate the
whole motorcycle around the rear axle. The drive shaft tube and the right side of the swing
arm carry this force to the frame thru the engine bolts and the swing arm mounting bolts
at the front of the swing arm. The engine itself would try to rotate around the output
shaft (where the counter shaft sprocket would be on a chain drive), this force is what the engine
mounting bolts are resisting.
So you really have more than 4 bolts at work here.

Offline Boomer

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Re: Just asking, where does the torque go?
« Reply #2 on: December 09, 2018, 01:03:32 pm »
When you wheelie the C10 the top 2 bolts on the final drive are in tension but the force is mostly carried by the lower half of the shaft tube pressing against the final drive.
Yes the whole weight of the bike plus rider is carried by the shaft tube via the swingarm pivot and the shock linkage.
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Offline Tour1

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Re: Just asking, where does the torque go?
« Reply #3 on: December 10, 2018, 01:23:22 pm »
Looking at the parts diagram I didn't see anything before the shock linkage so I think that is the first thing that takes any torque.  The right side takes its share of weight and resists some twisting along the axis of the torque tube.
Next time I take the rear wheel off I'm going to torque those 4 bolts very carefully at the final drive.  As I recall I had to use a box wrench on the inside bolts.  Maybe the torque wrench offset formulas (found in another thread somewhere) will be needed.
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Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #4 on: December 10, 2018, 01:47:13 pm »
Tour 1, why are you concerned? Did you have some type of torque problem?
I agree with RWULF... The torque from the driveshaft is being opposed. But the entire swingarm is carrying the force, not just the T-tube..
On the other end, all the motor mounts etc are carrying to opposing force.
   It's a strong system. Nothing should fail.
Are you looking at the 3 wheeler idea again?}

Ride safe, Ted

If I understand this correctly. The torque applied to the rear wheel is trying to rotate the
whole motorcycle around the rear axle. The drive shaft tube and the right side of the swing
arm carry this force to the frame thru the engine bolts and the swing arm mounting bolts
at the front of the swing arm. The engine itself would try to rotate around the output
shaft (where the counter shaft sprocket would be on a chain drive), this force is what the engine
mounting bolts are resisting.
So you really have more than 4 bolts at work here.
« Last Edit: December 10, 2018, 04:37:05 pm by connie_rider »
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Offline Jim Snyder

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Re: Just asking, where does the torque go?
« Reply #5 on: December 10, 2018, 02:10:21 pm »
Tighten the bolts and ride it !!!
"Some days you're the windshield, and some days you're the bug" Get used to it cause thats life !!!

Offline CRocker

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Re: Just asking, where does the torque go?
« Reply #6 on: December 10, 2018, 03:57:21 pm »
Ummm...acceleration?

Offline Tour1

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Re: Just asking, where does the torque go?
« Reply #7 on: December 12, 2018, 07:04:46 am »
Just a little bit of thinking about a 3 wheeler, the rest is the drive system in general.
Like, where could stuff bolt onto the frame to take away torque.
If I recall correctly, the final drive just bolts up to the torque tube, with the internal-splined sleeve connecting  drive shafts.  The final drive is aluminum or equivalent with 4 studs in it for the 4 torque tube nuts.  Eventually I was wondering how much I tightened those nuts.  Steel nuts on steel studs I likely do right without a torque wrench.
   But I do now believe that when trying to pull a wheelie, the final drive is trying to lift the bike just like when superman picks up a cruise ship from one end (and with one hand).
« Last Edit: December 12, 2018, 01:51:06 pm by Tour1, Reason: fixed the bolts vs studs issue »
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Offline DangerousDan

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Re: Just asking, where does the torque go?
« Reply #8 on: December 24, 2018, 05:09:32 am »
I had a couple days of obsession with trying to wheel y my first shafty .  It was perplexing to me .  So much power, but getting the timing was very hard for me.  Most the time I just leave some of my rubber on the road where I attempt it, occationally she flew up too fast and I put her down hard.  Too hard.  I haven't done it in a while, the physics of it  do tumble in my mind though.  It seems like a very tiny window one has to exploit to get the lift started, unlike all the chain drives I have owned.  But I'm a very new c10 rider, there must be a way.  Maybe letting my body flop back until my arms are extended then tighten hard enough to raise the center of gravity as my arms lock straight?  Suddenly absorbing the forward momentum?  Because when she goes up, she goes very quickly.  Too quickly.
So this is a life?  Lets have some fun!
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Offline DangerousDan

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Re: Just asking, where does the torque go?
« Reply #9 on: December 24, 2018, 05:25:20 am »
ops,, didn't mean to submit;
  Anyhow, it feels like all the torque is placed on a single spline, which on a chain or belt drive would be 2 or 3 links.  So the torques is so concentrated in such a small point, it is very hard to NOT over do it, or under power it, then the thousandth of a second has passed.  To where on a chain, its hundredths of a second, or even tenths.  Its not that shafties can't wheely, its just so damn terrifying because of the torque being packed into such a tiny space in time and motion.
So this is a life?  Lets have some fun!
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Offline Tour1

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Re: Just asking, where does the torque go?
« Reply #10 on: December 24, 2018, 03:02:40 pm »
My math and physics says at full throttle in 1st gear at the maximum torque RPM the torque would be the same at the rear wheel whether the front wheel lifts or not.  I recall a torque transmits equally through a solid structure (until it is opposed) so the torque applied by the final drive pinion equals the torque opposed by the final drive bolts and the torque created by the forward thrust on the rear axle times the distance to the contact patch on the rear tire. 
So in theory the maximum acceleration of the bike in 1st gear and its weight could tell you the maximum torque, if the tires don't spin.  Converting torque to burning rubber is the more difficult math problem.
Watching races I notice the tires seem to get bigger when they burn rubber at the green light.  The change in radius would affect the calculation.
An on-board accelerometer could record some data.  The most accurate numbers would likely come from having sensors across the road/track every foot or so with accurate timers.
On the other hand the front forks don't much look like they oppose torque but if they stoppie the bike they are just as torqued as a wheelie.
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Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #11 on: December 24, 2018, 04:13:50 pm »
In this Forum, there are torque curves available. {measured at the rear wheel on a dynamometer}

Ride safe, Ted
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Offline Nosmo

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Re: Just asking, where does the torque go?
« Reply #12 on: December 24, 2018, 04:30:00 pm »
Be prepared to replace the rear wheel drive hub soon if you keep doing this.  The splines will take it for awhile, but not for long.
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Offline DangerousDan

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Re: Just asking, where does the torque go?
« Reply #13 on: December 24, 2018, 05:34:06 pm »
Be prepared to replace the rear wheel drive hub soon if you keep doing this.  The splines will take it for awhile, but not for long.

 This feels like its directed at me  :)), I since have decided its too hard on the bike to pretend its a sports bike, and the only fun wheely is the kind from raw power over a hillock on the open road.  Throttle and gravity wheelies on C10 are much more gentle on Crysis, and wheelies on flat ground are embarrassing to attempt in public.  My front shocks and faring scream in agony when she slams down after punishing me with  the terror of a sudden threat of flipping over.  Not doing that again for a while, not sober anyhow  :beerchug:
So this is a life?  Lets have some fun!
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Offline Tour1

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Re: Just asking, where does the torque go?
« Reply #14 on: December 27, 2018, 03:54:53 pm »
In this Forum, there are torque curves available. {measured at the rear wheel on a dynamometer}

Ride safe, Ted
Tech pages, "C10 Power and Torque"
Downloaded pdf file which says it will open as read-only, as soon as I enter the correct password.
Does anybody know the correct password?
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Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #15 on: December 27, 2018, 04:14:34 pm »
easiest; Just go to Steve's site and look there.
https://sites.google.com/site/shoodabenengineering/replacement-torque-cams

Ride safe, Ted
« Last Edit: December 28, 2018, 04:47:32 pm by connie_rider »
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Offline MAN OF BLUES

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Re: Just asking, where does the torque go?
« Reply #16 on: December 28, 2018, 01:41:51 am »
In this Forum, there are torque curves available. {measured at the rear wheel on a dynamometer}

Ride safe, Ted
Tech pages, "C10 Power and Torque"
Downloaded pdf file which says it will open as read-only, as soon as I enter the correct password.
Does anybody know the correct password?

didja read the pop up? it explains what is related to viewing... and it give the applicable password.. write it down (copy/paste doesn't function for the popup) and then apply it when opening/  really quit simple.

well, I'm extremely sorry for that response I made...after looking, and attempting to see, it seems that the features on the tech section are severely lacking attention... please contact the site moderators, and request this is fixed, after all, you as a member are paying for it. (the archived data)
« Last Edit: December 28, 2018, 01:54:05 am by MAN OF BLUES »

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Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #17 on: December 28, 2018, 03:15:01 pm »
Below is an old note about a Muffler Comparison Test I did on my Dyno.
  I had just bought the dyno and didn't have it fully set up to record the plots at the time.
  But, it will give you some idea about the torque at the rear wheel.

If someone wants to plot these, please do so and post the plots.
I did it years ago, but can't find mine.


XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

I sent this to the 4 into 1 (Ontario) Pipe discussion.
 Steve saw it and suggested I start a new discussion so that people (that are considering a Baffelectomy) could see it.
   I ran 3 sets of mufflers on the dyno on Friday.
     Stock, Stock with Baffelectomy, and Cobra F1s.

NOTE: My computer guy wasn't there to help with printing the dyno charts, so my numbers are not exact.
           (I had to read the plots and "guestimate" the values for this list).
           So, my numbers are not exact, but they are pretty close.

Stock Mufflers
 RPM   HP  Torque
 2000  14    35
 3000  30    52
 4000  43    57
 5000  52    56
 6000  70    61
 7000  83    63
 8000  90    59
 9000  92    53

Stock Mufflers with Baffelectomy
 RPM   HP  Torque
 2000  14    38
 3000  32    55
 4000  44    57
 5000  56    58
 6000  74    64
 7000  86    64
 8000  93    61
 9000  94    55

Cobra F1s Mufflers
 RPM   HP  Torque
 2000  15    40
 3000  32    56
 4000  44    58
 5000  56    60
 6000  74    65
 7000  86    64
 8000  93    62
 9000  95    57

Peak torque; in all cases was at about 6500 rpm.
                     Stock 63, baffelectomy 64, Cobra's 65

Peak HP; in all cases was at about 8500 rpm.
                Stock 92, Baffelectomy 94.5, Cobra's 95

The numbers don't quite tell the tale here either.
 The plot for the Cobra pipes was smoother (more consistent) than the others.

The surprise was how much change the baffelectomy showed.
The Baffelectomy numbers are very close to the Cobra numbers, and modifying the stock mufflers costs a heck of a lot less than buying Cobra's etc...

Ride safe, Ted
« Last Edit: December 28, 2018, 04:48:34 pm by connie_rider »
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Offline WillyP

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Re: Just asking, where does the torque go?
« Reply #18 on: December 28, 2018, 04:06:56 pm »
please contact the site moderators, and request this is fixed, after all, you as a member are paying for it. (the archived data)

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Offline Tour1

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Re: Just asking, where does the torque go?
« Reply #19 on: December 28, 2018, 05:51:56 pm »
...
well, I'm extremely sorry for that response I made...after looking, and attempting to see, it seems that the features on the tech section are severely lacking attention... please contact the site moderators, and request this is fixed, after all, you as a member are paying for it. (the archived data)...
Don't be sorry, it came & went before I saw it.  Also I'm not cranky about member benefits provided by unpaid volunteers.

Meanwhile, I found the dyno charts on the Shoodaben website, and they said bout 60 lb-ft max for the stock bike, 65 lb-ft for the torque cams.  An old thread about gear ratios got me a figure of 80 mph at 5K rpms stock, which works out to almost exactly a 2 foot diameter tire.
The overall ratio in 6th is quoted at 4.53 so 60 lb-ft would be 271.8 lb-ft at the wheel, assuming that engine guys would focus on torque values at the engine.
271.8 lb-ft in 6th in 6th becomes 864.86 lb-ft in 1st.  That would make the front wheel load 169.6 lbs less at max torque, well below half the bike weight.

So, net results, I think the final drive studs & nuts would have to oppose about 865 lb-ft of torque.  Bumps & vibrations will add their own load there.
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Offline bajasam

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Re: Just asking, where does the torque go?
« Reply #20 on: December 29, 2018, 01:35:28 am »
i'm pretty sure your theory is flawed, you don't increase torque or hp with gears, using your math your saying your c-10 is putting out the same torque as a 6.7 litre cummins turbo diesel at the rear wheel. 

Offline works4me

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Re: Just asking, where does the torque go?
« Reply #21 on: December 29, 2018, 02:11:01 am »
i'm pretty sure your theory is flawed, you don't increase torque or hp with gears, using your math your saying your c-10 is putting out the same torque as a 6.7 litre cummins turbo diesel at the rear wheel.

Other than the math not accounting for parasitic or
frictional losses his numbers are pretty accurate.
I would knock off about 10% for real world numbers.

How do you suppose a measly 60 lbs-ft of torque manages to
accelerate half a ton of bike and passengers?

Offline Bob_C_CT

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Re: Just asking, where does the torque go?
« Reply #22 on: December 29, 2018, 02:07:57 pm »
Wouldn’t the failure mode of the final drive bolts be more of a shear and somewhat a tensional force with the rear axle and swing arm frame taking up most of these forces?
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Offline connie_rider

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Re: Just asking, where does the torque go?
« Reply #23 on: December 29, 2018, 04:53:49 pm »
Everyone, the 60 lbs-ft of torque were "measured/calculated" at the rear wheel on a dynamometer {probably} in 2nd or 3rd gear.
Your misunderstanding the math. Torque does NOT increase.

NOTE: The dyno test could have been done in 6th gear as well. {as a dyno uses engine rpm, wheel speed, time, etc to do the calculation's}
Because of the way the force is determined, the results of a 6th gear pull would be about the same {probably less due to losses} as a 3rd gear pull.
{The Engineers can explain better than I}.

Tour 1, I question why your concerned?
The design was used for 25 years...
{with turbo engines} Some have put as much as 200 HP against a Connie Rear End without it failing.
So, we know that the rear is plenty strong to hold things together with the stock {90 HP} engines.
What is your concerns?

Ride safe, Ted
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Offline bajasam

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Re: Just asking, where does the torque go?
« Reply #24 on: December 30, 2018, 02:01:20 am »
i'm pretty sure your theory is flawed, you don't increase torque or hp with gears, using your math your saying your c-10 is putting out the same torque as a 6.7 litre cummins turbo diesel at the rear wheel.

Other than the math not accounting for parasitic or
frictional losses his numbers are pretty accurate.
I would knock off about 10% for real world numbers.

How do you suppose a measly 60 lbs-ft of torque manages to
accelerate half a ton of bike and passengers?
using that analogy we could all just run briggs and stratton lawn mower engines and gear em up thru a 15 speed tranny til we had a couple hundred ft-lbs of torque....lol   sorry but it dont work that way pardner