Author Topic: 160 MPH High Speed Wobble  (Read 12159 times)

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Offline Uncle Jimbo

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160 MPH High Speed Wobble
« on: November 10, 2013, 01:31:42 PM »
Trevor Lyons started riding when he was just 8 years old. He has race motocross and hairscambles over the years. Now 26 and a 4x land speed record holder shows his skills at the BUB Motorcycle Speed Trials on the Bonneville Salt flats where he handled a 160 MPH high speed wobble as he entered the measured mile at top speed on his Lloydz Motor Workz V-Twin.

Tevor and his boss Lloyd Greer along with Klock Works Laura and Brian Klock work with at risk kids with there "Helping with Horsepower" program. More on that in future videos.

Watch how Trevor handles a 160 + MPH wobble.
http://youtu.be/n7kIUzs1AR0

Please like this video on YouTube and share it, thanks.

Thanks Brother Lou for sharing
Jimbo  :cheers:
From days of old, when knights were bold, and rode Iron Horses
24 Land Speed Records
M/PP 1350 AMA/BUB - M/CPG 1350 - M/CPF 1350 - LTA
M/PG 1650 - M/PF 1650 - AMA/BUB
A/PG 1650 - A/PF 1650 -  ECTA - LTA
Top speed to date 194.664

Offline rouse

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Re: 160 MPH High Speed Wobble
« Reply #1 on: November 10, 2013, 02:38:07 PM »
That will wake up the old pucker factor.

The problem with HSWs, is most of the time your not sure what started it, or just what gets it started.

Most of the time you come through it and not know what stopped it, just glad it stopped.

Glad he stead up on two wheels this time.

Rouse

 
Johnnie Rouse
Bike 4680 P-PP2000 SCTA record 153.325    A-PF3000 182.920
                              Texas Mile 152.518 PP class  186 A-PF Class
If you love your freedom thank a vet.

Offline Uncle Jimbo

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Re: 160 MPH High Speed Wobble
« Reply #2 on: November 10, 2013, 06:37:47 PM »
Trevor kindly tell us about your chassis. That was one rodeo ride, and am glad you rolled away with it and stayed upright.
  Nice goin !   :-o

Makes me wonder what started it too Rouse ?  I did notice a couple engine misfire/caughs at the start of it.  Do you suppose the interruption in the power flow to the real wheel could have started an oscillation ?  I know there are a lot of guys here at Landracing wayyy smarter then I when it comes to something like this.  I hope some of em will weigh in on this.  :cheers:

In 09 I had a eye opening shake on the Iron Ghost, turned out I reduced the trail numbers when I shortened the front end.
I wound up adding 5 deg. to the steering head and went back to the stock length forks and problem solved. 40 yr.old. Iron Head Sportster 147 mph

Jimbo
From days of old, when knights were bold, and rode Iron Horses
24 Land Speed Records
M/PP 1350 AMA/BUB - M/CPG 1350 - M/CPF 1350 - LTA
M/PG 1650 - M/PF 1650 - AMA/BUB
A/PG 1650 - A/PF 1650 -  ECTA - LTA
Top speed to date 194.664

Offline wobblywalrus

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Re: 160 MPH High Speed Wobble
« Reply #3 on: November 10, 2013, 10:44:11 PM »
Been there a few times.  Like Rouse says, it eventually stops.

Offline rouse

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Re: 160 MPH High Speed Wobble
« Reply #4 on: November 11, 2013, 03:42:53 PM »
Trevor kindly tell us about your chassis. That was one rodeo ride, and am glad you rolled away with it and stayed upright.
  Nice goin !   :-o

Makes me wonder what started it too Rouse ?  I did notice a couple engine misfire/caughs at the start of it.  Do you suppose the interruption in the power flow to the real wheel could have started an oscillation ? 

Jimbo

I can tell you that can do it. Once, I was running The Texas Mile and got to the finish line and just chopped the throttle with out pulling the clutch,, only ONCE. I nearly ran out of shutdown room before things settled down. That told me not to engine brake that bike again.. Period!!! (and there is not a caveat behind that Period!!!)

Rake and trail are very important factors * note * do not go fast on a V Rod without fixing the R&T, they are set up to look cool, not run fast.

Another thing is front wheel RPM vs. Rear wheel RPM, if that gets to far out (ie. rear wheel to fast or slow) you can have big problems. The wheel speeds needs to be within a certain % of each other or wobble will start, even if every thing else is right. A larger tire diameter on the rear will allow for more tire spin, as it works both sides of that % +/-.

Rouse

Johnnie Rouse
Bike 4680 P-PP2000 SCTA record 153.325    A-PF3000 182.920
                              Texas Mile 152.518 PP class  186 A-PF Class
If you love your freedom thank a vet.

Offline saltwheels262

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Re: 160 MPH High Speed Wobble
« Reply #5 on: November 11, 2013, 07:23:50 PM »
Geez.
good for keeping it upright.
bub '07 - 140.293 a/pg   120" crate street mill  
bub '10 - 158.100  sweetooth gear
lta  7/11 -163.389  7/17/11; 3 run avg.-162.450
ohio -    - 185.076 w/#684      
lta 8/14  - 169.xxx. w/sw2           
'16 -- 0 runs ; 0 events

" it's not as easy as it looks. "
                            - franey  8/2007

Offline joea

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Re: 160 MPH High Speed Wobble
« Reply #6 on: November 11, 2013, 09:31:55 PM »
i usually chop/roll off throttle, no clutch etc...and it has always slowed down in stable manner...

...it seems most of this stuff is  variable
from system to system ie veh to veh...
« Last Edit: November 11, 2013, 09:34:12 PM by joea »

Offline stay`tee

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Re: 160 MPH High Speed Wobble
« Reply #7 on: November 12, 2013, 01:07:47 AM »
 take my hat off to the young fella for riding that one out,,

i have found that the only way to diminsh a tank slapper/wobble is to keep on the throttle while easing on the rear brake, pulls them out nice and straight,, also helps if you have a rear tire go flat,,
First Australian to ride a motorcycle over 200mph at Bonneville,,,

Offline wobblywalrus

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Re: 160 MPH High Speed Wobble
« Reply #8 on: November 12, 2013, 01:34:09 AM »
Speed wobbles were routine when we raced big Jap bikes in the 70's.  Gradually it went away when the manufacturers paid attention to rigidity in the upper fork tubes, steering stem, and the frame around the steering head.

The triumph was a bad wobbler and I looked at this.  The frame was nice and rigid.  The forks, not so.  Some gorilla strength triple clamps were made along with some thicker walled upper fork tubes.

Another thing I did was to install some flat track triple clamps with inserts.  They could be changed and installed forwards or backwards to vary the offset distance between the steering stem and the fork tubes.  The bike was almost unrideable with the larger offsets.  It wanted to wobble in a bad way.  A bit of futzing around showed me the ideal offset for high speed stability and I used that for the new clamps.  The offset was reduced quite a bit to get it stable.

The bike in the video is a partial streamliner and the added fairing and tail weight makes it extra important to pay attention to the things mentioned in the previous paragraphs.     

Offline Koncretekid

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Re: 160 MPH High Speed Wobble
« Reply #9 on: November 12, 2013, 07:04:38 AM »
As humans, I think we have the instinct to over correct in a speed wobble which makes the  situation worse.  When I took the high performance riding school (road racing school) about a dozen years ago, they taught us to relax our grip on the bars and squeeze the knees for best handling and to minimize speed wobble.  Also reduces arm pump.

On my CB350 road race bike, I used later model triple clamps  from a 550 with reduced offset (forks to stem), and the dang thing liked not to go around corners at all!  I think Honda made them that way for better straight line higher speed handling.  When you reduce the offset you increase the trail, which is a good thing for LSR bkes.  I used this concept along with extremely stiff (1-1/2" thick lower, 1" upper) triple clamps with just 40mm offset compared to 65mm for the stock CB350 triple clamps on my A class bike.  I've only got to 145 mph so far, but no sign of a wobble.  However, I have experienced a slow weave if I don't keep my head down at speeds over 100 mph. And remember not to pick the head back up until the bikes slows down below 100 as well.  Also got that weave when I had a bias ply rear with a radial front tire.
Tom 
We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!

Offline generatorshovel

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Re: 160 MPH High Speed Wobble
« Reply #10 on: November 12, 2013, 04:44:59 PM »
The "good 'ol days"  :roll:

http://youtu.be/z3OQTU-kE2s

Tiny
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline wobblywalrus

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Re: 160 MPH High Speed Wobble
« Reply #11 on: November 13, 2013, 02:02:18 AM »
Thanks for posting that.  This is the best thing about landracing.com  We can learn stuff to save our butt.

Offline Koncretekid

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Re: 160 MPH High Speed Wobble
« Reply #12 on: November 13, 2013, 06:40:38 AM »
Great old video!  One thing he mentioned was that the slo mo camera showed that each fork leg was compressing independently of the other.  I would suggest that a lot of wobble may be eliminated by stiffening up the forks, triple clamps, and probably a larger better connected front axle.  Most of the newer bikes already have these features, but the old ones, including those shown in the video, do not.  And keep your head down, even when slowing.
We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!

Offline JimL

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Re: 160 MPH High Speed Wobble
« Reply #13 on: November 13, 2013, 11:00:04 AM »
'Bout 40 years ago I worked with a fellow who (in his younger days) was best friends with Dan Blocker.  That led to a chance lunchtime visit with an older Hollywood stuntman.  He explained that they could make "real nice wobbles" by loosening the front axle nut and the front fender bolts.  It allowed lower speed for the wobble, and safer get offs for the crash scenes.  It helped to run the right speed on a surface that had some evenly spaced bumps or grooves to get it working for you.

None of us knew anything about "gyroscopic precession" in those days, I bet.  Now you can learn all about it on the internet.  You only have to be able to tilt that spinning wheel a tiny bit, and it will turn itself into each tilt for you.

So....now we all take off the braced front fenders and go real fast.  Add some extra rake, along with too soft front springs and no travel limit....hmmmm.

JimL

PS:  for the last 3 years, I've been running schedule 40 PVC or ABS (slotted and hose clamped) on my forks.  With travel limited to about 1/2" under power (and zero on decel) the front end stays planted.  I actually learned this by accident, when I was curing too much front end lift by closing down the fairing opening above the front fender and adding forward weight.  I was trying to protect my paint on the top of the front fender, and the bike suddenly became more stable.  The older I get, the slower I learn. :-P

You can see it in this pic, on right edge....shown with no front wheel at full extension.
http://www.landracing.com/forum/index.php?action=dlattach;topic=12670.0;attach=40505;image

If you do this, be sure to pull them off and clean/oil the tube during cleanup.  I cut about a 3/4" wide slice out of the ABS or PVC so they will snap in place to hose clamp....no need to disassemble the forks to install or adjust.
« Last Edit: November 13, 2013, 11:05:44 AM by JimL »

Offline bak189

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Re: 160 MPH High Speed Wobble
« Reply #14 on: November 13, 2013, 02:47:43 PM »
It should be noted that all "speed wobbles" are not caused by the front end.....did the wobble occur at accel...decal... even throttle....wheel alignment...swing arm mounting....rear tire pressure.....too much engine power for the chassis/frame being used....can also be a cause for wobble....even the rider position on the bike (front end loading or not) One needs to look at all these factors in order to resolve a "wobble" problem...............................................
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