how to kill the givi / Hepco crash bar vibes Beta version!!! - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
General V-Strom Discussion Talk about all things V-Strom not limited to just one of the above models

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 33 Old 08-10-2009, 02:00 AM Thread Starter
 
Join Date: Jan 2008
Posts: 639
how to kill the givi / Hepco crash bar vibes Beta version!!!

These crashbars, are both inexpensive, and provide the most coverage for the $400 dollar side panels. but they do tend to vibrate some in the 4800-5300rpm range(ie a really sweet cruising range for the wee). I have not really been bothered by this much but I had a brain wave yesterday. And the beta version was tested today. I have found a soloution that will not eliminate the vibes but will reduce them to the level of no crash bars installed within 8-10%(this is from a displacement accelerometer on a vibescanner used to monitor industrial machinery)

here is a pic of the Beta version of the damper:



This came to me while cleaning a shotgun that had a mercury recoil suppressor fitted into the stock.

I did not want to pull the recoil pad on the shotgun(it is epoxied on) but I found a 3"long 3/4" pipe nipple in my junk drawer and some caps. I also have about 30 lbs of mercury left over from my shop (used for removing lead from gun bbls., and also in making Daguerreotypes) so I sealed a cap on one end filled the tube to within 1/4" of the top and sealed the second cap on. I now had the recoil supressor(uh damper) built and since I wanted to do a concept test I wrapped it in tape to build up the body dia larger than the caps. two worm clamps around the vibe damper after I padded the crash bar tube with masking tape.

I had measured the amplitude of the bar vibrations before the install, and after, and the motor mount vibrations, without the CBs installed.

the motor mount test spot yielded a displacement of right at.014"
the crash bar end showed a displacement of .112" without the damper.
the crash bar end showed a displacement of .006" with the damper on the damper mt side and a displacement of.011" on the opposite side. (these measurements were taken in fifth gear on the interstate on level ground with the throttle held with the rosta cruise at 4900, 5000,5100,5200, and 5300rpm the displacement numbers above are avgs. of each rpm point)

the seat of the feet and hands vibe scanner said holy shit this is just like no crash bars!!!

I installed the damper on one side only, hoping that it would cause the 2 sides to vibrate at non-sympathetic frequencies, thus producing destructive interferance transfered through the spreader bar from one side to the other to help reduce the vibrations even more. I will let you know in a few days if there is any benefit in running one on each side(the danger is that they may sync the vibes on both sides and produce sympathetic interference and make the vibes worse!) but a test is still in order.

Another nice thing about this rig is acts on all nodes of vibration (even though verticle is the primary node) It reduces the side to side shake as well.

OK I hear it now I don't have any Mercury laying around, go to Ebay and look for C&H or Break-o MERCURY TYPE shotgun recoil suppressors. and mount as per my pictures.

link to C&H: http://www.mercuryrecoil.com/#top

And by the way this works many many times better than filling the bars with bbs or lead shot (and winds up being lighter)

IMPORTANT, The more rigid your mt. is the better it will work, the commercial units should work even better than mine has, as they have a number of internal baffles, that give the mercury more surface area to push against. (I would look for the 7/8" dia 5 " long 16 oz model) my home brew has 10 oz of mercury in it. and is 4" long

I have tried just weights up to about 3 lbs, set about every where on the bars and the right amount in the right place works well but this works much better and is cake to install, it also dampens across the rpm range not just at a sweet sport like tuning with weights.

It really was like taking the bars off.

Now I am making no bs here this will not NOT make the strom bmw boxer smooth, but it will get you very close to the bikes feel without the crash bars, even when you have them on!
uzidzit is offline  
Sponsored Links
Advertisement
 
post #2 of 33 Old 08-10-2009, 09:45 AM
 
Join Date: Aug 2009
Posts: 88
Not so good vibrations

I have increased engine vibration on my 03 DL1000 around 5K on my bike with SW-MOTECH Crashbars/Engine Guards installed. Now I bought the bike that way so I don't know what it is like without the bars.

As a rule do crash bars enhance the passing of engine vibration to the frame? This is the only bike I've had them on.
So if I take them off will this likely reduce the 5K vibrations?
bdudemon is offline  
post #3 of 33 Old 08-10-2009, 10:13 AM
Stromthusiast!
 
Join Date: Mar 2007
Location: SLC, Utah
Posts: 90
Let us know when you get stopped for having a pipe bomb on your bike.

Last edited by ddreg; 08-10-2009 at 10:20 AM.
ddreg is offline  
 
post #4 of 33 Old 08-10-2009, 10:26 AM
Stromthusiast!
 
Warhammer's Avatar
 
Join Date: Aug 2008
Location: North Texas
Posts: 2,117
This phenomenon must vary depending on the model of crash bars. I have H&B bars on my DL1000, and I have no increased vibration at any rpm . The H&B bars are built very differently for the DL650. It seems that I have seen the most complaints about vibration from folks who have the SW Motech and Givi bars.

Uzidzit,
A couple of questions: Have you tried your damper on the vertical bar behind the one you have it mounted on in the picture? Any plans to try to make it look a bit better? I imagine you could use a similar pipe with plugs rather than caps to improve the look and negate the need for the wrapping to increase the diameter of the body. As for mounting, what about a couple of shotgun mag tube clamps? (Hey, this whole idea started with a shotgun!)


Man, those mercury filled recoil reducers aren't cheap! The cheapest one I could find is $53, and you'd need two of them to dampen both engine guards. Hey, Uzi, have you thought of trying this same thing on the handlebars to see what it would do to reduce vibration?

Last edited by Warhammer; 08-10-2009 at 10:37 AM.
Warhammer is offline  
post #5 of 33 Old 08-10-2009, 02:07 PM Thread Starter
 
Join Date: Jan 2008
Posts: 639
my bars are the Hepco bars.

the vibes did not bother me but they were there (put a hand on the bars while you are riding in the 5 k range you will feel it run through the range you will feel the bad spot). and yes I will paint it black and machine a nice alum. bracket for it in a while. I tried two today and it was not really any better than the single on one side, from a rider perspective, the vibescanner however showed a smaller displacement on the right bar.

yea they are not cheap that is why I mentioned finding them used on ebay.

I found it difficult to ride at that rpm actually out of habit I ride above 5500rpm, or slow cruise at 4500 this probably and adaptation I made without thinking about it. I will keep the fix on though because it does work and may decrease the speeding ticket chances at times from riding a bit faster to keep the revs in the smooth range.


mercury filled bar end weights may be just the ticket for the handle bars.

Last edited by uzidzit; 08-10-2009 at 02:16 PM.
uzidzit is offline  
post #6 of 33 Old 08-10-2009, 07:25 PM
Stromthusiast!
Super Trooper!
 
Join Date: Mar 2009
Location: seattle
Posts: 517
How did you measure those displacements? I'd think I'd rather use lead instead of something containing mercury. While both metals are potent toxins, the safer metal to use is lead since it is a solid. Also, since mercury is not that much denser than lead I think I'd stay away from anything containing mercury. I have filled my Givi bars with BB's and that reduced the vibrations, I think I will experiment with adding some lead weights too.

[SIZE="2"]2009 ABS DL650[/SIZE]
Arne is offline  
post #7 of 33 Old 08-10-2009, 07:41 PM
Cat Herder
 
LowAndSilent's Avatar
 
Join Date: Jun 2008
Location: Lynnwood, WA
Posts: 2,480
Quote:
Originally Posted by Arne View Post
How did you measure those displacements? I'd think I'd rather use lead instead of something containing mercury. While both metals are potent toxins, the safer metal to use is lead since it is a solid. Also, since mercury is not that much denser than lead I think I'd stay away from anything containing mercury. I have filled my Givi bars with BB's and that reduced the vibrations, I think I will experiment with adding some lead weights too.
Uh...yeah. +1 to Arne.

I also have filled the bars with BB's. $4 for one thing of BB's seems a little cheaper than buying those things.

'09 VStrom DL650A - Sold.
'04 Suzuki Burgman 400 - The wifes
'08 FJR1300AE - Miss Chievous.

WWGWD?

LowAndSilent is offline  
post #8 of 33 Old 08-10-2009, 07:42 PM
Stromthusiast!
 
Join Date: Jul 2009
Location: Raleigh, NC
Posts: 166
Do NOT ride to the airport! lol

What about some rubber washers?
seawolf06 is offline  
post #9 of 33 Old 08-10-2009, 07:49 PM Thread Starter
 
Join Date: Jan 2008
Posts: 639
Quote:
Originally Posted by Arne View Post
How did you measure those displacements? I'd think I'd rather use lead instead of something containing mercury. While both metals are potent toxins, the safer metal to use is lead since it is a solid. Also, since mercury is not that much denser than lead I think I'd stay away from anything containing mercury. I have filled my Givi bars with BB's and that reduced the vibrations, I think I will experiment with adding some lead weights too.
Quote:
Originally Posted by LowAndSilent View Post
Uh...yeah. +1 to Arne.

I also have filled the bars with BB's. $4 for one thing of BB's seems a little cheaper than buying those things.
the mercury recoil suppressors are sealed for life, and the solid lead will not work as well, it is not a matter of mass alone it is a matter of mass impacting a working surface, beyond the simple inertia.

this is the tool I used for reading the displacements:
http://www.pruftechnik.com/en/condit...ibscanner.html

you have to be in contact with the mercury for it to be a health and safety issue, and in its metallic form it is not as readily absorb able as most think, the oxide and vapors are what you really need to avoid and there is no contact in a permanently sealed container, kind of like lead unless you are inhaling vapors, ingesting dust, or eating oxides, metallic lead is much more benign than many think. (it has the same hysteria that motor bikes do oh god those things will kill you!!!!!!!!!!!!!) The biggest danger from lead is running into a piece of it weighing about 250grains being about .452" in diameter and traveling 700-1000feet per second!

Last edited by uzidzit; 08-10-2009 at 07:59 PM.
uzidzit is offline  
post #10 of 33 Old 08-10-2009, 09:30 PM
Stromthusiast!
Super Trooper!
 
Join Date: Mar 2009
Location: seattle
Posts: 517
Quote:
Originally Posted by uzidzit View Post
the mercury recoil suppressors are sealed for life, and the solid lead will not work as well, it is not a matter of mass alone it is a matter of mass impacting a working surface, beyond the simple inertia.

this is the tool I used for reading the displacements:
http://www.pruftechnik.com/en/condit...ibscanner.html

you have to be in contact with the mercury for it to be a health and safety issue, and in its metallic form it is not as readily absorb able as most think, the oxide and vapors are what you really need to avoid and there is no contact in a permanently sealed container, kind of like lead unless you are inhaling vapors, ingesting dust, or eating oxides, metallic lead is much more benign than many think. (it has the same hysteria that motor bikes do oh god those things will kill you!!!!!!!!!!!!!) The biggest danger from lead is running into a piece of it weighing about 250grains being about .452" in diameter and traveling 700-1000feet per second!
Yes, under normal operating conditions I'm sure the mercury is contained perfectly fine. I was more thinking -non normal working conditions-, i.e. accident. That might be a very different story.

Also, I see no good physical reason why this would work any better or worse than adding the same amount of weight in lead. The two properties that determine the main (the setup could potentially vibrate at multiples of this main frequency) resonant frequency of the bike-crash bar setup are geometry and mass. Adding the same weight in the form of lead in a similar container should yield the same results. Now, if you were to fill this tubes only halfway with Hg I might, potentially, expect different results.

the mercury recoil suppressors are sealed for life, and the solid lead will not work as well, it is not a matter of mass alone it is a matter of mass impacting a working surface, beyond the simple inertia.

Could you explain this?

[SIZE="2"]2009 ABS DL650[/SIZE]
Arne is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome