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  #1  
Old Aug 30th, 2007, 9:47 pm
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tycho tycho is offline
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Evoluzione torque arm - K1200s

If anyone has installed a Evoluzione torque arm on a K1200s, could you tell me if the longer attachment bolt goes on the front or on the back? Either way I've tried, the short bolt is slightly short on the rear and the long bolt is slightly long on the front. Thanks.
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  #2  
Old Aug 30th, 2007, 10:57 pm
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allikanbe1 allikanbe1 is offline
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i have no clue. why not email Ken at www.evoluzione.net and ask the expert?
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  #3  
Old Aug 31st, 2007, 12:30 pm
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evoluzione evoluzione is offline
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Quote:
Originally Posted by tycho
If anyone has installed a Evoluzione torque arm on a K1200s, could you tell me if the longer attachment bolt goes on the front or on the back? Either way I've tried, the short bolt is slightly short on the rear and the long bolt is slightly long on the front. Thanks.


the longer bolt goes on the front (if you have esa there is a bracket that attaches to the bolt) - the shorter on the rear. i'm not sure why the shorter bolt is too short - do any threads stick out past the end of the nut?
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  #4  
Old Aug 31st, 2007, 3:47 pm
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tycho tycho is offline
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evoluzione torque arm

I put the longer bolt on the front. The shorter bolt on the rear is just flush with the outer edge of the nut. Put locktite on all bolts as per instructions. Rode bike for 200 miles, checking tightness 2-3 times. Everything is fine and the difference in handling is quite noticeable (with all five shims on arm as per recommendation by Ken at Evoluzione from a previous thread). Buying the arm from Evoluzione was well worth the money and am quite satisfied. Thanks for the responses.
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  #5  
Old Sep 20th, 2007, 8:45 pm
bolev bolev is offline
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Do you know if there is any truth to this statement that Ihave read about changing the length of a torque arm on this bike. Here is what it says:

"The drive shaft does not have constant velocity joints (only normal universal joints) and therefore the output shaft must be as near to parallel with the input shaft, so any further increase in length would be inadvisable. It would cause an increase in vibration, tyre wear and impose extra stresses on all the paralever bearings."

I found that on this site http://www.sandbarcomposites.co.uk/...htadj-plate.php

I have the Evoluzione torque arm. I plan to install it this weekend. But if the statement above is true, I wonder what the effect will really be long term on the bike.
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  #6  
Old Sep 20th, 2007, 9:30 pm
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evoluzione evoluzione is offline
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Quote:
Originally Posted by bolev
Do you know if there is any truth to this statement that Ihave read about changing the length of a torque arm on this bike. Here is what it says:

"The drive shaft does not have constant velocity joints (only normal universal joints) and therefore the output shaft must be as near to parallel with the input shaft, so any further increase in length would be inadvisable. It would cause an increase in vibration, tyre wear and impose extra stresses on all the paralever bearings."

I found that on this site http://www.sandbarcomposites.co.uk/...htadj-plate.php

I have the Evoluzione torque arm. I plan to install it this weekend. But if the statement above is true, I wonder what the effect will really be long term on the bike.


i know you emailed us this question but i thought i should answer it here. when i first read it something didn't make sense. then i clicked on the link and understood. in the future, if you plan on asking questions and quoting a source, i would recommend that you include the actual quote, not just try and paraphrase. the actual statement sandbar makes is:


"Changing the rear ride height by changing the length of the paralever torque arm is not the correct way, because it also changes the angles between the various shafts in the drive train. The driveshaft uses normal universal joints (and not C/V joints) and the more that the input and output shafts deviate from being parallel, the greater will be the vibration and tyre wear. There will also be excess strain on the paralever bearings and probably the gearbox as well."


now to answer your questions. during normal riding, the angularity between all of the shafts is constantly changing (every bump you hit changes the suspension angles). i do agree that more angularity is not good but how much is too much? i can only go by the fact that the factory powercup race teams used much longer torque arms and after ten's of thousands of miles on hundreds of bikes we've not had any issues. i realize that sandbar is offering a different solution to the same issue (better turn-in) and i'm not sure i agree with everything they say but basically their statements are true. but i also feel that our design is well within the design parameters of the original suspension design.

bottom line, if you feel uncomfortable using our torque arm, please just send it back for a refund.
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  #7  
Old Sep 21st, 2007, 1:37 am
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chuckheinch chuckheinch is offline
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if you install the torque arm and plan on doing some aggressive riding, you will not be dissapointed. I installed the dogbones similar to the ones offered by sandbarcomposites, which in theory accomplish the same changes, and the difference is immediately noticeable. i have had them installed for at least 5000 miles and haven't noticed any changes in the mechanics of the bike in reference to vibration, tire wear, or mechanical deterioration.
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  #8  
Old Sep 21st, 2007, 9:54 am
bolev bolev is offline
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Ken,

Thanks for your reassurance. Having not been an individual that's made modifications like this to any f the bikes I've owned in the past, I definitely read their statement and got a bit skittish.

Judging by the rave reviews of your product on this and other sites, and not seeing anyone complain of any problems, I'm sure I've just been a bit over-cautious.

Thanks again.
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  #9  
Old Sep 21st, 2007, 1:36 pm
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JCW JCW is offline
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Quote:
Originally Posted by evoluzione
now to answer your questions. during normal riding, the angularity between all of the shafts is constantly changing (every bump you hit changes the suspension angles).


This is really the most important statement. The universal shafts are not even MADE to be parallel from the factory. The stock torque arm needs to be a little shorter if this was the case.

I thought the powercup bikes got around the ride height change with a longer shock rather than a longer torque arm. This really is the IDEAL solution as even new suspension plates change the leverage of the swingarm to a not stock value.
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  #10  
Old Oct 2nd, 2007, 2:23 pm
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sandbar sandbar is offline
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Er yes - or even no! Sort of!

I reckon that this one of those things where everybody is right - a little bit.

There can be no doubt that the reason for putting a second universal joint on a shaft is to cancel out the angular velocity variations caused by the output and input shafts not being in line on the first universal joint.

Here is a link to a Wikipedia page that can explain it much better than I can.

http://en.wikipedia.org/wiki/Universal_joint

The ideal scenario is that the output shaft from the gearbox should be parallel to the input shaft to the bevel drive, and the paralever system should form a perfect parallelogram. It is clear from the Wikipedia page that the further from this ideal the more fluctuations there are in the angular velocity. That would mean more vibration and increased tyre wear.

Now to the real world.

Quote:
Originally Posted by JCW
The universal shafts are not even MADE to be parallel from the factory.

Yes you are right - and the paralever does not even make a parallelogram. I guess design and production requirements meant a few compromises. But, neverthless, in standard form they are not far away and I guess that BMW find that the effects of the variation from ideal to be acceptable within their parameters for service life and smoothness.

But that does not alter the fact that the best solution is parallel shafts operated by a parallelogram.

Quote:
Originally Posted by JCW
I thought the powercup bikes got around the ride height change with a longer shock rather than a longer torque arm.

I am afraid that I am always sceptical about comparisons with the PowerCup racers. They only had to last about 150 miles on very smooth surfaces every few weekends and they had attention from mechanics that would be far greater than the majority of road bikes. Tyre wear was not an issue and increased vibrations would probably not be felt or noticed

Quote:
Originally Posted by JCW
This really is the IDEAL solution as even new suspension plates change the leverage of the swingarm to a not stock value.

That is not necessarily true. In any event surely the BEST solution would be to achieve the required ride height by changes in the length of the shock and THEN change the length of the torque arm to alter the shaft angles so that they are parallel at the midpoint in the normal suspension travel.

If you only use the torque arm then you are achieving the change in ride height by changing the angle between the shafts. If you use suspension plates then you are achieving the ride height adjustment without changing the shaft angles except in that there will be a slight change because paralever does not have an exact parallelogram

IMHO

Do I know what I am talking about? Probably not!!

sandbar
www.sandbarcomposites.co.uk
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