51 Re: K100RS Steering wobble: All potentials Tue Mar 19, 2013 5:08 pm
yankeeone
Platinum member
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Themason wrote:My source is a gentleman who built and tested the prototypes of the K bike. I can tell you this much. You can put 1984 transmission gears and shafts into a Paralever gearbox housing. I have done so. I didn't buy a whole Paralever gearbox for my Paralever conversion. My friend had a K-75 gearbox case with the Paralever mounting flange cast into it. He drilled that flange for the Paralever arm and he put my old gears and shafts into that case. That means, folks, that the geometry of the transmission input and output shafts of Monolever and Paralever gearboxes are identical, and it also means the drive shafts of Monolever and Paralever bikes are offset from the bike's centerline the same amount. If you compare Monolever and Paralever rear wheels, the degree to which the 4.5 inch wheel is offset to the left of the mounting flange is obvious. Monolever or Paralever, the right edge of the tire rides just as close to the swingarm, so the extra width comes by offsetting the tire centerline left.
My friend from BMW Research tells me BMW now does this deliberately because it aids straight line stability. He would know because he built them! He now builds bikes this way for customers, even having spoke rear wheels on old airhead twins laced with an offset to the left. I did much the same on a Harley Street Rod, offsetting the rear wheel to the right because the final drive pulley is on the left and exhaust is on the right, the opposite of the K bike, and like my Paralever conversion K, it now tracks dead straight. On the Street Rod I did this more to stuff a different wheel and rear pulley into the stock swing arm, but the effect on straight line stability was immediately apparent.
I can also tell you that on my Paralever conversion K bike the rear wheel is very much offset to the left. I first noticed this offset working on a customer K1100 when I was making money as a part time tech. I thought something was wrong with the bike but my friend from BMW Research told me that this was normal for those bikes, and that is when he explained the desirability of this feature.
Last edited by JimK on Tue Mar 19, 2013 10:26 pm; edited 6 times in total (Reason for editing : trying to figure out)
yankeeone wrote:Hi, I just read thru, so what was the problem? and what was the solution? I have had my k100RT up to 110 on the speedo, solid as a rock, I did have a k75c with a parabellum scout, and any thing over 90, the front would start to feel light, so I never went over 90.
Last edited by Themason on Thu Mar 21, 2013 12:04 pm; edited 4 times in total
Themason wrote:Rick, I don't need to read any books on this subject. My source of information is one of the gentlemen who built and tested the prototypes of these bikes when he was employed at BMW Research. He has more time on the test track at Nardo and other places testing prototype BMWs than most of us have total riding experience. Don't go all aggro on me. He is the one passing this knowledge along. You can take what he knows or not, that is your choice. No, I do not have factory engineering data to post here. He didn't walk away with that data. BMW does not give that knowledge away and their security is equal to that of the defense establishment I work at.
He knows what he learned with his hands crafting and testing the prototypes of the bikes we love. And, yes, I am saying, because it is true, that the distance from the motorcycle's centerline of a Monolever driveshaft and Paralever driveshaft on a K100/K1/K1100 are all the same. I have converted an '84 K100RS to Paralever and everything, including shock mounting points, just lines right up. The final drive on the Paralever is exactly under the shock mount of my formerly Monolever K. On this Paralever converted old RS the rear wheel is visibly offset to the left now, where narrow rear wheel of an otherwise identical '84 RS I restored to stock form is centered.
Btw, my friend has a nice plaque presented to him from BMW, which I have seen, for solving the sprague clutch problem on K bike starters. The new part with a pattern of oil drain holes is his creation. As for my own education Rick, it is a bachelors and a masters degree and I work in a defense lab that does things with materials and technologies you cannot even begin to imagine, and I ain't talking about it.
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Ghost who rides wrote:Come on guys , what's going on ?
We don't do this agro shit , that happens on other forums , or do we ?
One guy gives an opinion not suited to some and his ancestry is called into question ? WTF?
This site is about KNOWLEDGE of the K ,fun and camaradie are bonus points in the overall scene .
Let's not insult whatever contributions are made,
sure ignore what you think is BS , but aggresively
attacking and be -litel- ing ( ? ) the contributor hurts us all !
To be honest I saw this coming days ago and was gunna try to play peacemaker but like all my great idea's, great in hindsight !
This is not a contest guys ...... Peace and Goodwill for the effing K ?
G
1986 k75, 1985 K100rt, |
Jhepburn wrote:yankeeone wrote:Hi, I just read thru, so what was the problem? and what was the solution? I have had my k100RT up to 110 on the speedo, solid as a rock, I did have a k75c with a parabellum scout, and any thing over 90, the front would start to feel light, so I never went over 90.
Basically: On the GF's bike, the tyre pressures weren't optimal and neither was the tyre (switched to Pirelli SportDemon, perfect ever since).
On my bike: The headset bearing needed replacing, and the front tyre was completely wrong. It was a kevlar-belted supersport tyre my tyre expert put on. It turned out to be woefully wrong for the bike. With BT45s or a SportDemon - perfect ever since, and if I ever have handling problems now I know the tyres are either worn or off-pressure.
Last edited by GerryP on Sat Mar 23, 2013 11:14 am; edited 1 time in total (Reason for editing : speling)
Last edited by Themason on Sat Mar 23, 2013 7:23 pm; edited 3 times in total
Jhepburn wrote:I do use those caps, and have for about two years. In that time, I've been doing a 70km round trip for most of four days per week, with a regular weekend of 200-600km thrown in, and the front has been on about five different tyres now. I haven't had any problems and they still look new.
I may not put them on a bike intended for a going off-road, but since I also carry a puncture-repair kit with CO2 canisters and a mini hand pump, I'll take the risk of a stone breaking the cap.
I support the dont use the things as I have heard before that there is a potential problem. I once had a bird (about dove size) fly directly into my front wheel spokes. I dont think I need to describe what happened but suffice to say the mess was substantial and that could have easily broken the valve.MT350Explorer wrote:Avenger GT. Have you seen any evidence to support your suggestion that they fail? I'd genuinely like to hear it if you have.
As you say the valve cap holds the air pressure not the tyre valve. How does this increase the probability of a catastrophic loss of air?
I'm willing to change my view in the face of evidence or overwhelming opinion!
Cheers
Dave
DittoThemason wrote:Is it that hard to use a conventional tire guage? Just asking .............
ibjman wrote:TRY adjusting the steering head bearings (first)????
Tenox wrote:Must say - although it might be said already - that sometimes the wear of the front tyre is enough to cause wobble when both hands are taken off the handlebars. Even when the front tyre looks OK and still has track left and has right pressure. Atleast this was the case with my ex Yamaha TRX850 - wobbling cured by changing the front tyre. I did drive that tyre to "final" though since the woble occured only hands off. Even one finger on other handle was enough to keep bike steady.
Last edited by Tenox on Tue May 13, 2014 5:44 pm; edited 2 times in total
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