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Author Topic: Bike goes to the right when ya let go of the bars...  (Read 49605 times)

Offline Scott_

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Re: Bike goes to the right when ya let go of the bars...
« Reply #25 on: May 21, 2016, 08:40:36 AM »
I can't remember who, rbm or inge, or the context of the discussion, but non the less, the discussion was about faulty/out of spec, intermediate housings.

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Offline The Mighty Gryphon

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Re: Bike goes to the right when ya let go of the bars...
« Reply #26 on: May 21, 2016, 09:19:07 AM »
Can't add much to this discussion.  Everybody has covered everything I could think of plus a lot more. 

As far as engine shimming, here is the factory scoop on bolting the frame to the engine.  Download and go to page 144 0f 461.

http://www.k100.biz/pdf/OFF/K100_K75_2V_eng.pdf

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  • In my garage in Marilla, NY
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Offline Laitch

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Re: Bike goes to the right when ya let go of the bars...
« Reply #27 on: May 21, 2016, 09:59:01 AM »
Quote from: Scott_ on May 21, 2016, 08:40:36 AM
. . .  but non the less, the discussion was about faulty/out of spec, intermediate housings.
The discussion I recall with that condition cited was about premature input shaft spline failure. During one of my loiterings, I found a service bulletin in MOTOBRICK.COM's link to Vogel's service bulletin compilation. It indicated that positioning dowels were located on each side of the intermediate housing to correctly align the engine with the transmission. The implication was that if they were missing, trouble would follow. I didn't associate misalignment with tracking problems but rather with shaft spline failure. There might be other effects, too.
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Offline tsnap

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Re: Bike goes to the right when ya let go of the bars...
« Reply #28 on: May 21, 2016, 10:33:26 AM »
Yesterday I finished work on a bike (85 Hondu 750 cruiser shafty) that had been dropped on its Right  side, a slide from the looks of it.

Scraped case, mirror, stand, exhaust, tach, and plastic windshield gone with brackets remaining..  I test rode it, and it had no pull to a side, but the pullbacks were  barely noticeably lower on the Right  side when sitting on it.

 I once rode a goldwink that showed no damage anywhere, other than the front fairing was gone, but it pulled to the right constantly, almost impossible to make a short turn.

METAL HAS MEMORY.    I suspect that a part of the thread topic bike has been tweaked beyond tolerance for the metal part and is  bent, appears OK,  and failure shows up only under the stress of normal use. I suspect that it is a part in the fork.  May be a result of being dropped on its head.(not the brick head itself, but the other head)

tom (keyworts search button, donkey, techron, can you reed, no facebroke,etc)

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Offline rbm

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Re: Bike goes to the right when ya let go of the bars...
« Reply #29 on: May 21, 2016, 04:49:34 PM »
Deleted.  See Gryphon's post above.
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Offline The Mighty Gryphon

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Re: Bike goes to the right when ya let go of the bars...
« Reply #30 on: May 21, 2016, 06:29:12 PM »
Rob, is the link I posted not working?  It is in English and pretty straightforward.  I used it when I put the frame back on my 75RT last winter and it worked the treat.
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  • In my garage in Marilla, NY
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Offline rbm

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Re: Bike goes to the right when ya let go of the bars...
« Reply #31 on: May 21, 2016, 06:40:32 PM »
Sorry Gryphon.  It is working.  I was negligent in glossing over your post.
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Offline The Mighty Gryphon

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Re: Bike goes to the right when ya let go of the bars...
« Reply #32 on: May 22, 2016, 09:31:34 AM »
No problem, Rob.  I wasn't sure if it would open properly since it is a PDF file and I never posted one of those before.

BTW, I have to get up to the GTA to deliver some coffee to Ed.   Weather is nice enough now to justify a brickoliscious ride. 
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline bocutter Ed

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Re: Bike goes to the right when ya let go of the bars...
« Reply #33 on: May 22, 2016, 11:30:42 AM »
Quote from: The Mighty Gryphon on May 22, 2016, 09:31:34 AM
BTW, I have to get up to the GTA to deliver some coffee to Ed.   Weather is nice enough now to justify a brickoliscious ride.
Figured that coffee would have been consumed by now.  :hehehe
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Offline The Mighty Gryphon

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Re: Bike goes to the right when ya let go of the bars...
« Reply #34 on: May 22, 2016, 11:56:05 AM »
Still hanging on to it.  Got to get a chance to visit for more F&C.  trouble is I am pretty busy working 7 days a week now. Busy part of the sailing season.  Should calm down in a week or so.
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline bocutter Ed

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Re: Bike goes to the right when ya let go of the bars...
« Reply #35 on: May 22, 2016, 08:18:42 PM »
Quote from: The Mighty Gryphon on May 22, 2016, 11:56:05 AM
Still hanging on to it.
Damn man, crack one open. I have an espresso machine at home (use vac pak) and you've sampled the fresh ground at the shop. I might use one or two packs of that coffee summer camping. The rest will be Xmas presents ... I really just want the cans for Bwokx staple containers.  :lets-eat:
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Offline johnny

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Re: Bike goes to the right when ya let go of the bars...
« Reply #36 on: May 22, 2016, 09:42:47 PM »
look... as i understand it...

flat straight road... let go of the bars and the moto angles right... and its pushing the right bar forward that makes it go straight again...

when i push my right bar forward my moto will go to the right...

when i push my left bar forward my moto will go to the left...

taos here is pushing his right bar forward and his moto is going left...

countersteering can only be achieved after the tiors contact patch has started to lean... even minuscule...

what taos is describing could be one fork lower than the other... whack frame... whack engine to transmission alignment... whack swing arm... or simply the rear ride height too low which is initiating what is known as castoring or bicycling...

j o

 
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Offline The Dude

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Re: Bike goes to the right when ya let go of the bars...
« Reply #37 on: May 22, 2016, 10:01:01 PM »
What are the rotating and counter rotating lumps in the motor & transmission doing when he lets go of the throttle?
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  • Auckland, New Zealand
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Offline Martin

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Re: Bike goes to the right when ya let go of the bars...
« Reply #38 on: May 22, 2016, 10:22:51 PM »
This is a bit of a long shot, do you have anybody close by with a K75. If so you can possibly compare measurements with it to see if anything is out of alignment. Alternatively can you get the alignment measurements off a dealer.
Regards Martin.
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Offline kennybobby

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Re: Bike goes to the right when ya let go of the bars...
« Reply #39 on: May 22, 2016, 10:36:41 PM »
It's called "toe displacement" in the manual, and for some stupid reason bmw designed these bikes to have the rear wheel offset to the left of the front, which makes the bike pull to the right and wear a flat patch into the left side of your front tires--the shims between the frame and engine can only increase this offset and make it worse.  Cussed and discussed here:

focked up suspension design
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Offline johnny

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Re: Bike goes to the right when ya let go of the bars...
« Reply #40 on: May 23, 2016, 05:49:45 AM »
taosbrick is reporting when he pushes the right grip forward the moto goes left...
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Offline The Dude

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Re: Bike goes to the right when ya let go of the bars...
« Reply #41 on: May 23, 2016, 07:16:56 AM »
Quote from: johnny on May 23, 2016, 05:49:45 AM
taosbrick is reporting when he pushes the right grip forward the moto goes left...
Now that's not right er I mean correct.We all know what the Moto as you call them does when you do that.
Front wheel goes to the left causing the Moto to fall to the right.If you don't wack open the throttle or counter steer it's horizontal.Fast.  :falldown:I couldn't see any side car in the story....so.
Now,there's all the engine mass,transmission heavy shit on what side?My k drops to the right straight out of the box.Always did.So does avery body else's,I'll bet.The question is....By how much is it inclined to do that?
All I need to stop it is some light right knee pressure on the tank and maybe a bit of arse shift.
Martins idea is good but just ride the next Brick you find.
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  • Auckland, New Zealand
  • K75s
Current.
TR6R 1973 from new.
Moto guzzi 850 III .1983 from,almost, new.
K75S 1986 from new.vin-0103141
On my second millionth km.give or take a hundred k Kay's.
"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there."
All the best!

Offline TaosBrick

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Re: Bike goes to the right when ya let go of the bars...
« Reply #42 on: May 23, 2016, 09:01:52 AM »
My apologies Johnny, the way I said it wasn't clear. What I meant was that you had to hold the whole bizness to the right just a leetle, to keep it going straight, ie Pull on the right bar.
Phew. Everyone's faith in physics and counter steering has just been restored.
   Yeah, something is putt whack somewhere, but where? Upon examination, I can detect no shims at any of the mounting points. Will have to check the links posted in previous replies to get an inkling of how that all goes. Thanks everyone, for all the interest in this topic. Everything else with this bike is GREAT runs smooth and strong, a real mile-eater. Now if I could fix this One Thing it would be as close to perfect as a beest with going on 70k miles and a few scuffs could be.
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Offline 552255

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Re: Bike goes to the right when ya let go of the bars...
« Reply #43 on: May 23, 2016, 11:41:55 PM »
You can check frame/alignment with the string method, extending them forward on each side of rear tire, with carefull eyeball sight, ie. lying on floor to project the strings forward, on each side of front wheel, looking for it to be centered.  I had a bent frame, and found it to cause all kinds of issues...replaced it completely.  I rode it for many miles and chewed through rear tires before fixing it...
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Offline Martin

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Re: Bike goes to the right when ya let go of the bars...
« Reply #44 on: May 24, 2016, 01:00:22 AM »
552255 Bricks are offset as standard from factory by about .5".
Regards Martin.
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Offline TaosBrick

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Re: Bike goes to the right when ya let go of the bars...
« Reply #45 on: May 26, 2016, 06:26:05 PM »
Though the frame may be designed with an offset, I cannot imagine that it is also designed to drift to the right and munch rear tyres.
   So - frame shims. Again, where to install and how thick? As the bike is going right, my tenuous grasp of physics would lead me to take a Wild Ass Guess that the engine, transmission, and swing arm are cocked to the right as well. But how much? String method to determine?
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Offline kennybobby

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Re: Bike goes to the right when ya let go of the bars...
« Reply #46 on: May 27, 2016, 12:00:44 AM »
When you put the strings on it to check alignment you will find the centerline of the front wheel offset 5 to 8mm to the right of the rear wheel centerline. strings alignment

The lateral position of the front wheel is determined by the frame.  The rear wheel position is determined by the engine, tranny, swingarm, and rear-drive assembly.  There are only 5 bolts holding the frame to the engine assembly, 3 on the right and 2 on the left.  The front left frame tube bolts to the head on the inner surface, which is on the right side.  So for mounting there are essentially 4 rights and 1 left.

So the addition of any shims between the frame tubes and the engine will only increase this offset as they displace the frame to the right with respect to the engine--there is no way to reduce the offset by adding shims.

i rode my white 75S for over 100k miles wearing out lots of tires and spent lots of time trying to figure out this stupidity and tried numerous things to get rid of the offset so i could align the wheels.

What worked the best for me was to 'de-shim' the motor mounts-- i used a dremel tool with a carbide bit to mill 1/4" off of the right-side of the front motor mount castings in the head and the block.  i think 3/8" would be better and then the alignment could be fine tuned by adding shims back in as necessary.

bmw seems to make good engines but they failed miserably at suspension design in both cars and bikes.
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Offline TrueAce

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Re: Bike goes to the right when ya let go of the bars...
« Reply #47 on: May 27, 2016, 12:21:57 AM »
That is real interesting stuff, KennyBobby. I would have been too anxious of unintended consequences to go mill the mounting surfaces. What affect, if any, did you notice in handling after that was done? Anybody else out there tried correcting the half-inch offset in the front-rear wheels tracking? Maybe one of our wizened old brothers know the engineering rational of BMW in that design.
Good info KB! And I loved your brother RickyBobby in his movie......he done good!
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Offline The Dude

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Re: Bike goes to the right when ya let go of the bars...
« Reply #48 on: May 27, 2016, 12:42:02 AM »
Shims can only do so much with little effect on overal geometry,angularly or simply offset.I would have thought for tyres to,wear,that bad etc.etc.its bent ,more,somewhere else...
I could not find any shims on my '86K75S frame/motor,trans.'probably forgot them on my last reassembly..

More to do with poor dimensional accuracy in the frame welding process needing packing to prevent stressing the structure on original assembly....by the mainly Turkish workforce....I could be wrong...I do have a single rear wheel spacer though.
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  • Auckland, New Zealand
  • K75s
Current.
TR6R 1973 from new.
Moto guzzi 850 III .1983 from,almost, new.
K75S 1986 from new.vin-0103141
On my second millionth km.give or take a hundred k Kay's.
"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there."
All the best!

Offline Martin

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Re: Bike goes to the right when ya let go of the bars...
« Reply #49 on: May 27, 2016, 02:01:17 AM »
Go to the BMW internet riders website go to the section on suspension and check out Rob Lentini's article on checking wheel alignment.

http://www.ibmwr.org/ktech/wheel-align.shtml

Regards Martin.
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  • North Lakes Queensland Australia
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