What is the correct Rear wheel offset on 85 k100rs

[Chri5]

Hi
I have had a handling issue for a while it doesn't behave when cornering at any speed but it's dangerous at speed I have done most of the usual causes and I'm starting to think the frame any be out after it was stolen and ditched about a year ago

The things I've done

Changed tyres as there's were badly worn from the theirs doing burnouts I've also played with different pressures

Rebuilt the forks following the specs in BMW service manual which I should of done when I bought the bike oil wasn't really oil any more

Checked my steering head bearing (and tighten) as I do a lot of motorway

I haven't changed the rear shock but the travel is within spec and no leaks(it's original as far as I can tell)

My last MOT (UK road worthyness) showed a wheel alignment advisory which to my understanding can only be horizontal offset (left to right) all other alignment issues are a fail

I've looked high and low for what this offset is ment to be an I cant find solid information from a spec sheet I've seen every thing from 7mm to 20mm. My off set is roughly 35mm using the string method which I'm not convinced I'm doing right but the high offset could be the corse of my problem I have 1x 2mm spacer.

Does any1 know what the correct offset is. Is there anything I can do about it except buy a new to me frame and hope it's straight and true

Rebuilding the forks and changing the tyres only seem to of made the problem worse

[daveson]

Rebuilding forks made it worse so do the forks again. There is stuff on YouTube about it for bricks.

I usually use a straight edge instead of a string, with spacers to the rim,  but havn't done it on a brick. I'm guessing the offset should be about 0mm,  surely not 35.

Was the handling good before it was stolen?

[billday]

There's supposed to be a spacer ring between your rear wheel and the final drive. Is it there?

[Laitch]

I've looked high and low for what this offset is ment to be an I cant find solid information from a spec sheet . . .

High and low should include looking into the BMW K75/K100 2V Repair Manual available on this site in the Service Manual section—Chapter 46, pp78–80 for alignment/offset, and p. 67 for correct frame to engine spacing and bolt torque.

What are the handling symptoms? Which parts were replaced in the fork tubes?

[Chri5]

@ Davidson I've gone over the forks twice with no change and yes handling was fine before it was stolen

@johnny  no my lugs are not lubbed I'm running 110/80 front and 130/80 radials

@laitch god damn u I spent hours looking for that in that manual evidently not well enough before I turn to the internet but thanks

@billday yes I have 1x 2mm spacer

So the manual says 5mm max I'm going to get a straight edge bar today and take another measurement as my 35mm seems outrageously off

The handling symptoms are in a straight line upto 100mph (as far as I've taken it on the new rubber)  it's on rails tracks true no wobble or weave through acceleration and deceleration

Cornering anything over 15mph I feel like the bike is fighting the corner the handle bar wants to move left right to correct it's self against the rear in both left and right turn but more so on rights

The fork rebuild, I replace the o rings, oil , washers. rebuild may be to stronger word as I didn't disassemble the dampener thorough service might be more accurate. I have RAM progressive springs so there is no spacer tube.

So when I remeasure my offset to get a better measurement the only places I can think of for why its out are forks improperly fitted,swing  arm pivot bolts not seated correctly, frame not mounted correctly

So here is my logic on those possiblities

Forks  I've inspected the forks and refitted twice since it was stolen

Frame fitting - I have had the frame off when my clutch randomly exploded taking out my bell housing  and had trouble refitting but as per laitch to the rescue with the correct assembly process so I'm confident that is installed correctly

Swingarm pivot pins - I will inspect this today and report back

[daveson]

Forks shifted or bent?  Have a closer look at the forks,  check out the videos.

If the guy was caught that stole it,  the repairs might be covered.

[Chri5]

I've checked the stachens with a dial guage they are straight it's why I took them off in the first place. Unfortunately the little s**t wasn't caught

[Laitch]

. . . the little s**t wasn't court

I've consulted the Septic's Companion, but have been unable to translate this phrase. Does it refer to a personal physical ailment?

[Chri5]

No laitch it's just my in ability to speak my native language properly

[Laitch]

No laitch it's just my in ability to speak my native language properly

i'm glad you're ok. :-)

[The Mighty Gryphon]

Am I correct in understanding that your bike doesn't want to turn, but just wants to go straight?  Does it matter which way you are trying to turn?  A squatting rear end can alter the caster and trail of the forks and mess up the steering.

How long is your rear shock?  Is it shorter than stock? 

What is the spring preload on the rear shock?  Is it low, allowing the rear of the bike to squat?

What is the preload on the swingarm bearings?  Are they loose?

There is a specific procedure for assembling the forks.  Did you use it?  Here is a nice tutorial on troubleshooting and assembling the forks of an R bike, but the principles apply to the K.

https://brook.reams.me/bmw-motorcycle-rebuilds/1973-bmw-r755-rebuild-project/31-bmw-r755-install-and-align-front-forks/

[Chri5]

You are correct TMG the steering bounces left to right and back again and again as I corner in either direction which is more noticeable at speed. Especially on motorway to motorway slip roads (long high speed corners)

My rear shock is stock with the preload in the middle something I've never adjusted. Thanks for the link to the article I'm going to go back of my forks again I did follow the procedure in the BMW repair manual

I also found this article which I'm sure many of you will be aware of and references the above article
http://w6rec.com/duane/bmw/fork/chapter1.html

The work continues...

I will also post some pic up to show the offset I have tomorrow

[The Mighty Gryphon]

What is the length of the rear shock, pin to pin, when the bike is on the centerstand?

Have you lowered the front end? 

What tire sizes are on the bike?  Are you sure the front tire isn't squared off?

What is the clearance between the rear tire and the swingarm?  On my bikes it ranges from 45mm to 10-11mm, depending on tire size.  You mention an offset of 35 mm.  That would have the rear tire almost rubbing on the silencer.