jwetering
New member
Hey guys - sorry it's been a while....I've been busy 
So good news.
Some of you may remember that I was experiencing a pretty significant wobble while making sweeping turns - especially if the road surface was even a bit bumpy and especially at higher speeds (80+ mph). You may also remember that the problem started after I installed a new (used) set of fork tubes, a new front wheel, and a new head bearing after I rear ended a Honda Civic. I posted a bit of my problems here:
http://forums.bmwmoa.org/showthread.php?68984-90-k75s-steering-head-bearing-adjustment&p=885641&viewfull=1#post885641
I spent a year chasing the problem - given the circumstances it could have been a lot of different things and I tweaked and twiddled a bunch of stuff that wasn't quite right (tire size, tire condition, tire pressure, amount of fork oil, head bearing nut, bar-backs) - but as of last week I have absolutely solved my problem and I'm once again riding with confidence.
I'm posting here because the problem isn't all that uncommon and I hope someone benefits from my experience.
My research here and elsewhere led me to believe that the root cause was an imbalance between the front and rear suspension, and in the end that is exactly what it was....but not the way I thought.
First - It turns out that I had the preload on my new Progressive 412 rear shock ratcheted up way too much. After assuming for months that hard was better than soft I finally ratcheted it down from the second to hardest setting to the second to softest setting. This solved 85% of my problem. (In fact this shock had just been replaced under warranty before the crash, and I was running it with the same settings as the previous shock - so I wonder if there is variability between units.)
Second - it turns out that the springs in my new (used) front fork tubes were stock...and I'm pretty sure at this point that the springs in my old fork tubes were not. I installed a set of Progressive front fork springs and this solved another 85% of my problem. You read that right - I'm bending the rules of mathematics for this fix. The bike rides 170% better than it did. It's just bloody fantastic now.
I should have figured this all out earlier...ever since the rebuild the bike was crashing over bumps almost bucking me off. It was stiff as hell and this was doing me (and my back) no favours at all.
The bike now swallows rough pavement like it "ain't no thang" and sweeps and turns like an absolute champ.
The lessons I learned:
1) Upgrade your front and rear suspension together - Progressive springs front and rear in my case.
2) Dial some compliance into your suspension. Too firm is too firm for the real world.
Thanks for the help gents.
So good news.
Some of you may remember that I was experiencing a pretty significant wobble while making sweeping turns - especially if the road surface was even a bit bumpy and especially at higher speeds (80+ mph). You may also remember that the problem started after I installed a new (used) set of fork tubes, a new front wheel, and a new head bearing after I rear ended a Honda Civic. I posted a bit of my problems here:
http://forums.bmwmoa.org/showthread.php?68984-90-k75s-steering-head-bearing-adjustment&p=885641&viewfull=1#post885641
I spent a year chasing the problem - given the circumstances it could have been a lot of different things and I tweaked and twiddled a bunch of stuff that wasn't quite right (tire size, tire condition, tire pressure, amount of fork oil, head bearing nut, bar-backs) - but as of last week I have absolutely solved my problem and I'm once again riding with confidence.
I'm posting here because the problem isn't all that uncommon and I hope someone benefits from my experience.My research here and elsewhere led me to believe that the root cause was an imbalance between the front and rear suspension, and in the end that is exactly what it was....but not the way I thought.
First - It turns out that I had the preload on my new Progressive 412 rear shock ratcheted up way too much. After assuming for months that hard was better than soft I finally ratcheted it down from the second to hardest setting to the second to softest setting. This solved 85% of my problem. (In fact this shock had just been replaced under warranty before the crash, and I was running it with the same settings as the previous shock - so I wonder if there is variability between units.)
Second - it turns out that the springs in my new (used) front fork tubes were stock...and I'm pretty sure at this point that the springs in my old fork tubes were not. I installed a set of Progressive front fork springs and this solved another 85% of my problem. You read that right - I'm bending the rules of mathematics for this fix. The bike rides 170% better than it did. It's just bloody fantastic now.
I should have figured this all out earlier...ever since the rebuild the bike was crashing over bumps almost bucking me off. It was stiff as hell and this was doing me (and my back) no favours at all.
The bike now swallows rough pavement like it "ain't no thang" and sweeps and turns like an absolute champ.
The lessons I learned:
1) Upgrade your front and rear suspension together - Progressive springs front and rear in my case.
2) Dial some compliance into your suspension. Too firm is too firm for the real world.
Thanks for the help gents.
