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Old 06-15-2013, 03:04 PM   #886
Sauerkrautman
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Hi,


Quote:
Originally Posted by ontic View Post

I think I imagined what you did here, but I can't be sure. You seem to have proven that the bores in the clamps for the fork tubes are alligned. But if I am imagining you doing what you did correctly, then you probably didn't have the wheel in and the axle done up tight... so you might be back to axle spacing being incorrect?
yeah, with trying this I made sure, that the clamps are not the reason for the stiction. But still I'm not convinced. Since the clamps are the only parts I didn't change through the whole process...
The axle was loose all the time after I mounted the second set of the forks. I could push it through the holes with 1 finger.


Quote:
So this means that these new forks have not been cleaned, and by the top being stuck that badly, may not been cleaned in a long time?
Mine stuck terribly before I cleaned them out. Maybe a little heat (being careful not to cook the big Oring up the top... or just take the forks into a mechanics who has a rattle gun and a socket to suit. Maybe after a clean they will be just fine....
The previous owner of the forks told me, they were only 4000km driven, I tend to believe him. But if they were used 4000km for motocross-racing, they may need some attention.
I own a rattle gun, but I ran out of time, so I'll try this after the trip.
The forks don't have much stiction, when I push them down vertically (out of the bike).

So now I put back the original forks. They are so super soft, its like putting your head at a soft pillow, while the WPs feel more like a conrete block.
Here a photo of the bike, since it has the original forks now, only as a link.

@Ras Thurlo:
I have 6,5cm long spacers and the forks are pushed 1,5cm through the upper clamp. The front is about 1cm longer than the original one, but it depends of the clamps you are using.
The travel of the original forks of the R80/100GS is about 21,5cm, the WP forks have 28,5 cm (I'm not exactly sure about this value, but its easy to measure).
So, when you want the exact same travel as with the original forks, you need 7cm long spacers.
When you put them into the forks, put the fork at the bike and push them trough the clamps until the distance of the axle to the stearing head is the same as with the original forks.
Now remove the springs and push the forks all the way up to make sure the fender and other parts (at my bike, it were the tubes of the forks itself, which collided with the lower clamp) have enough space...
If there is not enough space, push the forks back a little bit and make the spacers that amount longer (or ignore it, like me ).



Regards,
Richard
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Old 06-21-2013, 08:34 AM   #887
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Quick update on my speed wobble... it is only happening at 70mph+ while on the freeway home. It is speed related as the pavement is pretty good in the commuter lane I ride in.

My front wheel was an eBay score (or not) and the rims does have some bends in it, the shop that intalled my TCK had to put on a ton of weight to get it balanced.....

So, could it be my crappy rim, could it be bad steering head bearing adjustment, or is it my dropping the triples down the forks and the impact of that on the trail?

Any advice form the peanut gallery on determining the cause and working toward a fix?

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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 06-21-2013, 09:53 AM   #888
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SL,

I had the same thing happen after switching to a TKC front with an Ultra Heavy tube. Felt like hitting a soft version of the rumble strip at anything above 50mph. My shop turned me away after rotating the tire 180 degrees and threatening to put 3-4 strips of stick weights on my rim. I now have twice the amount of spoke weights as you do, sir.

BT
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Old 06-21-2013, 09:56 AM   #889
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I've been running TKC's with no issue for the last eight years..... but haven't ever run a heavy duty tube
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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 06-21-2013, 05:29 PM   #890
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So, there is a lot going on. Many variables. I'm confused as what you meant about dropping the forks in the triple. Have you checked that both tires are round on the rims....remember my out of round rear tire causing pogoing in the front?! I would also measure top of the triple down to where the fork tube enters the bottom tube. My bike there is a 2mm variance assembled, I did have stiction when I didn't measure to be sure they were both the same length. The rim could certainly have an impact, maybe time to shop for a new one....at least they're pretty cheap.
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Old 07-02-2013, 08:01 AM   #891
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More thoughts on speed wobbles

Clearly I need to go back to square one. Somewhere about 60-ish mph my G/S develops a slight wobble. I can initiaite it by shaking the bike with my knees. Around 70 is happens with highway pavement bumps and can be quite scary.

I'm thinking it has to be the front end, as I haven't changed or adjusted anything in the back of the bike and it didn't have this issue with the stock front end.

Here are my likely places to look:
  • Steering head bearing adjustment. I'll add more pre-load this week. The handlebars fall to one side from center with a light touch on the bars, but the wiring harness may be causing some resistance and I may have too little pre-load
  • Front wheel - it was balanced by the shop that installed the new TKC, but has some bends and did need a ton of weight. The wheel bearings are new. I'll also check the axle torque, but can't feel any play (working on finding a shop to true and re-balance now)
  • Triple clamp height relative to the fork legs - don't know where to go here, or how much effect this may have on my issue. I have the fork legs sticking up 10mm above the top of the top triple. When the tops were flush with the triple the biek didn't fall into turns comfortably and it felt like I was steering around the front end (best way I can describe it).
Jenna isn't having this issue, and frankly I'm not sure if anyone else who bought triple to run the WP 50mm's every got their conversions completed and have done any miles...

Anyone have any words of wisdom?
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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.

SOLO LOBO screwed with this post 07-02-2013 at 10:01 AM
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Old 07-02-2013, 10:07 AM   #892
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Not really. If you can, run the bike down a very rocky, rough road. Or jump the shit out if it to be sure you seat the head bearings. Any pogoing at all??? Check that the beads are seated on both tires and I know, but check your pressures and PM me you address
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Old 07-02-2013, 07:14 PM   #893
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No more miles on either of the bmw's for me, so no words of wisdom, just some thoughts.

Front wheel- seems like the bases are covered there. A new wheel sounds like a good thing but it doesn't sound like your cause to me.

Triple clamp/fork leg height- a bit more complicated but I doubt that would be the cause. Sliding the forks up in the triples changes geometry, decreases your trail, and stability, and increases your turn in, giving you that nice fall into turns... but the 10mm really isn't that much of a change. I believe I shortened my forks by the same amount as you did (the full length of the black plastic spacer up the top). I also found that the steering felt a lot nicer with the forks slid up in the triples 10mm or so. The longer the forks were the more choppered out it felt and yes, it felt like you really had to steer the front end around. One thing to be aware of here is that the Rdubb triples with the WP50 forks (and their large axle offset) already represent a large change of trail from stock G/S geometry (I think my last measurement was about 13-15mm of increased axle offset). Thus, we've already reduced trail a fair bit, but predicting results from geometry theory alone seems problematic. If it didn't steer right with the forks all the way down, and it does with them slid a little way up, then unless we've really mucked up the geometry you've probably got it set right IMO.

From your list and symptoms, steering head bearings sound to me the most likely at this point and at least the easiest to test and rule out. Maybe try torquing them a bit too tight till you start feeling the low speed effects of too much preload, then backing them off just a touch setting them at the top of the torque range that rides well. See what you get on your torque wrench (I'd suggest going for a ride with the wrench in a backpack).
It seems to have been a contentious issue here but I'll just repeat my considered opinion: in a low (or virtually no) revolution speed application like this, it is not just about removing play, preload on the tapered roller head bearings needs to be able to deal with plastic deformation of the bearings, stem/nut elasticiy, etc, under loads and vibrations etc. As loads increase, with too little preload, you'll get 'play'. Of course you don't want to set it to a preload where you get any negative effects from too much preload, but you really don't want to set it too light.

Along with making sure your bearings are seated properly like Jenna said, make sure you have both the bottom and the top bearing covers on and that they are taking up all the clearance and transferring torque- miss just one of these covers and you won't be able to preload the bearings no matter how hard you torque that top nut- DAMHIK. The tolerance is just too tight.

Good luck.
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Old 07-03-2013, 08:09 AM   #894
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Quote:
Originally Posted by ontic View Post
Along with making sure your bearings are seated properly like Jenna said, make sure you have both the bottom and the top bearing covers on and that they are taking up all the clearance and transferring torque- miss just one of these covers and you won't be able to preload the bearings no matter how hard you torque that top nut- DAMHIK. The tolerance is just too tight.

Good luck.
Thanks for the reply Ontic,

I'm going to check and re-torque these this weekend.

I am using the BMW bearing cover (#8 below) on the top, and was looking at the bottom of the R-Dubb top-triple last night... It looked at bit like there is very little material transfering the load from the top triple to the bearing cover.

Here's a shot of the under side of the top triple (on the bottom)


I wonder if I should add a washer that is the same size OD as the bearing on top of the dust cover? It looks like the nut (#7) is doing that with the stock BMW set-up, or if the dust cover is fulfilling that role already?

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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 07-03-2013, 08:20 AM   #895
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Quote:
Originally Posted by SOLO LOBO View Post
Clearly I need to go back to square one. Somewhere about 60-ish mph my G/S develops a slight wobble. I can initiaite it by shaking the bike with my knees. Around 70 is happens with highway pavement bumps and can be quite scary.
This may or may not apply to your situation with WP forks but I experienced a similar scary wobble when I reinstalled my stock forks after some modifications. I tried everything, replacing TKC-80s, sending wheel to Woody's, adjusting steering bearing preload. What finally solved my problem was increasing the preload on the forks. I was running a very small amount of preload because I liked the 'suppleness' that setting provided. Increasing the preload from 3mm to 18mm (40% to 28% dynamic sag) made the high-speed wobbles go away. Should be easy enough to try adjusting preload to see if it has an effect on your problem.
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Old 07-03-2013, 08:32 AM   #896
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Quote:
Originally Posted by stickerbush View Post
This may or may not apply to your situation with WP forks but I experienced a similar scary wobble when I reinstalled my stock forks after some modifications. I tried everything, replacing TKC-80s, sending wheel to Woody's, adjusting steering bearing preload. What finally solved my problem was increasing the preload on the forks. I was running a very small amount of preload because I liked the 'suppleness' that setting provided. Increasing the preload from 3mm to 18mm (40% to 28% dynamic sag) made the high-speed wobbles go away. Should be easy enough to try adjusting preload to see if it has an effect on your problem.
Thanks SB.

My sag is something like 24% on the front right now, and if anything I suspect I don't have enough.... I am heavily leaning towards needing more pre-load on the steering bearings.
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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 07-03-2013, 06:03 PM   #897
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Quote:
Originally Posted by SOLO LOBO View Post
I wonder if I should add a washer that is the same size OD as the bearing on top of the dust cover? It looks like the nut (#7) is doing that with the stock BMW set-up, or if the dust cover is fulfilling that role already?
Interesting. The bearing cover is pretty thin and tinny from my memory (I had to shorten mine to work with my steering damper pin-tower clamp). You could look on the triple and the bearing cover where they contact if there is any sign that the bearing cover isn't up for transferring the load. I suspect it will just be sitting nice and flat between the meat on the triple and the bearing and would be OK, but I also think that adding a good perfectly flat strong washer there would not be a problem.

When you torque up your steering head bearings, see if you can easily and progressively reach too much resistance to turn the bars, if you can I think you are OK. When I was missing a cover I could keep torquing the top nut but bearing preload stopped increasing at a point. With such a fine tolerance I'd happily slip a good washer in there!
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Old 07-03-2013, 07:03 PM   #898
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Quote:
Originally Posted by hardwaregrrl View Post
Not really. If you can, run the bike down a very rocky, rough road. Or jump the shit out if it to be sure you seat the head bearings. Any pogoing at all??? Check that the beads are seated on both tires and I know, but check your pressures and PM me you address
what am I??? chopped liver
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Old 07-03-2013, 10:57 PM   #899
SOLO LOBO OP
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Quote:
Originally Posted by hardwaregrrl View Post
what am I??? chopped liver
No way!!

Sorry! I missed your post. I may get put and ride some dirt this weekend. If so, I promise to jump the shit out of my bike!

I still have some minor pogoing, but it seems to be less as I ride more (or get used to it maybe?)
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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 07-04-2013, 06:20 AM   #900
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Quote:
Originally Posted by SOLO LOBO View Post
No way!!

Sorry! I missed your post. I may get put and ride some dirt this weekend. If so, I promise to jump the shit out of my bike!

I still have some minor pogoing, but it seems to be less as I ride more (or get used to it maybe?)
Ha!

Start from the begining........check that the wheel is balanced and somewhat true. Same for the rear, and check you pressures, then wheel bearings, then steering head bearings. I never once had the shakes on the bike regardless of tire choice, or the fact that my head bearings were not properly seating and I commute 100 miles a day when teaching on I-85, avereage speed is 80mph as to keep from getting squished.

I forgot, did you check spokes? Did you buy a "new" wheel??? Have you tried to beat that one back into shape? Are the beads properly seated? I feel like it more than likely is the bent rim. Just the air pressure change on the bend at high speeds is enough to do what you're describing. Maybe send it out to be straightened......you haven't changed your front fender have you? And for giggles, check the caliper.
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