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Old 05-02-2012, 03:55 PM   #571
SOLO LOBO OP
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Quote:
Originally Posted by hardwaregrrl View Post
Hey, what are you guys using for torque value on the pinch in the lower, upper clamp and at the stem.??
As a talented sprint car mechanic I know well once advised me:

"make 'em tight enough they don't get loose, but don't make 'em too tight because you might just strip those F*$@*rs"
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Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 05-02-2012, 06:33 PM   #572
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So it's been more that two weeks since I rode my bike, and when I went to remove the bleed screws I got a nice "hiss" from both side..

A bit of trick bits ala ontic:










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Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 05-02-2012, 10:41 PM   #573
redboots
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Quote:
Originally Posted by hardwaregrrl View Post
Hey, what are you guys using for torque value on the pinch in the lower, upper clamp and at the stem.??
Whatever you decide, KTM say to locktite the stem pinch bolts... not the leg bolts though.

Cheers,
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Old 05-03-2012, 04:48 AM   #574
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Originally Posted by redboots View Post
Whatever you decide, KTM say to locktite the stem pinch bolts... not the leg bolts though.

Cheers,
John
Thanks John, also recommended to loctite the blind nut. SOLO had a lookie see about torque values on the leg pinch bolts. Looking at all sorts of manuals last nite, one thing stuck out...the upper pinch bolts have a higher value than lower. I don't know why, but that was a very common theme. I went 15 ftlb on the lower clamp, stem pinch, and blind nut. And 20 ft/lb on the upper pinch bolts. I did back off of the blind nut a bit before I went to town on the stem pinch.


Legs are a little lower in the top clamp compared to last time, i'm going to try and come home a bit early and hit my local whoops to seat the bearing, but I have to go to work tonight on the bike, a 90 mile round trip on the hwy. Funny thing is even with that bearing completly toast last saturday, I never ONCE felt it on the road!!

hardwaregrrl screwed with this post 05-03-2012 at 07:38 AM
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Old 05-05-2012, 04:34 PM   #575
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Bump

I'm laid out with a heavy cold this weekend. Can barely get myself off the couch let alone out to the cold windy shed.

Gimme some news!

Rather than continue to clog up this thread with my theorizing about different bearings and preloads and torques, after chatting with Marcus (roadsacallin) about his upcoming Scotts damper install, I asked him about his experience with these steering head bearings and these clamps/stem/blind nut.

He is going to check in here and enter the discussion sometime after his his current ride, suffice to say my paraphrasing is: he did have problems resulting in replacing notched bearings (around 18,000 Miles and 30,000 Miles), and he believed this was because they were not tightened enough, and he recalls feeling like the top nut (same newer 'short thread' nut that we have) didn't seem like it was up to the task of tightening the bearings to what felt right without the thread failing. After the second replacement (Capetown), he tightened the blind nut more than he ever had before (no torque value remembered), and things have been OK since (though the roads ridden since have also been much better).
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Old 05-05-2012, 05:38 PM   #576
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This isn't good news...... I'm thinking that the next time I have to change the bearings, I will be pressing this stem out and putting a bmw stem in. I'm hoping to be riding next weekend some nice off road routes up in N. Carolina!!

Ps sorry about the cold....eat lots of raw garlic!!!



Quote:
Originally Posted by ontic View Post

He is going to check in here and enter the discussion sometime after his his current ride, suffice to say my paraphrasing is: he did have problems resulting in replacing notched bearings (around 18,000 Miles and 30,000 Miles), and he believed this was because they were not tightened enough, and he recalls feeling like the top nut (same newer 'short thread' nut that we have) didn't seem like it was up to the task of tightening the bearings to what felt right without the thread failing. After the second replacement (Capetown), he tightened the blind nut more than he ever had before (no torque value remembered), and things have been OK since (though the roads ridden since have also been much better).
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Old 05-05-2012, 06:32 PM   #577
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Originally Posted by hardwaregrrl View Post
This isn't good news...... I'm thinking that the next time I have to change the bearings, I will be pressing this stem out and putting a bmw stem in. I'm hoping to be riding next weekend some nice off road routes up in N. Carolina!!

Ps sorry about the cold....eat lots of raw garlic!!!
Paraphrasing others is always a little risky, buy yeah, bad news and OK news I suppose.
Bad news- seems to be don't run them too loose or you will probably have problems. OK news- that top blind nut can probably take a bit more torque than it feels like it will- I don't know how much, and don't quote me on that
If Marcus' bike has been OK since Capetown, with this same set up and a more heavily torqued blind nut- then things may not be so bad at all.

I'll be setting mine with the longer threaded blind nut that I have and torquing it up until I get the right feel and fall away point (which is the only way it makes sense to me, not a ktm manual talking about lighter (mass) and 'smaller' contact angle bearings). I suspect on mine this will be around and possibly over 35-40 ft-lb torque (and whatever it is I'll take note). There is a fair bit of usable thread in the top of that stem (not utilised by the short thread blind nut) and using the longer threaded nut did change the feel of torquing it up for me.
One thing Marcus also mentioned is that he thought of getting a steel blind nut (bought or machined). Maybe one of the steel swing arm doo-dads with the same thread could be modified and used?

Personally, at this point, I still wouldn't be planning on a stem swap- I doubt the situation is that dire- my feeling is we've got a blind nut and threaded stem system that is not ideal for the torque required to preload our bearings, but that by carefully exploring into the margin of safety designed into this stem, it can be made to work.

About the cold, thanks. I haven't been sick for over a year and a half, so it is kinda hitting me hard.
And garlic, yeah, I'm due for another dose. I'm on ginger lemon and Echinacea tea now. I also make a killer chicken soup (very heavy on the ginger, garlic and chilli) and I am trying to muster the strength to head down to do some shopping to cook up a pot full.
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Old 05-05-2012, 11:25 PM   #578
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Quote:
Originally Posted by hardwaregrrl View Post
]I will be pressing this stem out and putting a bmw stem in.]
There's always this option as well:

http://www.roemerteam.de/inhalte/bmw...zialteile.html
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Old 05-06-2012, 03:01 AM   #579
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Originally Posted by Airhead Wrangler View Post
There's always this option as well:

http://www.roemerteam.de/inhalte/bmw...zialteile.html
Thanks AW....i just don't like the female threads on the stem. From a repair standpoint, it makes more sense to me to have male threads. It certainly is easier to seat the bearing. Off to work on the bike. Been riding 90 miles round trip and no problems or loose front end.!
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Old 05-07-2012, 08:30 AM   #580
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Started to recover from my flu today so considering I've taken today and tomorrow off work() I got a bit busy.

I think I may have figured out part of the reason I am having trouble preloading my bearings properly, I'll get to that at the end.

First I set about shortening my forks.
Nothing new to show here that Solo hasn't already. Thanks to his write up and PM's it was pretty easy. I have shortened them by the full length of that black spacer. I'm not sure if this is exactly spot on for G/S measurements, but it feels pretty close.

here are the 'special tools' I improvised.
Protaper bar risers with two layers of leather around the cartridge tubes and clamped in the woodworking vice.



worked great.

next, that damn triple pin thing- I just found some rollers from an old needle bearing from my 4x4 that fitted perfectly and then a couple of vice grips and some heat applied around the thread, and it turned and cracked the the thread easily enough.




Some time soon I'll have to go to the trouble to actually make that special tool- I just didn't have the patience tonight (as it is going to have to be a pretty good fit to work well). At the least, next time I'll find my other set of vice grips so that I can use three pins instead of two.

Not much different here to Solo aside from the colour of the PVC pipe I used for my new spacers. Well, they are KTM forks aren't they
As you can see, new spacer same length as the black spacer that is being removed.





Did both forks, put it all back together, and we now have a much shorter front end- suddenly the side and center stands work again.

I haven't loctited the few threaded bits that seem to want it inside the forks as I will only be running them like this for some testing- and pretty soon they'll be pulled apart again and probably lenthened a little bit and who knows what else before I put them back together for the final time.



Next I set about exploring the old blind nut and bearing preload issue.

First off I made a steel blind nut out of a swing arm thing out of my spare parts.
A little bit of welding and grinding and what not,

from left to right is, the old KTM aluminium blind nut with the long thread, the new KTM aluminium blind nut with very little thread, the steel blind nut I made with maximum thread that will work in the stem (pretty much exactly the same as the nut on the far left), last to the right another of the swing arm things I made the nut out of.


new long thread steel nut vs new short thread aluminium nut- the washer on the steel nut is aluminium and is from the old KTM aluminium nut I have.







After making my new steel blind nut I torqued my head stem right up... pretty damn high (over 60 ft-lb)and it didn't do much-
what I think I figured out is that the top of my stem is probably hitting the bottom of the washer under the blind nut before my torquing up of the blind nut preloads the bearing enough.


I did a test with some soldering wire under the washer between the washer and the top of the stem, torqued it up, and sure enough the very thin soldering wire got squashed.
It is not too clear but that is squashed thin soldering wire on top of the washer there.



Why this is happening to me?
At present I have not fitted a top bearing cover because I need to cut it down in order to get it to fit with my scotts damper pin tower- it is quite possible that the tolerance on this stem is that tight that this very thin removal of spacing between the bearing and the triple clamp means that I haven't been able to preload my bearings properly.
Hopefully this will be fixed when I fit my bearing cover, and if not then I will make up a washer/spacer thing (to go under the blind nut washer but around the top of the stem) that will let me pull the stem a little bit further into the top triple clamp. Does that make sense? (I hope so)



Besides all this, after all my thought into the different bearings issue- I still feel quite sure that we need to torque our bmw bearings a bit more than the KTM manual calls for.

I also tried my suggestion of keeping the bike on the centre stand and loosening the lower triple fork tube pinch bolts and the upper triple stem pinch bolts, and then torquing up the blind nut, and it worked much better for me as the nut was no longer having to pull the entire front end up.

Cheers,
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Old 05-08-2012, 12:54 AM   #581
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A little update,

Got the bike back together, including reconnecting all my temporary (and unlabeled ) electrics that had been pulled apart from all this front end wrangling.

I put new stock bmw bearing cover/seals above and below the top and bottom bearings. The top one I had to cut right down to fit with my HPMGuy Scotts damper pin tower.
All up I suppose I might have added 1-2mm of shimming...? and what do you know but I can now torque up the blind nut and it acts like it should- continuing to predictably tighten up the steering beyond 10-20 ft-lb . The top of the stem is no longer hitting the bottom of the blind nut washer before the right preload is reached. I must say, I am fairly impressed with the exact tolerance that Rdubb designed these for- barely a mm of wiggle room but with stock bmw bearings and seals in their right places it will work- without the seals it won't.

With my steel blind nut I played around with a lot of different torques on that top nut- to me it feels like the range is somewhere between 20-30 ft-lb. At 20 ft-lb I can't feel any wobble, but the bars fall away at the slightest tilt from center and they fall with no resistance whatsoever, and 30 ft-lb has a bit too much drag and doesn't fall very easily or quickly (though it still falls). Calibrated over two different torque wrenches (my clicker and my old deflection beam which both agreed), I've set mine at 25 ft-lb where it feels just right to me.
If anything, I feel like I may have set mine a little loose (I plan on checking it frequently as the bearings settle in)- but maybe not, maybe I've set it a bit too tight.... however I can't see any way that 7.4 ft-lb would work.


And wow, what a difference riding these forks shortened- cornering is a lot nicer. The bike feels nimble all over again but so so solid and planted in the front end. In contrast it was feeling a bit chopperesque with the full length forks, even slid up in the triples as far as I could.

I played around with my fork clickers a little bit- both clickers all the way out, very nice and plush with an almost empty tank and no load on the bike- both clickers all the way in, nice and firm, thankfully a bit too firm so that it should be usable when the bike is loaded down more. Then I tried both clickers in the middle for a while (18 clicks out) and it seemed very nice.

I need to get a slightly more road-friendly front tyre on as this ridiculous motorcross tyre howls at speed and feels like I'm riding on rubber marbles if I lean it over too far Before then it will be hard to fine tune the forks for the road manners as far as oil weight goes, but for now this Penrite full synthetic ATF feels pretty nice.
They list it as an equivalent to a 10W fork oil.

anyone else got some updates
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Old 05-08-2012, 03:32 AM   #582
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Originally Posted by SOLO LOBO View Post
With the inner damper rod removed, you invert the rod and unscrew the "tap rod" from the "piston rod". As usual, I didn't have the fancy WP vice jaws that lightly by firmly hold the piston rod without marring it, so I improvised...


The spring was a tight fit, and I had to wiggle it off while gripping it with pliers

Just thought I should add, when I got to this point on both forks the opposite end of the damper rod (the top) unscrewed rather than how it happened for Solo.
Whatever end cracked first was going to go and I had no choice in the matter but at least it meant I didn't have to try to get that spring off.
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Old 05-08-2012, 04:56 AM   #583
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I;ve got nothing new. Hit the whoops again and the front is still tight....so I think I may be out of the woods with that. Bought Race Tech suspension bible per AW suggestion and have been reading that. There is a good "test" section in the book that I'm going to try out. I checked my notes again and realized I used 20 ft/lbs on the blind nut. Worked like a charm. The machinist had mentioned something that I forgot to mention. When he cleaned up the threads for me he told me that the blind nut was designed to be pinched as it was being tightened into the stem. The threads look identical to me top and bottom on the blind nut, what did he mean by that? That would indicate that the stem threads would be tapered, but I don't see that????

Hoping to do a few hundred miles off road this weekend, so should be good testing for the new bearings!!!!
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Old 05-08-2012, 05:24 AM   #584
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Since AW recommended that book, I've almost bought it a couple of times now. I'm not quite as efficient on amazon as I am on ebay One day I'll get it right.

And yeah, at least we are in the same ball park, 20ft-lb felt solid but on the lighter end of the scale for me. It is something I am going to keep checking until I feel like I get it right- I'd rather not run them too loose again so if 25 is good I'll inch it down a bit next time and see what I can get away with.
And here is one of the advantages of having a top nut that sets the bearing preload- we can actually easily use torque wrenches on them unlike the under clamp crown nuts- once I figure out the torque that works best it should be a cinch to set without mucking around with fall away of the bars (always a little difficult with cables and stuff confusing it)

I don't know what your machinist meant about pinching the blind nut. There is nothing unusual about those threads that I can tell, I've screwed a steel swing arm thing all the way to the bottom of the threads and even turned with fingers it rides smoothly and easily the whole way. Luckily all my heavy torquing hasn't damaged my threads!
John's point about the one-piece blind nut-washer possibly being pinched by the triple clamp was interesting (getting pinched on the washer where it sits in the depression of the stem pinch section- it would be a neat idea, however although it is very close, there is a 1-2mm of clearance around the washer so it doesn't actually get pinched.

If it is a concern that 20-30 ft-lb is not enough to reliably hold that blind nut in place over time (is that the concern?) maybe once the bearings are preloaded, then the stem gets pinched and then the blind nut gets torqued up a bit more just to hold it in place? I don't know.
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Old 05-08-2012, 10:09 AM   #585
redboots
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Quote:
Originally Posted by hardwaregrrl View Post
...he told me that the blind nut was designed to be pinched as it was being tightened into the stem.
Does he not mean the top triple, center pinchbolt? Thats the only thing that will stop the nut undoing. I doubt that 20ft/lbs will hold it for long without.... imho...

Cheers,
John
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