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Post by buzzin on Dec 8, 2008 9:59:34 GMT -5
Ok guys, a nice mistery to solve here:
When I let go of the bars, and braking on the engine, the front end starts to wobble, like a tankslapper, just not quite as voilent (although it might come to that if I don't stop it).
I had no such problems in the summer during the rideouts then (just let go to relax the arms during long drives).
It's also not apparent when you just drive, I feel no vibrations in the front end during normal driving or when braking with the front/rear brake.
Does anyone have a clue as to what I should check/replace?
I was thinking the wheel bearings or even a ill-balanced front tyre, but then someone else suggesten the front suspension (which hasn't changed since summer...)
Any clues are welcome...
(so is a bit of nice weather so I can work on the bike....)
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Post by Jake on Dec 8, 2008 10:32:03 GMT -5
Apparently, the usual things to check are: • Distorted rim • Worn front wheel bearings • Axle or axle holder not tightened properly www.hawkworks.net/manual/12.html#12-2-troubleshootingThe only time I’ve ever had this problem is when I first fitted a windscreen…..and the steering started to wobble at speed on the motorway. I sorted it by stiffening the rear suspension slightly, so that more weight was transferred to the front. |
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Post by McF on Dec 8, 2008 12:01:57 GMT -5
Where to start  So many things could cause it: Front Tyre - worn, wrong inflation Front Wheel - distorted (buckled, dented), Wheel Bearings worn, Spindle loose Forks - wear in bushes, springs lost their strength, loose, incorrectly aligned Steering bearings - incorrectly adjusted Rear Tyre - worn, wrong inflation Rear wheel - distored, loose bearings, spindle loose Swinging Arm Bearings - worn, loose, sticking Rear Suspension - poor damping, spring pre load incorrectly set Weight / Balance - Screen fitted? top box, panniers, tank bag Does this happen at a range of speeds? Is the screen influencing it especially in cross winds? Have you tried taking left hand off and lightly holding the throttle open with finger tips (ie to prevent deceleration)? Has anyone else had a ride to confirm your worries? I'd start with the tyres and check the Wheel Bearings Then take off the luggage and try it again Then experiment with different pre load and damper settings on rear shocker (no luggage) Then get my prayer mat out! |
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frog
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Post by frog on Dec 8, 2008 14:14:22 GMT -5
I think McF has this one nailed although I'd start with steering head bearings.........
Frog
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Post by McF on Dec 8, 2008 14:41:40 GMT -5
I think McF has this one nailed although I'd start with steering head bearings......... Frog Technically I'd agree, especially as the bearings may have "set", but having to go through the rigmarole of removing the top yoke to get at the adjustment - I'd personally wimp out and leave it until all other avenues exhausted  |
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frog
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Post by frog on Dec 8, 2008 15:22:01 GMT -5
I agree adjustment can be a little difficult and replacement sheer bl**dy awkward. However checking is not so bad. Fairly good test for head bearings........... if it rolls like a drunk at 15-20mph on a flat good road with your hands off the bars I'd deffo look at head bearings.... Be VERY careful people and do this at your own risk etc ;D NB Take one hand off first - hold lightly with the other - quite often that'll be enough show up the problem.  As long as you can get the front wheel off the ground checking of the bearings to confirm is quick and easy. If you have no centre stand what I now call the 'McF technique' works great - see my posting on no centre stand...  Frog |
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Post by buzzin on Dec 8, 2008 17:23:06 GMT -5
Thanks for the suggestion folks! I'll have a look at the head bearing....although I am not looking forward to replacing that  (ps. I have a centerstand...so should be easy to check) ehm...having never fiddled with those kind of bearings before...are they hard to replace? (I see motozoom sells them for 50 euros, so it's not too expensive) To be more clear: Nothing structurally changed since riding it without problems. Only changes are a new rear tyre (problem existed before that though) and some extra KMs on the clock... As usual I ride with a small screen fitted and a topbox, but this didn't change either...so should be something that's just been worn down... Perhaps it's not a bad idea to replace the wheelbearings anyway....looking at wemoto they aren't that expensive either. But not before I have the wheel rebalanced  |
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Post by McF on Dec 8, 2008 17:39:40 GMT -5
As long as you can get the front wheel off the ground checking of the bearings to confirm is quick and easy. If you have no centre stand what I now call the 'McF technique' works great - see my posting on no centre stand... Frog As much as I'd like to take the credit, it actually goes to super hero Dave Skelton (probably only known to Blitzman and I) of Frontline Bike Shop in illustrious "South Bank". and to be honest, I had clean overlooked the fact that you can lift the front wheel of the floor and give the head bearings a good shake  Many thanks Frog Buzzin - good luck |
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Post by Jake on Dec 9, 2008 4:24:12 GMT -5
A point on checking tyre pressures which McF mentioned….. I found recently that my rear tyre was losing pressure more than it normally does. So I suspected a slow puncture… which puzzled me because both my tyres contain ‘Ultra-Seal’ which is supposed to seal punctures when they occur. When I checked however, I could find no sign of a puncture. I then checked the tyre valve and found that quite a lot of air was escaping , so I deflated the tyre and replaced the valve core pin. The valve ‘pin’ (for want of a better term) unscrews, you need a special tool to do this but they’re easy get hold of from any car-supply shop together with replacement pins. Buzzin, I seem to remember that you said your BT45 front tyre was ‘cupping’ but I’m guessing that you've replaced this tyre by now. But did you replace the valve pin once the new tyre was fitted? Maybe the wheel needs re-balancing, as you’ve suggested? It seems more likely though, that depending on what mileage you’ve done, the wheel (or head) bearings need replacing….. Hope you get it sorted soon... |
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Post by hubcap on Dec 10, 2008 10:11:37 GMT -5
My front end does exactly the same thing, I'd have put it down to an ill-balanced tyre myself, though it could also be the headstock loose, everyone who's ridden my bike has said the steering's very fast.. Mind I'm too scared to let go of my bars for more than a few seconds so hopefully it won't cause any issues.
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Post by Jake on Dec 10, 2008 11:40:57 GMT -5
I had similar problems, Hubcap... After I had Hagon springs fitted and put 15w oil in the forks and fitted a fork brace and windscreen, the steering got a bit too fast and twitchy.....  But I solved it by stiffening up the rear suspension gradually.... |
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Post by hubcap on Dec 10, 2008 11:44:46 GMT -5
I just got used to it, it feels about normal after I've been riding the CG for a while, lol!
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Post by buzzin on Dec 10, 2008 14:21:25 GMT -5
The first front tyre, that was really badly cupped has been replaced.
Air pressure is fine on the tyre.
A quick check of the bearings seems to indicate they are fine, they feel solid. (no movement)
But I will check them out anyway, as I get the feeling they are original....and after 15 years and 80.000 km they might as well be replaced. (then again, I just don't know. previous owner didn't specify what had been serviced and what hadn't)
Just to be on the safe side: What tyre pressure do people usually use here for a BT45 front?
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saxby
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Post by saxby on Dec 10, 2008 15:53:46 GMT -5
i had similer problems . i replaced a lot of parts on the frount end and the ony thing that fixed it was taking the Steering bearings out .. they seemed fine but i had a 2nd set and fited them and it worked , but that was for me .. it coule be any of the falts listed by MCF
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Post by everydaybiker on Dec 14, 2008 18:24:49 GMT -5
Steering head bearings often cause this. With the front wheel off the ground the bars should move freely from lock to lock without any resistance from the bearings.
At the moment my 650 steering has a notch in the centre position not unlike the halfway point on your bass or treble knob on your home stereo! It homes quite nicely there (except that it's not supposed to...).
Needless to say, I have a new bearing set ready to replace when I get the chance....
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