Front End issues (wobbles)

Discussion in 'Airheads' started by ChristianJS, Jul 25, 2012.

  1. ChristianJS

    ChristianJS Adventurer

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    Hey guys. I'm having some front end issues with my 75 R90. I get some wobble in the corners, and a bit on straights. Also feels overly spongy. I'm thinking steering bearings? I have not touched it since I got it, and the bike sat for quite awhile.
    #1
  2. mykill

    mykill odd

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    Is the bike new to you?
    Have you ridden airheads before?
    If you dive the front end does it return slower than it compresses?
    Bounce your ass on the seat. Pogo or slower return?


    I would start by checking wheel bearings and steering head bearings for notchiness or binding, as well as changing the fork oil. I suspect the fork oil will be the chunky style. Check rear S/A bearings for play and grease.
    #2
  3. boxerkuh

    boxerkuh Been here awhile

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    Yep, that sound right. Once you have the front off the ground move the handlebars back and forth. If it feels "notchy" the bearings will need to be replaced. If it is not notchy you may try to tighten them up a little bit and that may do it. However, since you just bought the bike and it has been sitting for a minute, the grease may just be hard.... what would I do? I would check it, tighten them up a bit, order the bearings and go in for a look see inspection. If you need the bearings you have them on hand, you might get lucky and only need to clean them up and repack them. Then you have the bearings for a later time.
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  4. ChristianJS

    ChristianJS Adventurer

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    I had a couple of airheads in the past. I recall the stiffness or lack of, but the wobble is not something I noticed in the past. I will check this stuff out and go from there.
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  5. ChristianJS

    ChristianJS Adventurer

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    Ok, my manual has not arrived yet. Any links to a how to on tightening?
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  6. mfp4073

    mfp4073 Long timer

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    just to throw this in there, and probably off because I didnt get it in corners. But I had a front tire cause wobbles. It was a metzler and had 8k miles on it at the time. I could just firm up my grip on the bars or lightly hit the front brake and it would go away. When replaced the tire the wobble was gone. Had checked bearing and everything else but found nothing. I am about 11k miles into new tire bridgestone tire and never come back.
    #6
  7. disston

    disston ShadeTreeExpert

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    It sounds like you have a 37 year old high mileage Beemer that runs. These bikes are just right for the rider that wants to learn to take care of everything themselves. High maintenance is another description that might apply but many parts of the Beemer are fine for miles and miles of enjoyable riding once they have been properly attended to. Your front end is likely to need much more attention but starting with the steering bearings is fine. I think somebody else also mentioned changing the fork oil. I also recommend this.

    The handle bars and the handle bar mounts need to be removed. It is helpful to remove the steering dampener Parts thru the center nut but not needed to remove if you would rather leave them in place.

    The center nut is 36mm. There is a box wrench in the on board tool kit with this size. Remove 36mm nut. Under this is the slotted nut that is the adjustment for the steering head preload. There is a hook wrench in the on board tool kit that fits the slotted nut. Bearings should be adjusted with a slight preload, about 7 ft/lbs. Then the center nut is replaced and while the slotted nut is held to prevent further tightening when tightening the 36mm center nut. The center nut is put on tight, I forget the actual ft/lbs but it is tight, to prevent the slotted nut from loosening.

    Here is a long article about Airhead front ends. You will hopefully not need everything on these pages but you probably need more of this than you think;

    http://bmwmotorcycletech.info/frontforks.htm

    Here's one more to the point, maybe;

    http://w6rec.com/duane/bmw/steeradj/index.htm

    Both these sites are maintained by people very active in the Airhead world. You'll be referred to them often if looking for info.
    #7
  8. ChristianJS

    ChristianJS Adventurer

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    Ok, thanks for the responses. Based on testing, it appears there are bearing issues that I will attack soon. But....It's funny what MFP said. I have a Metzler on there, and upon closer inspection, it is full of dry rot.
    #8
  9. mfp4073

    mfp4073 Long timer

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    Mine wasnt and looked decent enough. I had read some ancdotal info about head wobbles and metzlers. Was also in need of a new rear tire due to wear. The bridgestones were higher mile and cheaper than the metzlers so I went that way for those reasons. And poof, went away. Like I said. It may not be it, but if you are going to replace tires anyway...... especially if you dont find any other smoking guns.
    #9
  10. DaveBall

    DaveBall Long timer

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    And, if you are taking the head bearings out due to being stiff or appear to have a bit of notchiness, you don't always have to replace them. Give them a good soak in a degreaser and work them to get the old dried out crap out of there. Then regrease with a quality wheel bearing grease. I have done this to many a set that others would have replaced. Those bearings are not under a whole lot of stress and the usual reason for the notchies is dried up grease.

    You may want to invest in an inexpensive bearing greaser cup thingy, don't really know what to call it at the moment. It is a funnel shaped thing with a tube in the middle and a bowl to fit over top of the bearing. You use your grease gun to pump grease thru the bearings until you get clean stuff coming out. Works great to ensure that you have grease thru out the bearing.
    #10
  11. ChristianJS

    ChristianJS Adventurer

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    See MFP,, my bike just sat. tire looks perfect otherwise. I'm used to ducatis, and very grippy tires. This is a whole other animal. I don't like the Metzlers at all.

    Dave, i don't have the notchy feeling, but i'm getting a lot of play when I move the front end around. I get the regrease procedure and all that. The only thing is my concern about cleaning. I remember as a kid, WD40s, gasoline, etc, would wreck our skateboard bearings
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  12. mykill

    mykill odd

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    I personally hate Metzeler Lazers. I too have experienced an uneasiness with them leaned over. They tend to cup and get weird. My beloved Avon Super venoms are no more, but I rode a friends R80 with new Michelins and it felt great.
    #12
  13. carpetburn

    carpetburn Been here awhile

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    2 new michelin pilot actives cured a similar problem for me, i had tried everything mentioned above to no avail- problem was front bt45
    #13
  14. ME 109

    ME 109 Long timer

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    I think two brand new tyres are the first requirement when trying to work out a wobble on a 'new to me' bike.
    Nothing like a flattened off rear to get things wobbling.

    It's amazing how some can find lasertecs to be a champion mountain road race tyre and others despise them.
    I've never run one on the rear, just the front. Maybe that's the issue.
    #14
  15. ChristianJS

    ChristianJS Adventurer

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    I've heard good things about the Super Venoms (discontinued and replaced by Road Riders?). What are your thoughts?
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  16. DaveBall

    DaveBall Long timer

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    Is this turning into a tire thread? :evil I like my Bridgestone Spitfires, as they suit my style of riding and get good mileage out of them with good grip in all weather conditions. Plus they are pretty cheap compared to some of the others, at least where I live. I average at least 2 sets per year, due to the high mileage I put on (about 25,000 per year).

    If you are feeling a lot of play in the front end, definitely adjust those head bearings. Not all that hard, once you have played with them for a bit and find the "sweet spot". The trick is to get the right amount of load on them and tighten down the nut without adding more load. Play with it and you will get it right. The way I was taught by a factory trained mechanic, back in the day, was to have bike on centre stand and adjust the bearing load. You should be able to set the bars to pointing straight ahead, then with a very slight touch to one side or the other, they should slowly swing to full stop. Not to fast, and not stop part way. I do it with the tank off, so that I don't slip with a wrench and damage it.
    #16
  17. erimille

    erimille Adventurer

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    Sorry to ask what might be a silly question, but how does the dampening knob relate to this problem? I had assumed that tightening the dampening knob to zero in on this sweet spot would have been the easier way of adjusting the bearing load.

    --e ('72 bmw r75/5 ... also trying to minimize a front end wobble)
    #17
  18. disston

    disston ShadeTreeExpert

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    The dampener on my bike has been disconnected for ten years. I was told it does nothing for the safety of the steering. The steering works fine on a properly set up Airhead front end without a dampener. If there is a problem a dampener will only hide the problem not cure it. If you really think there is some advantage and want a dampener I suppose that's OK too. But I don't consider it a safety feature, item.

    Proper tire is a start. Too loose a steering bearing can cause a tank slapper. Be sure you check this ASAP. Too tight a steering head bearing will wear the bearings out fast. It's true that cleaning and regreasing may cure notchiness but if the bearings show shadows and feel notchy with out grease I change them.

    I did steering head bearings a couple of months ago on my 1975 R90/6. I expect every part of my bike to perform to the standard that was built into her. I never regret putting in new bearings. I also replaced all the wheel bearings, first time in almost ten years and the swing arm bearings.
    #18
  19. DaveBall

    DaveBall Long timer

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    Disston, I never said NOT to replace the bearings. I was only suggesting that a lot of people change bearings when they don't really have to. I have seen head bearings that were so stiff I thought they were rusted, until I got them out and saw the congealed mess. Cleaned up real nice and once new grease in them, they were like new.

    Now wheel bearings are a totally different issue. They are under a lot more stress and if one decides to pack it in at a high rate of speed, the results just are not pretty. Been there, done that, after a wheel replacement at a BMW dealer. They did not even grease the damn things, just left the packing oil on them. Dumb so called mechanic did not have a clue. Totalled the axle, brand new recall wheel and nearly me. The dealer did replace everything and was extremely apologetic, but I have never gone back for any mechanical work there.
    #19
  20. disston

    disston ShadeTreeExpert

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    Dave I was not trying to disagree with you. Cleaning the grease can fix a notchy steering bearing. But I thought it worth while to mention the shadows they sometimes get and to look for the notchiness with light oil on them before reassembly. I didn't word it quit like that but that's the idea I use for checking them. Mine were not too bad really but I could see the shadows.

    I don't think we disagree. Maybe just draw the line a little different.

    I think a lot of dealers had problems with that wheel recall some years ago. Not too many that have anybody can do much Airhead work. I'm lucky I live close to Bob's, even tho I do my own work. Parts service at Bob's is great and if I have a question they let me go over to the shop and ask somebody there. I try not to bother them tho. I never had a SnowFlake wheel. If I did I'd be tempted to not exchange it because they might be worth something some day as a wall hanger. Might not be a good idea really. I understand they will still exchange them now after all these years if you show up with one from a bike that the VIN # says hasn't been exchanged yet.

    Charlie
    #20