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Old 07-25-2012, 07:58 AM   #1
ChristianJS OP
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Front End issues (wobbles)

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.
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Old 07-25-2012, 08:08 AM   #2
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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.
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Old 07-25-2012, 08:10 AM   #3
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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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Old 07-25-2012, 08:20 AM   #4
ChristianJS OP
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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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Old 07-25-2012, 12:26 PM   #5
ChristianJS OP
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Ok, my manual has not arrived yet. Any links to a how to on tightening?
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Old 07-25-2012, 01:55 PM   #6
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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.
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Old 07-25-2012, 02:03 PM   #7
disston
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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.
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Old 07-25-2012, 02:08 PM   #8
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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.
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Old 07-25-2012, 03:51 PM   #9
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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.
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.
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Old 07-25-2012, 04:01 PM   #10
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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.
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Old 07-25-2012, 06:13 PM   #11
ChristianJS OP
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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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Old 07-25-2012, 09:35 PM   #12
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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.
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Old 07-26-2012, 12:14 AM   #13
carpetburn
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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
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Old 07-26-2012, 12:41 AM   #14
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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.
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Old 07-26-2012, 04:40 AM   #15
ChristianJS OP
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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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