Wheel question

[rtallent]

Here's one for the tech gurus!

I live a long way from my dealer, so I bought my R1200R a set of Scorpion Syncs from Dennis Kirk and brought the rear tire and the wheel to the local (highly over-priced) Suzuki dealer I used to deal with to mount and balance it. Mounting--no problem. Balancing--no way. They couldn't do it. Said they didn't have the right size cone for the balancer to fit my wheel. So I brought the wheel to the local private ace mechanic (makes drag cranks and can fix anything kind of guy). He had trouble too, even though he had the right size cone and previous experience with BMW wheels.

What he found was abnormally high weight required (2.50 grams on the left side and 1.50 grams on the right. He said 0.5 to 0.75 grams is more usual.) The weights were so high he figured that either he was doing something wrong, or the wheel is bent. He has a call in to Handy about the balancer to see if they make a piece he can bolt the wheel to to be sure it is on perfectly. In the meantime, I brought the wheel home, mounted it on the bike and rode to another great mechanic I know closer by who has a run out gauge. He measured the run out and found 29/1000 on the left side and 16/1000 on the right side. He thinks this is very high and so does the other guy. I can't feel it when I ride, but my ass-o-meter may not be the most sensitive.

I called the service department at my dealer to ask what the run out tolerances are for a 2007 R1200R rear wheel and they will look into it and get back to me, probably tomorrow.

So...Is it likely the wheel is bent? Does anyone know what is normal run out for these wheels? If it is bent and since the bike has low miles (~8000), no previous tire changes and no history of stunt riding or other abuse, could this be a warranty issue? By the way, the original tire had no weights on it. Also, a wobble was noticeable when the wheel was on the wheel balancer but not when the wheel is mounted on the bike.

Any help greatly appreciated. Thanks in advance.

[deilenberger]

Bob - the wobble on the wheel balancer is a big clue it's not mounted correctly on the balancer. This wheel has to be done with a fixture that the wheel bolts up to and the fixture is mounted in the cones in the wheel balancer. BTDT with a friends local shop (he has a SnapOn balancer..) If your shop wants to spend about $100, I can get you the PN of the wheel adaptor (it's from BMW..)

I'd visit your dealer and see if they will balance it for you. They DO have the correct tools to do this, and that should tell you if the wheel is excessively out of balance. They also can check it for run-out.

[rtallent]

Bob - the wobble on the wheel balancer is a big clue it's not mounted correctly on the balancer. This wheel has to be done with a fixture that the wheel bolts up to and the fixture is mounted in the cones in the wheel balancer. BTDT with a friends local shop (he has a SnapOn balancer..) If your shop wants to spend about $100, I can get you the PN of the wheel adaptor (it's from BMW..)

I'd visit your dealer and see if they will balance it for you. They DO have the correct tools to do this, and that should tell you if the wheel is excessively out of balance. They also can check it for run-out.

This is great info. Thank you Don. If the part will work on a Handy wheel balancer, I'm quite sure my guy will want it. He takes a certain amount of pride in being able to handle anything that comes his way. In fact, I might just buy it for myself! My dealer (who I support every chance I get!) is about 250 miles away and, while I know it's a good excuse to take a ride (unfortunately mostly highway), I don't have time to devote a day to this right now. If you could get me the part number I'll pass it on and be very grateful to you. Thanks again!

[deilenberger]

Rob,

83 30 0 442 813 - made for a K1300 series bike, which uses the same wheel pattern as we have. There is also a tool made for the K1200 series (late ones) PN 36-3-582 (0442813)<-- note similarity to other tool number..

[NeilS]

Bob,

I agree that if the wheel runs true on the bike and not on the balancer, it's not mounted on the balancer correctly.

But I'm wondering if you have a "units" problem about the amount of imbalance. There are about 28 grams in an ounce, so if the required "excessive" weight is 2.5 grams, that's only about .09 ounce. The "standard" stick-on wheel weight is 1/4 ounce, so you wouldn't use a weight at all with 2.5 grams of imbalance. Or is the mechanic really saying the required weight is 2.5 ounces? That would be too much.

[rtallent]

Don -- Thanks for the part number.

NeilS -- You're probably right about the units, I may have misunderstood him. Since he felt that what the balancer was showing was probably unreasonable, it must have been ounces. My bad.

[rtallent]

After several weeks of waiting (ordered 6/4!), I finally received the part Don suggested, brought it and the wheel to my mechanic and got the wheel balanced without a problem -- worked like a charm. Thanks again Don!

ps: When I called my dealer to ask what acceptable runout is on the wheel (1.5mm, they said) it came up that they have a hard time balancing these, too. They were thrilled when I told them about the special tool!

[deilenberger]

Bob, glad the number worked! It's helpful having a friend in BMW Motorad once in a while