Monday, December 6, 2010

R1200GS Wheel Carrier R&R

Achtung!!!

Das Gelände Straße hinterrad flansch gebrochen hat.

-or-

Watch for cracks in your rear wheel flange...



I was brought to light on this issue last year and sure enough, my rear wheel carrier (flange) also had one of the lobes that carries the rotor cracked. Knowing this would be an issue, I kept an eye on it. During a FD service prior to a trip to the Ozarks last Oct, I looked again and saw one more crack that has been there (crack was stained) and one new. Although not sure, this may also be an issue with any bikes with the newer style FDs (link on top) and not just the GS. Do yourself a favor and take a look at yours. At least one of the failures I saw, the rotor broke free during a low speed maneuver. Can't imaging the outcome had it been at speed.

Got to looking for parts and was surprised the local dealer (Gulf Coast) had a competitive price to the internet. Looking a little more, Chicago BMW had a 20% off sale with free shipping so I was able to save $100 vs buying local and paying taxes. I usually try to support the local business but hey, that's a pretty good savings. Also purchased was a ABM stainless wave rotor from Beemer Boneyard at a reasonable price.

Although it took three weeks to get the flange (lost in space somewhere) I finally had parts and needed to gather some tools. Things needed that most may not own are:

External snap-ring pliers.
Axle puller with draw screw. (Can get from Autozone but has no draw screw. I got a piece of 5/8 all-thread and a nut and made one.)
Center for axle. (Can buy from BMW but have a lathe so I made mine.)
Propane torch.
Infrared Thermometer.
T40 long shank bit. (Need this for rotor removal and re torque)
Torque wrench.

Looking at the RepRom, I started by removing wheel, caliper, rotor and snap-ring. I mounted the puller on the flange and center into the axle. I made sure to adjust the mounting bolts to get the puller centered by watching as I rotated the flange and watch the run-out of the draw screw. I adjusted the three bolts mounting the puller until no run out was visible. I then tightened draw screw good and snug. Don't expect any movement as this is an interference fit and will require heat.



Make a mental note of how the splines look at this point. Here is how mine looked.



I cut a piece of thin aluminum to fit between the flange and FD to shield it from the next step.



I heated the flange on the area where the wheel meets the flange (do not get the axle hot) while rotating it using the puller. I was careful not to use the torch up near the top where the ABS sensor is but rather at the aft most point. As I heated, I would check with the IRT, looking for the release temp of 100°C. Once there, I noticed the splines have moved a small amount. I popped the tranny in first and started tightening the draw screw and was pleased to see the flange pull right off the axle with very little resistance.

I inspected and cleaned the seal area. With the shield and torch placement, it felt like heat transfer was minimal into the FD.



Failure Emanate!


I looked at the two parts to see any differences and only found the seal shield is pressed on rather than machined . Other than that, I could find no differences (other than the new one didn't have four cracked lobes).






I put the new part in the oven and set it to 225. After a good soak, I tested it with the IRT and had it to 110°C so I dawned my welding gloves and carried it out to the bike. Is didn't slide right on so I tested it again and it had fallen to 85°C. With it in place, I used the torch to bring it back up by heating the face in a circular motion, keep the flame in the indention where the verbiage is. Once at 100°C, I tapped on it with a block of oak and it started sliding on the axle so I drove in on home until it shouldered up on the bearing race.



After cool down, I reset the snap-ring in its groove (make sure this happens otherwise the flange is not seated properly) and re assembled brake components using torque specs from the Rep Rom.

I don't know if this had any bearing but I tried to run the slack out of the rear caliper by cycling the pedal but nothing would happen. I then turned on the system and tried to use the servo. This produced a "Brake Failure" warning and the self test would not pass. I cranked the motor and cycled the pedal. At first, I heard no servo then after a few more tries, I could hear R2D2 whine. I cycled the ignition and the servos tested and passed this time. My guess is I should not have tried to take the slack out with the pedal but let the system do it. Dunno...

Disclaimer. I am not an expert nor do I claim to be. I supplied this information as an FYI on an as is basis for any to use at their own risk. Your result may vary...




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