Contents
In page 02 BMW R75/5 General Tear Down, I show to remove the swing arm from the transmission and the rear drive from the swing arm. This is what I started from.
Swing arm disassembled from Frame
This page covers removal and replacement of the swing arm bearings and races and the powder coating of the swing arm.
I ordered the swing arm bearing removal tool and the following parts from Cycle Works in Kansas.
| 31 41 2 000 331 | Swing arm dust seal, Qty (2) |
| 07 11 9 985 005 | Swing arm bearing, Qty (2) |
Here’s a picture of the tool; “some assembly is required”. This is explained in the included instructions, and I’ll show you how it goes together.
Cycle Works Swing Arm Bearing Puller Kit
I found the design of this tool very clever; combining common hardware with a clear understanding of how materials behave under stress. Very slick.
Assembling The Cycle Works Swing Arm Bearing Puller
First, put the plated nylon lock nut on the plated 16 mm bolt until the threads are just past the top of the lock nut with the bolt and thread faces aligned. In a moment, it’s clear why aligning the faces matters.
16 MM Bolt with Nylon Lock Nut-Faces Aligned
Next, screw four of the long socket head bolts into the plate with the six threaded holes leaving two adjacent holes open.
Four Socket Head Screws In the Plate
Screw the bolts into the plate until they are even with the bottom of the plate.
Screws Even with Bottom of the Plate
Now, place the 16mm bolt with locknut inside the four socket head screws. Ah … that’s why the bolt and nut faces need to be aligned 🙂
16 MM Bolt Surrounded by Four Socket Head Screws
Next, put some wheel bearing grease on the top of the 16 mm bolt head. Finally, screw the other two socket head screws into the plate so the 16 mm bolt is surrounded. Then, place the head of the socket screws on the work bench, adjusting them in their holes so all the heads sit flat on the top of the bench.
The long threaded rod has a taper on one end and a hole for an Allen head wrench on the other. Put a little wheel bearing grease on the tapered end. Using an Allen wrench, screw the threaded rod into the center hole of the plate until it touches the bottom of the 16 mm bolt.
Screw Threaded Rod into Center Hole of the Plate
At this point, the tool is assembled, so its time to use it. As shown here, the dust seal has a metal sleeve in the middle.
Dust Seal with Metal Sleeve
Use a screw driver to the pop the sleeve out of the dust seal. It comes out very easily.
Removing the Spacer
Insert the Allen wrench into the threaded rod. Then, place the heads of the six socket head screws on top of the rubber part of the dust seal and push down hard enough to deflect the rubber seal and tighten the center threaded rod. This pushes the 16 mm bolt head under the heads of the six Allen head bolts spreading them outward under the edge of the dust seal. Keep tightening the center threaded rod until you see all six Allen bolt heads are lodged under the lip of the dust seal as shown below.
Six Bolt Heads Under the Lip of the Dust Seal
Puller Positioned to Remove the Dust Seal
Now, put the metal cylinder over the threaded plate so it is centered on top of the swing arm and not touching the edge of the dust seal. Then put the steel plate and the washer on the center rod and thread the 17 mm nut finger tight down on the washer. Check to be sure the metal cylinder is still centered on the outside of the swing arm and is not touching the edge of the dust seal.
Cylinder, Top Plate and Washer Ready for Nut
Use a box end 17 mm wrench to tighten the nut pulling the threaded rod and the dust seal out of the swing arm. If the puller pops out of the seal, you didn’t tighten the threaded rod tight enough to spread the six Allen head bolts far enough under the lip of the dust seal. Back off the threaded rod, reinsert the Allen head bolts and tighten the threaded rod a bit tighter and have another go.
Use 17mm Box Wrench to Pull Dust Seal
And here you see the dust seal has been removed an is captured by the heads of the six socket head screws surrounding the 16 mm hex bolt head.
Dust Seal Removed Inside Cylinder
When I tightened the center threaded rod, I over tightened it so the 16 mm bolt head extended too far and got trapped by the socket head screws. When I unscrewed the center rod, the 16 mm bolt wasn’t able to come loose and I couldn’t get the dust seal off the six bolts. So, put the aluminum plate, washer and nut back on and keep tightening the center threaded rod until you hear a “pop” which is the head of the 16 mm bolt going past the socket head screws.
16 mm Hex Bolt Head Pushed Past Screws
Now, you can remove the dust seal from the six Allen bolts. You can unscrew two of the socket head screws to free the 16 mm bolt and slide it back inside the Allen head bolts. Then screw the two Allen head bolts back into the plate being sure all six bolt heads are level.
To remove the bearing, just stick your finger in the center and pull it out. If you are a gentleman of refinement, you can use your pinkie finger to extract the bearing from the race. 🙂
Refined Gentlemen’s Method of Bearing Removal
The bearing race is removed using the same technique: set the heads of the six socket head screws under the edge of the race and tighten the threaded rod until they spread out under the edge under the race.
Ready to Pull the Bearing Race
Again, put the cylinder, metal block, washer and nut onto the threaded rod and use the 17 mm wrench to pull out the race.
On the shock side of the swing arm, there is a metal cap under the race to keep grease from filling up the hollow center section of the swing arm. Mine was stuck to the bottom of the race hardened grease. Fish it out if it doesn’t come out with the race.
The vertical lines you see on the inside of the race in the picture below are due to Brinelling.
Grease Cover and Bearing Race
This is caused by the tapered roller bearings pounding against the race and deforming it. The rollers never fully rotate as the swing arm only moves up and down, but doesn’t rotate in a full circle. Eventually, the rollers indent the face of the race. I expected this due to the age and mileage of these bearings.
Flip the swing arm over and repeat the process on the drive shaft side. There is no grease cover under the bearing race as the tube surrounding the drive shaft blocks any grease from entering the hollow center of the swing arm.
Powder Coating the Swing Arm
I don’t want to remove the drive shaft under the philosophy of “let sleeping dogs lie”, but I am going to have the swing arm powder coated. I want to prevent any direct hits to the universal joint and it’s bearings during bead blasting, Here’s my solution: a custom fabricated Progresso “sock can” over the universal joint. This took me several hours to fabricate, but it was well worth the time.
Progresso Soup Can “Sock” Over the Universal Joint
If you want a “soup can sock” of your own, send me an Email with your mailing address and I’ll let you know how much it will be with shipping, handling, and if you live in Colorado, sales tax.
I added a warning note about protecting the surface on the other end of the drive shaft tube where the rear drive mounts to the swing arm.
Note to Powder Coater
Installing the New Races and Bearings
Here’s the picture of the swing arm after powder coating. The soup can sock seemed to keep the universal joint from being bead blasted.
Powder Coated Swing Arm
I washed the swing arm thoroughly to remove any residual debris from the bead blasting.
I cleaned up the powder coat over spray from the arms that hold the bearings. One arm was fully coated inside and the other had minor over spray. That’s my fault as I should have put a masking tape note over them as I did on the rear drive gasket surface. No worries. It’s easy enough to remove the powder coating.
Powder Coat Inside Swing Arm on Drive Shaft Side
I use a sanding drum on a Dremel tool and then follow up with 600 grit paper so the inside surface is smooth and shiny. It is easier to drive the race in when the inside of the arm is smooth and clean.
Dremel Sanding Drum and 600 Grit Used to Remove Powder Coat
The shock side of the swing arm has a cover plate that retains grease but the drive shaft side does not. Here are the new parts in order of assembly, top to bottom, inside to outside, with the drive shaft side parts on the left and the shock side on the right.
Swing Arm Bearing Parts-Top to Bottom, Inside to Outside, Left is Drive Shaft Side, Right is Shock Side
I started on the drive shaft side. I put the races in the freezer for an hour to shrink them. I put some engine oil on the outside of the race and use the Cycle Works aluminum block to drive the race into the opening keeping it parallel with the sides of the hole. The race wants to rock side-to-side when it starts, and I found tapping the sides of the race, going around the circumference with a soft mallet, helped seat it squarely in the hole before driving it in.
Race, Aluminum Block and Engine Oil
Using the flat side of the aluminum block and a hammer, drive the race into the arm until it’s flush with the top of the arm.
Using Cycle Works Aluminum Block To Drive Race on Swing Arm Side
Race Flush with Swing Arm Tube
Then, using the shorter side of the aluminum block, drive the race all the way into the arm until you hear it ringing indicating it is seated.
This is the shock side arm cleaned and sanded with 600 grit wet paper.
Shock Side of Swing Arm-Hole Clean & Polished
The cover plate is indented and goes into the bottom of the tube and the race sits on top of the plate on the raised edge.
Shock Side, Grease End Cap Orientation
The cover slides in easily so you don’t have to drive it in.
Grease Cap Installed on Shock Side
Just as you did on the drive shaft side race, use the flat side of the aluminum block to drive the race flush with the top of the arm and then use the short edge to drive the race deeper until it bottoms out on the top of the grease cover.
Shock Side Showing Bearing Race and Grease Cover Installed
I use NLG2 EP (Extreme Pressure) red grease and hand packed it into the bearings. I didn’t use my pinkie this time, but did wear my formal black gloves when I inserted the bearing into the race.
NLG2 EP Red Grease
Greased Swing Arm Bearing
Swing Arm Bearing Installed
Next up, install the dust covers and sleeves. The swing arm pivot pin slides through the sleeve and then inside the bearing. I’ll cover installing the swing arm pivot pin when I write up installing the swing arm in the frame.
Bearing Dust Seal
The sleeve goes under the rubber seal of the dust seal with the wider flat, or hat, of the sleeve against the face of the bearing. You can insert the sleeve after the dust seal is installed and it will look like this.
Dust Seal with Sleeve Inserted so Flat of Sleeve is Under the Seal
Use the flat side of the aluminum block and a gentle tap with a hammer to drive the dust seal in until it is flush with the top of the arm.
Driving Dust Seal with Aluminum Block
Then, push the sleeve through the rubber seal in the dust cap so it’s centered in the dust seal and the hat is completely under the rubber seal.
Dust Seal with Sleeve Installed
All done. After powder coating and new bearings, the swing arm is ready to install in the frame.
Revisions
2019-11-16 Typos.
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Hey Brooke,
I was wondering about your swing arm powder coating. I noticed you decided not to remove the drive shaft before sending it out. Are you concerned about how the heat involved w/ the powder coating will affect the bearings inside the drive shaft?
Thanks,
S
Hi Seth,
Thanks for coming by and looking at the project. The powder coating process heats the parts to 350-400 F or so for 20-30 mins to melt the coating. There are no rubber parts in the swing arm U-joints and they are lubricated by the gear oil. So, I don’t expect any issues with this approach. To remove the drive shaft from the swing arm is not straight forward due to the high torque on the nut and the interference fit between the shaft and the coupling to the rear drive unit. That’s why I decided to keep the shaft inside the swing arm and protect the U-joints from the powder coat material.
I’ll get to find out if there is any problem when I get the bike on the road (it’s still sitting waiting for me to finish the new paint job), but I don’t expect any difficulties.
Best.
Brook.
Thank you for this tip. I was close to remove the shaft as I am also powder coating after removing bearings.
I was also thinking about powder coating the engine but I am worried about it might melt anything… even removing the electrical parts such the alternator, diode board etc.
What do you think about this last matter?
Thank you for all the help I get from your site for my 1976 R100 S.
Hi Francisco,
If you powder coat the engine, you have to completely strip it down and remove everything including the crankshaft and main bearings. That is not “routine” work and requires very precise measurements to install new main bearings and shim them.
The other issue with powder coat is to keep it from getting inside the engine block and potentially blocking oil passages and galleys. Should that happen, you destroy the motor.
Powder coat melts around 400-450 F. I suspect the engine block never gets that hot so likely the powder coat won’t melt.
That said, I personally wouldn’t powder coast an engine block. I might paint it (frequently, I’ve seen custom airheads with all black engine blocks) as there is less chance of getting paint where you don’t want it than powder coat. And it’s easy to touch up paint when it gets nicked from gravel. You can’t add powder coat to a nick to repair it
Best.
Brook.
Thanks for the response and the SUPERB write up of your project. You’ve done a fantastic job compiling all the information out there for these bikes. I’m tearing apart my /5 as we speak and I’ve enjoyed following your progress.
cheers,
S
Thanks for taking the time to document how you did this. I’ve got my /5 blown apart an was trying to remove the bearings to powder coat the swing arm as well. The clymer manual is very vague on this process. I also decided to leave drive shaft in. Waiting for the puller to come from cycle works. Probably would have gave up on this part if I didn’t come across this. Thanks again.
Hi Chris,
You’re welcome and I’m pleased my work is helping you complete yours. It’s great to hear about another airhead getting ready to go back on the road.
Best.
Brook Reams.
Hey breams. How if at all did you remove the frame Id plate on frame. The one on the front of the neck.
Hi Chris,
I didn’t remove it, but I should have. I covered it with a layer of duct tape, but the bead blasting dulled the black paint on the plate.
To remove it, you remove the steering stem. I believe you can use large screw driver and push the end of the rivet out from inside the steering stem tub. Then you can grab the head with channel lock pliers and pull them out. If that doesn’t work, try grinding the ends off inside the steering stem with a Dremel tool and a grinding stone bit. New rivets are available from BMW and from Hucky’s (http://www.bmwhucky.com/).
Hope that helps.
Best.
Brook.
Great write up.
Thanks for sharing it.
Cheers
Chris
Hi Chris,
Thank you and thanks for stopping by.
Best.
Brook.
Hi there,
on my R100/7 (1977) is rear wheel off the center around 10mm against sub frame center to the left. Any idea how to adjust, or its just factory setting? Thanks for any help.
Hi Filip,
The rear wheel is located off-center in the frame on purpose. However, the swing arm mounts in roller bearings and it should be centered in the frame as I show in this write-up. If the swing arm is not centered, it will put a lot of stress on the drive shaft u-joints causing them to fail eventually.
–> http://brook.reams.me/bmw-motorcyle-rebuilds/1973-bmw-r755-rebuild-project/33-bmw-r755-install-swing-arm-and-rear-drive/
I hope this helps.
Best.
Brook.
Hello Brook,
Let me just start with a big thank you for your fabulous blog. I’m refurbishing my first motorcycle, a 75 R90/6 and your blog has been amazingly helpful.
I have finally gotten the frame free and intend to powder coat it and the swingarm.
My question: Since I intend to replace the races in the frame and the swingarm, it seems more logical to leave them in for the powder coating process and then remove and replace them after. Thereby, not exposing the new races to the powder coating temperatures and blasting. Does this logic match your experience?
Hi Mike,
Sure, that makes sense to me. That said, you should tell them to plug the hole the bearings go in anyway. Either way should be fine. Either approach avoids having the outer race exposed to 400-425 F temperatures, although I don’t think that would hurt the outer race.
Best.
Brook.
I have a 74 R90/6. I haven’t ridden for a couple yrs. i started having carb problems (ethynol) took carbs off & to a cycle shop, had them totally cleaned & reworked…left carb NEVER worked again. Could hand choke it & wouldbegin to RUN…til that gas burned out, then it would backfire through the carb, BLOWING the carb OFF MACHINE. Made a gas tank out of plastic tool box, cut holes for fumes to draw out, made holes for inlets. bike hasn’t run for more than 2 yrs, mthen only one carb. Had to crank and crank, but it started and ran “pretty good on one carb. Well, got it hooked up to burn fumes, cranked it maybe TWO turns, & it FIRED RIGHT UP, but was idling at 5000 rpm. adjusted carb idle to 750, & rivedit, & rive it, & RIVED it. Turned to 10,000, idled it then rived it five times QUICK. Response was TERRIFIC…BUT…when gas is disturbed it gets COLD. So I
had run a i/16” exhaust pipe through intake pipes, coiled ionside at the bottom (in the gas) on fifth rive;;;BLEW the top off the tank & FIRE, WOW!. ruined a new tire, melted fender,lights and light bar, ruined new battery (I use a large car battery in one of the saddlebags).I was extremely impressed with how EASYILY it started & response, ,but next time will leave out the hot line. I lack about 200 miles having 300,000 on the bike. I need to replace u-joint boot, swing arm bearings, etc…HOW do I take swing off of frame? I have been in to the rear before (changed gear rati then back again) BUT…I need some one with experience to throw rocks at me & get my attention…other words, I need some one to point thingws out to me…Help?
Hi George,
You will find the procedure to remove the swing arm, and other disassembly procedures, in this documentation.
http://brook.reams.me/bmw-motorcyle-rebuilds/1973-bmw-r755-rebuild-project/02-bmw-r755-general-tear-down/
I hope that helps.
As to the rest of your post, I don’t know what to say, except the problem started after someone rebuilt your carburetors. In my humble opinion, they made a mistake somewhere and the mistake should found and addressed rather than attempting the dangerous work around’s you have tried.
Best.
Brook.
Hi,
I purchased a swing arm off of Ebay to use in a motorcycle that I am building. The swingarm looks like the one in your articles. I find that when I grab hold of the end of the driveshaft that I can easily pull it out of the driveshaft housing/swingarm. When I reinsert it and jiggle it a bit it will engage the splines inside and I can turn the wheel buy turning the driveshaft which seems normal to me. My question is……is it normal to be able to pull the driveshaft out like that? Thank you for your help.
Hi M. Rice,
None of the ones I have worked on would allow the drive shaft to come out of the swing arm without removing the rear drive coupling first.
Best.
Brook.
Brook,
It has been said many times already, but your documentation is immensely valuable!
I was gifted a crashed ’78 R100/7 (bent frame and forks) and an ’80 frame and forks for the same that I am in the process of rebuilding.
In following your posts, I have a question about greases. You refer to Honda Moly 60 paste (replaced by 77?) which seems to be no longer produced. I do see on Euro MotoElectrics a spline lube paste and presume it is a suitable substitute.
I have also seen referenced both “bearing grease” and “Red LP-2”. Are there other greases I need to be aware of? Can you share where each is to be used?
As I am down the road in Englewood I hope to make it to one of the gatherings this summer.
Troy
Hi Troy,
I have no experience with Euro MotoElectric’s spline lube paste, so I can’t advise you on that. The Honda Moly Paste 77 is the substitute the currently practicing airhead mechanics advise us to use.
For the work on the swing arm bearings, I use Red LP-2 to pack the bearings. I also use it for the wheel bearings and the steering head bearings. Those are the only sets that require this grease. The transmission bearings are lubricated with gear lube while the engine bearings are lubricated with engine oil.
BTW, I often use “bearing grease” to refer to generic wheel bearing grease. My tub of it was acquired in 1980 and it’s not empty yet. 🙂
We hope to see you at an upcoming Colorado Airheads Beemer Club (CO-ABC) event. If you haven’t joined out web site, you can do so here:
–> https://downtomeet.com/ColoradoAirheadsBeemerClub
Best.
Brook.
Thanks for the great write up Brook. Without it, I could not have figured out this little gem of a jig on my own. I had it figured out except for using the 5/8 bolt and lock nut as a spreader for the 6 screws. Ingenious.
The old girl won’t be all that pretty when I’m done, but she’ll run and ride like new.
John
Hi John,
The tool from Cycle Works should come with the instructions, but I guess Dan forgot to put them into the bag before he shipped it to you. Send him an Email and let him know so he can send you the instruction sheet.
It is a very clever design. 🙂
Best.
Brook.
How can I get one of your soup can socks?
Hi Partick,
Easy. Have a bowl of soup. 🙂
Best.
Brook.
Of course you are right… I forgot to think about the engine seals, they´d melt…
I saw other sort of paints like DupliColor Engine Enamel and even some wrinkle finish but they do need to be baked later at around 90ºC. Since engine has not wires installed now I thought about using a heater gun as not a large surface needs to be painted now. Not sure is this “baking” is enough though…
What method and materials would you suggest for the engine painting? Any special primer?
Many thanks for your tips and for your webpage again, I would never dare to get into these mechanics without your instructions.
Engine seals can be removed easily of course, the problem would removing bearings and crankshaft for a newbie…
Hi Francisco,
I’ve used brake caliper paint which is heat resistant for the valve covers. If it was applied to the engine block, when you run the engine, the heat from it will bake the caliper paint and help harden it, so you would not need to try to heat it externally.
Best of luck on your project.
Best.
Brook.