Topic: CB400F Rear Wheel Bearing Retainer Ring & Bearings

[RichM]

I saw similar threads posted but not exactly the same. I just bought a "new" very clean '75 400F. It had been previously worked over with thorough cleaning and, I'm certain, replacement of several parts. After a ride today, I noticed after letting off the gas and then getting back on it, the bike would "skew" to the side a bit. When I returned home, I decided to tighten the loose chain. That's when I saw that the rear wheel bearing retainer was totally unscrewed from the hub (with the attendant metal shreds). I removed the axle and then noticed that the left wheel bearing had a larger inner diameter than the right bearing and it didn't engage the axle. The bearing retainer is toast, but my real worry is that the surface threads in the hub are worn badly on the outside. The left bearing must be replaced, but without having a full size tap, could I likely clean the threads with a small tap with the same threads/mm and just run over the inner hub? Is there a better and maybe faster way to do this? Thank you in advance for any and all help!

[Terry in Australia]

You could try to clean up the threads with a thread file (from an engineering supply) but if they're buggered, you'll need a new hub.

I imagine (but don't know for sure) that using some sealant between the threads and then staking the retainer would stop it from coming loose, and as it has no side load on it anyway (the axle spacer holds the bearing in place) this wouldn't be a safety issue.

More than likely a PO has removed the retainer ring without drilling out the punch marks where it was staked at the factory first, and has mangled the threads. Best of luck! Cheers, Terry.
 

[RichM]

Something to think about Terry. Thanks!

[70CB750]

If you have a  tap with the same pitch, you can use it to clean and repair the thread. It works well in aluminum, basically you run the tap like a comb alongside the thread.

[RichM]

I'm going to try that now. This seems like an obvious question, but are both real wheel bearings supposed to have the same inside diameter or is there supposed to be a sleeve that fits inside the left bearing?

[RichM]

The "combing" of a tap worked great! I also, then, made a tool to screw the ring fully back into the hub. Thanks for the suggestions!
Now, should the INNER diameter of the left side bearing be larger than the right side hub bearing? This bearing race engages nothing and allows the bike to shift when going from gas off to gas on. The 4into1.com bearing description states that the inner diameter is not the same for the two bearings. How can that be if there is not a sleeve to engage the axle?

[Terry in Australia]

G'Day Mate, sorry I can't help, I've never owned a CB400F. I had a 350F 18 years ago and the rear wheel was probably the same, but I don't remember any oddities relating to the wheel bearings.

I'm sure someone will be along soon though, can you amend your title to specify that it's a 400? That might attract some experts. Cheers, Terry.