The Long Haul Part 4: The Rear End
Texas to Ohio to Minnesota and Back Again on a 1974 Honda CB450
Step 1: Pull the Wheel
We know it's all too easy, and tempting, to go haul ass on an old bike the minute it fires up. It's a magic moment and all you want is to hop on and ride, we get it, but cool your jets. Once your suspension, tires, drivetrain, and brakes are in good shape you'll be up and going faster, smoother, safer, and most importantly, further.
It doesn't matter if you start with the front, back, or both ends at once. We flipped a coin and started with the back end, in which the first step is getting the rear wheel off the bike. You'll need to disconnect everything attachd to the hub, including the sprocket and drum brake before you can pop the wheel off.
The chain can simply be broken at the master link, assuming you have one. If for some reason you don't, you'll need a chain breaker to drive a pin out. The chain can be pulled out from under the chain cover, and the new chain can be threaded back on if you connect the new one to the old one. However, you'll need to remove the chain cover to replace the front sprocket and rebuild the clutch lifter mechanism - two procedures we highly recommend. Use the length of the old chain to determine the length of your new one before ordering it, and bear in mind if you change sprocket sizes this will effect the required chain length. If you want tips on sizing your chain watch our video on How to Count Links on Your Motorcycle Chain.
Removing the drum brake is fairly easy, disconnect the bolt at the stopper arm and also the threaded fitting on the pull-rod. Chances are you'll need to remove the chain cover, unless you've got the bike configured is such a way that the wheel can fall downwards once the axle is removed. Finally, the wheel can be removed once the axle is pulled out from the left side. To do this, you'll have to pull the cotter pin from the archer slot in the castle nut to the right. Crack that big nut loose and remove it. From there you can tap out the axle and the wheel is free. If you're thinking of replacing your shock absorbers this is the time to do that. If they're factory originals and are super squishy you might enjoy a fresh spring-damper assembly.
Give the rear of the bike wipe down, and now we're ready to replace the front sprocket. To do this, remove the two hex bolts in the retaining ring and bingo, the old sprocket's free! It may help to shift you bike into gear so you can get down on those hex bolts. Also it might not be a bad idea to drip some loctite on those bolts upon reinstallation for piece of mind.
Section 2: Love the Wheel
With the rear wheel off there is a number of things to address. If your bike has seen many many miles, inspect the wheel bearings. If they're crunchy or loose with excessive play or are hanging up in certain spots this is the time to swap them out. Ours are still spinning smooth so we left them in there for now. Otherwise, these are the 3 key things to do to: install a fresh rubber, a new sprocket, and rebuild the brakes.
Chances are the tire that came on your bike is as hard and cracked as the one that was on our long haul bike. Not only does rubber naturally dry out over time, but water and gunk builds up inside the rim producing rust. If you've come this far, do it right and just change your tire. Even if a previous owner did it, you'll probably need to again soon anyway. While we don't currently have an in depth tire-changing video, we do have a video on fixing a flat tire on the side of the road. A bead-popper and tire-tamer makes the process easier, but aren't absolutely necessary. In addition to the tire itself, the parts and tools you will need to get this done are as follows:
Next we swapped out the rear sprocket. This requires removing a large external snap ring that is too large for any of the snap ring pliers we had in our shop. If you don't have them either, some patience, persistence, and a flathead screwdriver or two should get that thing loose. The sprocket connects to four studs with some flange nuts. Do not lose track of these studs! Many people do and think they're easily replaceable - they're not. Different bikes use different configurations to mount the rear sprocket, but this is how the 450 did it. And though it pains me to utter these words, "installation is opposite of disassembly."
Thirdly and arguably the most important part of this article is rebuilding the rear drum brake. Compared to hydraulic systems I find the mechanical drum brakes refreshingly simple. Once the brake panel assembly is pulled from the drum/hub we've got a video to show you how to do the brake rebuild: CB450 Rear Drum Brake Rebuild Video
- CB450 Rear Drum Shoes (#1015)
Section 3: Mount the Wheel
With the rear wheel clean and back together with fresh parts, it's time to put it back on the bike. The axle (cleaned and freshly greased) goes on first through the chain tensioners, swing arm, hub, spacer, swing arm again, other chain tensioner, washer, and big castle nut. Make sure the big nut is tight and lined up with the hole in the axle so a fresh cotter pin can easily slide through.
The drum brake linkage is straightforward and simple to adjust so long as it's not dragging or excessively loose. On the flip side, it is easy to make the drum brake too tight as to lock up the rear wheel. We like to adjust rear it to where you really have to rotate your right toe down to get the brakes to start to lock up. Also, this is time to readjust the pedal height to where it is comfortable for you.
Last but not least is the new drive chain. You'll need to adjust your chain tensioners to make up for your new, un-stretched chain. Use the index marks on the swing arm to ensure both sides are at the same spot. You might be surprised how much these chains stretch over time, sometimes they can stretch futher back than the axle can travel in the swing arm slot. Your chain should put the wheel fairly far forward leaving room to adjust as the new chain stretches. The master link clicks-on with a flat-head screwdriver or pair of pliers. Best practice is to install it so the open side is facing away from the chain's direction of motion (so that a rock or other random debris is less-likely to knock it loose). Don't be surprised if you need to adjust your brake linkage anytime you change the position of your wheel.
Put some air in the tire and some chain lube on your new chain and the back half of your bike should be ready to roll (those of you who wheelie everywhere, you're now good to go). For the rest of us, stay tuned for our next inst-haul-ment of our Long Haul CB450 Project: The Front End!