[HenryNorfolk]

Checking/adjusting the wheel alignment on my recently acquired CB350K2. With the rear axle positioned so the aligning marks on the swingarm are same each side, the front wheel is off to the right by @ 17mm (11/16"). I noticed the front tyre is closer to the left fork by @ 4.5mm (3/16"), so the front wheel should actually be a little further to the right! Which means that when I get the front wheel properly centred between the forks, the alignment is going to be out by about 21.5mm ie. nearly 7/8"!

Okay, I need to get the front wheel adjusted. (The PO said he'd rebuilt the wheels himself, and 'it was quite easy'. Hah.) Before I worry about the frame's straightness .... A couple of questions:

Can the alignment marks on the swingarm (rear fork) be relied upon for accuracy (assuming the frame and swingarm are straight)?

How do I go about checking whether the rear wheel's rim is running true on its hub? (Is that measurement called 'dish'?)

 

[mike in idaho]

It's called wheel offset, sounds like he got things off a bit. I wouldn't trust alignment marks to be perfect, line up the wheels with a straight edge or a tight string, then see if the marks agree.

 

[HenryNorfolk]

Thanks Mike. I've always wondered if those marks on the swing arm can be perfectly accurate. I prefer to check by eye or straight edge. Do you know how I check the rear wheel's offset?

 

[Boomer343]

It is almost impossible to get the offset wrong if using the OE spokes. I have rebuilt at least 20 of these wheels and never had issues or checked offset.
When I do Triumph or Norton wheels then I do have an offset spec but even then it almost falls into place by itself.
I have seen axles spacers put in the wrong location.
I have used a laser to align the rear sprocket with the drive sprocket but have also used a gas welding rod and locking pliers to align the parts. Usually an eyeball and spin is all it takes. Forget the marks on the swingarm, too many variables.

 

[Honda John]

Checking/adjusting the wheel alignment on my recently acquired CB350K2. With the rear axle positioned so the aligning marks on the swingarm are same each side, the front wheel is off to the right by @ 17mm (11/16"). I noticed the front tyre is closer to the left fork by @ 4.5mm (3/16"), so the front wheel should actually be a little further to the right! Which means that when I get the front wheel properly centred between the forks, the alignment is going to be out by about 21.5mm ie. nearly 7/8"!

Okay, I need to get the front wheel adjusted. (The PO said he'd rebuilt the wheels himself, and 'it was quite easy'. Hah.) Before I worry about the frame's straightness .... A couple of questions:

Can the alignment marks on the swingarm (rear fork) be relied upon for accuracy (assuming the frame and swingarm are straight)?

How do I go about checking whether the rear wheel's rim is running true on its hub? (Is that measurement called 'dish'?)

Hello, the short answer as to accuracy of swingarm alignment marks is they are often as much as a full mark out of alignment. That causes a lateral stress to forks, frame, swingarm and everything in between. That stress is "stored" in forks, frame ect. The rear wheel is not properly aligned and tries to track to the right usually, from forward pull of left side drive chain. The more wear in components like swingarm bushings/bearings, wheel bearings, fork assemblies, the more mis-alignment, which makes the bike want to wobble or weave, not track in a straight line, especially when chassis stress builds and releases on bumps in a turn. The wheel mis- alignment causes instability, due to stress stored in chassis components.
This motorcycle alignment tool was purchased by me many years ago (1980?) and I have aligned many bikes. Very few have accurate alignment marks. After alignment I stamp new marks to swingarm or chain adjuster. I don't know if the Henter tool is still available, but it makes a noticeable improvement to bike stability, and if you let go of handlebars bike goes straight. Good Luck HJ

 

[HenryNorfolk]

Thanks for the advice guys. The front wheel offset bothers me a bit so I'll just double check that it's not an axle spacer in the wrong place before I get the offset corrected. I'll ignore the marks on the swingarm and set the wheel alignment by eye and straight edge.

 

[Emil1957]

Do you have the original fork and fork bridge installed? Or could it be from a CB250B4 or CB350B4 model?

 

[mike in idaho]

Measure from the spoke flange of the hub to the fork leg on either side, that will tell you if the hub is centered in the forks.

 

[HenryNorfolk]

Measure from the spoke flange of the hub to the fork leg on either side, that will tell you if the hub is centered in the forks.

Good idea Mike. Thanks.

 

[fxray]

Henry,
After you get your centerstand working properly, set the bike up with the back wheel off the ground. Grab the back of the wheel and see how far it moves from side to side. There is a good chance that the swingarm bushings are shot, and you will find significant left/right motion that shouldn't be there. A little play there will be magnified when it is projected to the front wheel. That would affect your alignment check.

Also, if your bike has stock tires, the rear tire (3.50x18) will be wider than the front (3.00x18), and that width difference must be taken into account when you check alignment. Here is a diagram to show this. The difference here is more exaggerated than on your bike, but the principle is the same:

If you have a decent pair of calipers, you can measure the actual width of your front and rear tires. Subtract the difference and divide by two. That should equal how far away your string or straightedge is from each side of the front tire during your alignment check.

You asked earlier about checking trueness of your wheels. Another term for that is runout. Here is a diagram showing how a dial indicator is used to check lateral and vertical runout. The chart of specs is for a 350 Honda:



This isn't a Honda wheel, but the principle is the same. This picture shows vertical (radial) runout using a Harbor Freight wheel balancer stand and a dial indicator.

 

[HenryNorfolk]

Thanks for that fxray. I gave the r/wheel a waggle before the centre stand mount broke, and there was no discernable play, so I'm pretty sure the PO replaced the swingarm bushes.

Thanks for those nice illustrations. The runout tolerance data is useful thanks. Yes, I do compensate for the difference in tyre width when checking alignment. I checked/adjusted it by eye, ignoring the marks on the swingarm. Offset, as Mike pointed out, is the name for the amount that the rim is off to one side or the other from the centre of the hub, and I checked the front wheel again and the rim/tyre is approx. 4.5mm (3/16") closer to one fork. The spoke flanges of the hub are equidistant from each leg, so it's not an axle spacer problem. The spokes will need adjusting to get rid of the offset and bring the rim back to the centre. I took the bike out for a ride along the coast road. It steers okay 'no hands' but I think I can feel I'm compensating for a very slight pull to one side. When front wheel offset is corrected it should be pretty good. I'd still like to know how to check rear wheel offset, as I don't know if the swingarm is symmetrical like the front forks, so it's hard to know how to measure it.

 

[HenryNorfolk]

Do you have the original fork and fork bridge installed? Or could it be from a CB250B4 or CB350B4 model?

Good question. I think they are original, but I'm not sure how to identify the difference. I'm not familiar with the B4 models.

 

[fxray]

Measure from the spoke flange of the hub to the fork leg on either side, that will tell you if the hub is centered in the forks.

Yes, that will tell you if the hub is centered in the forks. Then measure from the wheel rim to the fork leg on either side. If the hub is centered, but the rim is offset, then the spokes need to be adjusted. If the PO got the offset wrong, he may have trimmed the ends of the spokes where they protrude through the rim, and they may be short when you correct them. More than likely you will be OK. A rule to remember is that you must first loosen spokes before you tighten other spokes to move the rim.

 

[Flycast47]

This could also be helpful Chain Alignment Tool - Motion Pro

 

[HenryNorfolk]

Yes, that will tell you if the hub is centered in the forks. Then measure from the wheel rim to the fork leg on either side. If the hub is centered, but the rim is offset, then the spokes need to be adjusted. If the PO got the offset wrong, he may have trimmed the ends of the spokes where they protrude through the rim, and they may be short when you correct them. More than likely you will be OK. A rule to remember is that you must first loosen spokes before you tighten other spokes to move the rim.

Yes, I was thinking that the tyre needs to come off so that when the rim's offset is corrected spoke length can be checked. I've never attempted wheel building but I might have a go myself if the guy I used to go to isn,t available.

 

[HenryNorfolk]

This could also be helpful Chain Alignment Tool - Motion Pro

Thanks. That looks useful.

 

[vintrace1300]

Thanks for the advice guys. The front wheel offset bothers me a bit so I'll just double check that it's not an axle spacer in the wrong place before I get the offset corrected. I'll ignore the marks on the swingarm and set the wheel alignment by eye and straight edge.

All are correct, that the marks on the swingarm are frequently inaccurate. Actually, I've found more often than not, based on an accurate measurement from the swing arm pivot centerline to the rear axle centerline. Make sure the front axle is installed properly, end-for-end. The nut needs to locate the wheel asssembly while the "dummy" side of the axle sort of "floats" to a position the forks like, in order to not bind through their travel.

 

[HenryNorfolk]

Thanks vintrace1300. You're right, in that the marks on the swingarm are to be ignored. They're not correct on either of my Honda twins.

I'll take your advice and slacken the front axle pinch bolts and work the suspension a little to see if the axle moves and settles in another position. I'll re-measure the position of the rim/tyre between the forks before deciding on offset adjustment. I'll be pulling the front end apart soon. I have noticed that there's a little sticktion in the fork action. There's oil leaking from the r/h fork seal, and I want to look at the front brake's linings as it is not working well.