Topic: Aligning rear wheel

[eurban]

In theory, should the rear wheel of my bike (78Cb750K) be on the same centerline as the front wheel or a parallel one?  Intuition would strongly have me believe the it should be on the same centerline but I figured I would ask here. . . . .  I am planning on checking my rear wheel alignment (to see if can I trust the factory marks on the swing arm/chrome brackets) using a "reality" type method with two straight edges each just contacting two points on a rear wheel side.  The straight edges will be long enough to reach the front of the front wheel.  I will probably use two long flourescent light tubes (light weight, rigid and straight - ----recommended in a article that I read in a chopper rag).   Assuming that the centerlines are the same, when the rear wheel is aligned with the front (front wheel straight ahead), the distances from the straight edge to front tire rear and the front tire front should all be equal on both sides.  The main reason for my initial question is that a rudimentary check using less than perfect edges yielded what appears to be an offset centerline.  Thoughts?  Thanks.

[Gibson]

Everything i've ever seen tracked the same lighn.

[amattel]

Here's a comment by HondaMan

Yeah, I'm a fan of the "voluptuous look" of the early 750. It has those lines....I still have the stock pipes, too, because the K4 and earlier ones provided the best ground clearance on those dragging corners. And, the Rockies are full of my scratch marks!

The K0 frames are to die for, especially if you can get the front wheel hub with it. They were better steel, thicker walled (.05mm thicker) and they did not wobble at 140+MPH on wide, sweeping turns.

Check your wheel alignment like this:
1. prop the bike upright (not on centerstand), as vertical as possible - or, get a friend....
2. Adjust the rear wheel so that the marks on both sides are dead equal (the marks are good on these swingarms).
3. Tie 2 strings onto the rear wheel. Rotate it until they are as high to the rear as you can get it, while pulling the strings to the front wheel, without hitting something underneath. You are going to measure the parallellism of front against rear wheels.
4. I use 2 wooden blocks for this part: set the strings on each side of the rear tire so they touch the tire on the front sides, then anchor them to the wooden block (nails?).
5. Set the front wheel straight. You'll probably find that the wheel is offset to one side. So, measure how much, then start adjusting spokes. TAKE YOUR TIME. You'll find it to be either 3mm off or 5mm off center, if someone else hasn't already tried this.

The wobble is caused by the front and rear wheels being parallel, not in line. When you're done, you may notice the odd-looking difference of wheel spacing between the front fork tubes. Remember that "look", then look for it when you see your next K0 model...it's a secret...but it's out in plain sight!

He is refferring to alignment issues wiht K2 bikes... not sure if they apply to your model.  IF they are parrallel rather than in-line, there can be head-shake issues and he also talks about wiping out in high speed corners because of it... He has said that if you can get it to within 1/8 in. that you are in good shape...

Adam

[byidesign]

If it is possble to stop at a junkyard for a piece of steel flat stock, of maybe1x1 angle iron,
      the light bulbs would work, but if one breaks you don't want to breathe the mercury,
   or risk glass in your eyes.

[eurban]

I will hopefully find time over the weekend to pursue this matter a bit more. . . . .Hondaman's post is interesting but I am (at least yet) not sure that I like the idea of shifting the front rim's centerline to correct an offset.  I will confirm that the front rim is actually centered over the front hub and also properly centered in the front forks and I don't think that i will go beyond that up front.  As to the rear, I guess I will also check to see how the rim centers over the rear hubs centerline (I assume that it should) and then using the straight edges or string lines etc adjust the rear wheel so that it is either on the same centerline as the front wheel or on a parrallel one.  If there is an offset then I will scratch my head a bit more and try to figure out if something is amiss.  If I was going to "customize" I might try altering the rear wheel spacers to shift the rear wheel into center.  Chain alignment would have to be kept in mind though.  Any more thoughts?

[CB750F2]

G/Day. I recently checked the wheel alignment on my 78 F2 using a string line across each side of the rear whell and pulled tight to the front of the front wheel and held in place by a couple of heavy weights. I then adjusted the rear wheel to track in line with the front. Once the wheels were in line and the chain tensioned correctly I marked the rear adjustment scales for later reference. I hope this helps. Pat from Australia.l

[dusterdude]

eric,i just make sure the wheel tracks in a straight line with the chain.seems to do ok for me.

[amattel]

G/Day. I recently checked the wheel alignment on my 78 F2 using a string line across each side of the rear whell and pulled tight to the front of the front wheel and held in place by a couple of heavy weights. I then adjusted the rear wheel to track in line with the front. Once the wheels were in line and the chain tensioned correctly I marked the rear adjustment scales for later reference. I hope this helps. Pat from Australia.l

This is what I have done so far with my 750k2.  The issue is about how much this moves the chain out of alignment with the front sprocket.  I am also considering adjusting the spacers on the rear wheel...  The first step, which I haven't gotten to yet, is to precisely measure the parallel offset between between front and rear when rear is aligned to tick marks on swingarm.

I am not a full-on racer type of guy so it is not as critical for me as it may be for others.

Adam

[bryanj]

Get your wheels in line using a straight edge, you may find that the marks on each side are not the same but moving the same number each side is ok. Assuming all spacers are standard the chain will not be enough out of line to make any difference. Having PDI'd too many Hondas to think about this is the recommended way

[eurban]

Thanks for the replys so far.  I found some time today to investigate a bit further.  Btw my vehicle is a 78 750k with a gl1000 front end. The bike is on a lift and I adjusted it to be standing straight (vertically plumb) up by referencing off the centerline of the swingarm bolt.  The front wheel rim is indeed centered over its hub.  However the entire wheel is about 1/6th " closer to the left fork leg than the right.  This would equate to 1/32" off center assuming properly straight forks and triple tree setup.  This seems to be pretty much how honda built it since the rotors line up perfectly centered in the slot in the carriers.   The rear wheel rim also seems to be properly centered over the rear hub.  However the entire assembly is about 1/4" closer to the right side of the swingarm than the left which would equate to 1/8 " off center.  I used measuring reference points that lined up (along a vertical line going up from the axel) as close as possible to the pivot point for rear alignment (the axel)  to minmize any effects caused by the wheel being out  of alignment.  For some of these measurements I had to use a level.  I also measured a bit farther forward from the edges of the rear wheel to the shafts of the rear shocks and again found that the wheel was about 1/4 closer to the rt side than the left.  To check the alignment marks on the swing arm I dropped a plumb line down from the center of the steering stem tube and marked a piece wood. I then drew another mark 1/8" to the rt  which should be the actual centerline for the rear wheel since it is shifted to the rt 1/8"  Running two striaight edges off the rear wheel I found that the pointers are off by about 1/4" from center . . . . . .I would certainly like maximize the handling of my bike so making some adjustments would seem to be in order.  As best as I can tell the alignment marks are not to be trusted.   Using  the straight edge method across the front wheel does not take into effect the offsets of each respective wheel and would seem to result in a rear wheel that is not pointing straight forward.  I don't think that this would be the ideal setup for handling. If I point the rear wheel directly at the1/8th  corrected plumb bob mark then I should have a rear wheel that points staight forward but is offset from the front wheels centerline by 3/32"   Without any mods, this would seem to be the best option.  I would be curious to see what measurements others would come up with for the "centerness" of the rear wheel.  The easiest measurement to make is the distance (holding the tape level) from the wheel or rim to the shock shaft. To the best of my knowledge all my rear wheel parts are stock true and installed correctly.  Since I have a bunch of spare parts I might try shortening the left side spacer and then add a washer to the rt side.  Any additional thoughts and or measurement results would be greatly appreciated.

[mwvachon]

After reading everything posted here, I do have one observation. It seems that the priority is the rear wheel. It must first be correctly set in relation to it's hub via spoke adjustment. Just about every rear wheel I've worked on had the rim centered to it's hub. You certainly wouldn't want to intrude into the chain space and there doesn't seem to be much sense in pushing the rim further off the opposite direction. Next, the rear wheel needs to be 'square' to the bike itself. This can be accomplished a number of ways (as documented in this thread).

Once that is accomplished, you can then begin to assess how the front wheel sits in relation to the center line indicated by the center of the rear wheel. As stated earlier, this is mostly accomplished via spoke adjustment. Also insure correct spacers are used and positioned properly. Some of the copied quotes that exist in this thread were also responses to an earlier posting I entered on frame questions and a wobble I noted. Some time ago, I had trued the front rim on my K1 750, but didn't even consider where the rim should have set in relation to it's hub - I just centered it! Then came the wobbles! They only happened if I tried to ride 'hands-off', but disconcerting at any rate.

Another point - I'm surprised no one has mentioned the use of laser pointers. Straight edges and string are all fine-n-dandy, but when I reassemble the K1, I plan to try using a laser to 'dial in' my wheel alignments. Thoughts?

[HondaMan]

Wow. I think I started an agrument. 

Here's one tried-and ture method we used in the shops where I worked: tape-and-paint a straight line on the floor, longer than the bike. Move the bike up next to it. On the CB750, measure from the middle of the engine, between the center carbs (this is the COG horizontally on this engine) over to your Line. Pick a point on the rear to call your "reference", like maybe the center rib of the tire. Measure that distance to the Line. This gives you a straight line through the bike, true or not, from which to reference everything else.

Now, measure the other things, like front sprocket, rear sprocket, front wheel, to the Line. Use plumb lines for the vertical drops to the floor, then measure from there to the Line. Then get down to subtracting the differences from the imaginary line through the bike and the errors will show right up.

This method removes all guesswork and turns it into calculator fodder.

[eurban]

Hey Hondaman-

At this point I am pretty sure that I have measured the errors in my bike.  Rear wheel is set to the right from the centerpoint of the swing arm,the shocks and  the frame rails)  by about 1/8" and the front is shifted to the left (from the centerpoint between the forks) by about 1/16" (a bit more than I posted earlier)  As best as I can tell all parts are good and straight and installed correctly.  Rear alignment marks appear to by off.  So the question is what (if anything) do about the offsets?  Thanks

[dusterdude]

eric,funny you mention your rear tire being offset to the right a bit,mine is offset to the left a bit.kinda makes you wonder.

[mwvachon]

Eruban -

I don't have my 750 assembled yet, so I've got nothing close to that to reference the offsets you observed. I do like Hondaman's low-tech approach to getting the alignment measurements, though. At this point, it seems the only option you'll have is to tweak your spokes to shift the center of each rim in the direction you feel it needs to go. A word of caution here - adjusting the spokes also effects the distance from the hub to the rim (called run-out). If you want to insure your rims stay true and you don't alter the run-out, you can use an inexpensive and 'on-the-bike' method for doing so. All you need is some medium sized solder. Pull a length out long enough to wrap around the swing arm and have the other end point at the outside edge of the rim. Use a second length to do the same on the other side of the rim and point this part onto the inside edge of the rim (either side of the spoke rib). You need to be able to rotate the wheel freely and see where the contact point variations may be. (see my VERY lame drawing). Also be sure not to over tighten the spokes. They should be just tight enough to give you a clean 'ding' note when you tap on them. I'm too cheap to invest in one of those spoke torque thing-a-ma-jingies... You need to take your time and go slow. Depending on how picky you want to be, the process will take several hours.

[8 Track]

Wow, guess it's out to the garage again!  I figured my mild (sometimes nonexistant) head shake was from wrong/ worn out tires.  I know my wheels aren't true; I've seen them wave to me when the bike's on the centerstand, but not so bad it affects my smooth ride.  Now I've resisted asking this question for a year now, hoping I could find a post somewhere for the answer, but guess what?  Can't find it, so here it goes...  My bike pulls barely slightly to the left riding no hands.  Is this normal?  I've done the string test two times to 1/64" (did a sprocket change) and the pull wasn't affected.  I've also fiddled with the front forks, since I raised the front end back to stock.  It was lowered by P.O.  I've even thrown the back tire out of alignment and no dramatic effects.  I think I'm still on the subject here, since it's an alignment issue.  Well, thanks again for an excuse to get out in the garage!  (My wife is getting a little fed up!)

[KB02]

Another point - I'm surprised no one has mentioned the use of laser pointers. Straight edges and string are all fine-n-dandy, but when I reassemble the K1, I plan to try using a laser to 'dial in' my wheel alignments. Thoughts?

When I reasembled my 750, I was so excited that I just had to take it out for a ride. I notiucer the handle wasn't any where near as good as a I expected it to be. A little checking, about 20 more PSI in each tire (Oops), and the handling was better but not much. Then I alligned my tires.

I went to Home Depot and bought one those cheap, little lazer levelers and used that for alignment purposes. I did everything using the lazer and my right eye, so I know it's not perfect, but it's darn close and one heck of a lot better than it was before

[HondaMan]

Hey Hondaman-

At this point I am pretty sure that I have measured the errors in my bike.  Rear wheel is set to the right from the centerpoint of the swing arm,the shocks and  the frame rails)  by about 1/8" and the front is shifted to the left (from the centerpoint between the forks) by about 1/16" (a bit more than I posted earlier)  As best as I can tell all parts are good and straight and installed correctly.  Rear alignment marks appear to by off.  So the question is what (if anything) do about the offsets?  Thanks

Sorry to be gone so long: been tied up rebuilding 3 broken Fords - all broke at once.   

Since you've changed the front end, you may have to chase the alignment issues with spacers, at least at first. This makes it harder to set up the front brake, though, if you change the front spacers. I'd start with the rear, making it true to the COG centerline of the engine, for balance reasons. Then, check the chain alignment issue. Then, go after the front wheel. Make sure it's vertical, then adjust for left-right. I prefer to move rims by realigning spokes instead of spacers, simply because it causes less "other" problems.