Topic: Is my frame bent? Is my method flawed? Lot of pictures!!

[albertaboy]

Is this how it's done?? what do you guys thinK?  This is a 2:41 you tube vid on checking alignment.
MOT: Prepare & Pass - Wheel alignment

[Ewan 500K1]

dunnoa about all that messing with string carry on ..... flourescent light tubes do it for me as a straight edges for wheel alignment checks

[754]

Btw all levels are self checking, turn them 90 degrees to check if you set up off motor mounts or swingarm pivot use a straight rod .. You can see if your swingarm has any twist, easily with that method.

[albertaboy]

Alberta - the video is a perfect example of how to do it at home. If you did follow this method, what results did YOU have?

Did you ever determine from either bike shop, "how" your 3/4" appeared? Was it an alignment front/back or vertical racking, etc?

I'm going to try the string test if I can get time later today.
 
I did not ask enough questions at the time. It would be different today with as much wrenching, reading and interest I have today. To my disadvantage, I'm going on misunderstanding the problem and my faded memory of what I was told.   I recall shop 1, questioned the swingarm bushing and wheel spacing, but he seemed focused on the front end. He told me to go home and "just stand back and look you can see it".    But that was just that I couldn't see it so I found shop 2.  Shop 2 after much denial, eventually agreed with shop 1. and shop 2 wanted to start with the front end.  A little bit of hot headed frustration, I took the bike home and dismantled it.  I might be asking the impossible from you guys. 

If I could restart this thread maybe the better question would be:
I'm in a position of taking an untitled frame , that If I build a bike on, I risk failing an inspection.  How to I check that this frame is suitable with a reasonable amount of certainty??  Seems like the string or fluorescent tube idea, also suggested, is my best??

[albertaboy]

Btw all levels are self checking, turn them 90 degrees to check if you set up off motor mounts or swingarm pivot use a straight rod .. You can see if your swingarm has any twist, easily with that method.

Frank,
I have never looked the swingarm too closely. I'll do that too.

[754]

The pic in #28;
 Get two lighttubes..fluorescent type put one against rear wheel vertical, hold with maybe a bungey cord,
 Now block front wheel so it looks straight to frame. From behind
 NOW, FASTEN a second lighttube. Vertical to front wheel.
 THEN stand back ...have a look..and what do you see..when eyeballing the two tubes against each other

 Should take 20 minutes, nothing to do with wheel allignment, but will tell you if frame is straight..

[lucky]

Is this how it's done?? what do you guys thinK?  This is a 2:41 you tube vid on checking alignment.
MOT: Prepare & Pass - Wheel alignment

The film is ok for the back wheel as far as measuring from the swing arm pivot center to the center of the rear axle.

On the FRONT you must measure the gap at the front and rear of each side of the front tire..
IF the steering head is straight just make sure the tire is the same distance from the tire to the inside of the front forks. Use inside deviders.

[lucky]

You cannot measure the frame as shown in this photo.
That is why you must have the fixture with the cones,
That way the steering head is vertical measured by the CENTER of the axis of the steering head pivot.
Not by sheet metal stampings that were welded to the steering head neck.

[lucky]

While i am certain your response is technically correct, it's not relevant to "his" situation. We have seen the pictures of his frame, and it certainly does not have a removable cage. So, any ideas on "this" frame where the 3/4 could be IF the frame doesn't visually  show damage to it?

Everything I said IS relevent to the OP about measuring his frame.

[lucky]

You are on the right track .


Just use this modified photo and you can find out what you need to know.

Just make sure the swing arm pivot tube is the same distance from the ground on both sides AND LEVEL. Then if the front forks are level by putting a level on the side of them,  it means the steering head is NOT twisted.

On the rear swing arm if the center of the axles are the same distance from the ground and the bike is level (swing arm pivot tube being level allready) ,it means the swing arm is NOT twisted.


You are done!

Click on this photo for a larger version.

[heffay]

LOL lucky... you know there's a text option in your editor, right?   

[Kickstart]

Lucky,

What's the best way to make sure the swing arm pivot tube is level?
I assume you can't just put a level on top of it, or can you?

Thanks,
Chris

[albertaboy]

Lucky,

What's the best way to make sure the swing arm pivot tube is level?
I assume you can't just put a level on top of it, or can you?

Thanks,
Chris

Lucky, Thanks very much. I'll run these checks and yes, as Chris asks, how do you.  I dont want to assume at this point.

[Kickstart]

Measure each end of the pivot bolt to the floor. Double check with a level set up below it that the level itself is "leveled".

So mark a dot in the center of the bolt and measure from that? 

I guess you'd place a level on the floor (and level the level), then measure from the center of the swing arm bolt down to the level - making sure to shim under the center stand until the measurements were equal.... then measure the rear axle.  I suspect you also have to make sure your floor is level (or move your level to the back of the bike when you measure the rear axle.)

Alberta - if you're feeling ambitious, measure from outside left edge of rear tire to outside right edge of front tire. Then do opposite side. Each side should be equal (measure the hypotenuse of 2 rectangles). Nothing like math to verify anything.

Not sure if that will work based on Hondaman's description of the front wheel hub offset. (or maybe you would just measure one side 4mm off the tire?)

[brooze72]

If you are using the measuring from each side of the axel centre to the floor method, you have to make sure the neck is perpendicular to the floor.  I wouldn't use the centre stand

[754]

Floor may not be level, pull swingarm check shaft for level.

[Aurelia B20]

During the 70's in France, a company named Ydral sold a kit for controlling a frame, example with a 500 Four frame :




After mounting the kit you had to control if the two bars were perfectly parallel. Cheap and easy 

[albertaboy]

Lol.  Thanks everyone who stickin this out with me. That's great!!. I had an unexpected guest for two nights. We had a 12 inch dump of snow and they were stranded here.

I got out this am and did the string test.  First 4 shots of each wheel both sides just for reference of the spacing. If you see anything wrong??

[albertaboy]

Then I drew a mega long straight line on the floor and with the set up on the center stand, I carefully aligned the wheels together the best i could. Following the video posted eariler in this thread. I found the measurement almost exact. Off by 1 mm and equal at the front and back of the front tire. Again pictures look off kilter but it measures 5mm on one side and 6 mm on the other.  Pretty close? No?


dont know how this pic got tilted. sorry.


I have measured the swing arm pivot and rear axle from the floor but yet not being able to assure the floor is level, all I'll say at this time, all four points measured equal. Off by 1/16 of an inch. Later today hopefully once company is gone, I'll get back out there.

So far Im feeling good about the string test.

[754]

As you have both wheels on, i suggested the vertical tubes method, it will work regardless of level. But things could still be off side to side. The only way it could probably be bent at that point is, a straight back even pushback of front end, or a twist of the swingarm and neck, which both being equal is unlikely.

 Anyway if you try that and it checks out, it is probably ok.
 Keep in mind they were not dead straight from new, well most were not.

[Aurelia B20]

PS Aurelia - will this approach still work if I don't read French? ;-)

No problem ! 

[Magpie]

I thought I had a bent frame too so I got 2 lengths of angle iron and did this: go to page 8 of this thread and scroll down, of course you need the wheels on the bike. http://forums.sohc4.net/index.php?topic=60120.175
We also used a carpenters laser aimed from the centre point of the rear hoop towards the steering head to see how that looked.
One fellow here made a set of cones that will fit in the top and bottom of the steering head, drilled them so a piece of straight rod would fit tightly through the holes and stick up a fair way above the steering head. He then found the centre of the rear hoop and using magnets and a larger carpenter's square set the square on the hoop so the long leg of the square was pointed up. He then stepped back to see if the rod and the square were in line or if the rod pointed off to either side of the square. It told the tale of one of my frames - dammit. Cliff.

[albertaboy]

As you have both wheels on, i suggested the vertical tubes method, it will work regardless of level. But things could still be off side to side. The only way it could probably be bent at that point is, a straight back even pushback of front end, or a twist of the swingarm and neck, which both being equal is unlikely.

 Anyway if you try that and it checks out, it is probably ok.
 Keep in mind they were not dead straight from new, well most were not.

Frank,
Assume  the bike had a header at some point.  The forks and triple checked out as straight- checked by shop #2. I guess a PO could have replaced the obvious damaged parts.  I still don't see any cracked welds or tube deformity or cracks.

About the swing arm. I've now removed it and only using eyesight, it looks very very slightly twisted.  Can you describe how you would go about checking it? What is an acceptable tolerance?

I'd have to buy some tubes and get a helper as the center stand would interfere with the tubes.  I re-did the string test. I leveled the bike on the center stand, by installing the rear lower engine bolt and then the level across that.  I got the same results as I posted earlier today.  Monday I'll contact shop 1 and see if they cant pull up this bike from their records or tell me exactly their test.

[albertaboy]

You are on the right track .


Just use this modified photo and you can find out what you need to know.

Just make sure the swing arm pivot tube is the same distance from the ground on both sides AND LEVEL. Then if the front forks are level by putting a level on the side of them,  it means the steering head is NOT twisted.

On the rear swing arm if the center of the axles are the same distance from the ground and the bike is level (swing arm pivot tube being level allready) ,it means the swing arm is NOT twisted.


You are done!

Click on this photo for a larger version.

Lucky, This is good. I've come back and re read this and I think I answer my twisted swing arm question in reply 54 above.  Leveled the rear like you said. I found my pivot point was equal but the axle point was off... 1/16 to 1/18 max. Seems small to me but I know better.  754 and Lucky (or anybody) what is an acceptable tolerance?

Cliff. I think I have the material to recreate your test. Another check or two cant hurt.  Want some of my snow??? Please.
You are on the right track .


Just use this modified photo and you can find out what you need to know.

Just make sure the swing arm pivot tube is the same distance from the ground on both sides AND LEVEL. Then if the front forks are level by putting a level on the side of them,  it means the steering head is NOT twisted.

On the rear swing arm if the center of the axles are the same distance from the ground and the bike is level (swing arm pivot tube being level allready) ,it means the swing arm is NOT twisted.


You are done!

Click on this photo for a larger version.

[lucky]

Lucky,

What's the best way to make sure the swing arm pivot tube is level?
I assume you can't just put a level on top of it, or can you?

Thanks,
Chris

Yes... just put a level on top of it and use shims under the center stand until it is level.
Then check that the front forks are perpendicular by putting a level on the side of the fork tubes.