OK, I have two frames: one that was crashed hard enough to bend both fork tubes, and now the clutch throwout lever scrapes the inside of the right frame rail when the clutch lever is pulled.
I'm a little nervous about putting more time & energy into transferring the parts into the new, used frame, wondering if I will have just as big a problem as now.
The new frame is good in the obvious places (neck plates), but I'm wondering if I can measure both frames in the same places, and hopefully find more room in the new frame?
Thanks.
Measuring a frame for straightness
Re: Measuring a frame for straightness
Rob, I think more than the fork tubes got bent. If it just involved the fork tubes and the rear SUB-frame, it might be OK, but it sure does sound like the main frame got tweaked someplace you cannot discern.
Diagonal measurements MAY show the differences, also checking parallels/straightness using "witness" bars on the warious parts.
THE BIG QUESTION IS....IS IT WORTH THE CHANCE?
Using the crashed frame may invite some instabilities at even legal speeds. You don't need that.
Duane can address this, I'm sure.
Diagonal measurements MAY show the differences, also checking parallels/straightness using "witness" bars on the warious parts.
THE BIG QUESTION IS....IS IT WORTH THE CHANCE?
Using the crashed frame may invite some instabilities at even legal speeds. You don't need that.
Duane can address this, I'm sure.
Clemson, SC
R100s, R75/5
R100s, R75/5
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Duane Ausherman
- Posts: 6008
- Joined: Thu Aug 12, 2010 12:39 pm
- Location: Galt California
- Contact:
Re: Measuring a frame for straightness
Take it to a dealer with a frame jig. It only takes a couple of minutes to check. Give them the $20 and be sure. Or, send it out for straightening.
Don't take this risk.
Don't take this risk.
Ask the Indians what happens when you don't control immigration.
frame jig
Finding someone who has a jig to test the frame(s)
or sending the frame(s) to a shop like Frame Straight
for measuring and repair might be the best case scenario.
If I was in your shoes, I'd not hesitate to begin by measuring the frame myself –
using the /5 frame alignment tests as prescribed by Duane.
Then, I would pursue the above second option IF results are questionable or did not meet my expectations.
The BMW frame jig is not a magical device or even so very complicated.
It works by using simple trigonometry – i.e. two sides of an isosecles triangle will be equal in length.
From Duane's site:
"BMW supplied a frame jig for testing frames. It bolts up into the head stock of the frame and has arms that go back to the swing arm pivot holes. A special bolt that is sort of a "bulls eye" and gets inserted into the pivot pin holes. One can easily see how far and which way it is bent."
Understanding the jig's principles and some careful measuring should give you a solid understanding
as to the condition of the frame(s).
A thought:
The heavy lower frame rails combined with the engine mounts and engine bolted to it
create a relatively stout "structure" –
My bet will be that this relationship has not been compromised.
There are a number of other 'weaker links' that will bend first !
or sending the frame(s) to a shop like Frame Straight
for measuring and repair might be the best case scenario.
If I was in your shoes, I'd not hesitate to begin by measuring the frame myself –
using the /5 frame alignment tests as prescribed by Duane.
Then, I would pursue the above second option IF results are questionable or did not meet my expectations.
The BMW frame jig is not a magical device or even so very complicated.
It works by using simple trigonometry – i.e. two sides of an isosecles triangle will be equal in length.
From Duane's site:
"BMW supplied a frame jig for testing frames. It bolts up into the head stock of the frame and has arms that go back to the swing arm pivot holes. A special bolt that is sort of a "bulls eye" and gets inserted into the pivot pin holes. One can easily see how far and which way it is bent."
Understanding the jig's principles and some careful measuring should give you a solid understanding
as to the condition of the frame(s).
A thought:
The heavy lower frame rails combined with the engine mounts and engine bolted to it
create a relatively stout "structure" –
My bet will be that this relationship has not been compromised.
There are a number of other 'weaker links' that will bend first !
and ...
Another thought:
I'm thinking that a good indication of the straightness of the lower frame rails and / or SA
could be tested / measured by installing the engine, trans, and SA to spec,
and then using a straight edge to check the alignment of output shaft center (carefully marked)
as compared to the center of the SA tube (carefully marked) along it's length.
These centers should all be coincident.
i.e. if the SA tube is skewed relative to the output shaft – something might be bent.
or if the output shaft is not square with the SA pivot points – the frame might be bent.
This, essentially, was the process used on CRo for alignment.
(although, unlike a stock bike, the front & rear wheel centers are coincident, too ...)
The white paint marks on the trans case and white line along the center of the SA
remain as testament to the procedure.
Comments ?
I'm thinking that a good indication of the straightness of the lower frame rails and / or SA
could be tested / measured by installing the engine, trans, and SA to spec,
and then using a straight edge to check the alignment of output shaft center (carefully marked)
as compared to the center of the SA tube (carefully marked) along it's length.
These centers should all be coincident.
i.e. if the SA tube is skewed relative to the output shaft – something might be bent.
or if the output shaft is not square with the SA pivot points – the frame might be bent.
This, essentially, was the process used on CRo for alignment.
(although, unlike a stock bike, the front & rear wheel centers are coincident, too ...)
The white paint marks on the trans case and white line along the center of the SA
remain as testament to the procedure.
Comments ?
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Deleted User 61
Re: Measuring a frame for straightness
yeah - WAY too deep for this part-time shade-tree mechanic.Comments ?
The last part I came close to understanding was your description of the BMW frame jig.
I wrote Oak a while back asking for his advice. This is what he had to say:
"Rob:
Sorry---I don't have a frame jig which is necessary to check the frame. No
easy other way that I know of. BMW has a jig they loan to dealers upon
request but I suspect there would be labor and 2 way jig shipping costs involved.
And you would need to bring the frame to a cooperative dealer. Normally
unless the total job is run thru the dealership such as in an accident repair,
it is unlikely you will get much cooperation unless you personally know the
dealer. Shipping a frame two ways coupled with the shipping headaches and
paperwork, and labor costs, is not a very profitable experience for the
dealer. And there may be a separate fixture for a R65 frame. Not sure.
About the most I can help you with is I may have a good R65 frame around
but would have to look in the collection. Sorry I cannot be of more
assistance..Good luck............Oak"
Oh, and other than the lever scraping the frame, my bike seems to handle fine right now. But I never did take it to highway speeds.
So you think my subframe may have been bent, as well?
clutch arm
When did the clutch arm start rubbing on the frame?
Immediately after a crash?
Immediately after a crash?
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
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Deleted User 61
Re: clutch arm
After the replacement engine was installed in the original frame.gspd wrote:When did the clutch arm start rubbing on the frame?
Immediately after a crash?
My original post back in March:
http://boxerworks.com/phorum5/read.php? ... #msg-62340
You don't seem to have participated!
Re: Measuring a frame for straightness
So, let me get this straight.
After the crash, the arm did not rub on the frame.
You changed the engine, used the old transmission and arm, and the arm now rubbed.
So you changed the frame and it still rubs?
Are you sure you have the engine/frame spacers all in the right place?
Some bikes have thick and thin ones and their position matters.
What if you loosen the engine mounts, move things around a bit and re-tighten them.
Maybe the arm pivot has too much play?
Maybe the arm angle is not what it should be. It is adjustable.
Post a pic.
I've never seen a airhead frame bend there, actually I have a hard time picturing how it could, especially in a little pinky tipover.
After the crash, the arm did not rub on the frame.
You changed the engine, used the old transmission and arm, and the arm now rubbed.
So you changed the frame and it still rubs?
Are you sure you have the engine/frame spacers all in the right place?
Some bikes have thick and thin ones and their position matters.
What if you loosen the engine mounts, move things around a bit and re-tighten them.
Maybe the arm pivot has too much play?
Maybe the arm angle is not what it should be. It is adjustable.
Post a pic.
I've never seen a airhead frame bend there, actually I have a hard time picturing how it could, especially in a little pinky tipover.
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
-
Deleted User 61
Re: Measuring a frame for straightness
Well, now I feel I should pull my engine mounts and measure the spacers for thickness.
I tried the online parts fiche, but that spacer is no longer listed on the R65 pages (Max and RealOEM), so i can't tell if they are all the same part #.
That is why I like having the old hardcopy, it shows the parts that have since been discontinued. Of course, it is at home and I am at work.
http://www.realoem.com/bmw/showparts.do ... g=46&fg=65
I tried the online parts fiche, but that spacer is no longer listed on the R65 pages (Max and RealOEM), so i can't tell if they are all the same part #.
That is why I like having the old hardcopy, it shows the parts that have since been discontinued. Of course, it is at home and I am at work.
http://www.realoem.com/bmw/showparts.do ... g=46&fg=65