Strange Frame
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concours said:Very well. I fold my tent. Thanks for the engaging discussion.
Didn't mean to cut you off...just your position is very strong to the opposite of what we were discussing. You shot holes it the "Straightest Commando" article which most people agree is a guideline for correcting the issues with the Commando frame.
The ill handling and tracking issues with Commando's is well documented and many of us have experienced this, some to a very scary extent. You seem to think there is nothing wrong, even with documentation to back up what we are trying to discuss. The use of inches or mm to measure alighnment is common pratice yet you said that was the wrong way to do it. "Grunting" a bent frame back into shape is not very precise and while under normal riding may seem "okay", when pushed someone is going to get hurt.
The OP is trying to do that with his frame. It may "seem" okay but from a safety standpoint I wouldn't ride it until the critical positions were verified.
We have been trying to point that out.
It's okay to disagree, but when our opinions differ we just have to leave it at that instead of trying to discredit each other. Your opinion is different that's why I said you need not worry about it. Your happy with the way your bike handles. I want mine to be the best it can be. We differ there.
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These diverse views on engineering practices are, in my mind are very educational and informative... Who is right and who is wrong, will never be resolved.. Each persons expectation are llways going to be different...... .
I spent 5 hours removing the swingarm spindle today.. Initially created a bolt/nut pulling set up to work in with belting the crap out of the other side.. That didnt work so got the oxy torch out and applied "some" heat to swing arm.. All i could do was get about half a turn on the nut with a spanner, belt the other side and repeat 30-40 times and gained about 25mm of movement (3hrs later).. At least it was moveing and the fridge was full of beer... After 3rd beer i had a revelation come to me, (Oh and it wasnt Mother Mary) Impact gun, why dont i used the impact gun.. So bit more moderate heat from oxy and impact gun set to pull 40mm bites and the rest is history (5 hrs later)
Had enough for today.. On the bright site tho pushing n poking the swingarm during todays episode i found that the arm is chromed..
Well at least where ive scratched the cruddy undercoat off.. Hopefully the PO hasnt sanded it (lazy bugger) looking good so far.. So tomorow is clean and check swingarm for straightness/alignment then the cradle to find out where the existing misalignment is out.....
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concours said:
I have just had a read of WSC..... Concours i agree with your comments completely
............ I got side tracked abit and almost lost focus when "Checking the main frame" and the ISO holes were out .038"-.043" ..Wow i thought. Not being real familiar with Imp measurement i went to the shed and got the verniers out and dialed up .043" , then i did it again... :shock: :shock: :shock: :shock: .... WTF.... :shock: :shock: :shock: :shock: ... If somebody is going the get his "Ken" to weld up and re-"machine" a hole for that amount.............. well what can you say :roll: :roll: :roll: :roll: ...... Bla Bla Bla........... WSC ............ Bored with too much money IMO...... You would want to hope it is the WSC... Not at all practicable in the real world where people have "other priority's" for income ........ .
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Thats a millimeter . If on the front mount - say 3 in. apart , thats 4 mm or 5 / 32 " over a foot . With ONE METRE Bars through the mount , thats 13 MM or HALF an INCH .
Which is ATROCIOUS .
Again , if the Iso Tube is 2 in. dia. , thats over TWENTY FIVE THOU . and we're trying to shim it within 2 thou . Therfore youve a Thousand percent ERROR .
Actually chopping the cradle out & thowing a new pair of tubes in isnt a big deal . A friend had his 70 straightened three times after his ' mate ' T boned a Merc on it .
( His first reaction was ' Trevor ' ( or whoever ) and Trevor . as he had flown over the boot and landed on his head / helmet . K/Oed . Third Reaction was MY BIKE .
ANYWAY , the ' memory ' had the tube wander after a bit of use . So was scrapped as useless . CHECKING , would be frame clamped at say rear pin , and lever on front
mount individually. - see if the tube moves as esilly to either side , and returns to datum . A few bits of wood and a tyre iron would do the trick .
But , unless you get alignment rods through the Iso Mounts , to eyeball . Where a iota of missalignment is easilly discernable - you could find it has a FEW NASTY TRICKS
ON THE ROAD . Another friends 70 always pulled left under hard brakeing . When a P & T truck did a U turn on him , commuteing- it broke his leg in three places trapped.
Where he could have just gone over the bonnet effortlessly if it braked straight . :? 8) :mrgreen: ( Bit like horses , you need to know how to get clear if required ) .
THEREFORE you need a scientific and logical approach , to ensure ' symetrical ' characteristics . You could get assymetric if the welder knocked of for smoko half way through .
Might explian a few rouge chassis . Ordinarilly the distortion would be symetrical if SYMETRICALLY welded . But then theres the side stand . :shock: A few thou of growth there.
Usually a weld will ' grow ' a joint in 16 Guage , so you douse it a dull red , to shrink it to original dimension . Or at bright red to crack it . :cry:
Which is ATROCIOUS .
Again , if the Iso Tube is 2 in. dia. , thats over TWENTY FIVE THOU . and we're trying to shim it within 2 thou . Therfore youve a Thousand percent ERROR .
Actually chopping the cradle out & thowing a new pair of tubes in isnt a big deal . A friend had his 70 straightened three times after his ' mate ' T boned a Merc on it .
( His first reaction was ' Trevor ' ( or whoever ) and Trevor . as he had flown over the boot and landed on his head / helmet . K/Oed . Third Reaction was MY BIKE .
ANYWAY , the ' memory ' had the tube wander after a bit of use . So was scrapped as useless . CHECKING , would be frame clamped at say rear pin , and lever on front
mount individually. - see if the tube moves as esilly to either side , and returns to datum . A few bits of wood and a tyre iron would do the trick .
But , unless you get alignment rods through the Iso Mounts , to eyeball . Where a iota of missalignment is easilly discernable - you could find it has a FEW NASTY TRICKS
ON THE ROAD . Another friends 70 always pulled left under hard brakeing . When a P & T truck did a U turn on him , commuteing- it broke his leg in three places trapped.
Where he could have just gone over the bonnet effortlessly if it braked straight .
:? 8) :mrgreen: ( Bit like horses , you need to know how to get clear if required ) .THEREFORE you need a scientific and logical approach , to ensure ' symetrical ' characteristics . You could get assymetric if the welder knocked of for smoko half way through .
Might explian a few rouge chassis . Ordinarilly the distortion would be symetrical if SYMETRICALLY welded . But then theres the side stand . :shock: A few thou of growth there.
Usually a weld will ' grow ' a joint in 16 Guage , so you douse it a dull red , to shrink it to original dimension . Or at bright red to crack it . :cry:
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Matt Spencer said:
I agree. It seems that we are not communicating the relationships of the measurements to the distance very well. Maybe what you wrote will help...I wish we had a diagram to show the relationships...it might help for people to see how it translates to a huge problem with the wheel alignment on the ground.
Matt Spencer said:
Yes...and then do something about the error.
Matt Spencer said:
Yes...operator variable...not to mention two different welders. Or Mondays and Fridays
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olChris said:
This may be true...but in this case we are talking about safety. In looking at the pictures of your "straightened" frame I don't see how you can be sure that the critical points are properly aligned...I can see clearly in the pictures that the "tube's" look closer, but can't figure out how that tells you anything about the swingarm alignment to the fork tube...
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concours said:
I measure for square with the frame on the surface table, precision bar through head bearings mounted on equal blocks. Steering axis height from table gives the datum for the frame centre line. It makes sense the centre line bisects the rear iso brackets. So the rear of the frame is raised until the mid point between the brackets is same height as steering axis centre +/- 0.0005", measured with a vernier height gauge. 13" length precision bars then go through front and rear iso brackets and compared to a vertical datum (tool makers block) and gap at end of bar is measured in two points 90 deg to each other. Same procedure to check swingarm spindle axis. I agree it's not good practice to mix units when talking about right angles and referring to inches, but it's easier to measure a gap than an angle in this instance. Measurements on my frame varied between 0.020" - 0.040". Especially around bumpy bends the bike would wallow and become uncontrollable unless I eased off the throttle. After accurately repositioning iso holes and checking there was no discernible gap (effectively square) between swingarm axis check bar and vertical datum , the bike goes around 90mph corners, heeled over, without problems.
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olChris said:Al-otment said:olChris said:
The one I've got is granite, they seem to be more readily available than cast iron and obviously don't rust. After several billion years of pressure granite is apparently a very stable material. Only photo's I've got are on my website http://www.parallelengineering.co.uk/ (work in progress on site) I'm hoping to make a living at something I would enjoy more than the current job. I'll have to get a camera for next years holidays
That service that you intend to offer will be very handy to motorcycle rebuilders/restorers.... i assume that picture provided within your website is the "Surface Table".. I would have thought there would have been "fixing points" at various location around the table for push/pull equipment.... Obviously not, so when you find a "misalignment" in a frame how do to straighten it ????
I don't bend frames straight. The service I offer is precision alignment, primarily to correct manufacturing misalignment. This is done by accurately repositioning relevant mounting holes e.g iso bracket holes on Commando's, swingarm pivot holes on conventional frames. If a frame is accident damaged I can get it bent by a third party to 'jig accuracy' and then I'll carry out the precision alignment to get everything square and in line.
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Heres the guy who did my frame and many for Kenny Dreer and others. He'd be a good resource should you have a question or two for someone who really knows what they're doing.
http://www.snowcrest.net/gte/
http://www.snowcrest.net/gte/
concours
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Thanks dennis, I didn't feel cut off, just wanted to step back and let some other opinions surface.
"You shot holes it the "Straightest Commando" article which most people agree is a guideline for correcting the issues with the Commando frame."
I DID shoot holes in it. As to whether MOST people agreeing with it, well, maybe many haven't chimed in or felt a need to.
"The ill handling and tracking issues with Commando's is well documented and many of us have experienced this, some to a very scary extent. You seem to think there is nothing wrong, even with documentation to back up what we are trying to discuss. "
Scary is a subjective thing, first time I rode a Commando (owner warned of sloppy Iso's, squared rear tire) I felt the hinge, still ran with the pack, (NOT the "Parade Pack") no drama, just a little rider compensation. I never said nothing is wrong, I said that it's ridiculous to try and "build a bridge with feeler gages" (that's a figure of speech for the above mentioned). The money shot here is: The handling of the Commando was compromised by the isolastic system design. For the right reasons (to make a paint shaker from hell engine civilized) and the engineering compromise included a less than rigid frame. Does that compromise affect feel? Yes. Is it scary? At some speeds/conditions/riders, yes. The "blueprinting" of the frame will not make those inherent design traits go way.
" The use of inches or mm to measure alighnment is common pratice yet you said that was the wrong way to do it."
I didn't say it was wrong, but rather, because it is an incomplete statement, (misleading to those who don't work in the fabrication field) tells nothing about the magnitude of the error, I said I discounted it (the author, in an above post, later fleshed it out so it was valid data that can be considered). If you're going to use decimal linear measurement, then there are other parts to the geometry to make a complete picture. The lack thereof makes me discount it as marketing hype.
"Grunting" a bent frame back into shape is not very precise and while under normal riding may seem "okay", when pushed someone is going to get hurt."
I had posted no comment on the OP's frame straightening (although I wholeheartedly agree with it). I would cold straighten as he's done and bet my and a pillion loved one's life on it.
"It's okay to disagree, but when our opinions differ we just have to leave it at that instead of trying to discredit each other. Your opinion is different that's why I said you need not worry about it. Your happy with the way your bike handles. I want mine to be the best it can be. We differ there"
I hope I didn't seem to "discredit" anyone. I'm sure the guy re-machining a frame to +/- .0005" is talented, knowledgeable and qualified to do so. ("lunchtime" sarcasm not withstanding :roll: ) My stance has been on challenging the CHOICE to apply that degree of precision to the bikes frame, and I stand by that viewpoint.
Agreed, difference of opinion, no worries, all good. I did, however, fail to see this was a poster here, who is offering this service. I thought it was someone with access to machinery/skills and putting forth the proposition it's the answer to handling quirks. Had I noticed it was a business, I would not have challenged it, and not interfere in any way with people's perceived need for services. As for your bike being the best it can be, that's a great goal.
Thanks for a gentlemanly discussion. :mrgreen:
"You shot holes it the "Straightest Commando" article which most people agree is a guideline for correcting the issues with the Commando frame."
I DID shoot holes in it. As to whether MOST people agreeing with it, well, maybe many haven't chimed in or felt a need to.
"The ill handling and tracking issues with Commando's is well documented and many of us have experienced this, some to a very scary extent. You seem to think there is nothing wrong, even with documentation to back up what we are trying to discuss. "
Scary is a subjective thing, first time I rode a Commando (owner warned of sloppy Iso's, squared rear tire) I felt the hinge, still ran with the pack, (NOT the "Parade Pack") no drama, just a little rider compensation. I never said nothing is wrong, I said that it's ridiculous to try and "build a bridge with feeler gages" (that's a figure of speech for the above mentioned). The money shot here is: The handling of the Commando was compromised by the isolastic system design. For the right reasons (to make a paint shaker from hell engine civilized) and the engineering compromise included a less than rigid frame. Does that compromise affect feel? Yes. Is it scary? At some speeds/conditions/riders, yes. The "blueprinting" of the frame will not make those inherent design traits go way.
" The use of inches or mm to measure alighnment is common pratice yet you said that was the wrong way to do it."
I didn't say it was wrong, but rather, because it is an incomplete statement, (misleading to those who don't work in the fabrication field) tells nothing about the magnitude of the error, I said I discounted it (the author, in an above post, later fleshed it out so it was valid data that can be considered). If you're going to use decimal linear measurement, then there are other parts to the geometry to make a complete picture. The lack thereof makes me discount it as marketing hype.
"Grunting" a bent frame back into shape is not very precise and while under normal riding may seem "okay", when pushed someone is going to get hurt."
I had posted no comment on the OP's frame straightening (although I wholeheartedly agree with it). I would cold straighten as he's done and bet my and a pillion loved one's life on it.
"It's okay to disagree, but when our opinions differ we just have to leave it at that instead of trying to discredit each other. Your opinion is different that's why I said you need not worry about it. Your happy with the way your bike handles. I want mine to be the best it can be. We differ there"
I hope I didn't seem to "discredit" anyone. I'm sure the guy re-machining a frame to +/- .0005" is talented, knowledgeable and qualified to do so. ("lunchtime" sarcasm not withstanding :roll: ) My stance has been on challenging the CHOICE to apply that degree of precision to the bikes frame, and I stand by that viewpoint.
Agreed, difference of opinion, no worries, all good. I did, however, fail to see this was a poster here, who is offering this service. I thought it was someone with access to machinery/skills and putting forth the proposition it's the answer to handling quirks. Had I noticed it was a business, I would not have challenged it, and not interfere in any way with people's perceived need for services. As for your bike being the best it can be, that's a great goal.
Thanks for a gentlemanly discussion. :mrgreen:
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concours said:
Thanks for taking the time to clarify your position. I really appreciate that and I have to say it came across in a much better light than the previous back and forth. The internet tends to do that sometimes particularly when we expect each other to understand things we each see differently. I in no way am an expert on Norton handling and as you read and research the subject there are so many different opinions it becomes difficult to weed through them all.
I like the WSN approach because that is the world I come from and understand. That's not to say I haven't pulled a car fender out with the tractor in my day, but I understand precision. Is it nessesary? I really can't answer that question. It seems to me that if it were possible (and I'm still not convinced it is possible), to get the positions more accurate with relation to the fork tube, and actually prove that there is a difference, it should improve the tracking of the bike if the iso's are properly adusted and in good condition.
I like you owned a new Norton in 1976 and to be honest it handled pretty well. It was a revelation at the time to ride a British bike without the vibration and truthfully that is what I remember about that bike, the smoothness of the ride. I do remember some "quirky" feelings particularly when coming off the throttle in turns, but after the first time I never came off the throttle anymore...so you learn to ride any bike based on how it performs I guess.
To some degree we may be over analysing this, which I think is your point. For me it is a quest for knowledge and understanding "if" it can be improved. Lots of times in the end we throw out much of the information we learn after we try it and it doesn't seem to give the results we hoped for...I may find myself there at some point, and then will have to come back and tell you that you were right...but I'm a bit like a kid sometimes...I have to try it myself
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concours said:
I mentioned the following point in a previous discussion - how did Peter Williams manage to post a record lap around the Isle of Man on a design incorporating isolastics? This was the F750 monocoque, quote "the best handling bike he'd (PW) ever ridden". He also posted a 97mph lap (thats average speed) on a Commando production racer. Both designs "compromised by the isolastic system design" and the Production Racer with "the engineering compromise included a less than rigid frame". Both your points are incorrect. The only compromise was the production process on standard frames. Peter Williams told me ALL his racing frames were checked for alignment. My bike is proof the faults are caused by inaccurate frame geometry, absolutely not by the Isolastics. I'll guarantee any Commando that I carry out alignment work on will have none of the typical factory Commando handling faults. http://www.parallelengineering.co.uk/
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:roll: Anyway back to the swingarm and spindle... I cleaned up the spindle and its housing and reinstalled it.. At rest it lined up to the spine tube centreline as per photo.. But the spindle and spindle housing within the cradle was, as we say down here, like a "dick in a shirt sleeve" meaning it was fairly loose. Although the spindle to bushes was a nice firm push fit..
So tomorow's project is turn up another spindle that will be custom fitted to the cradle tube O(oversized from wear and rust .010ish) which i have honed out with a brake slave cylinder hone, and as i cant get new bronze bushes from Kmart, i will hone those out too (if required) to suit new spindle...
As i will be turning the spindle out of mild steel, drilling and preparing to accept the central locating bolt, which in turn is to be replaced by a grease nipple. In the spindle where the 2 miniscule oil weepage hole are, i will open up to 3mm each side with 2 hole each end so the grease will actually lubricate the swing arm... Then harden it.
Does anybody want a pictorial step by step to case hardening of the spindle......... Oxy and a drum of sump oil !!!! Anyone can do it...
.
So tomorow's project is turn up another spindle that will be custom fitted to the cradle tube O(oversized from wear and rust .010ish) which i have honed out with a brake slave cylinder hone, and as i cant get new bronze bushes from Kmart, i will hone those out too (if required) to suit new spindle...
As i will be turning the spindle out of mild steel, drilling and preparing to accept the central locating bolt, which in turn is to be replaced by a grease nipple. In the spindle where the 2 miniscule oil weepage hole are, i will open up to 3mm each side with 2 hole each end so the grease will actually lubricate the swing arm... Then harden it.
Does anybody want a pictorial step by step to case hardening of the spindle......... Oxy and a drum of sump oil !!!! Anyone can do it...
.
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olChris said:
The S/A pivot assembly should be lubricated using EP140 OIL, (check your manual, Section F8) not GREASE, as the bushes are made of sintered bronze.
http://britmoto.com/manuals/Manuals/750_man.pdf
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L.A.B. said:
You are correct LAB. Thats what the manual say's... This package has never seen oil or grease since manufacture IMO, The bronze bushes seem "good" the spindle is pitted and undersize-ish.. cos it had no lubrication........ Im going to put grease in there so that it cant drain/weep away.. It will always better than no oil.. IMO... Its not as though the bushes going the react to grease...
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Well OK then, i still will put larger weep hole in at the 3 and 9oclock, fit a "snorkel" with cap to pump oil in the central point... No biggy..
But why, is there a problem with grease ?????? or is it just the deviation from the "Manual" that is a problem...
But why, is there a problem with grease ?????? or is it just the deviation from the "Manual" that is a problem...
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The Commando S/A bushes are porous (sintered bronze) and once "charged" with oil they remain "self-lubricating" for an extended period. The sintered material doesn't have to be kept constantly "wet" with oil, so all that's required is a little periodic re-lubrication.
If grease is pumped into the spindle gallery, it clogs up the assembly, and the grease won't permeate through the sintered bush structure. I know some people can't get used to the idea of using oil and have modified the assembly to use grease but whether that sort of thing is entirely necessary or beneficial is (in my opinion at least) debatable.
If grease is pumped into the spindle gallery, it clogs up the assembly, and the grease won't permeate through the sintered bush structure. I know some people can't get used to the idea of using oil and have modified the assembly to use grease but whether that sort of thing is entirely necessary or beneficial is (in my opinion at least) debatable.
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