Rims too heavy...

[foreda]

Rims

Thanks... Keep in mind this was a god-awful amount of work (I'll never admit how long this took, but this will likely be the only set I ever do...) as these are very rough castings and the 'register' between the two mold halves wasn't all that good either. If you decide to attempt this, get yourself some 'aluminum' files (yes, there is a difference) as regular files and die grinder bits will clog quickly. I found that spraying the die grinder burrs with WD40 helps...

Damm Steve.. I was going to get you to do mine since you did such a good job! I'll bet you were ready to get past that job!!

[WMarshy]

Steve, any chance you did anything to the rear rim?

[latexeses]

Chalking a file will help to keep it from loading up.

As for lightening up the wheels. Do what a retired veterinarian friend of mine suggested when someone asked him what might be an easy way to keep old wooden floors from squeaking.....

Go on a diet.

There are some programs out there from Autodesk like "Inventor" that you could draw the wheel into a file and the program would tell you where the stresses are. You could then make your changes and see if you are in trouble with your modifications. Head down to the nearest Jr. College and snoop in the CAD classroom. You can probably find a kid who know the program and would do it for a drive through lunch.

[WMarshy]

Chalking a file will help to keep it from loading up.

As for lightening up the wheels. Do what a retired veterinarian friend of mine suggested when someone asked him what might be an easy way to keep old wooden floors from squeaking.....

Go on a diet.

There are some programs out there from Autodesk like "Inventor" that you could draw the wheel into a file and the program would tell you where the stresses are. You could then make your changes and see if you are in trouble with your modifications. Head down to the nearest Jr. College and snoop in the CAD classroom. You can probably find a kid who know the program and would do it for a drive through lunch.

I have many hours in that program, no need to get anyone else to model it for me. Never used the FEA features in it thought, would be fun if I had it on my personal machine...

[TopCatGr58]

Any one ever try lightening the stock rims on these beasts? The thought came into my head, maybe dilling some holes in the webbs of the spokes and maybe removing some other material from them... Might be a crazy idea but, dont plan on going XSessive and making them unsafe... just reduce unsprung weight...

Any ideas...? With a little luck, this might be the next 'oil' thread!

Someone mentioned the Swirly mags, and just looking at one in the Forum Top image, I just noticed that there wasn't ANY Web material between the pairs of spoke ribs on the swirly wheels. It appears to me that a majority of the strength is in the edges of the ribs and not the webbing itself, and so putting several large round holes down the center webbing probably wouldn't reduce the strength of the rim/spokes much at all!? But yeah, seeing the wheel in a special cad program that would show/illustrate the stress points would be nice to see. I don't know what computer technology or development analysis Yamaha had available to them in the late 70's when they designed the wheels, so perhaps they are overengineered like much of the bike is?

T.C.

[Eveready1100]

Or you could swap the straight spoke wheels for the swirly ones. I think they were fitted to the XJ's over there. You'd save over a kilogram each with no other mods at all

[DAVINCI]

Any one ever try lightening the stock rims on these beasts? The thought came into my head, maybe dilling some holes in the webbs of the spokes and maybe removing some other material from them... Might be a crazy idea but, dont plan on going XSessive and making them unsafe... just reduce unsprung weight...

Any ideas...? With a little luck, this might be the next 'oil' thread!

What a great idea. Be sure to post the pics when they fail.

[WMarshy]

What a great idea. Be sure to post the pics when they fail.

Maybe I'll use full synthetic oil and put 40 psi in my tires and crash from that too!

[James England]

What a great idea. Be sure to post the pics when they fail.

Or, heaven forbid, get someone else to post the pix on his behalf........

I don't want inadvertantly to start an urban myth but I do seem to recall in the late Seventies, when cast alloy wheels began to be more popular, people were warned not to mount kerbs at too high a speed as the wheels could deform, or crack. Those of use with spoked wheels quoted this incessantly. I wonder if it was a load of rubbish started by spoke and rim manufacturers??

[DGXSER]

I am certain there is material that could be removed without compromising the strength of the wheels. It would take some analysis though to figure out exactly where and how much.

In the aircraft industry, weight is the mortal enemy. Every bracket and clamp and component is reviewed for what material can be hogged out of it to lighten it up. It is sometime amazing how little material provides the same structural integrity. But the key to it is always knowing how and where the forces will be applied, drawing a line that connects those points, adding some thickness that must be determined by the analysis of the components and the materials characteristics, then hogging out in between the lines.

So, it should be able to be done to the spokes of the wheels, but I would not venture to guess where or how much.

[crazy steve]

Steve, any chance you did anything to the rear rim?

I never did post pics of the finished wheels...

[IMG][/IMG]

As to the pros/cons of cast vs laced wheels, the big advantage for cast is they're more rigid (less flex) compared to a laced wheel. Weight-wise, it's pretty much a wash on bikes where they offer both, assuming an aluminum hub, 40 spokes (typical) and steel rim; you can save a few ounces by fitting a alloy rim. The big weight difference is the required tube on the laced wheel.

The downside to cast is the same thing that makes it 'better'; being more rigid, they will bend rather than flex, so won't take quite the same beating a laced wheel will...

[James England]

It would take some analysis though to figure out exactly where and how much.

There are a lot of varied forces at work too..... weight, bumps and potholes in the road and especially braking. There's a lot of mass, often travelling at high speed and then slowing, perhaps very rapidly indeed. That's not the sort of time to find out whether the CAD programme was accurate after all..... I love modifications and have, thanks to this very forum, done several with great success, but wheels are something I really wouldn't want to mess with. They're a bit too important.I can live with an exploding CCT or modified regulator/rectifier but not a front wheel shattering into bits when I put the brakes on too hard. OK, it probably wouldn't happen, but I'd always be thinking about the holes I'd drilled in the wheel..... it would spoil my ride!

[latexeses]

You can put stress anywhere you want it on a design program. Including stresses found in braking or lateral stresses. You can put stress in as many directions as you can imagine on a part just to watch the stress load change. When that part of the design is satisfied then they start prototyping.
You can bet your socks that any wheel out there right now has been looked at by just such a program. It saves THOUSANDS of dollars. Track time and track failures cost too much to be guessing.
James, I'm with you.."it would spoil my ride"

[jetmechmarty]

What a great idea. Be sure to post the pics when they fail.

I'd always be thinking about the holes I'd drilled in the wheel..... it would spoil my ride!

I'm afraid I'd have to go along with these sentiments. I seriously doubt that doing a structural analysis of the wheel would be worth the effort. For those familiar with the process, I suppose it's fun to chatter about.

Weigh the XJ wheels. That may prove the simple solution.

[DGXSER]

I did not say it as completely as I could have, but I agree that while it could be done, I would not want to test the ride the bike it had been done to. I had my brief meeting with ground that equated to multiple contusions and fractures, my mortality was completely confirmed and is well documented in X-rays and reports.