Topic: Info on Carbon Fiber

[fishhead]

 I am looking for very light weight alternatives for caliper mounting brackets that  I make.
 
 Here's one set up that I have been toying with (GL 1000 forks, 6 piston calipers).

 The caliper mounitng brackets are made from 1/2 inch aluminum and weight 6 ounces each.



I thought I could save some weight by using 2 peices of 3/16 inch aluminum instead of the 1/2 solid peice.
(my supply store didnt have 1/8 inch in 6061)





 I got the weight down to 4.5 ounces each, but I had to machine 14 seperate peices to do it. The 2 peices of 3/16 are seperated by an aluminum "washer" and one peice (dowel) on the outer 3/16 peice is press fit through the whole assembly to hold it all together. All that machining for very little weight loss doesnt really seam worth the effort.

Comparison of new and old brackets. Other than construction, they are identical (fit the same application)



I could machine the 3/16 inch peices down to 1/8 inch each and probably save some more weight or even slot the side plates to shave some weight, but I am thinking about possibly doing them in Carbon Fiber.

 Is carbon fiber suitable for this type of application?
What other lightweight material could be used for these brackets.
I have looked at Titanium, but it is expensive as all get out.
 Any help would be appreciated,

[FunJimmy]

Personally, and no offence intended. If I where that concerned about the minimal weight savings carbon would make, I’d put down that extra piece of pizza. You really don’t want to compromise a safety item like brakes! It reminds me of a post on a sport bike forum where this guy was bragging about the weight savings of running only one disc & caliper. WTF was he thinking? You might find saving on reducing the spoke count too, but would you?

[fishhead]

Nah, No offense taken.

 Just going by the looks of the old solid brackets, they look heavy. I've had a request for lighter weight caliper brackets and Carbon Fiber looks to be a possibility (if feasable). All the machining that went into the new brackets doesnt really seam worth the extra effort to save 1.5 ounces. If I could cut the weight of the caliper brackets in half,(and be as strong as the aluminum ones) it may be worth the effort then.
  I havent slotted the side plates of any of my caliper brackets because it may weaken the brackets and I would prefer to err on the side of safety and leave them solid.
 

[Steve_K]

I like the way you machined the parts.  It make not be a light as you wish, but it looks cool.  No opinion on whether it is strong enough for the job.  Machineheads will like it.
Steve_K

[crazypj]

You would save a lot more weight with better quality calipers and more modern forks
 I would take a look at probably load path and use more curved mountings.
 Would it be possible to utilise one of the original mounting holes and just make a 'half' bracket ?

PJ

[Zaipai]

Not sure about the carbon fiber, however it was what J Britten used for his front suspension, I am thinking if it can handle that it could handle break bracket. However I don't know for sure. Nice work on that bracket tho!

[ColinMc]

They use carbon fiber for landing gear on some super high end private aircraft...but i'm assuming you have somewhat of a budget? lol

[754]

Fish, this is my take on it. The way I like to make stuff.
 Use the  1/2 inch plate, using a radius edge cutter take out as much of the inner solid part as you can.. leave around 1/8 in or .150 ish untouched and mill down to same thickness on the part you leave in the middle... if you cut this thru the middle it would look like a channel, radius corners are a must.

 Now if your mounting uses thru bolts, turn down the bushings between 1/2 plate and caliper, to look like spools, ie thinner in the middle (more weight comes off the od), but original diameter at the ends.

 That will shave weight,& improve looks, they will be just titz when they are done..

[HavocTurbo]

Maybe I just cannot lay it very well but high strength applications of carbon fiber in that small of a size would be expensive as hell. Probably machine laid and formed to exacting specifications.

Only reason why I say that is the part is so small yet is subjected to so much force that any mislaid piece could cause failure.

I've tried to use carbon fiber in high tension strength areas and after 6 years of doing it I still cannot get stuff to last very long. Low tension is fine though.

Check out anyone who uses CF as frames and such (confederate) and I'll bet they are computer controlled forms. High $$.

[fishhead]

I was thinking more along the lines of getting CF stock (plates,tubes,rods) and machining the parts out simular to the Aluminum parts shown.  The parts be press fit together and also would be epoxied together to make them act as 1 peice.

 I'm not going to make a mold and lay up CF in it to make the brackets. That would be too much work in an area I'm not familiar with.

 I may end up making an aluminum "reinforced" CF bracket just to see if it can be done. I can't find a definitive yes or no to if it can be done only in CF or not. CF is supposed to be a "miracle" material (stronger than/lighter than,etc). The CF suppliers sell it, they just dont offer very much technical info on it.
 Thanks for the replies,

[FunJimmy]

CF is supposed to be a "miracle" material (stronger than/lighter than,etc). The CF suppliers sell it, they just dont offer very much technical info on it.

The only concern that I would have is that carbon fiber doesn't fail slowly, but can explode catastrophically and that would be disastrous on a brake component.

Check this vid out.

Keep us posted though.

FJ