Modifying standard NC30 axle? reducing weight

[james66]

Hi everyone

Trying to source another aluminium rs250 axle but cannot find one so the next route im looking down is to lighten the standard axle

due to it being steel its stronger than aluminum so some of the mass could be reduced, has anyone done this or seen it done?

ive had a good look at where it could be lightened, the face is round so im thinking it could be squared off slightly + drilled between the wheel drive studs but still leaving some meat around the disc stud mounts
the axle tube that goes inside the rear wheel has no structural support, if you look at where the wheel mounts all of the support on the wheel is on the inner edge of the wheel on just the thicker part of the tube + the wheel nut + bolt hold it against the hub pretty much deeming the tube useless, so that could be drilled or even cut off completely

any thoughts on this?

cheers

[Drunkn Munky]

There was a thread a while back where someone was doing away with the spindle and somehow threading the wheel side of the axle and using a big nut like the works axle uses but i think the guy doing it deemed it unsafe so abandoned it. Personally i think atleast for the track this would have been fine, the stock axle looks massively over engineered to me.

I'lll see if i can find the thread

[CMSMJ1]

http://400greybike.com/forum/viewtopic. ... 1acda66ce1

that one?

[Drunkn Munky]

Thats the one

[CMSMJ1]

Bonus.. fell on it's arse..but a good read

[Drunkn Munky]

I think the guy got worried that if he modified all those axle's for people and they shit themselfs then he would be held liable which i can understand.

Id go for one, it would still be 20 times stronger than the alloy axle i use to have and if racers were ragging those round tracks on RS250's (or it may of even been of a NSR500V) then im sure the modified NC axle would stand up to a bit of track use.

[pauliealdridge69]

the center pin does support both inner and outer edges of the nc rim. When i cut the center pin off of mine it was easy to see you couldnt trust it alone. All the stress would be on the thin m18 bolt. I'd have no problem drilling and lightening it...i made a ti pin and had it pressed in and drilled the back plate too. Because its so central to the rotation the gains would be negligable though as there is no leverage in the mass carried....lighter wheels would be so much more beneficial than the hub. I bet if i missed a couple of meals it would help me go faster more lol

[dgunthor]

sounds great but as above, unless you weigh 9 stone, i can see plenty of cheaper, more effective weight to lose...

[james66]

thanks for the replies guys

tony (drunken monkey) knows the spec of my race bike + its rather light as it is, 148kg + im still running a steel fuel tank, just finishing the mold for fibreglass dummy + to have an aluminium fuel cell
heres a spec
Carbon front dymag at 2kg + Marvic rs250 magnesium rear just 3.2 kg
pvm rs250 wheesl for wet
daytona 675 radial front end
ally clock mount
minimum rear subframe (still meaning to make an ally one
Lithium battery
completely chopped loom
ally clipons
520 chain
so realy theres not alot more i can look at apart from titanium bolts on the stressed areas (expensive) + aluminum bolts on the non stressed places, theres not enough non stressed places to bother having ally bolts + the tank + subframe are in motion

with the axle its not so much overall weight im trying to save, its the unsprung weight which will helps the suspension respond better, the difference when i put the wheels on was like night + day, transformed the bike

ive looked today + the only part of my rear wheel that touches the centre shaft is the inner edge but then again the spacer under the nut for the rs250 wheel gues inside the wheel slightly + around the axle so there is more than likely an element of support when under pressures

ill get the grinder out over the weekend + the drill + see what i can do, ive got a couple of axles spare
still fancy the aluminium on though :)

cheers
james

[Neosophist]

thanks for the replies guys

tony (drunken monkey) knows the spec of my race bike + its rather light as it is, 148kg + im still running a steel fuel tank, just finishing the mold for fibreglass dummy + to have an aluminium fuel cell
heres a spec
Carbon front dymag at 2kg + Marvic rs250 magnesium rear just 3.2 kg
pvm rs250 wheesl for wet
daytona 675 radial front end
ally clock mount
minimum rear subframe (still meaning to make an ally one
Lithium battery
completely chopped loom
ally clipons
520 chain
so realy theres not alot more i can look at apart from titanium bolts on the stressed areas (expensive) + aluminum bolts on the non stressed places, theres not enough non stressed places to bother having ally bolts + the tank + subframe are in motion

with the axle its not so much overall weight im trying to save, its the unsprung weight which will helps the suspension respond better, the difference when i put the wheels on was like night + day, transformed the bike

ive looked today + the only part of my rear wheel that touches the centre shaft is the inner edge but then again the spacer under the nut for the rs250 wheel gues inside the wheel slightly + around the axle so there is more than likely an element of support when under pressures

ill get the grinder out over the weekend + the drill + see what i can do, ive got a couple of axles spare
still fancy the aluminium on though :)

cheers
james

Somewhat controverial suggestion but have you thought about ditching the swinger completly and using a stock swinging arm.

not only will you get more choice of wheels and tyres you will save a bunch of weight.

viewtopic.php?f=62&t=28349

Have a look at this one? RCV's bike using an FZ swinger