Lightweight rear rotors

[Kurlon]

So, I see a certain machinist popular on this forum makes a lightweight rear rotor for the 3TJ. Is it cut out from scratch or is it a cut down OEM unit, and as a follow up any reason it couldn't be cut out of Aluminum instead? (Yeah, I know it'd never last, but for a race bike where I never actually USE the rear brake...)

[Evilchicken0]

If it isn't against the rules I guess you could do it. Does it have to be a working brake ... You could use alloy pistons and pads or a lightweight caliper

[Morespeedvicar]

I have wondered if your desperate to save weight (and i mean desperate) if you could graft on a pushbike disc and caliper!!!!!???? They dont weigh much at all.

But dont blame me if you end up in a hedge tho.......

lol

[Kurlon]

I know people who have done just that. I know an AMA team that got caught with a cardboard rear rotor once, they glued aluminum foil to it and it supposedly passed tech at least once before they noticed...

For racing, it just has to convince the tech inspectors that it's functional. Typically all they do is pump the rear pedal and confirm they get proper resistance in it...

[Kayla850]

I have wondered if your desperate to save weight (and i mean desperate) if you could graft on a pushbike disc and caliper!!!!!???? They dont weigh much at all.

But dont blame me if you end up in a hedge tho.......

lol

I use a 3mm thick, 208mm diameter stainless steel disc on my 400. It weighs around 330g compared to around 800g for a standard disc. I suppose a 5mm thick, 210mm diameter ally one would weigh around 330g as well. You could probably get away with 4mm ally if you don't use the rear at all.

As far as scrutineering goes, it only has to work once per weekend

[Morespeedvicar]

wow thats well thin, I'm surprised they dont check min thickness at scrutineering, hell of a weight saving tho. Cool.

[Kurlon]

wow thats well thin, I'm surprised they dont check min thickness at scrutineering, hell of a weight saving tho. Cool.

Tech requirements just state functional, they don't say anything about required specifications. :D

Oh, speaking of mountain bike calipers: https://lh6.googleusercontent.com/-ho1M ... cs+045.jpg

Kayla, I'll be ordering a rotor or two from you I think. :D

Have you made front rotor blades before? The 3TJs call for a 4mm thick rotor OEM, all the aftermarket companies are shipping 5mm thick units. I don't know if it'd be easier to make a whole new blade, or machine down an existing one?

[Evilchicken0]

Front brakes are different steel, remember they heat up so any difference in the steel can warp it.

You could try a 6 bolt Ducati front wheel - the brakes are a similar fitting to the Yamaha ones
ISR will make you special rotors

[The Novice]

other options.

Go on a diet, take a dump, don't wear undercrackers, have a haircut, do you really need both big toes..........?

There is a few more grammes.

[Kurlon]

I already have to wear kids' gear for some items, I don't think I can drop any more weight there. I just skip eating altogether on race weekends, nothing to 'purge' before the main event that way. I need my undercrackers or my leathers give me such a pinch... Male pattern insecurity is already setting in, no need to take a hatchet to what's left. Can't loose my toes, I finally found boots that fit and I'm NOT going shopping again! :D

On the wheel front, if my friend was still doing salvage I'd be all over the Duc option as they'd be EASY to source... unfortunately he's moved on. This R6 conversion looks pretty straight forward so far, just the rotor thickness that's bugging me. ISR lists all their custom rotors as being 5mm thick but I'll sling them a query just the same. I suppose if going all out I could get them to do up a single 6 pot to mate with a 320mm rotor, that'd save some much weight both on the bike and out of my wallet...