Aftermarket rear brake rotor options?

[sp838]

Curious to know about replacing the chunky, clunky rear brake rotor with some more svelte. Has anyone done this? Is the hole pattern on our rotor more or less standard? I haven't started researching this yet, but figured I'd start here. If anyone has any insights, please share!

[sp838]

So, here is what I've found so far.

 

EBC makes a direct bolt on rear rotor, model number is MD692C. I just spoke with the their sales rep, he laughed when he looked it up. Said they have never sold a single one of these in the US.

 

Galfer makes a rotor that would work: the DF005W, although it has a 6mm smaller diameter. Haven't examined the contact between the pad and disc yet to see if losing 3mm of contact would be a very big deal, I'm guessing that it really wouldn't be that bad.

 

Both would offer significant weight reduction compared to the stock Brembo disc, which translates into a huge rotational mass savings, as well as less unsprung weight. I'm definitely going to be doing this. Not sure yet which one, leaning towards the EBC one because it has the correct outside diameter.

[Tom M]

Finding the lightest rear tire that you can might be a better approach if you're looking to cut down on unsprung weight and rotational mass.  Have you lifted your assembled rear wheel with the bevel box attached?  It must weigh at least 50lbs.  I doubt that saving maybe 1/2 pound on the brake rotor is going to make any noticeable difference in performance. 

 

That said, if you want a cooler looking brake rotor then go for it and please post a pic! 

[sp838]

Every little bit helps  !

 

Definitely will post pics if/when I do it. Also looking into replacing all the big chunky bolts with titanium hardware.

[Lucky Phil]

So, here is what I've found so far.

 

EBC makes a direct bolt on rear rotor, model number is MD692C. I just spoke with the their sales rep, he laughed when he looked it up. Said they have never sold a single one of these in the US.

 

Galfer makes a rotor that would work: the DF005W, although it has a 6mm smaller diameter. Haven't examined the contact between the pad and disc yet to see if losing 3mm of contact would be a very big deal, I'm guessing that it really wouldn't be that bad.

 

Both would offer significant weight reduction compared to the stock Brembo disc, which translates into a huge rotational mass savings, as well as less unsprung weight. I'm definitely going to be doing this. Not sure yet which one, leaning towards the EBC one because it has the correct outside diameter.

Your kidding me right? have you ever lifted the rear wheel of a V11? I was in shock at the  massive weight of the rear wheel of a std V11 the first time I removed one as i'm used to dealing with real sports bike wheels such as those on my 1198 Ducati  and GSXR1000 Suzuki track bike. It was there and then that I decide that excellent handling was never going to be achievable with the V11 as on top off all that wheel lard there was still the weight of a bevel  box and 1/2 of a reaction rod and drive shaft to consider.

So a 3mmx 6mmx 230 mm ring of disk rotor material missing is but a drop in the bucket of lard that is the std rear end and it wont make a scap  of difference in the real world.

BTW the first thing I did when I felt how ridiculous the weight of the rear wheel/drive assy was on a Guzzi was to go and buy a decent high quality rear shock purly out of sympathy for the poor old std Sachs unit. The rear shock on a V11 has a man sized job to do thats for sure.

Ciao 

[tikkanen]

I bought a pair of BrakeTech rotors for my Scura (front) so give them a try - they are very professional in business and I can only recommend their work. See http://www.braketech.com

 

And yes, that rear wheel is a real fatty, my god it's bulk heavy…. 

 

Cheers

Søren 

 

[sp838]

lol LuckyPhil. Don't you worry your pretty little head over me! I have the rear shock on my to-do list. I will also be adding bracing to the swingarm, replacing its bearings, replacing wheel bearing with ceramic ones, milling out the porckchops, and hopefully swapping the cardan shaft for a billet one if they ever are available again. Replacing all hardware possible with titanium. Every little bit counts. Especially on things that rotate under power or are unsprung. The Galfer rear rotor weighs 2.15 pounds. Titanium hardware weighs half of what regular steel weighs. I haven't weighed it yet (I will though) but I'm willing to bet that the Brembo rear rotor weighs over four pounds. Losing 2 pounds of rotating mass is not totally insignificant. And doing all the little insignificant things eventually adds up to something meaningful. Plus it's fun. Improving things is never a bad idea. This is my hobby, I thoroughly enjoy it. That said, I will draw the line at certain things, don't think I'll be installing Alpina wheels anytime soon... Unless I hit the lotto, then it's on. $165 for new and better brake rotor is not going to kill me.

 

tikkanen, I saw your brake rotors in another thread, and I am very very impressed. I just swapped my front end so will be directing my attention elsewhere for now, but those rotors are definitely going to happen sometime in the not so distant future... Maybe next winter.

[GuzziMoto]

I agree with the others, you could not run the rear brake rotor all together and you would not notice it, until you tried to stop.

If you want to run an aftermarket rear rotor, go for it. But if the swept area of the disc does not match the swept area of the pads issues can arise. The pads, if they overhang off the outer edge of the disc, can wear down until the the parts of the pad that do not contact the disc (and thus do not wear) are touching. When that happens you pretty much loose the ability to apply that brake.

Other options are there are companies out there (or you might be able to do it yourself, or find a local machinist who can) that will fill the brake disc full of holes to make it as light as possible. Brake discs are pretty tough so it may be hard to do it yourself with a harry home owner drill press, but where there is a will there is a way.

Another option would be to, as you already mentioned, buy an aftermarket brake disc. But I doubt you will see a 2 lb reduction in weight there. Unless the aftermarket rotor has considerably less material it will not weight considerably less.

[Tom M]

My  :  Titanium bolts would a complete waste of money on a 500+ pound motorcycle.  Dropping a few pounds of body weight would be healthier and cheaper.  Put the money saved toward a better rear shock or better yet rider training if you really want to go faster.

 

Here's a good program for a regular street rider like me.  http://www.totalcontroltraining.net/

[sp838]

First look at the contact between the pad and the stock disc looks like it is inset a little bit with regard to the outer edge, so a 3mm difference might not be a big deal... I'll know for sure either way once I get the disc. If it doesn't work, I'll just return it. And yes, the Galfer disc weighs only 2.15 pounds, it has very little material compared to the stock unit. The EBC disc is an exact match for the outer diameter of the Brembo stock one. I'll use that one if the Galfer one doesn't work out. It is a little bit more substantial than the Galfer disc, but it too weighs less than the Brembo one, at 3 pounds.

 

Tom, I really do appreciate your concern for my finances and for my general health, but I'm not asking you for permission on how to spend my money or how to customize my bike. Also, buying titanium hardware doesn't preclude ALSO buying a new rear shock. I intend to do both (and more), thanks. When I'm done my bike will no longer be 500+ pounds, though it sounds like yours still will.

[docc]

Mine only weighs 500 pounds when it's out of gas.

 

FWIW, an early (2000) stock (worn out) front Brembo rotor weighs 1798 grams/ 3.96 pounds. I can't imagine the rear weighs that much, but I don't have one off to weigh.

[sp838]

docc, the front rotors are floating type, they have an alloy center carrier. The rear rotor is fixed type, it is made from a solid slab of stainless steel. So while the rear rotor has a smaller diameter, it being made of solid steel means that it is likely just as heavy, if not maybe even heavier than the front. Guesstimating "it's smaller therefore must weigh less" doesn't work, because the two rotors not really comparable by virtue of how they are made. I'll weigh the rear rotor. If I'm wrong, I'm wrong. No skin off anyone's back. At worst I'll have a slightly lighter, way cooler looking rotor. I can think of worse things.

[docc]

Ah! That makes sense (of course).

 

Looking forward to your rotor solutions as my rear is going to the thin side. These latest EBC grinders don't sound like they are being too kind to the rotor!

[docc]

Wait! What? A magnet sticks hard to my front's center carriers!

[motowarren]

lol LuckyPhil. Don't you worry your pretty little head over me! I have the rear shock on my to-do list. I will also be adding bracing to the swingarm, replacing its bearings, replacing wheel bearing with ceramic ones, milling out the porckchops, and hopefully swapping the cardan shaft for a billet one if they ever are available again. Replacing all hardware possible with titanium. Every little bit counts. Especially on things that rotate under power or are unsprung. The Galfer rear rotor weighs 2.15 pounds. Titanium hardware weighs half of what regular steel weighs. I haven't weighed it yet (I will though) but I'm willing to bet that the Brembo rear rotor weighs over four pounds. Losing 2 pounds of rotating mass is not totally insignificant. And doing all the little insignificant things eventually adds up to something meaningful. Plus it's fun. Improving things is never a bad idea. This is my hobby, I thoroughly enjoy it. That said, I will draw the line at certain things, don't think I'll be installing Alpina wheels anytime soon... Unless I hit the lotto, then it's on. $165 for new and better brake rotor is not going to kill me.

 

I like your thinking. Go for it. If we all sat around saying this or that isn't worth the effort why would we want to ride old air-cooled, pushrod, v-twins