M695 single disc alignment problem

[cencalal]

To save some weight I'm trying a single disc/caliper front brake.  Found the smaller master cylinder from a single disc 620.  Got a Ferodo FMD0147RX rotor that fits several Ducati models - aluminum carrier, correct bolt pattern, 320mm dia., 15mm offset.  Then a Brembo 65mm 2-pin caliper (20.6713.00) that measures 32mm from it's center line to the mounting surface at the fork.  It looks just like the one for the 748, 996, 998, but is from a Polaris/ Victory bike, and is dark grey instead of gold.  I end up with the caliper about 2-3 mm inboard of centered on the rotor.  Did I buy the wrong part?  These Brembo calipers are on BMWs and other makes and are cheaper than those listed on ebay for Ducatis - do they have different offsets?

Thanks

[stopintime]

Don't know about the caliper, but the normal disc offset is '10 mm'. I quote sign the 10 because it's not actually 10 however you measure, but still called 10.

Sure the axle spacers are correct and where they should be?

[cencalal]

Axle spacer is as it was and wheel is centered - forgot to mention I have the adjustable Showa forks from an '05 M1000S, which were fine with the OEM two piston calipers and zero offset rotors.  I don't think a 10mm offset rotor would work - it would be too far in the other direction.

[stopintime]

If so, we're back to the caliper...

[cencalal]

Measured again, looks like 10mm offset rotor is what I need - and some new glasses.   

[stopintime]

This is what I wrote about the offset:


About the 10mm offset rotors..... I went back and copied something i put together about the offset - it's not actually 10mm. This is not meant to confuse you - just showing you the reality, so you don't get confused if you start measuring. AFAIK, everyone call them 10mm even if they know they're not. It's just easier.

Offset is a strange story. The rotors I used are the ones commonly referred to as "10mm offset", but they are not actually 10mm. They are 5mm, 7mm, 9mm or 11mm depending on how they are measured.

5mm - on a table, outside up, measured from table to inside of rotor
7mm - as above, but measured to the middle of the 4mm thick rotor. This is how Brembo does it.
9mm - as above, but measured to the outside of the rotor
11mm - as above, but including the buttons

http://www.ducatimonsterforum.org/index.php?topic=44464.0

[cencalal]

Thanks for that.  I'm doing the opposite of what most would do - going to a single front brake.  I'm light (140) and so is the bike, and it looks like this is going to save 4-5 pounds.  The stock brakes with sintered pads have been fine for my needs, but I like to tinker.  Makes it easier that none of these brake parts are proprietary sizes - the rotor is used by lots of makes, as is the caliper - Moto Guzzi, Aprilia, BMW, and I wanted the grey color that you don't see much on Ducatis.  (Looks good with my grey hair  )  Got the M620 13mm master cyl so that it matches my clutch master.  

[stopintime]

16 mm master is more than usual for one caliper.

[cencalal]

Corrected - meant to say 13mm.  If this works out well I'll put up a few photos.

[thorn14]

I would definitely do 15/16mm master. My bike started out with the stock master as a single disc and the single most noticeable upgrade was swapping for a 16mm master. I used an R6 radial master because it was Brembo and wouldn't be out of place.

[ducpainter]

I would definitely do 15/16mm master. My bike started out with the stock master as a single disc and the single most noticeable upgrade was swapping for a 16mm master. I used an R6 radial master because it was Brembo and wouldn't be out of place.

Some people like the additional power a 15/16mm master provides, but many don't like the loss of feel with the larger master.

The same holds true of upgrading to a radial master on dual discs. All the power, and none of the feel.

[thorn14]

True.

A tradeoff I was willing to make because I was keeping it single disc and was not comfortable with the poor braking performance stock under aggressive riding. Over time I also moved to a 4p4p caliper, braketech iron rotor, and an assortment of pads.

A 15mm would be the sweet spot.