320 disc, 6 pot caliper

[Hphenning]

Hey. I'm the proud owner of a double disc XS. Working on a conversion to 320 discs, with 6 pot calipers. The left side is well with a 10 mm spacer, but on the right side, it seems the spokes are much closer to the caliper. So much that I find it hard to even fit the caliper, so it will not touch any spokes. Is there anything about the hub that I misser?? Is the hub different from one side to the other??

 

[arcticXS]

I converted my -77 XS with double discs to a SINGLE 320 mm disc and a 4-piston Brembo caliper, on the RIGHTHAND side.
After a mockup using a 4 mm thich Ducati disc with 10 mm offset, and packing the bolts with washers until I had spoke/caliper clearance, I ended up with 23 mm disc offset being required. I then ordered a custom disc from ISR in Sweden, 5 mm thick and 23 mm offset. This disc and the Brembo caliper is a tight fit, maybe 2 mm clearance between spokes and caliper, and the same between fork leg and disc.
If you are using a 4 mm thick brake disc, a 12 mm thich spacer would be enough, when using the same Brembo caliper as I did. You don't say which calipers you are using, or the measurement from caliper/disc centerline to inside surface of caliper.
In any case, perhaps you should consider using only one disc? I am fairly sure that a single 320 mm disc, a 6-piston caliper and a well matched master cylinder will be a vast improvement over the stock twin disc setup, and a lot lighter as well!

 

[Hphenning]

Hi. A 5 mm ebc wave disc, and the 6 pot comes from a Suzuki Hayabusa.
I started of on the left, which was "easy", so therefore I am pretty confused about the left side. Is the hub sides different, are the spokes different, what what what did I miss.
Maybe sticking to only 1 disc will be the answer. Thoughts has been there onde once before before.

 

[arcticXS]

As I said, I did the RH side, ending up with a custom disc with a 23 mm offset and 5 mm thickness. I assume you are using a "Ducati spec"disc with 10 mm offset, since you mention a 10 mm spacer.
So if your front wheel, as well as mine, is running straight and true, it looks like the hub is offset a little bit to the right, relative to fork legs and rim.

I decided to fit my single disc on the RH side, as I also have a custom spoked disc brake rear wheel, and the RH side sort of is the "good side" when a bike is on the side stand, showing off both upgraded brakes......

The ISR disc I have, with 23 mm offset, requires no disc spacer. It weighs around 1550 grams, and has the "anti rattle" configuration recommended for street use. An ISR race disc will rattle over bumps, but weighs 100-150 g less.

And with regards to brake performance, one of my Ducatis has a single 320 mm ISR disc, stock Brembo 4-piston caliper and EBC Green pads. This is a 2-finger brake capable of making a modern 120/60-17 radial tyre squeal...So a single 320 with a 6-piston caliper should be more than enough for a skinny 19" bias ply tyre.

 

[retiredgentleman]

Hey. I'm the proud owner of a double disc XS. Working on a conversion to 320 discs, with 6 pot calipers. The left side is well with a 10 mm spacer, but on the right side, it seems the spokes are much closer to the caliper. So much that I find it hard to even fit the caliper, so it will not touch any spokes. Is there anything about the hub that I misser?? Is the hub different from one side to the other??

On my 1978 SE, and probably on other years as well, the wheel does not mount in the centre between the forks, as one might assume. That means the left disc and the right disc will have different dimensions when measuring from the forks.

2 front discs with each having 6 piston calipers is ridiculously way overkill. I use a single stock disc with a Brembo 4 piston caliper and its the most braking you could ever possibly use. The extra weight of the second disc/caliper is just a negative to bike handling.

Yes, I know you want that "racing" look, but you're better off with just a single disc on the front, especially if you use a 6 piston caliper.

 

[Hphenning]

Ok. Thank you.
The 6 pot thing is, as you correctly assume, just for the look of it.
Think I'll start of with the one disc only. Summer is knocking on the door, so it wants, demands, to be ridden.
Maybe I'll be satisfied with the look with only one disc.
Otherwise I know what to do next winter ;-)

 

[Hphenning]

So there it goes with one disc

 

[tonyc]

It looks just fine. As R.G said the second disc is not needed.

 

[arcticXS]

Yes,
A single 320 is more than enough, as long as your master cylinder is matched to the caliper. A standard XS master for a twin disc setup, as well as the Hayabusa master will be too big for a single caliper, even a six piston one. What piston diameters does your caliper have?