Ducati Sporting Club UK > DesmoDue Race Series > DesmoDue - General Questions and Chat > Breaks :(

[mat2hew]

Just a follow up on the single/twin disk thing I did 3 or 4 races ago, I managed to get a p4 break calliper and decided to go to 1 disk for the weight saving,, many people said "DON'T BE STUPID!" But me being me did it any way. since then I have crashed, pulled out of races coz the breaks wern't working after boiling the fluid and used 3 sets of pads which cost £50 a set! Castle Combe totaly destroyed a new set of pads (which I have still got to pay chaz for... I'll run over and see you first thing in the morning at Pembry, sorry)

So... I'll be going back to the twin disk set up with my old heavy calipers for Pembrey.

Matt #72

p.s. I do listen to everybodys advice, even if I then decide to learn the hard way... Please, Please keep it coming!

[Ray]

Just one suggestion, Use castrol SRF fluid, about £50 a litre but yer disc will be glowing red and the seals on fire long before the fluid gives up.

Never ever had a fluid related problem using it on two wheels or four.

Ray

[paynep]

What master cylinder are you using, 'cos Rattler used a single P4 on his 620 and it seemed to work for him?

Mind you he tended to use his collarbone to stop.........


PS How much for the P4?

[mat2hew]

You can have a look at it if you want, but I think it is broken!

[Fastfasulli]

Hi, I find your story surprising. I have been running P4's (currently with the Lucas pads in - from Chaz), 916 master cylinder, single disk, standard issue (free) shell brake fluid and had no pro blem with brakes at all. I ran consistently in the top 10 last season and had no brake problems in the rounds that I have attended this year. I have also run Bendix pads and had no issues.
Maybe I'm not going fast enough :-)

[Ghost]

Harriet runs a single disk, she is going fast enough.

[chris.p]

Originally Posted by mat2hew

since then I have crashed, pulled out of races coz the breaks wern't working after boiling the fluid and used 3 sets of pads which cost £50 a set! Castle Combe totaly destroyed a new set of pads Matt #72

2 Questions Matt.

1/ What disc are you using??

2/ What brake fluid are you using??


Chris

[rossco572]

Brake disks all have various different designs and shapes to suit all different kinds of usage but a theory that i discussed with Ghost when he had simmillar pad usage problems was that the edges on the cut aways on his discs were knife edged and not chamfered, therefore every time the brake was applied, the pad wear was accellorated. it may just be worth going over your disc and using a dremmel with a small grinding stone chamfer all the edges that come into pad contact and see what effect that has on pad life? hope this helps

[Rattler]

As Payned said above, I ran single disk with P4 for almost a couple of seasons on my 620. I found that pad wear was dreadful until I found the right combination of pad / disk.

The brakes were plenty good enough and really improved the turn in of the bike and reduced unsprung weight massively.

[skidlids]

One of the main ideas behind wavey discs was that they clean up the surface of the pad everytime you apply the brakes, hence higher pad wear but no glazed or contaminated pad surface.

Dallas also runs single disc with a 4-pad caliper, gripping on a SPS cast fully floating disc and connected to a 16 X 18 brembo radial mastercylinder, seems to work fine for him and pad wear is pretty good. Brembo pads I think

From what I could see at Combe it looks like Matt Lawsons disc isn't centred in the caliper and looks like it has been brushing aginst the protruding casting of the caliper designed for the pad to sit on.

I did mention to him about checking the thickness of the speedo spacer.
I had a similar froblem at the first ever DD race meeting back in 2005 and crashed out of the first race with brake failure and pulled out of the other two races when the lever went soft and almost came back to the bars. On each occasion the brake worked fine after it had cooled down. In my case it was the captive threaded boss in the early forks not recessing far enough, so I counterbored the fork a bit deeper and cured the problem ready for the next meeting which was Castle Combe, where they worked fine even if I did only manage a 1m 29.2s best lap.

Another cause of this can be a bent wheel spindle, the later hollow ones are quite prone to bending in a crash and then cause the Disc to run slightly out of line with the caliper.
New ones cost £52 I know this as I have recently bought two