Breaks :(
 

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!

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

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......... :lol:


PS How much for the P4?

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

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 :-)

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

Of course going fast could be the secret to not wearing your brakes out!!

Although not as fast as Harriet, I also use a single disc. And we both use Vesrah pads, which are absolutely amazing and are the key to longevity and performance. I am just coming to the end of my first set of pads this season, which have the races at Snetterton, Mallory, Oulton, Cadwell and Castle Combe, together with trackdays at Cadwell, Brands and Rockingham without any issues. They would probably last for Cadwell 2 as well, but I'm scared of them falling out when they get too thin...

I get my Vesrahs from Kurveygirl.com in the States, but Harriet will be able to tell you a UK stockist. The Bendix pads are quite good, but wear out too fast. I used a set per race on the 996.

Harriet also weighs approx half the weight of most of us ....:)

2 Questions Matt.

1/ What disc are you using??

2/ What brake fluid are you using??


Chris:burn:

disk theory ???
 

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 :)

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.

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

Kev, your point about the disk rubbing against the caliper might be right.

When fitting the front wheel, I found that it's important to spin the wheel and apply the brakes before the spindle is fully tightened.

IIRC, I'd fit the spindle through the forks and wheel, tighten the pinch bolts on the side where the spindle (wide part) goes through first, (non nut side)then fit caliper, spin the wheel and hit the brakes, this would centralise the disk in the caliper (all being equal). Then drop the bike off the front stand (to ensure there was no force from the stand causing issues) and then tighten the main nut and then tighten the pinch bolts on the nut side.

If that makes any sense?
Tim

Don't you mean:


:lol:

Bit different to how I do it Tim
Once I have pushed the spindle through as far as I can and tapped it home with the nylon end of my prop stand I then do the 28mm nut as tight as I can until it tries to turn, then nip up the pinch bolts on the right fork soo they grip the shouldered end of the spindle. Then I fully tighen the 28mm nut, tighten the pinch bolts on the left (Speedo side) fork. I then undo the pinch bolts previously nipped up on the right hand side. Fit the caliper, pump the brake lever until the pads can stop the wheel spining.

I then take out the front paddock stand. Then with the front wheel on the deck pull on the front brake and pump the forks up and down so everything aligns itself as the right fork can move along the wider part of the spindle, allowing to finally tighten the right fork pich bolts.
Works a treat providing the Spacer replacing the speedo is the correct width and the spindle is in fact straight

Hmmm, now I remember ensuring there was a ferw mm of the axle poking out from the side of the fork leg (not flush) to get the single disk centered up!! It was only after the pads were very low that I had any issues with proximity to the caliper though.

Nah, he was too busy making the tea!!! ;)