Way to shiny.

V

Vince

Hero member
Every few years I get stuck in torrential rain and I lose a huge percentage of my front brakes. Its been suggested I need to deglaze them and I had a look today. I couldn't believe how smooth and shiny my original 280mm discs are, they have a mirror finish. I hear green scourer pads are the go to sort this and then brake cleaner spray. Never done this ever, always do the rear drum when it gets a tyre.
 
??????? Deglaze the pads ok, but not the discs.  Shouldn't need to though, you've got 4 spots, the old 08's are shit in the wet.

A couple of hard stops will de- glaze the pads. Scourer on the discs makes no sense
 
we used to have to deglaze the discs with scotch pad and water then air line off, on endurance racers a few years ago (not Laverda's) it did seem to work well, and did no damage six hour national class series it was.
CLEM
 
My front brake works well most of the time, that's 4 spots on 280mm std 3c discs and a 16mm remote reservoir master. Lately, they have lost a tiny amount of initial bite, probably need a full fluid change and bleed. Its in flooding rain that results in massive fade that I would really like fixed. There is plenty of lever resistance but not much stopping when that happens and I DONT like that.
 
Are your discs solid or drilled? I had the discs on my 3C drilled, it seemed to help although I can't say that from recent experience.

cheers,

bazzee

ps for a truly terrifying experience try riding a Triumph Trident T160 with original chromed steel brake discs (front and rear) in the rain. What on earth made them think that chrome plating cast iron discs was a good idea.
 
I fitted four pot callipers, (ten years ago) but I also thought it wise to fit discs that those callipers are routinely run on, and got some 320mm ones from a fleemarket in Italy, a bit knackered but OK for a test (I re-bushed them later and have also bought a brand new pair as spares) I also (eventually) fitted a master cylinder that those calliper's are routinely used with, although the Kawasaki Z750 one I bought for fifteen quid worked very well for ages, and all is good wet or dry, I doubt that you can buy pads for the four pots that will work well in all conditions with antique cast iron discs, and they are so bleeding heavy! put the Brembo's back on.
CLEM
 
I'm wondering if fitting four pot calipers has something to do with the glazing.

Most of the time on a road bike, your braking is quite gentle. You're not hauling on the anchors 100% all the time like you do on the race track. The larger pads in the 4-pot calipers means a lower pad pressure for the same braking effort than the smaller pads of the 2-pot calipers. Over time, the low pad pressure might tend to polish the disks more than if they were grabbed harder by the small pads.

It's the same principle with cylinder bore glazing in an engine that's only ever run at partial load.
 
Interesting postulating Cam. Given Vinces meeger 125kgs and 240kgs of bike, I reckon his brakes aren?t exactly used to pull up a partial load. My ZXR, triple pots, have so much bite, I can hear them making contact from the slightest pull on the lever.

I?m leaning toward the little 280mm dia rotors being the culprit.
Add 40mm dia and see what happens Vince.
 
Upgrading to 300mm discs is a huge step, going to 320mm is gigantic!  Reckon the weedy stock forks will be seriously overwhelmed.

The stock 38mm Marzocchi on my RGS had a hard time with 300mm Suzuki discs and Brembo 4-pots.  The M1R now copes well with the slightly larger 310mm discs, even these brought about a noticable improvement in brake performance.  I'd never go back to cast iron discs, stainless steel works so much better under all conditions, given the right brake pads.  Lucas/TRW carbon/ceramic compound pads work great, last well and don't chew up the discs unduely.

Something that is often over-looked in regard to cast iron discs, is that once deep surface rust has set in, this must be removed entirely to restore proper performance.  If left to be rubbed off by the pads, only the soft outer part of the oxidation will wear off, leaving a tough, darkish layer that has a miserable friction coefficient.  Not only is dry performance poor, but wet braking is almost non-existant.  Cast iron discs need to be shiny!

piet
 
Im running original cast iron discs (very shiny, ) steel braided lines, new ceramic wotsit pads from paddy, and a Grimeca m/ c on my Jota. It really is quite enough, no need to risk overwhelming the forks..or the frame(Clem😉) mind you, cant deny the ridiculous engine and stopping power of mySP1 on a spin last night wasnt fun.
 
Talking about discs and brakes... my ?new? Laverda 1000/1 was abandoned for 20 years, so the discs are rusty but in good condition (thiknesswise), is it possible to recover them? What would be the best way to remive that rust?
Miguel
 
michipons said:
Talking about discs and brakes... my ?new? Laverda 1000/1 was abandoned for 20 years, so the discs are rusty but in good condition (thiknesswise), is it possible to recover them? What would be the best way to remive that rust?
Miguel
Click to expand...

A set of brake pads and some spirited riding.
(If you really wanted to, you could give them a wire brushing to shift any loose stuff beforehand).
 
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