Front Brake rotor

[Mikep328]

Last year I posted a thread re my efforts to improve my '76 400's front brake from useless (rear had more stopping power) to "good."  I was pleased with the results and have been happy with the brake performance.  No, it won't do stoppies!

Recently a friend (in the US) has suggested that for even better brake performance, a "modern" disc rotor would bring greater improvement.  He does a lot of restoring and opines that current brake rotors have a better coefficient of friction than '70's rotors and thus, better feel and stopping power.  This is due to improvements in the rotor material.

As I have stated, my CB400s brakes are good for normal use with no need for "advanced planning" for braking.  OTOH, they do not have the feel/grab of the brakes of, say, the current CB500 I have rented/been riding for a week on the Isle of Man (for the manx GP).

 So, based on his suggestion, I am ordering the DSS rotor!  It's a rather expensive "experiment" that could end up improving nothing.  If that's the case, he won't hear the end of it!  I have three different sets of pads to try.

I'll report the results here!

[Johnwebley]

What material is the DSS rotor made of??



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[AshimotoK0]

I seem to remember that the 1st production British  bikes with disc brakes fitted  had cast iron rotors. Think Honda's were stainless steel...unsure what grade of SS though.

[Bryanj]

Hondas are stainless and the Triumph discs were chromed cast iron.
I fitted a cast iron disc to my 500 back in 76 and found dry weather braking no different but wet weather so good it locked and threw my off, i put the stainless back on

[Laverda Dave]

My 1976 CR750 Honda Rickman has cast iron rotors with Lockheed calipers, amazing stopping power but they do rust at the slightest hint of moisture. Same applies to my 1982 Jota, cast iron drilled rotors with Brembo brakes, very impressive braking but again, will rust very easily and will actually seize the disc to the brake pads!

[Mikep328]

The DSS rotor is (per DSS) "cast iron and steel."   Out of curiosity, I cleaned it with brake cleaner and spritzed some water on it and there was no rust the next day so whatever it is, it is at least LESS prone to rusting than solid cast iron.  My cast iron brake rotors on other bikes will begin rusting if they just hear the word "water!"      

I installed it this morning, no issues at all.   It took maybe 20 minutes from start to finish.  I didn't have my riding gear with me so bedding-in will have to wait for another day.  I decided to leave the Versah pads (new last year and only around 100 miles on them) to see how they work compared to the OEM rotor.  I also have a new set of DSS organic pads and a set of Brembo ceramic pads.  So if the current pads don't strike my fancy I'll try the others to see which ones have the best feel/power with the new rotor.  Of course, I may find that I wasted money on a rotor! 

[Mikep328]

Went out today to bed-in the existing Versah pads with the new DSS rotor.  It would be more correct to fit brand new pads but I was specifically interested to see if I could tell any difference with the only change being the rotor.

 I used the same break-in procedure (posted by Oddjob) I had used when I did my prior brake work late last year.  Upon completion of break-in, the brake was a bit better than before the rotor change.  Of course, the question is, is it £200 better (price of the DSS rotor after VAT/shipping)?  Well, I can "howl" the front tire with the brake and although I didn't try, I'm confident that based on the pressure required to "howl," I believe I could lock the front wheel which I definitely could not previously.  BUT the difference is not dramatic and did not turn the brake into being capable of a two finger "stoppie".  The work I did previously (with the OEM rotor) made the brake quite good - comfortable for any normal riding that I do. 

So, is it worth £200? Hey, any reduction is stopping distance could be the difference between a crash and not.  Looking at it that way, since £200 will barely cover the cost of a dinner/drinks for two at a decent restaurant, I could argue that the rotor is worth skipping one of those dinners!  BUT I hoped for more based on a friend's raving about how much better 'ALL' new rotors are better than old ones and my conclusion is that it is not worth £200 as a performance "upgrade" over an OEM rotor. 

NOTE that DSS does not claim that it is a performance upgrade over the OEM disc - it is stocked as a replacement rotor and it is very nicely made/machined/fits perfectly!!  So if you need to purchase a rotor, I would absolutely recommend it...and you WILL get a bit better performance over the OEM! 

[andy120t]

Is that the same as a front brake disc?

[McCabe-Thiele (Ted)]

That's a shame that to date the brakes only feel marginally better.
I would not be surprised if they might improve after 400 or so miles.

My 400 brakes are fitted with Brembo Carbon/Ceramic they have only done 200 miles since fitting them - each time I ride it they feel slightly better.

I have the same pads in my 500 that has barely done 15 miles - so far they are pretty poor - early days for sure.

[McCabe-Thiele (Ted)]

Is that the same as a front brake disc?

No, discs are under the front Mudguard - rotors are under the front Fender.

[K2-K6]

interesting outcome and good comparison.

I find, on all type of material for both pads and disc, that using brake cleaner on the friction surfaces takes longer than you'd think to dissipate. They really don't show their best until properly burnt in and up to full potential.

Certainly worthy of more time in running them, also sticking as much heat into it as practically possible to make sure they "clean" up before a full judgment.

[McCabe-Thiele (Ted)]

On my 500 I used Meths on my front Discs applied with 1000 grit,  so far a complete waste of my time it's made no difference.👎

[Mikep328]

Being naturally curious, today I removed the Versah pads, cleaned the rotor with brake cleaner, installed organic (DSS) pads and went out did the same break-in.   I don't know if this would apply to any organic pad/this rotor or not but the result was that a good brake with the Versah pads became an unsatisfactory brake with the organic pads - less initial bite and a lot more pressure required to get less stopping power/much greater stopping distance.  Totally unacceptable.

Tomorrow I'm going to do the drill again, this time with new Brembo ceramic pads.  If they aren't at least as good as the Versah pads, I'll reinstall the Versahs and bed them in (again).

[K2-K6]

Being naturally curious, today I removed the Versah pads, cleaned the rotor with brake cleaner, installed organic (DSS) pads and went out did the same break-in.   I don't know if this would apply to any organic pad/this rotor or not but the result was that a good brake with the Versah pads became an unsatisfactory brake with the organic pads - less initial bite and a lot more pressure required to get less stopping power/much greater stopping distance.  Totally unacceptable.

Tomorrow I'm going to do the drill again, this time with new Brembo ceramic pads.  If they aren't at least as good as the Versah pads, I'll reinstall the Versahs and bed them in (again).

Definitely interesting to hear your experience with straight comparison of materials Mike.

From trying many brake pads in different vehicles and use profiles over the years, I'd agree with your observations of these two so far. Quite different in character aren't they!

Ceramic pads, I feel are generally consistent often without a potent initial bite, linear build up of braking effect with  increasing line pressure, may need more absolute mastercylinder pressure to capitalise on the far reaches of friction.

Emphasise (think I noted before) that it takes longer than many think to clear disc cleaning effect and develop fully the pad's ultimate potential.  Much heating often needed through harsh applications 

[Mikep328]

We plan on a ride tomorrow - maybe I'll leave the DSS organic pads in place and put more heat into them, see how they feel when I get back home. 

FWIW the Vesrah pads are, per the label also "organic."   Vesrah describes them as: "Vesrah Organic - Japanese brake pads made from metal alloys, a blend of carbon-kevlar, and many other components." 

There are dramatically more visible "metal particles" in the Versah organic pad as opposed to the DSS organic pad.