Topic: Vintage Disc Brakes with Modern Performance - How to Accomplish?

[coyotecowboy]

Yeah, thats right.  Mikes XS has a pretty good selection of masters, and their prices are good too.

[tygrant]

i found a guy selling MCs on ebay pretty cheap like this one, its a 12.7 mm but it loks pretty dam nice for the prices, its even got the switch for the brake light that i need so i can get rid of the presure switch housing. and its an angle resevoir so its better for my clubmans. 3

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=140289374970&sspagename=STRK%3AMEWAX%3AIT&viewitem=

[moham]

I have been following this thread, on a 75 550f, the stock C piston is 38mm, MC is 14mm, that chart if im reading correctly says i should be running at largest a 12 mm MC... not taking into accout travel... is that correct?

I had to read the whole thing a few times to understand it but if you believe what he says, "Single piston calipers are much happier in the 14:1 to 12:1 range" and then find that range on the ratio chart then you're left with an MC of 10 or 11mm. One question: are you sure about 38mm being the stock caliper on the 550? The only reason I ask is I thought that 38mm was the stock 750 size and that 550s were a smaller caliper piston (but I haven't verified that assumption). Look back a few posts to the reply BobbyR got back from the Vintage brake guy. Anyhow, hopefully I haven't muddied the waters.

[Really?]

I'm trying to concentrate on this thread, but Bert's avatar keeps distracting me............... 

NO CHIT!

[bert96]

 

[tygrant]

il just mic my old piston when i get home... its not more complicated than that right?

[moham]

il just mic my old piston when i get home... its not more complicated than that right?

I was flipping through the shop manuals today and saw that the early 750Ks are showing the same MC and caliper piston size up until 77 when (the manual notes) the caliper piston size changed (and I'm assuming the MC size changed as well, though I could not find the spec). It's possible the change occurred prior to that but I couldn't find it in the text. I will say that my K8 caliper piston is for sure bigger than the 550K0 caliper piston I have. Anyhow, maybe somebody with more detailed knowledge of the model timeline changes could verify for us?

[moham]

I recieved a response to my email, I like this outfit. Here is what he wrote:

It all starts with the pads. K0-K5, I have a Borg-Warner race compound that works well on the
street, or the EBC Black. For the later caliper. I have the Ferodo Platinums. After a SS line, the
next biggie is an 10 or 11mm master cylinder, for a more modern leverage ratio.

OK, so having established the need for a 10-11mm MC (for single caliper, old set-ups), where do we source these? So far, I've only found MikesXS as having 10-12+...anyone found any others?

[Joksa]

Cast iron is the way to go guys - sintered pads and cast iron rotors = stopping power in the wet, dry, whatever...

Isn't there a generic rule NOT to use sintered pads with iron rotors?

[goon 1492]

ON watching powerblock yesterday I noticed that the wd-40 truck they are building got the brakes updated with stainless rotors it made me think that maybe the stainless is an upgrade from cast iron.
I will check into this more and get back later......

[moham]

ON watching powerblock yesterday I noticed that the wd-40 truck they are building got the brakes updated with stainless rotors it made me think that maybe the stainless is an upgrade from cast iron.
I will check into this more and get back later......

Here's a snippet from Braketech's FAQ: (edit: here's the link: http://www.braketech.com/index.php)

"MY FRIEND TELLS ME CAST IRON BRAKE ROTORS WILL CRACK AND COME APART, IS THIS TRUE?
Traditional materials and manufacturing methods have kept the door open to problems associated with thermal stress fracturing or simply put, cracking. This phenomenon is primarily focused on the use of gray irons and particularly individual mold casting. That process creates difficult to control porosity problems during the casting procedure. Porosity weakens the structure and reliability suffers. We address this core issue in several areas by spec’ing high grade Ductile Iron, not Gray iron. Then using a computer controlled continuous cast process to produce high quality heat treated iron ingots (giant bars, often referred to as billet). These are then cut into plates with highly specialized saws and CNC machined. The rotors are double disk ground to a tight tolerance and finish to insure flatness and parallelism. This material and method eliminates porosity, creates a homogenous and consistent grain matrix structure that is both very stable and very strong.
See Tech Talk: Ductile vs. Gray Iron

WHY SHOULD I CONSIDER CAST IRON BRAKE ROTORS OVER STAINLESS STEEL?
Over the years, cast iron has proven itself to be an excellent rotor material providing superior "feel" and producing a higher coefficient of friction at the friction couple. If you're looking for genuinely improved performance in terms of both braking power and modulation, then this is for you. If rain and or high humidity is the rule and rust potential a concern, you may wish to consider the alternative in our new AXIS range which is now offered in premium 400 series Stainless Steel as well.

CAN I USE ANY BRAKE PAD MATERIAL ON CAST IRON?
Generally speaking, most organic (semi-metallic) brake pads are good for use on iron rotors. If in doubt, contact the manufacturer for details regarding specific use for this application. Ferodo Platinum, CP911, CP901, 4004F, 3485F, 3410F and I/D450 are all good for this. Although the various sintered metal pads will perform quite well, they generally operate at substantially higher interface temperatures (by as much as 150 degrees [F] at peak). The result is usually shortened life span of the rotor and as such, sintered metal pads are universally not recommended unless specifically denoted otherwise. "

[super pasty white guy]

Some good info at HEL about brakes and performance  http://www.h-e-lusa.com/BRAKE-INFO.htm

Anyone know what typical / maximum operating temperatures are for our brakes, or similar?
I did some searching and came up empty.

spwg

[Joksa]

http://www.ducati.ms/forums/showthread.php?t=30771

[BobbyR]

I have read this thread and also continued writing to the brake supplier. I have come to some conclusions:

Honda was probably conservative when they put a disc brake on a production bike. They did not want people going over the handlebars. Pressures were probably kept low on purpose.

Brake Pad technology has probably improved over the 1960's. Just like the chain alloys.

A SS rotor is the only way to go. Who wants a rusty rotor out in plain site.

I have assembled most of the parts I need for dual disc conversion. I may try upgrading the pads and changing the MC to something more robust.

If that fails, I will go to the second disc.

[moham]

Well, it sounds like we've got some different people trying a couple (slightly) different routes. It will be interesting, in a couple months, to have everybody report back their individual experiences. We've at least, after 7 pages, gotten somewhat closer to answering the OP's question, right? This has been one of the more informative threads I've read/followed lately...

[Terry in Australia]

A SS rotor is the only way to go. Who wants a rusty rotor out in plain site.

Well a stainless steel rotor looks nicer Bobby, but I had cast iron discs on two of my BMW's after the OEM items wore out (both high mileage bikes, as you'd expect) and the stopping difference was night and day!

The funny thing was the surface rust that would form after riding in the rain or even just washing the bike would actually help the braking process, by slightly "pitting" the surface, and providing more friction.

The more I think about it, the more I'm inclined to take a couple of old CB750 discs over to Gyro at Ecco engineering and get him to install some cast iron rotors for my "Endurance Racer" project, they'll look a lot more "period" than some late model discs I'd planned to install. Cheers, Terry.  

[BobbyR]

A SS rotor is the only way to go. Who wants a rusty rotor out in plain site.

Well a stainless steel rotor looks nicer Bobby, but I had cast iron discs on two of my BMW's after the OEM items wore out (both high mileage bikes, as you'd expect) and the stopping difference was night and day!

The funny thing was the surface rust that would form after riding in the rain or even just washing the bike would actually help the braking process, by slightly "pitting" the surface, and providing more friction.

The more I think about it, the more I'm inclined to take a couple of old CB750 discs over to Gyro at Ecco engineering and get him to install some cast iron rotors for my "Endurance Racer" project, they'll look a lot more "period" than some late model discs I'd planned to install. Cheers, Terry.  

Interesting and throws another point to ponder. I did sandblast my rotor a couple of year ago and I think I have better response.
Interesting note, when we do high speed brake test on trains, they run a machine over the rails to clean the rust, since rust increases braking distance. The machine does leave tooth surface.

Merry Christmas Mate

[HondaMan]

 

Boy, am I thick! I never thought of sandblasting the disc to see what it might do for it. I have several, and I'm gonna try it with one. Of course, I can't RIDE with it until the mountains thaw, but I'll have something to drool over until then, at least!

[lordmoonpie]

A SS rotor is the only way to go. Who wants a rusty rotor out in plain site.

Can't agree with you there Bobby - my cast iron rotors, two on the 750 and one on the Bomber look great. The reason is that one made they're galvanised lightly and so the only bit that ever gets rust on it is the swept surface of the pad. All you do is use the brakes to clean them up - simple and they kep looking brilliant and lifting the back wheel whenever I want....

Now if you use plain cast rotors then yes, they can get a bit unsightly, but, the choice is yours - personally I'd rather look a bit untidy and know I'm gonna stop than be the corpse with the shiniest rotors LOL! 

[voxonda]

I agree with the lord here, Have used several combo's on the JAPAUTO replica. OEM disks with K7 calipers and Ferodo pads and a Grimeca 19 mm MC. Does not stop at racepace! Turned down and drilled Honda rotors with Grimeca 40 mm double piston calipers, much better! But now am going to the rusty old cast iron ø300 Brembo's to get some real stopping power, probably go back to 16 mm MC for more feel.
Blasting or even give it a good rub with #80 sandpaper and do not use brake cleaner!!! also give a better response!

Happy days and keep the rubber down.

[Joksa]

19mm sounds quite big for original calipers (38mm?). I am looking for 14mm to go with standard dual calipers.
I also need to get some (steel) discs (laser) cut to my application (GZP 305 wheel in CB 500).


http://forums.sohc4.net/index.php?action=dlattach;topic=32296.0;attach=54110;image

[fastbroshi]

F it, I'm callin' Brembo.

[BobbyR]

The answer is out there somwhere