Topic: Brembo rotor

[gsb]

Hi !
I have k2 frame without forks yet. I dont found anymore but I know Brembo rotor was on cb 750 with spoke whell on this forum . I would like to know what model of rotor was used with spacer (320mm)and second it is posible to use forks from Yamaha RD 350 F2 WITHOUT triple trees .I think Turboguzzi has writen about this forks-any experience about how long are they ?
Thanks for help
gsb

[turboguzzi]

if you are talking about my setup, i have stock 500 forks with 275mm suzuki discs and small brembo f05 calipers

Bwaller runs 35 mm RD forks (nicer) that fit straight into the honda triple trees with thinned honda discs and same f05 brembo calipers.

if you are racing, i dont think that this setup will be strong enough for a heavier 750, so going up to 300-320 mm discs is a good idea

of course, if your racing rules allow floating discs you will have more choice of discs, our rules dont allow them

I am not aware of any brembo discs that fit the honda hub.

You might have more answers by  posting in the general forum, quite a few people there do strange brake conversions 

TG

[bwaller]

Actually mine are CB750 forks, but the RD350 forks are the same diametre so you should be able to just use your original triples. You'll need different springs using these on a 750 though.

edit; re fork length, I can't help with RD, but have some notes from a latter RZ350 (80's Canadian model) The length from axle center to top of triple is 30".

[voxonda]

I use lightened, drilled Honda disks with Grimeca 16 m/m main cylinder, Brembo F08 calipers and Ferodo CP211 pads. Like hitting a concrete wall!

[gsb]

Hi !
What about clearence -spokes with f08 calipers ?Are they mount with custom plates on forks.
Do you have some pictures or advice what must be custom build ?.
gsb

[voxonda]

Hey gsb,

Clearances will be minimal with the oem spoke wheel. That is why I mostly use cast wheels, but on my Japauto replica I use spoke wheels. I shaved 1.5 millimeter from the back to have some more space and use thinned Honda disks, so the calipers can come out another 2 millimeter, but............... due to bending of the spokes under load they still tend to touch the calipers. Then spaced out the disks to very close to the legs. Imho the best option is to use wider triples so the legs can come further apart. Problem solved, or use modern calipers which I will not 'cause think they do not belong on these bikes. Brembo, Grimeca, AP racing have some very good calipers specially with good pad material.
I must have a pic of the custom adaptors I used on the K6 fork, but now I only use the 35 m/m of the F2 or the DOHC series. Much better and easier to adapt to calipers.

[turboguzzi]

Hi !
What about clearence -spokes with f08 calipers ?Are they mount with custom plates on forks.
Do you have some pictures or advice what must be custom build ?.
gsb

most guzzi's and ducatis form the 70's had spoked wheels with F08's, so just use the very common grimeca hub from that period and the problem is solved. it has straight spokes that do not bend outwards so has much more clereance

[voxonda]

+1 on TG's response,

Have a Grimeca hub and wheel lying here to replace the Honda hub, to avoid problems.

[gsb]

Hi !
I have read F2 forks are 1"longer  -ca 2,5cm ? Idea with modern caliper -hmm  ,i have option with PRETECH caliper from UK .It was bold on original forks with caliper adapter on original drilled rotor.Caliper had 6 pistons so only one rotor was used.Problem for me will be -i can not certifcate 6piston caliper on 40 year old bike ,so option with Grimeca will be better for me with eventualy F2 forks. I will order new whell with Morad -Akront  rim in Germany -so  where can i find these hubs from Grimeca  or can I use old guzzi -Ducati whell mount new rim and then adapted rotors ?
Thanks gsb

[voxonda]

Hey gsb,

You can find them here:
http://www.discovolantemoto.co.uk/wheels/cat_23.html?page=1

Cheers, Rob

[nippon]

Hello,

I wanted to use spoked wheels, too and I have had the same spoke clearance problem with Ceriani fork and Lockheed brake calipers.
I took a Moto Guzzi hub and made adapter plates from Moto Guzzi bolt circle to Honda disc bolt circle.
Then diameter of the discs has been reduced to 285.00 mm. Now i have 7 mm clearance on each side.

More pics, here:
http://www.classiccyclecity.com/gallery/thumbnails.php?album=52&page=3

and
http://www.classiccyclecity.com/gallery/thumbnails.php?album=52&page=9

nippon

[Retro Rocket]

Nice work as usual Thomas....

[gsb]

Hi !
Sorry for slow response ( work in OP -Hospital) ,but your solutions are great .I think to go classic so
Guzzi or Grimeca hub are the way to go for me .I will use standard 19" whell.For calipers i think grimeca will be fine especialy for 2 rotors.I have a question for Nippon - Are the rotors bold thru  hub ,or each side separatly ,and if I can buy whole hub with rotor adapters for him .Plans will be also fine -I have friend with CNC so there is no problem to fabricate adapters .
Thanks
gsb

[nippon]

Each plate is bolt on seperately. Otherwise it will not work. The bolts for the adapters to the hub are counter-sunk. The bearings are located in the adapter plates. See attached file.
The width of the plates depend on the calipers and fork you want to use.

nippon

[Jim F]

I don't have Brembos on my CR special but I do have RC51 with 6 pot calipers with a GL1000 wheel
I forgot why I didnt use Brembos, but I think it had something to do with the hole pattern from the original hub to the adapter that
I had to make. I put the rotors as close to the inside of the forks as possible but still had to shave some material off of the back side of the
calipers to clear the spokes. but I used 6 pot ZX6 calipers so there was a lot more area that these took up than say original AP calipers or
a single piston caliper...............also made the hangers to fit this package but thats another story
Oh,,,,,,,,,,,, The reason I used the RC rotors was because the RC rotors had 6 holes and 6 holes in the Honda hub so I could space them
in the middle of each hole on the adapter. I think brembos have 5 holes (From a 999 Dukati or a 1098,1198). I had to make the hangers because there was no room after spacing to mount them on the inside of the forks. It looks more chunky this way but thats all I had to work with

Jim

[gsb]

 Hi !
very interesting also -do you use only GL whell or also komplet forks .RC rotors have 320mm ? that will be also elegant for me . How many mm  shaved of on calipers to clear the spokes ? Triple trees are cb750 or also gl1000.?
Thanks gsb

[Jim F]

The whole front end is from a GL1000
I matched the angle of the spokes and machined that same angle on the back of the calipers
Not sure how much I took off but I did break threw to the piston area but just had to weld that back up
and did a pressure check to make sure about the welding
I think there is 4 or 5 mm clearance

[gsb]

Hi !
I like rc51 rotor -only spacer and is done on original hub.I think I can not omit modern caliper -Pretech vom UK
its very slim and also on original forks must be enough clearence to  the spokes .I will contact PRETECH about data how thin is caliper to post here on forum .
Thanks gsb