Topic: CR750 brakes - opinions

[livefast_dieold]

mhhh... nice solution but those are not standard fork legs, neither he is using spokes wheels. So maybe he has some extra room here and there.

[bwaller]

Can't help with AP's because I'm using the small Brembo F05's. They had to be relieved to fit.

Tim V is going through mounting a larger Brembo F08 on a 750 hub & spokes. He's spacing the rotors away from the hub to help clear. I'll ask him to jump in here.

[TimV840]

Yeah, I need help too Brent! 

So far, I have just laced up this CB750K hub with Buchanan SS spokes to a 1.85 X 18 Akront-like flanged wheel. Brent suggested using a front rotor from a GS750(it's lighter, and thinner(5mm)), which needed some minor milling to fit the CB hub. I bought a Brembo F05 caliper to try, but since I have a newish *11mm* Brembo master cylinder, I thought the bigger F08 caliper would work better(according to Vintagebrake.com's chart). On paper, it's still not ideal, but better. That F08 is HUGE though. I'm still tinkering, but I think I'll be possibly machining the inner lower fork leg(CB550) for more room plus making a spacer between the rotor and hub. Then, I have to make up a bracket....found a few good ideas in this forum, thanks to Brent. Hopefully I can play with this later this week or on the weekend.



Are all the CB disc hubs the same width?

BTW, this is going on a new CMR custom framed 350 twin road racer. Should be just under 300lbs wet, so maybe that F05 with a smaller(10/11mm) bore m/c should be looked at. Or another new set of wider triples...

Wish I could help more.

TimV

EDIT : Here are a couple photos to show the size difference.

[livefast_dieold]

Thanks!

The solution with the GS750 disks seem quite interesting, I've a pair of F05 calipers at home, but I'm wondering if the 08 will be better.
Can you use sintered brake pads with the suzuki disks?

Any other calipers I should take a look into?

[bwaller]

I can add for a 145kg bike two F05's are certainly more than adequate, but on a heavier bike larger calipers might be wise. I used those thin Suzuki rotors on a street bike because they're much lighter. Turboguzzi then used them on his racebike. He used CP211 pads with those rotors so no problem. These are only 276mm though so again maybe a mismatch??

[turboguzzi]

i never seen the f05's on anything bigger than 600cc (and light 600's like pantha's..) i think you really need f08 with thicker discs on a cb750 that will weight around 175-180 kgs....
i have the GS 280mm discs on my 500. too thin for a 750 IMHO.... you need more heat sink/metal mass with +40 kg more....
300mm discs could help you get away from the spokes, but at the end, the only solution will be new fork triple clamps so that you can put the discs further away from the spokes. stock sohc triples have no room.
cant see any cheap and simpe solutions right now, sorry....
look at any spoked wheel with f08 or lockheeds and youll see they have wide spaced fork legs and discs

[livefast_dieold]

I'm doing the measurments, let's see what can I do...

Why do you think GS disks are too thin? They were made for a 750 as well

[livefast_dieold]

Any suggestion on a completly different fork?

[turboguzzi]

I'm doing the measurments, let's see what can I do...

Why do you think GS disks are too thin? They were made for a 750 as well

750 street bikes from that period were seriously underbraked, specially in track use.... see your CB that's why these UP-grades are needed...
in my gpz 750, the stock 280mm discs just didnt work, had to go up to 300mm after first season (and quite  few missed braking markers!) 

[livefast_dieold]

I've probably found a solution, using a moto guzzi 850 T5 front fork. Fork diam is 40 mm which is not bad :-)

[turboguzzi]

sounds good
also the grimeca hubs that were used on old guzzis had very narrow spokes spacing to allow clearance to the big 08 calipers....
just check the 2015 rulebook, last time i saw it fork diameter limit was 38mm...

[livefast_dieold]

I'll see if the honda wheel fit properly.

They have increase fork diameter to 42 mm in the new rulebook!

[bigalk4]

I use standard honda forks with home made brackets, you have to machine some material off back of fork leg , will be working on bike next weekend prepping it for new race season , will post more pics and info if needed

[scunny]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

yes please, more pics of that lovely machine

[SOHC4 Cafe Racer Fan]

I use standard honda forks with home made brackets, you have to machine some material off back of fork leg , will be working on bike next weekend prepping it for new race season , will post more pics and info if needed

Can you make me a set of those mounts, or at least share the drawings/specs so I can get some fabbed.  I am mounting the same AP Racing calipers to a pair of forks.

[01Thomas]

No to hijack the thread, but I have a pair of F08's for sale if anybody here is keen?

[754]

Do you guys have to run wire wheels? I know of a mag that has more clearance than spoke wheels, and comes in 18 and 19 inch..

[Artracing]

I wanted to open this topic again because I am having the same problem. Getting Brembo F08 to work with
spoke wheel, I  have 18 inch front shoulder rims. GP35 forks with Ceriani triple tree.
Looks like shimming both disc out will just miss. Shaving/Milling the back side of F08
would help a lot. I bought new Ceriani triples and would hate to swap them out for wider ones.
An further developments on this topic.

Rob

[slikwilli420]

I use standard honda forks with home made brackets, you have to machine some material off back of fork leg , will be working on bike next weekend prepping it for new race season , will post more pics and info if needed

Can you make me a set of those mounts, or at least share the drawings/specs so I can get some fabbed.  I am mounting the same AP Racing calipers to a pair of forks.

Don,  I could help out with that. I'd be happy to brainstorm on some designs. Won't be all 21st century CNC but I'm sure we could do something cool.

[slikwilli420]

I wanted to open this topic again because I am having the same problem. Getting Brembo F08 to work with
spoke wheel, I  have 18 inch front shoulder rims. GP35 forks with Ceriani triple tree.
Looks like shimming both disc out will just miss. Shaving/Milling the back side of F08
would help a lot. I bought new Ceriani triples and would hate to swap them out for wider ones.
An further developments on this topic.

Rob

You need a wider spread on your triple trees. If you can get me a usable stem I can help with the rest. See the link in my signature.

[Artracing]

I wanted to open this topic again because I am having the same problem. Getting Brembo F08 to work with
spoke wheel, I  have 18 inch front shoulder rims. GP35 forks with Ceriani triple tree.
Looks like shimming both disc out will just miss. Shaving/Milling the back side of F08
would help a lot. I bought new Ceriani triples and would hate to swap them out for wider ones.
An further developments on this topic.

Rob

You need a wider spread on your triple trees. If you can get me a usable stem I can help with the rest. See the link in my signature.

Thanks for the offer.
I need to keep the Ceriani triple tree. I did a mock up yesterday. Bad news. The F08 are way to big/ fat.
I shimmed out the disc about 5/16 , well beyond the fork edge, and they still hit the spokes. Taking 1MM shave off the back wouldnt help either.
My wheels are not mag wheels, so I can't say it would work on them.
I wanted F08 just for vintage period.  I would have liked the Fontana, but I think they are similar to AP , and I assume
I would have the same problem.  I'm trying a set of P34 off a 94 Ducati 900SS today.

Rob

[slikwilli420]

I wanted to open this topic again because I am having the same problem. Getting Brembo F08 to work with
spoke wheel, I  have 18 inch front shoulder rims. GP35 forks with Ceriani triple tree.
Looks like shimming both disc out will just miss. Shaving/Milling the back side of F08
would help a lot. I bought new Ceriani triples and would hate to swap them out for wider ones.
An further developments on this topic.

Rob

You need a wider spread on your triple trees. If you can get me a usable stem I can help with the rest. See the link in my signature.

Thanks for the offer.
I need to keep the Ceriani triple tree. I did a mock up yesterday. Bad news. The F08 are way to big/ fat.
I shimmed out the disc about 5/16 , well beyond the fork edge, and they still hit the spokes. Taking 1MM shave off the back wouldnt help either.
My wheels are not mag wheels, so I can't say it would work on them.
I wanted F08 just for vintage period.  I would have liked the Fontana, but I think they are similar to AP , and I assume
I would have the same problem.  I'm trying a set of P34 off a 94 Ducati 900SS today.

Rob

Is it a "need" or a want?  I can approximate the Ceriani shape while giving you a wider spread which will allow you to use the parts you want. Those front end are way too narrow to work with CB wheels which is why I got away from the stock trees.

[754]

The Ceriani top tree has a lot of height.. Hard to make a billet one look even close..
 Are you firmly stuck on wire heels .. I know of a mag that has the MOST clearance..and they are reasonable.. And come in 18 and 19 inch

[turboguzzi]

I wanted to open this topic again because I am having the same problem. Getting Brembo F08 to work with
spoke wheel, I  have 18 inch front shoulder rims. GP35 forks with Ceriani triple tree.
Looks like shimming both disc out will just miss. Shaving/Milling the back side of F08
would help a lot. I bought new Ceriani triples and would hate to swap them out for wider ones.
An further developments on this topic.

Rob

very easy to solve ducatis and guzzis from the period had 08s AND wirewheels..... simply use the grimeca hub that has very narrow spacing width wise between spokes. of course that at this point you need different discs....
the picture is missing the bearing/disc carriers

[Artracing]

I wanted to open this topic again because I am having the same problem. Getting Brembo F08 to work with
spoke wheel, I  have 18 inch front shoulder rims. GP35 forks with Ceriani triple tree.
Looks like shimming both disc out will just miss. Shaving/Milling the back side of F08
would help a lot. I bought new Ceriani triples and would hate to swap them out for wider ones.
An further developments on this topic.

Rob

You need a wider spread on your triple trees. If you can get me a usable stem I can help with the rest. See the link in my signature.

Thanks for the offer.
I need to keep the Ceriani triple tree. I did a mock up yesterday. Bad news. The F08 are way to big/ fat.
I shimmed out the disc about 5/16 , well beyond the fork edge, and they still hit the spokes. Taking 1MM shave off the back wouldnt help either.
My wheels are not mag wheels, so I can't say it would work on them.
I wanted F08 just for vintage period.  I would have liked the Fontana, but I think they are similar to AP , and I assume
I would have the same problem.  I'm trying a set of P34 off a 94 Ducati 900SS today.

Rob

Is it a "need" or a want?  I can approximate the Ceriani shape while giving you a wider spread which will allow you to use the parts you want. Those front end are way too narrow to work with CB wheels which is why I got away from the stock trees.

It's a want but it appears that I will have to change the tree. Which pisses me off. I clearly asked questions to the supplier on this configuration. He obviously lead me down the wrong path to make the sale. The CB is a little out of my wheelhouse, so to speak, so I relied on the supplier, without doing research.  If I knew I had to do my own engineering I would have taken a different approach. Normally I do my own engineering.
Since my front and rear wheels are already done. New shoulder rims, new spokes, modified hubs, drill and reground disc, larger front axle and new bearings to match, mounted tires. Already to go with new triple tree and new racing forks.
I was lead to believe, all I need is to design disc shims and caliper mounts, run them on my CNC and I'm done.
Gggggrrr.
Send me PM  we will talk.