Topic: Aftermarket brake calipers

[longshanks]

I was wondering if you guys knew of some good aftermarket calipers, preferably dual-piston, that will fit directly onto a front cb750 K6 disc. The PO cross drilled the rotor and put a Kawasaki dual piston caliper on it but its much too small and only grabs about half of the surface area of the rotor. Plus it squeals right now and I noticed that the pads are perfectly parallel with the disc. Not to mention, one of the pads is missing half of its brake material. 

I suppose I could put the stock Honda caliper back on but it seems that people always have issues(pistons gumming up, rust) and since I have a slotted rotor why not go dual piston and add SS lines in the future? 

Or should I go a step further and go dual disc and are there significant benefits to this??

[Bankerdanny]

unless you are racing or do a lot of two-up riding I don't see why the stock setup wouldn't be sufficient? Could they be stronger? Of course. But using a caliper setup from another bike seems like a recipe for get worse brakes not better.

Based on your description of how the caliper fits now I can't believe that you are getting better than stock brake force.

I have a lighter 550, but this Sunday I spent the afternoon with a passenger (first time ever with a passenger for any length of time). I weigh 230 by myself, so with my friend we were easily 400+ pounds and my single front disk/drum rear had no issues at all stopping us.

[lone*X]

There have been several threads over the years on adapting different calipers to the SOHC's.  All required unique machined adapters to fit the stock forks, and properly sized master cylinders to actuate them.  A lot of trouble.  I would go back to a stock caliper and MC and make sure it was all properly rebuilt, and use stainless brake lines to tie them together.  If you must have increased braking on the front find a GL1000 front end and swap the whole thing in for dual disc brakes and a properly sized MC.  "Probably" a lot less work and expense.

[longshanks]

It stops really well actually even though my front shocks "dive" a bit.( Time to rebuild )
Right now I feel like it stops better than the stock caliper because its a dual piston but I don't really feel its necessary and I don't really want to wear and outside edge on the rotor because its not sized correctly.

[lone*X]

If you can, how about posting a picture of how the Kaw caliper is mounted.  Also, what MC is it using?  Just curious.

[Hannibal Smith]

Currently machining adaptor etc. for my CB550 using a Brembo P08 setup-this is what I am dealing with here.

1- The swept area on the stock disc is "huge" (tall) and most, if not all dual piston calipers run around 40mm at the largest, where stock disc is minimum 45-47mm, so in a nutshell, you will have acres of unused disc if you combine dual piston caliper with the stock disc.

2- Caliper body clearance- I am running a custom 24mm offset carrier, and my caliper body is running as close to the spokes as possible (few millimeters)-you only have so much space to deal with, basically you will be looking for a caliper that does not exceed 25mm from pad to backside of caliper, and this is disc diameter dependent.

3- I am going to run a 300mm disc for the clearance, anything smaller, and the system won't fit (with my P08 caliper).

Anyway, I used to do this stuff for a living many years ago on racebikes, so I have quite a bit of experience in this department, let's see some pics-

[Patrick]

One other option you could consider. The front forks of early 80s CB750s (DOHC) came with dual disk, dual piston brakes. They also are a direct bolt onto SOHC 750s. I switched one on one of my past 750s. That bike would STOP. You have to switch the whole front fork/triple tree assembly, but it is an easy install.

Patrick

[longshanks]

Ok fellas, here are the pics as requested.

[Retro Rocket]

I would make those Tokico calipers work, they are far better than the originals. I would be looking at upgrading the discs to something more modern, not only will they work better but the will be far lighter. There is another forum member here that specialises in this type of conversion. This is the guy here. Fishhead

http://forums.sohc4.net/index.php?topic=55632.0

[Hannibal Smith]

Ok fellas, here are the pics as requested.

That setup is wrong, no ifs ands or buts. Determine the height of the brake pads first, and this gives you the target swept area requirements for your disc- or you can cross-reference what the caliper got spec'd on.
With those single sided dual piston calipers you have plenty of room, and carrier offset can be as little as 18mm with a 280-300mm disc.
I would keep that caliper, source a proper disc and then machine your adaptor, the stock caliper leaves a lot to be dcesired.

[fishhead]

Discs:
   The "band" is often referred to as the area of contact that the brake pad makes on the disc.
 Generally, there are 2 different styles of "bands"
  A wide band disc (like the stock CB 750 discs) uses the height of the brake pad to make contact with the wider band of the disc. These are usually considered "old style" and use a tall (height) pad with a shorter (front to rear) brake pad(usually a round pad or square pad).
   A narrow band disc uses with width (front to rear) of the brake pads to make contact with the narrower band of the disc. The calipers for the narrow band discs usually have a shorter (height) brake pads with a longer (front to rear) brake pad than a wide band discs would use. The narrow band brake pads are "generally" more rectangle shaped.

So, I would say that you have a "narrow band" caliper on a "wide band" disc.

  Generally, the narrow band discs are thinner than the (vintage) wide band discs. The cut out in the narrow band calipers (for the discs) are also thinner to accommodate the newer thinner disc. I'm not saying that you can't use a newer caliper on the older discs but the tolerances get alot tighter than if the caliper was on a newer narrow band disc.

Would I use the brake system pictured above?
 No.

Here's why..

I love the CB 750's, but I hate their front ends and front brakes and that is usually the first thing I get rid of in favor of a *surprise!!* GL 1000 front end. I just prefer the beefier GL front end to the stock CB front end. I putzed with a big brake kit for the CB 750K, but it would be too timely and expensive to produce because the disc and the (inside the fork leg) caliper mount fight for the same "real estate". Do a search on SOHC as there are others who have made brake kits using the stock CB front forks.

Can you use the brake system pictured above?
 If you feel comfortable with it, why not?

Personally. I don't like the way the caliper is "hanging" by 1 "leg" and I would keep an eye on it for any signs of fatigue(cracks,etc) from use. I prefer to mount adapter/calipers more solidly with a more secure adapter mounted with 2 larger bolts to the fork leg.

Just my opinion.....

[longshanks]

Discs:
   The "band" is often referred to as the area of contact that the brake pad makes on the disc.
 Generally, there are 2 different styles of "bands"
  A wide band disc (like the stock CB 750 discs) uses the height of the brake pad to make contact with the wider band of the disc. These are usually considered "old style" and use a tall (height) pad with a shorter (front to rear) brake pad(usually a round pad or square pad).
   A narrow band disc uses with width (front to rear) of the brake pads to make contact with the narrower band of the disc. The calipers for the narrow band discs usually have a shorter (height) brake pads with a longer (front to rear) brake pad than a wide band discs would use. The narrow band brake pads are "generally" more rectangle shaped.

So, I would say that you have a "narrow band" caliper on a "wide band" disc.

  Generally, the narrow band discs are thinner than the (vintage) wide band discs. The cut out in the narrow band calipers (for the discs) are also thinner to accommodate the newer thinner disc. I'm not saying that you can't use a newer caliper on the older discs but the tolerances get alot tighter than if the caliper was on a newer narrow band disc.

Would I use the brake system pictured above?
 No.

Here's why..

I love the CB 750's, but I hate their front ends and front brakes and that is usually the first thing I get rid of in favor of a *surprise!!* GL 1000 front end. I just prefer the beefier GL front end to the stock CB front end. I putzed with a big brake kit for the CB 750K, but it would be too timely and expensive to produce because the disc and the (inside the fork leg) caliper mount fight for the same "real estate". Do a search on SOHC as there are others who have made brake kits using the stock CB front forks.

Can you use the brake system pictured above?
 If you feel comfortable with it, why not?

Personally. I don't like the way the caliper is "hanging" by 1 "leg" and I would keep an eye on it for any signs of fatigue(cracks,etc) from use. I prefer to mount adapter/calipers more solidly with a more secure adapter mounted with 2 larger bolts to the fork leg.

Just my opinion.....

Yeah, the caliper is mounted off of the front fender by some custom mount the PO fabricated. So are you saying that its too much hassle to fit a new, thinner disc on the wheel hub? That's all I'd be interested in doing at this point since my MC and caliper seem to be working well. Swapping out a GL front end sounds like a lot of work, money, and drifting away from a stock set-up if I ever choose to revert back. (I have all the stock parts)

[fishhead]

 So are you saying that its too much hassle to fit a new, thinner disc on the wheel hub? That's all I'd be interested in doing at this point

No, I just don't know what disc you would need.

[754]

320mm Ducati and maybe Yamaha big discs bolt on but have less offset

[longshanks]

 So are you saying that its too much hassle to fit a new, thinner disc on the wheel hub? That's all I'd be interested in doing at this point

No, I just don't know what disc you would need.

I haven't a clue either. I think I found the same caliper though so now I know what I have.  http://cgi.ebay.com/ebaymotors/06-04-08-05-DL-SV-KATANA-GSX600-GSX750-BRAKE-CALIPER-LH-/230553733272?pt=Motorcycles_Parts_Accessories&hash=item35ae12c898#ht_3038wt_941

and I also found a gsxr rotor here:  http://cgi.ebay.com/ebaymotors/04-05-SUZUKI-GSXR-600-750-FRONT-ROTORS-GSX-R-ROTORS-/290572406963?pt=Motorcycles_Parts_Accessories&hash=item43a77710b3#ht_500wt_956

I'm sure the mounting holes are different for the wheel hub. Even if I do find the right caliper and rotor, I want to mount off the fork and not the fender like the PO did, right?

[scottly]

I used rotors from an 80's Yamaha; same bolt pattern as the 750, but the center hole is larger. Also, they have slightly less offset, so I machined a spacer/centering ring.

[Hannibal Smith]

I used rotors from an 80's Yamaha; same bolt pattern as the 750, but the center hole is larger. Also, they have slightly less offset, so I machined a spacer/centering ring.

Exactly, 1980's Guzzi stuff can be adapted, but you must turn a 4mm support "ring".............You are getting away with murder (with the pics you posted-original poster) but there are certain basic rules that apply, and your current setup violates too many. It is one of those things...........if you have to ask, it is beyond your current skill level.

[longshanks]

320mm Ducati and maybe Yamaha big discs bolt on but have less offset

They bolt directly onto the cb750 wheel hub? What do you mean by offset?

[longshanks]

I used rotors from an 80's Yamaha; same bolt pattern as the 750, but the center hole is larger. Also, they have slightly less offset, so I machined a spacer/centering ring.

Exactly, 1980's Guzzi stuff can be adapted, but you must turn a 4mm support "ring".............You are getting away with murder (with the pics you posted-original poster) but there are certain basic rules that apply, and your current setup violates too many. It is one of those things...........if you have to ask, it is beyond your current skill level.

You are right in saying it is beyond my skill level. I'm thinking if I can't do it then I'll pick up a used stock caliper. I did however, have the common sense to know that the way the PO set the brake caliper off the fender is NOT a good idea! 

[Hannibal Smith]

320mm Ducati and maybe Yamaha big discs bolt on but have less offset

They bolt directly onto the cb750 wheel hub? What do you mean by offset?

Offset is the distance from the hub "face" or backside of the disc carrier to centerline of the brake disc itself, this determines caliper location. I plot this on a geometry calculator, then determine interface offset with the "adaptor", then determine pad height with swept area, forces induced by braking, and the square inverse of MC piston the caliper piston, then calculate lever ratio foot pounds (186.2 pounds etc.) with lever travel desired to achieve PSI we want (785.6 etc.) at the pad.......................this is standard math to get brakes correct.

[longshanks]

320mm Ducati and maybe Yamaha big discs bolt on but have less offset

They bolt directly onto the cb750 wheel hub? What do you mean by offset?

Offset is the distance from the hub "face" or backside of the disc carrier to centerline of the brake disc itself, this determines caliper location. I plot this on a geometry calculator, then determine interface offset with the "adaptor", then determine pad height with swept area, forces induced by braking, and the square inverse of MC piston the caliper piston, then calculate lever ratio foot pounds (186.2 pounds etc.) with lever travel desired to achieve PSI we want (785.6 etc.) at the pad.......................this is standard math to get brakes correct.

Got it. Almost.     Is the "adaptor" the caliper?

[Hannibal Smith]

To add- Bigger MC diameter, less travel but less PSI- smaller diameter, more travel more PSI, depends on the track. If we have a super fast track, we might have to run a smaller MC piston to get the PSI, but the racer will have to grab more lever.......it goes on and on!

But- we know that you can get away with murder on a bike, and I hate to discourage someone from making their own stuff.........but your current setup is super sketchy!

[Hannibal Smith]

Adaptor or interface, coupling, bracket etc. is the machined component that ties the caliper to the fork.

[longshanks]

To add- Bigger MC diameter, less travel but less PSI- smaller diameter, more travel more PSI, depends on the track. If we have a super fast track, we might have to run a smaller MC piston to get the PSI, but the racer will have to grab more lever.......it goes on and on!

But- we know that you can get away with murder on a bike, and I hate to discourage someone from making their own stuff.........but your current setup is super sketchy!

Note taken. I'm assuming the "track" is the circumference of the rotor?

[longshanks]

So given your heavy knowledge on the subject, are you aware of any set-ups that people use when going aftermarket?