Opposed modern calipers/rotors on '83 GS1100ED

[Henway]

I thought I should start another thread because this is specifically NOT for twinpots.


I see what the major issue to putting on opposed brakes is: offset from the wheel. The current rotor offset of 16.5mm has a gap between the rotor and the wheel spokes of 39mm. All the current sportbike opposed calipers have about 41mm of thickness behind them, so they are 2mm too thick and will hit the wheel spokes.
There is about 8mm of gap between the rotor and the fork bottom, which means the offset could be a max of 24.5mm.
Here is a hellaciously difficult to navigate, but thorough listing of ALL offset, inner diameter, outer, and everything EXCEPT bolt diam/distance from center:
http://www.galferusa.com/WebExchange/DF%20W2007.pdf

So far, no luck with ebay.
I've made a spreadsheet with all the possibilities because their site is so bad.
Based on the assumption that I want about 21.5mm, have as close to an ID (without going smaller) of 56, have the largest possible OD (310) and 6 holes that match up, the best match is:
drum roll please.....


DF042 - from a 1994 Honda RVF750RR (RC45)


Wish me a whole lot of luck finding a used one!!!


However, there are some other possibilities:
DF041 1998 CBR900RR
DF326 1986 GSXR1100RR (5 holes)
DF690 1989 GSXR750RR, 1988-1994 GSXR750, 1989-1993 GSXR1100 (5 holes)
DF314 1989-1996GS500E, 1994RF900R, 1995GSF1200 Bandit, 2000GSF1200 Bandit S (5 holes)

DF321 1998GSX750, 1997VZ800 Marauder (5 holes, 300mm)

DF059 1989CB 1, 1997CB400 Four, 2005CB400, 1998CB600 Hornet (296mm)

DF061 2000 599 (296mm)

DF317 1998Katana 600/750, 1999-2003SV650 (5 holes, 290mm)


If anyone wants the spreadsheet, I have a bunch of extra information.


Has anyone done this yet?
Are my measurements correct? Input?


I figure that once there is enough clearance virtually any caliper that has the same rotor size will work and that will be "child's play" comparatively. Another question--if the rotor is 310 or 300, does it matter "that much" if the caliper is meant for a 320? Lots of RC51 and other 320mm calipers out there....

[salty_monk]

You won't be able to drill a 5 bolt rotor to fit the 6 bolt Suzuki wheel in my experience.... There just isn't room, one of the original holes will interfere.
The only chance is to get one with a hugely bigger PCD & invent your own "carrier" for it (i.e. a second spider to centre & fix it to the hub).

The 1998 CBR 900RR is a good one, the PCD is the same as Suzuki & you only need to enlarge the holes a little from 6mm to 8mm. That one is 310mm.

In answer to your caliper question - maybe, it depends. Sometimes you can run the caliper in a spot where you get full pad to rotor contact, sometime you can't. You'll have to buy some bits & try it like I did... that's pretty much the only way as you can't get hold of CAD drawings for them.

Dan

[Henway]

Thanks for the response.

I'm thinking there's maybe another way to massage this.

If I space out the rotor to the side by 6mm, I may be able to hook up CBRF4 or other 280mm disc caliper and clear the wheel with the STOCK rotor. Brand new pads may not work--I believe the Suzi rotor is 1mm wider than the CBR.

If this is the case, I only need 6mm aluminum stock to make a spacer, new grade 10.9 M8-1.25 x 35 rotor bolts (7mm longer than stock), and then the actual mount. I might not have to mess around with new rotors....

Since I'll have bolts that go just as far as the originals I don't think there will be problems with the spacer. Even searching Wikipedia I can't figure out what the "7" on the head of the original bolts mean.

[salty_monk]

It's japanese for tensile grade.

[GregT]

I make stepped spacers to center the disc on the hub - steel or aluminium - either will do.
If you're buying replacement bolts look for grade 8 or equialent.

Greg T

[Henway]

Would 10.9 be too brittle or a problem?

http://www.allensfasteners.com/detail.asp?Product_ID=1452+HEX+FLANGE+BOLT

[GregT]

Sorry, that grade description - if it is one - means nothing to me.
Ask the supplier for a recomendation - specify the usage

I'm in New Zealand and fasteners here are a mixture of British, US and Japanese specs - with the US stuff being rare so I'm not familiar with all the grade descriptions.
Too brittle could be a problem - some ductility is desirable

Greg T

[Nessism]

10.9 is similar to bolts marked "9" by Suzuki, or Grade 8 for SAE hardware. Should work fine for that application.

[fishhead]

I haven't done many Suzuki big brake kits, butthis is from what I have found from making kits for other makes.
Some calipers (meant for smaller discs) have the arch of the pads to match that particular disc. Usually it is not a problem and can be used with larger disc, but sometimes it does present a problem (pads hang over the disc or wont seat "down" on the disc far enough with out hitting). It can be a crap shoot when mixing and matching this stuff.
Spoke wheels usually dont offer the spoke to caliper clearance that mag wheels do. You are also limited by the fork width (you have to work with the space that you have). Often times you can use a larger diameter disc to get more clearance (spoke /caliper).
Heres a photobucket link that shows 330mm discs and AP Racing 6 piston being put on a 1981 CBX front end. I didnt have the camera to take pics of the caliper brackets being made. 330mm discs were needed to gain the clearances (clearances are still very tight). Smaller discs wouldnt do.
http://s111.photobucket.com/albums/n...albumview=grid
Heres an album of some of the kits I have made in the past.

http://s111.photobucket.com/albums/n130/dgfischer/Fishhead%20Big%20BRakes/?albumview=grid

Heres a pic of one of my latest kits (GL 1000 forks, 310mm discs, Tokico 6 pistons).

My new website

http://www.fishheadbigbrakes.com/

Fishhead

[Henway]

Fantastic work!

I see you like the 330 and 320mm rotors a lot. I take it most at this size are "custom" and not found at the salvage yard? The largest rotors I saw on the Galfer brake site were 320s for Ducatis.

I have some specific questions for you.

What is the max thickness of a spacer are you comfortable with? Does the thickness not matter so long as the mounting screws go all the way into the wheel? I see you also have to change the bolt holding the caliper to fork to face outwards many times. Have you ever had to shave that bolt head for clearance? What grade aluminum are you using?

Galfer tech department has been helpful, but even they don't know critical information. Like what offset means. They're not sure whether it's TOTAL width or net width (not including the rotor thickness.) Nor do they know the radius of the bolt pattern from center (nor bolt spacing). Pretty critical stuff to NOT know. And the tech that said he'd get back to me has taken 2 days so far.... Though it SEEMS as though offset is TOTAL width because my spare RS125 is supposed to be 17mm offset but that is it's total width, not net width.

I'm focusing in now on ONE size and rotor. As Honda calipers for 296mm rotors are the most common ones on ebay, I looked for the largest possible rotors that have the most offset. None of the 320 or 310 rotors have much offset (because I'm scared of having too wide of a spacer and losing strength--valid concern?) and the largest offset is 23.3mm on a 2004CB600F (called the 599 or the Hornet outside the US). Also a good thing is I can get them brand new for under $150 for the set. The offset on the GS1100ED rotor is currently a TOTAL of 22mm, so I still need 8mm spacer. These old rotors have a LOT of offset!

I drew up the spacer in Google Sketchup and converted to .dwg. The only thing I'll have to do is modify the width of the spacer when I get the rotor and caliper in my grubby hands and can do final measurement.

[fishhead]

Fantastic work!

I see you like the 330 and 320mm rotors a lot. I take it most at this size are "custom" and not found at the salvage yard? The largest rotors I saw on the Galfer brake site were 320s for Ducatis.

Most of the discs I use are OEM discs and are modified to work on the application intended. I have done alot of 320mm disc kits, but I have only done 1 330mm disc kit. I will probably use more 330mm discs in the future.

I have some specific questions for you.

What is the max thickness of a spacer are you comfortable with? Does the thickness not matter so long as the mounting screws go all the way into the wheel?

As long as the disc adaptor is securely mounted to the wheel, and the disc fits between the forks, it should be fine. All you are "really" doing with the disc adaptors is "extending" the hub (width).
The further you get away from the hub(width or radially), the more you will need a "centering ring" milled into the adaptor to keep the disc centered (a shoulder for the disc to rest against- see CBX "fits like a glove" pic) simular to the way the stock disc fits tightly on the stock hub.
Making the hub wider (with adaptors) can cause interference with the speedo drive and the bolts that now hold the disc/disc adaptors can also interfere with the speedo drive.

I see you also have to change the bolt holding the caliper to fork to face outwards many times. Have you ever had to shave that bolt head for clearance?

Not usually. I have had to shave some bolts down for clearance of the speedo drive.
Heres a KZ 900 310mm disc kit . The stock 4 disc mounting bolts needed to be shaved down about 2 mm to clear the speedo drive.


The GL 1000 6 piston kit pictured above also has the disc mounting bolts reversed for speedo clearance (the nuts are mounted on the speedo drive side as apposed to the stock bolts being put throught from the speedo drive side (the GL has 6 through bolts going through the hub to hold both discs on instead of 6 disc bolts on each side) for speedo drive clearance.

Some bolts have shorter heads than others, look around for alternative bolt sources.(McMaster, fastenal,MSC,etc). Using button allen head bolts (disc) may get you more clearance than a hex head bolt.

What grade aluminum are you using?

6061. Recently I have been toying with Ti, CroMo and other alternative metals. Aluminum machines the easiest.

Galfer tech department has been helpful, but even they don't know critical information. Like what offset means. They're not sure whether it's TOTAL width or net width (not including the rotor thickness.) Nor do they know the radius of the bolt pattern from center (nor bolt spacing). Pretty critical stuff to NOT know. And the tech that said he'd get back to me has taken 2 days so far.... Though it SEEMS as though offset is TOTAL width because my spare RS125 is supposed to be 17mm offset but that is it's total width, not net width.

Try EBC for more information.

http://www.cyclebrakes.com/html/catalogs.html

I'm focusing in now on ONE size and rotor. As Honda calipers for 296mm rotors are the most common ones on ebay, I looked for the largest possible rotors that have the most offset. None of the 320 or 310 rotors have much offset (because I'm scared of having too wide of a spacer and losing strength--valid concern?) and the largest offset is 23.3mm on a 2004CB600F (called the 599 or the Hornet outside the US). Also a good thing is I can get them brand new for under $150 for the set. The offset on the GS1100ED rotor is currently a TOTAL of 22mm, so I still need 8mm spacer. These old rotors have a LOT of offset!

Alot(most) of the newer sportbike discs are very flat and have little offset if any. That is why alot of my kits have "disc adaptors" - AKA "disc spacers" to give the needed offset.
I use that same disc for many different applications and it is a good starting point.

Fishhead

[Henway]

EBC rotor catalog converted to Excel

Thanks for the better link. Unfortunately it doesn't list the CB600F.
Through some deft handiwork, I've converted their entire listing into an excel file. Now you can sort for whatever is your most important dimension and find all the sportbikes that work. If anyone wants it I can send it to you.

[Henway]

Will finally be finished with this Saturday. Will have pics up on Sunday with a ride report.
Learned how to use CAD/CAM.
Learned how to DIY anodize.
Again, pics on Sunday.

[Henway]

Finally have MODERN brakes on the bike. Two fingered braking and I can actually FEEL something through the brake lever.

[Henway]

You can barely see the 5mm spacer here to match with the CB600F rotors so I could get enough clearance: