Topic: CB550 track bike front brake options

[Kevin400F]

I'm instructing on a regular basis now for Texas Track Days, and the little CB350F/400F hybrid track bike is often outgunned by the students on modern 600 supersports bikes.  I need to finish my 550 track bike so I'll have I little more grunt down the straight.   I'm planning to run dual discs on the front, and at the moment I'm using a combination of '79 CBX fork tubes with clip-ons over the top triple, '78 CB750F sliders, and '79 CBX caliper mounts, calipers and 19"x2.15" Comstar wheel.  I would really rather have an 18"x2.15" (or 2.50") front wheel.  A wire spoke wheel would be fine.  So far, I haven't found any options to allow me to run the dual '79 CBX five-hole front disks with a wire-spoke style hub, or on an 18" Comstar. 

Now for the scary part......  I'm actually considering (at probable great risk to life and limb, he-he...) combining a dual-disc style Comstar inner hub with the spokes from an 18" CM400 Comstar front wheel, and use a wider 18" Comstar rim if possible.  The 18" Comstars from the CM400 series don't have "thru-bolts" for a second disc, and have a 1.85" wide rim.  I've pulled up all the posts warning not to disassemble Comstars, but with the proper size and strength fasteners I don't think there would be any risk.  Questions at this point include: is the 18" Comstar inner hub width and spoke bolt pattern a match for the 19" Comstar?  Also, is the rim rivet hole spacing the same for the 19" front Comstar and the 18" rear Comstar?

Feedback, anyone??

Kevin in TX

[paulages]

mine runs (what i believe to be) a DOHC cb900SS front end, with drilled disks and aluminum rims laced to the stock hubs:


i haven't been able to take it to speed yet, but i can tell you: those brakes are tight.

[Kevin400F]

Paulages, those appear to be the same style calipers I'm using, and the discs are apparently the SOHC 6-bolt type.   Have the discs been thinned?  Did you have to modify the mounts or shim them to align properly with the discs? 

Another option I'm considering is adapting the the lighter "5-bolt" type discs by boring the center hole to match the OEM 550 spoke-type front hub and and redrilling for six mounting bolts.

Kevin

[Triffecpa]

I used a late 70's/Early 80's rotor on the front of my CB400F race bike.  (5 bolt I think)  I redrilled the holes to match the 4 bolt CB400 hub and then had a custom bracket made to mount a twin piston EX500 caliper.  I also use VF500 front forks.  Single disk at this point, but with HH pads it's got plenty of brake.

I use a stock Honda CB400 hub laced to a 2.15x18 alloy rim

Also got a buddy who races a CB900F with stock rotors and stock Honda twin piston calipers.  With HH pads he's real happy with the brake performance.  He uses a Honda CB750SC Nighthawk (I think) front wheel that is a 18x2.5 cast mag.

TR

[paulages]

Paulages, those appear to be the same style calipers I'm using, and the discs are apparently the SOHC 6-bolt type.   Have the discs been thinned?  Did you have to modify the mounts or shim them to align properly with the discs? 

Another option I'm considering is adapting the the lighter "5-bolt" type discs by boring the center hole to match the OEM 550 spoke-type front hub and and redrilling for six mounting bolts.

Kevin

i didn't build that bike- it was built by wes barker in the late 70's, who is still very involved in the vintage racing scene here in portland. he builds lots of stuff for the formula 160 guys. i need to go talk to him about it soon-- got the bike third hard from the person he built it for in 1980 or so. i'll measure the disks when i get a chance, but i don't think they're thinner. the frame was stiffened up with WAY too much steel, so i don't think weight was considered quite enough, but i guess the original racer was a big guy. if i were building the same bike now i'd do lots different (and i think my 718 will handle better and be more powerful eventually), but it was pretty state of the art at the time.