Topic: need road racing transmission CB550

[cb550fcafe]

CB550 transmission is giving me fits. Lots of missed shifts. Has caused one bad wreck at RA and an off track at Gingerman while leading. I had the dogs cut already @ FBG and it has not helped. Looking for gear box alternatives. Nova sells one for the 500/4. Not sure if that will fit.

[Tintop]

Have you checked with Davies Motorsport, also BWaller may have some suggestions.

[turboguzzi]

"alternatives"? like a few options? cant believe that there's much beyond Nova's solution.... And i thought the later 550 boxes were better than the 500/4 anyway...
Just curious if you were able to identify the issue more in detail. undercut dogs will help keeping dogs engaged.... missed shifts sound like a different problem, no?

[Rod]

"alternatives"? like a few options? cant believe that there's much beyond Nova's solution.... And i thought the later 550 boxes were better than the 500/4 anyway...
Just curious if you were able to identify the issue more in detail. undercut dogs will help keeping dogs engaged.... missed shifts sound like a different problem, no?

+1 notwithstanding the issue of the road ratios, the standard box was fine on the track but usually started to complain by jumping out of gear when it was getting tired & time to undercut - 3rd gear seems the one that plays up first in my experience, endorsed some years ago in a chat with Graham at Nova RIP. With TG, if it's a missed gear problem then something else is going on.

[cb550fcafe]

"alternatives"? like a few options? cant believe that there's much beyond Nova's solution.... And i thought the later 550 boxes were better than the 500/4 anyway...
Just curious if you were able to identify the issue more in detail. undercut dogs will help keeping dogs engaged.... missed shifts sound like a different problem, no?

+1 notwithstanding the issue of the road ratios, the standard box was fine on the track but usually started to complain by jumping out of gear when it was getting tired & time to undercut - 3rd gear seems the one that plays up first in my experience, endorsed some years ago in a chat with Graham at Nova RIP. With TG, if it's a missed gear problem then something else is going on.

before racing the engine I had all the parts REM finished. At the start of the season I would have frequent issues missing an up shift into 4th gear (false neutral) So I removed the gear box and sent to Fast By Gast to have the dogs cut for road racing (up & down). I replaced the shift forks, shaft, shift drum, lever that rotates drum, changed rear sets for quicker lever action. I went back to race. Missed 4th gear once in a while.

I get to Road America and battling for the lead, come out of the long sweeping right hander, get to the chicane where it would be 2 down shift and the gear box gets "tangled up" gear clattering, motor stalls, pretty sure I locked the brakes and down I went. Broke my damn toe and a bunch of body work.

I chalked it up to rider error.

Following weekend at Gingerman, leading on the last lap, approach turn 1, its 2 down shifts, trans get "tangled up" again. It would not down shift, I could feel in the shifter the gears just trying to engage but they wouldn't. No engine braking! Holy #$%*. I'm off track. Get her slowed down, goes into gear, I'm mowing the grass. I get back on and finish 2nd.

This gear box has had everything done to it that I can think of. I need to fix it before it kills me.

[cb550fcafe]

can a CB500 gearbox be used in a CB550 engine?

I ask because Nova makes a racing gear box for the 500

[bwaller]

Maybe remove the lower case but leave the gearbox assembled and shift it through the gears. Look for end play in the shafts and engagement issues.

I just wonder about shims in correct places first Kevin. Also be sure any mating gears that are not engaged have ample clearance.

Check the screw on the end of the shifter drum is tight so all the pins aren't loose. Spacers installed correctly in the shift mechanism. The shifter shaft "hooks" that rotate the drum aren't worn? Also the rollers (neutral and gear finder are also not over worn. I made new ones with mini bearings.

Good luck, something sounds amiss.

[bwaller]

You'd best check with Nova about the 500 box. There are several differences.

[cb550fcafe]

You'd best check with Nova about the 500 box. There are several differences.

they never answer the phone or reply to emails. I sent them an email on the topic a while ago.

[Rod]

You'd best check with Nova about the 500 box. There are several differences.

they never answer the phone or reply to emails. I sent them an email on the topic a while ago.

Have spoken to Nova and they will call me back with an answer on 550/4 compatibility tomorrow - watch this space.

[cb550fcafe]

You'd best check with Nova about the 500 box. There are several differences.

they never answer the phone or reply to emails. I sent them an email on the topic a while ago.

Have spoken to Nova and they will call me back with an answer on 550/4 compatibility tomorrow - watch this space.

thank you!

[peter400four]

Well,
I'm certainly no expert in this area (anyone reading my requests for help would know that) but it is my belief the 500 and 550 gearboxes are not compatible. Also, as was mentioned earlier, the 550 gearbox is supposed to be an improvement on the 500. I certainly hope it is, because I got a 550 motor, because of these "accepted" improvements. I will attach the 500 barrels, pistons and head to keep it as a 500, because it's used for historic roadracing too, albeit at the opposite end of the field to the original questioner Mr cb550cafe 

[scottly]

changed rear sets for quicker lever action. I went back to race. Missed 4th gear once in a while.

Please post a side view of your current shifter/rear set setup.

[maxheadflow]

I bought a brand new CB550F back in 76 and put basically 66000 miles on it. At 10K it got a Yoshimura street cam. Later it got cb650 pistons. Bike got run pretty hard in the mountains. Luved smoking RD400s.  Early on it had issues with up shifting. I found the issue to stemmed from too much travel of the shift arm.   I ended up welding up the slot in the shift arm where the shift  return spring stud pokes through to limit the travel. To set travel, with access to the arm, upshift to the next gear and hold in position. You should have the slightest bit of clearance between the pawl and the pin on the shift drum in say 3rd gear.   That corrected my issue.  Also make sure that the shift detent roller  is not worn on the pin it rides on.  This is a real common issue.