Holy*^#&$

Just got back from a run on my 850 Commando. My buddy was up from Calgary and was on my Bonneville and we were having a bit of a road test. We crossed over a little bridge when on the far side my rear wheel locked up solid. Absolutely terrifying 30 seconds with the bike fishtailing left and right, no doubt due to my inexperienced imputs along with incoherent screaming. After getting to the side of the road it was noted that the chain was really tight and the brake cable was dislodged from the rear where the cable exits the outer cover and fitting and jammed tight.
I have not rode the bike for some time due to surgery but prior to that had no problems whatsoever. After nursing it home and getting it on the bike lift. It was found that when rotating the wheel the chain would get very slack at one point and then extremely tight at another point of the revolution. Obviously a new chain is in order but am at odds as to how it all happened and why. I had recently adjusted the primary chain to correct tension and had therefore had to adjust drive chain and brake as well. I followed the manual to the letter, or so I thought, in doing the adjustments. All worked well on the ride until the lockup. Not sure what I am asking for here. What may I have missed or neglected to check. Any similar happenings?
Brian
Alberta, Canada

Where you at?

Are you up in Edmonton? There are at least two otehr guys on this forum from there. Not that I can help with the prob but thought we could get together some time and hit the streets

It could possibly be the gearbox layshaft bearing seizing that caused your lock up. The warning signal for this is when the kickstart drops on acceleration. I have a Commando that has started this and I have stopped riding it until I replace the layshaft bearing.

If you are able to roll the bike now, this would tend to point away from the layshaft bearing, however it is possible that the bearing jammed and then things broke free again. Any weird noises coming from the gearbox?

You could drain the gearbox oil with the thought in mind that if the layshaft bearing has let go you might see some remains of it in the oil.

Brian J rowe said:

After getting to the side of the road it was noted that the chain was really tight and the brake cable was dislodged from the rear where the cable exits the outer cover and fitting and jammed tight.

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Brian,

Just a thought, are you sure the rear brake cable was routed correctly? The cable must be routed over the footrest plate. If it has been routed underneath the alloy footrest plate, the rear suspension when compressed hard, (by a bump in the road?) can cause the rear wheel to lock up? The Norton factory technical dept. issued a service sheet about this problem. The cable can foul against the footrest plate as the suspension compresses, and then brake is pulled on by the suspension compressing further?
Normally the brake frees off when the suspension extends, leaving some riders wondering what happened, as everything appears normal again -until the next time. But in a severe case possibly the brake could have stayed locked on?


It's something to check anyway?

I live in Leduc actually. There are two Commandos in Leduc that I know of. Would be fun to get a few together for a ride. There is a chap in Calgary doing the very thing on the 11th of Sept. Not a club just a gathering of like minded Commando owners. Sounds like all clubs start this way.
After the lock up and freeing the brake cable, , other than chain that was either too tight or too loose depending on rotation all was fine but will drain gerabox regardless. Can;t hurt to try. Will put new chain on tomorrow and set it up again.
many thanks
Brian
Leduc ,Alberta

Commandos are quite hard on chains and it's quite usual to find tight spots after a bit of mileage. If you set it up on a loose spot then it can be like a bow string within half a revolution.

Did the rear lock up after a bump ? Is your rear brake cable routing all O.K. ? If wrongly done it can pull the brake on at full suspension travel.

The other thing that I might be inclined to check is the condition of the spacers within the rear hub and brake drum. I'm sure that I've read of soft ones and if you have a crushed example it could cause all sorts of odd symptoms. A quick visual check should suffice.

As L.A.B suggested it was indeed the fault of the brake cable as the cable routing was underneath. When looking at it it is obvious that it was made to go over the aluminum bracket. It was like that when I got the bike but a simple enough error. Yes it did happen after a rather healthy bridge to road transition bump. Anywayit now is sporting a new chain and a re-routed brake cable. I am going to take her out for a little spin right away and check the length of my skid from yesterday.
Thanks again for all the help and advice. Great forum
Brian

When putting my Commando together, I initially routed the brake cable under the Z-plate, as there was a slight groove in the plate that corresponded to the cable running that way. After seeing a couple other Commandos, I realized it made more sense to route it over the plate and changed it.

I'm glad I did.

Glad you survived your panic stop, Brian.

Re:

BillT said:

When putting my Commando together, I initially routed the brake cable under the Z-plate, as there was a slight groove in the plate that corresponded to the cable running that way. After seeing a couple other Commandos, I realized it made more sense to route it over the plate and changed it.

I'm glad I did.

Glad you survived your panic stop, Brian.

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Dredging this one up. I had some rear wheel issues and finally got it solved. Took it all the way down to check the hub bearing and circlip. Put it all back together and am trying to resolve an issue with the brake cable. It rubs across the top of the Z Plate and digs into it. Is there a way to avoid that? It has done this for years. I guess it is just bugging me more now.

Re: Re:

drones76 said:

Dredging this one up. I had some rear wheel issues and finally got it solved. Took it all the way down to check the hub bearing and circlip. Put it all back together and am trying to resolve an issue with the brake cable. It rubs across the top of the Z Plate and digs into it. Is there a way to avoid that? It has done this for years. I guess it is just bugging me more now.

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Sounds like the cable could be too short?
Have you tried routing the cable between the exhaust mounting plates instead of behind the inner plate?

My cable rubbed a groove into the top of the Z plate too. Stock normal stuff.

Does your tight chain coincide with one revolution of the rear wheel or one revolution of the gearbox sprocket? work out which and you have the source of your problem. eccentric rear sprocket or eccentric gearbox sprocket.

gripper said:

Does your tight chain coincide with one revolution of the rear wheel or one revolution of the gearbox sprocket? work out which and you have the source of your problem. eccentric rear sprocket or eccentric gearbox sprocket.

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This is an old thread from 2008.