TLS brake pulls left

I have not ridden a front drum Norton for a while but the drum transfers the braking force from the the brake plate supporting the shoes to the right lower fork, putting pressure on the right fork tube disproportionately, I have several single disk brake bikes that brake steer to a degree. I suspect this is normal but should not be very concerning unless you are really hammering the brake. Check to make sure the lower triple clamp bolts, axle nut and axle pinch bolt are all tight as looseness would make this torque steer much worse. From time to time I forget to tighten the axle pinch bolt since I normally take the bike off the lift first so I can bounce the suspension to help encourage the forks into parallel first. I can feel that something is wrong as soon as I get the bike to speed.
 
wildbill56 said:
my 1970 Commando pulls to the left under braking.......new Avon tire, good brake shoes, new bearings....spooky
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I see this topic come up in other MC forums also. I personally can't see how front brakes can cause a MC to pull to either side. If that was the case any bike with a single disc up front would go in circles every time the brake is applied. I think your problem is somewhere else and applying the brakes triggers the issue.
I would loosen up every bolt on the front end and go through the recommended the tightening procedure, then try and find a flat road with no crown or camber (or that crappy chip seal paving) and do some testing.

A rear wheel that is out of alignment can cause issues like that because the bike is not tracking straight.
 
Does the bike still have the original style mudguard and stays?

TLS brake pulls left
 
wildbill56 said:
fresh bike build from a long sitting project
Click to expand...
It really sounds as if the forks are twisting when you brake. Is everything tight? What happens if you stand in front of the bike with the front wheel between your legs and push / pull on the bars? Any noticeable twisting?
 
that was an uncomfortble feeling with a JPN replica front fender.....felt like a Schwinn bicycle doing the knees/wheel test. I replaced it with a socck fender with 2 stays.....no more wiggle in that regard. Goiung to check the front to rear wheel alignment with a straight edge next.
 
Sometimes the pinch bolt on the bottom of the slider. and the bolts on the bottom fork yoke, might need to be loosened. and the forks straightened by holding the front wheel with your legs and physically flexing the whole assembly with the handle bars. If the clamps have been tightened when there is a slight twist in the forks, it can be released.
 
Does the Brake cable have the in line brake light / adjuster still in it? Not sure how it would make it pull to one side or the other, but it was on my brother's bike and made the brake "spongey".
 
Well, I checked the wheel alignment and the rear was shifted slightly right. I suspect mixed 71975 and aftermaarket iso parts mixed.....built up a fresh mount with a new RGM kit.....we'll see. I loosened everything up and re tightened all the ountings after relaxing it with no weight on the rear wheel.
 
ilikevelos said:
I have not ridden a front drum Norton for a while but the drum transfers the braking force from the the brake plate supporting the shoes to the right lower fork, putting pressure on the right fork tube disproportionately, I have several single disk brake bikes that brake steer to a degree. I suspect this is normal but should not be very concerning unless you are really hammering the brake. Check to make sure the lower triple clamp bolts, axle nut and axle pinch bolt are all tight as looseness would make this torque steer much worse. From time to time I forget to tighten the axle pinch bolt since I normally take the bike off the lift first so I can bounce the suspension to help encourage the forks into parallel first. I can feel that something is wrong as soon as I get the bike to speed.
Click to expand...
I've come across this a few times with drum and disc breaks and it was usually the pinch bolt. Owners are rightly concerned that they may overtighten the pinch bolt and break one of the lugs off. Try torqueing up the pinch bolt up to the recommended 15Ft/lbs with the spindle nut finger tight and attempt to turn the spindle. If it turns that's the problem. What I've gotten away with if the spindle turns is to increase the pinch nut torque by say a couple of ft/lbs until the spindle is nipped up. Remember the torque required for next time. Clearly you've got to use a bit of common sense and don't greatly over torque the bolt.
 
cash said:
I've come across this a few times with drum and disc breaks and it was usually the pinch bolt. Owners are rightly concerned that they may overtighten the pinch bolt and break one of the lugs off. Try torqueing up the pinch bolt up to the recommended 15Ft/lbs with the spindle nut finger tight and attempt to turn the spindle. If it turns that's the problem. What I've gotten away with if the spindle turns is to increase the pinch nut torque by say a couple of ft/lbs until the spindle is nipped up. Remember the torque required for next time. Clearly you've got to use a bit of common sense and don't greatly over torque the bolt.
Click to expand...
and use of a suitable washer in the gap will prevent over tightening, once axle is gripped.
 
wildbill56 said:
yes, oroginal fender, new fork uppers, seals, oil....
Click to expand...
Presumably an upper is a stanchion? This means that work has been done on the forks which has a good probability of being the source of the issue.

New bushes? Correct and matching oil levels? All bolts correct tension and all aligned properly?
 
well, the 1970 rides well after the iso swap. breaking it in currently. thnx for the help on this... a first for me
 
Deets55 said:
I would loosen up every bolt on the front end and go through the recommended the tightening procedure, then try and find a flat road with no crown or camber (or that crappy chip seal paving) and do some testing.
Click to expand...
In the above process, tighten everything back up STARTING FROM THE BOTTOM TO THE TOP.

Have a helper hold the front wheel as straight as possible.

Tighten axle. Bounce forks a few times to check for any stiction (resistance to smooth compression & decompression), holding the front brake fully activated.

Tighten fender mounts. Bounce forks again.

Tighten bottom yoke. Bounce forks.

Tighten top yoke. Bounce forks.

All should be well.

If at any point, you encounter stiction, your problem is in THAT area. (either top of fork stanchion tube travel, or bottom of travel). Sort the problem, and start over.
 

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