Front Brake Judder

[martin.brown]

My 1957 NH 350 (acquired last autumn) is a nice ride but has front brake judder under heavy or medium braking. Shoes look fine, but were greasy when I took them out; previous owner must have overgreased bearing or brake fulcrum. I cleaned them well, but problem persists. Is the problem in the brake, or could it be worn forks? The forks don't seem to have any wear, but maybe I'm not so good at checking them. (my first post)

[brenton.roy]

Hi Martin,
Welcome to our forum. I'm not a brake expert, but would think it is more likely the shoe / drum contact than the forks.
Does the brake bite overly? Will it pull the bike up easily?
Brenton

[keith.hodgenia]

This is not a problem you should live with, we have had brake backplates fail. Once brake shoes have been covered in oil/grease it is very difficult to get rid of it, you can clean it off but it often comes back to the surface again when the brake gets hot. I would check that there is a chamfer on the leading edge of the brake shoe lining and that the brake drum isn't oval. Keith.

[Steven.Carter]

Welcome Martin, Steering head nuts loose, can you feel any play if you hold the front brake on and rock the bike back and forth?

Steve

[Knud.Degnbol]

You can't clean greasy brakeshoes. Change them.
Let your friendly neighbour brakeservice man put oversize brake linings on the shoes. Then turn them to the size of the drum. Now you can brake with 2 fingers most of the time.
Knud

[nevhunter]

Oil on shoes. replace linings. With alloy hubs often they go out of round with hard usage. This always seems to be a problem. On the bigger conicals I have had them almost become unuseable after a few hard applications. Skim the drums dead on centre, as accurately as possible. The brake plate has been known to break on these brakes
Once a fork depresses it is LESS likely to deflect because of bush wear, but put the bike on the centre stand and check forks and steering. It is more likely to exaggerate the problem than cause it though. Nev

[john.nash]

I'd actually check the easy stuff first that can cause the front end to judder:

1. loose head bearings .. jack up the front, slacken the damper and pull the legs (with wheel attached) back and forward. Should be less than minimal play in the headstock.
2. wheel bearings . while wheel is off ground then try to twist it backwards and forwards. less than minimal play
3. excessive wheel runout .. while wheel is off ground, then spin wheel with a fixed pointer (like a screwdriver on a brick) touching the rim. minimal run out again
4. play in forklegs
5. check for a loose brakeplate, torsion arm etc

If those are all good, then while the wheel is off the ground then spin it hard and use the brake. If you're lucky it might give you some clue if any of the surrounding parts are loose

Apart from that, the earlier advice holds; stuff like a warped drum (whch will require skimming) and contaminated shoes.
Warped drums show up very well on MOT brake testers, you can see the needle jump up and down with the lever pulled at a set limit.

Whereabouts are you Martin ?

[martin.brown]

Hi Everyone,
Thanks for all the replies.
Knud, I seem to remember something from my long lost youth about not being able to clean greasy brake shoes, so I think I'll get some brake shoes on order and meanwhile check out the other points.
I'll let you know the outcome, but it may be a while as since I've retired I've got far too much to do
Thanks again
Martin
John, FYI, I am near Stirling in land of mists and mountains.

[robjameson]

Hi Martin,

If you do order some new linings, make sure you get them riveted on as well as bonded to the shoe. I know quite a few people who have had the lining come off the shoe if they are just bonded - for some reason the adhesive doesn't seem to like the alloy.

Cheers,

Rob

[martin.brown]

Hi everyone,
Just to update you, finally got around to getting linings and checking the bike out in the cold Scottish autumn. Very much improved, but still a slight tendency to judder when braking at speed - well, say 40mph. Braking is now good enough for enjoyable riding and we'll see how we get on. Over winter I'll check the forks etc. again. thanks again; more questions will follow I am sure.