Juddering front brake,...Have I been silly

[Gearbox]

Just removed the front forks and changed the oil seals, refilled with oil and replaced, now the front brake judders very badly.
Front brake is a 180mm full width unit with a twin leading shoe plate fitted. Used to work very well and smoothly.
I have loosened the axel and the brake anchor and applied the brake when pushing the bike along, then tightend everything up. Still judering.
Just asking for thoughts and sugestions please, before I take the wheel out again and check everything.
Many thanks

[CheeserBeezer]

I think you're going to have to take the wheel out anyway. I suggest you taper-off the leading edges of the brake shoes and make sure all fulcrum pins and cams and spindles have a small amount of grease on them. Also, make sure the cable is silky smooth.

[RDfella]

As I read it, this happened after working on the forks, but no mention of work on the brake. I'd be looking at how the forks could cause this. Are the head bearings OK with no slack? Is there wear (well, there always is on old machines, but we're talking excessive) with the stanchion fit in the tubes? Did you tweak any of the spokes? This can pull the brake drum out of round and create shudder.
As Adrian says, could be linings need a chamfer, but why now and not before?

Edit - Apologies for the mis-type, I meant Andrew, not Adrian  (assuming, that is, it wasn't an autocorrect error).

[CheeserBeezer]

As I read it, this happened after working on the forks, but no mention of work on the brake. I'd be looking at how the forks could cause this. Are the head bearings OK with no slack? Is there wear (well, there always is on old machines, but we're talking excessive) with the stanchion fit in the tubes? Did you tweak any of the spokes? This can pull the brake drum out of round and create shudder.
As Adrian says, could be linings need a chamfer, but why now and not before?

Who's Adrian?!

[Billybream]

On the fork leg there is a tang which locates into a slot on the brake plate, these are often a mismatch and are sometimes shimmed, if there's play there, this will show up as judder.
Had to build up my brake plate with weld to fit the fork tang

[Gearbox]

Thank you all for the imput. I had been using the bike and had no issue with the brake. (It was new a little while ago and only done about 500 miles) Removed the wheel, mudguard etc to get the forks out as they were leaking. Removed the oils seal holders and replaced the seals, refilled with oil and reassembled. Now juddering.
I will pull the wheel out and have a look at the shoes, but would be surprised if there is a problem there. Chassis and forks etc are Goldstar if it makes a difference. I don't recall a tang on the forks as the brake stay is bolted to the forks and brake plate.

See what appears at the weekend

[KiwiGF]

Just a thought, the brake stay can “bend” the brake plate if it does not fit correctly, and maybe cause the juddering. On my bike washers both ends of the stay make sure the brake plate fits properly, and doesn’t move when the stay bolts are tightened up.

If possible the brake should be on when tightening up the axle.

[BSA_54A10]

Did you touch the fork bushes ?

[Gearbox]

Brake worked perfectly prior to changing the fork seals. I only remeoved the fork seal holders and changed the seals before refitting. Brake is the 190mm full width Goldstar option with a Dow version of the twin leading shoe arrangement. I have Dow damper filled as well.
I guess I will have to pull the brake apart and check it, then carefully reassemble the forks and wheel, brake stay and mudguard to see if I have twisted something

[Gearbox]

The front end has been apart, wheel out and brake plate removed. All looked good, chamfers in the right places etc. Cleaned up the shoes and drum, but they were not particularly dirty with the brake plate only being about 18 months old.
Forkes loosened in the lower yolks and also in the top. Refitted at the top, refitted wheel loosly and backed off the mudguard mounts, all floppy at the front. Pulled the Dow dampers from the forks and noticed that they were dry. I know the forks were extended, but I added some fork oil (same as the oild used when I did the seals) so the dampers were immersed. Same ammount each side, judged by measuring the level from the top of the forks. Refitted dampers and tightened top nuts.
Bounced the front end about using the front brake, then checked alignment of the wheel to handlebars, tightened the wheel axle and the lower fork yolk bolts, then the mudguard mounts.
It does seem better, but not had a decent run on it yet