[Mick Bailey]

I was out for a run on my Wife's Electra-X on Sunday (I sold my own bike but am still looking for a replacement) and at 60mph the bike suddenly slowed to 40 and ran extremely lumpy, with the throttle almost wide open. I was on a fast stretch of dual carriageway and couldn't stop safely for about a mile. As soon as I rolled of the throttle the bike squealed the front tyre and stopped on its own. I could see smoke billowing from the front wheel.

The paint on the disk was burning and the caliper too hot to touch - the brake was locked solid. When everything had cooled down the wheel moved again and I was able to make it back home though the front brake wasn't working right and was running quite hot.

When I took the wheel out the disk had dished outwards by almost 3mm - scrap. But the more sinister side of things was the pad material had delaminated from the backplates on both pads. There's a heavy layer of rust that had caused the pad material to separate. I'd inspected the bike just two weeks ago and there was plenty of pad thickness and good braking, with no evidence of anything untoward.

The bike is used only in dry weather and these are OEM pads with no wear to the disk or scoring.

So the replacement parts arrived today - EBC MD847disk and EBC FA228 pads with the NUCAP NRS retention system which prevents debonding, plus fluid change. It all looks really nice.

But the message from this is just because the pads have plenty of thickness don't assume they're OK. Take them out and inspect for cracking between the pad and backplate. Or just replace them anyhow even if they look to be fine. I count myself as lucky this happened the way it did - the pads could equally have broken up under heavy braking.

[Boxerman]

You were very lucky there!
Thanks for advice, mines is a 2009 Eletra EFI and I think the pads are original but still have plenty meat on them [not done many miles]. In view of what you said, perhaps I should change them.

Frank

[Bilgemaster]

I cannot say whether this may be relevant to Enfield hydraulic brakes, but a common enough issue on older cars is that the inner rubberized portion of brake lines can swell over time. The result is that while the pedal may be powerful enough to force fluid into the wheel cylinders, the springs (in drum brakes) or "float" (in disk brakes) may not be enough to expel the fluid back through the "cloggy" hose once the brake is released. The result is a shoe or pad-rubbing "meltdown" since the brake cannot disengage. Before replacing the pads and rotor and calling it a day, a close examination of the free flow of any flexible brake line(s) in the brake circuit or simply replacing them might be in order. Similarly, a good look at the caliper's seals or a rebuild might be a wise precaution, since the extreme heat of such a meltdown cannot have done them much good.

[Mick Bailey]

I've had the swollen flexible hose issue with an old Mitsubishi Pajero and it is something that I do check for and a good point to raise here.

My annual routine with the Enfield is to change the fluid and inspect the caliper for free movement on its sliding pins when the lever is released.

After a good deal of thought and studying how the pad has delaminated, I can see that the lifted pad material had wedged between the backing plate and the disk rotor. In all the years I've had bikes and cars this is the first time I've seen corrosion between the pad and backing plate. I've previously made up quite a few piston retractors for different vehicles using old pads - remove the friction material and drill a hole in the plate for each piston and a nut welded on to take a bolt. Even with heavily worn pads the remaining material always puts up a real fight and needs heavy chiselling/grinding to clean off.

The seals looked OK but I'll follow your advice and get a seal kit just to be certain.