New disks and pads

[Clifford Pope]

Good point. I thought I had checked these carefully, also the track rod ends and wheel bearings, but I'll check again. But it did all start with the new discs and pads. The old discs only juddered when braking at speed.

[johnnydog]

Have you read the following articles I referred to by Powerbrake Brake Tech, Clifford? That should answer all your queries about brake judder, the causes and remedies. Your brakes should not be juddering just because they are still in the bedding in period. The problem will be more deep rooted, probably not helped by the pads binding when new because of the oversized pad thickness. Believe me, the information given by Brake Tech given IS correct, and as I have previously said, I know from bitter experience!

[Clifford Pope]

The judder is gradually diminishing. It is now only a very slight shimmy at about 40 mph when first pressing the pedal. If I press a bit harder the judder goes.

I've read the article, and the bit about transfering surface deposits to the discs during the bedding in period, also the fact that that this can be imperfect if the discs overheat or conversely locally cooled by pad contact while at rest.

The suspension and steering and bearings are all perfect - no play.

So does this mean
a) the discs/pads will continue to bed in and the judder will eventually disappear?
or
b) the discs are now damaged and they will need skimming or replacing?

It is now established that the pads are genuine Lockheed old stock, not quite the original ref number, but the only one now available and vouched for by CW.

I'm now heartily sorry I ever bought new discs. In 47 years of running old cars I have never before replaced brake discs. A few minutes work with an angle grinder and sandpaper has been good enough for me, and brakes have always been good with no judder.
I may yet put the old ones back on !

[johnnydog]

In my 35 years of Triumph 2000 ownership, I have never had the need to fit new discs due to wear. I fitted replacement discs complete with hubs to my late Mk1 last year, but only because they were severely corroded from being laid up for 25 years, and the replacements were an original good set from a Mk2. Modern discs appear not to be made to last like the original discs fitted to Triumphs - some manufacturers today recommend that discs are replaced on modern cars every 2nd or 3rd pad change!! Which leads me to question whether remanufactured discs for our Triumphs are made from butter like modern car discs; if so I would avoid fitting replacements if possible unless you are lucky enough to find some genuine and original new 'old stock'.
It only takes about 100 - 200 miles to bed brakes in with normal driving; using the procedure outlined in the previously mentioned technical articles requires successive applications of the brakes from about 50 mph down to 10mph (without coming to a stop) using reasonable / firm pedal pressure, and immediately accelerating back to 50 and driving for a minute to allow the brakes to cool, before repeating the process. How many times this is carried out varies but the main point in the 'cleaning' of the disc face is that the car doesn't come to halt with your foot hard on the brake pedal as this is the point when the transfer of friction material to the disc from the pad occurs in one spot resulting in high spots and eventual judder. When you are satisfied the discs have been 'cleaned' and bedded in satisfactorily, the car must be driven for about 10 - 20 minutes with the minimum of braking to allow the discs to cool properly. It pays therefore to carefully choose your road for the procedure ie. one with no traffic lights, the appropriate speed limit and preferably when quiet. Easier said than done!
It's also suggested that every now and then it is beneficial to carry out a few hard brake hard applications as above just to keep the brakes smooth and progressive.
I would try the above to eliminate the judder you can feel through the pedal.
All this possibly seems over the top, but the judder won't disappear on its own.
Best of luck!

[David Withers]

Cliff, I see that you didn't receive a reply to your question as to what is meant by the piston having a cut-away portion as those on your 1967 callipers don't seem to have one. I distantly recall this cut-away being introduced, and I think it would have been a little later than your car. It may have been introduced to reduce brake noise - or perhaps judder!

I haven't seen any comment, in my quick read through this thread, as to any check being made on the run-out of your discs. If it's more than .004" it can cause judder in the very conditions you relate. Perhaps the new discs weren't machined true? My son found this with one of a set of discs bought from GSF for his Skoda, and it took him quite a while to realise that it was the fitting face being out-of-plane with the braking face that was responsible for causing a judder.

Following up on John's point about modern cars having soft discs, a friend of mine bought a new Audi several years ago, and his only real complaint about it was that it needed new discs at every major service (something like 25-30,000 miles apart). I suspect that modern discs are intentionally soft so as to assist with braking, however I've always found the Triumph 2000 system, properly set-up, to be perfectly fine under all conditions including hard braking downhill with a heavy trailer in tow... and the discs never seem to wear out! Perhaps slightly more pedal pressure is needed than with a modern car, but I'd rather have that than having to keep watch for disc wear and then suffer the hassle and cost of replacement.

[Clifford Pope]

Thanks David for the information about the piston cut-away.
I have I think eliminated run-out, by using a screwdriver resting on the caliper edge and spinning the disc as if using a lathe with a tool rest. I can't detect any wobble or high spot. I'm not sure that it would diminish spontaneously over time if it were run-out?

The discs were original and certainly worn down - only just above the minimum spec, and vastly thinner than the replacements (CW), which is why the un-relieved pads won't fit.

Why such a faff getting the Triumph's discs run in? I've replaced discs on several Volvo 240s over the years and never gave a thought to running them in - just fit and go. Perhaps these are are more substantially built with greater mass, so less prone to judder.
I have replaced a 2000 disc once before years ago because of damage. Naughtily I only replaced the one, but there was no problem with judder or imbalance even.
I still suspect the available pads are not held so firmly in the calipers as the originals.

Anyway, they are improving over time with a regime of gentle braking and cadence braking to avoid prolonged constant application.

[Mike Stevens]

I think modern discs need replacing more often also because modern pads are more abrasive. The Triumph system was designed with asbestos pads in mind but as these are now not allowed, I believe the modern types are made of more abrasive material.

Cheers,
Mike

[Clifford Pope]

I've found one of the original pads in my parts box, and the attached photo shows the differences between the original and replacement.

The original was presumably a Lockheed LDB 735, the new a Lockhead LDB 736, as supplied by Chris Witor and Rimmers, as being the only replacement now available.

Note:

1) the original is deeper, and projects further towards the disc centre
2) it has a slightly larger surface area
3) The profile of the metal backing is cut away more on the replacement, so is held less firmly in the caliper slot
4) There are two notches on the edge of the backing plate close to the projecting lug, which the spring clips engage in, so steadying the pads more securely.

Finally, which is not apparent, the 736 is much thicker, with consequences already noted in the thread.

The new pads are original asbestos old stock, but presumably meant for some other vehicle or Triumph model.

[Clifford Pope]

Update:
The judder disappeared after a few weeks, and the brakes have been perfect, until about a week ago when it started to creep back in. It vanishes if I touch the brakes quite hard, then release and apply more gradual pressure, but comes back next time I brake.

It feels very much as if the pads do not fit securely enough in the calipers, and need a bit of encouragement to settle themselves.
This would fit with my observation that the only pads now available are not quite the same shape as the old ones (see my photos).

Could it be that the slots in the calipers are worn, letting the pads chatter about? It seems odd that no one else has had this problem.

[tony]

Just wondering if it's possible to get new pads bonded to original backing plates ?
Tony.