Old clonk/clunk - New trial

[harrytr5]

Like t0 see that also Marco

Regards Harry

[harrytr5]

Thanks I have just seen it and the same kit in my MOT Station.

Regards Harry

[stuart]

1 hour ago, Z320 said:

That wouldnt show wear up and down on the trunnion thread though. Jack up under the spring pan till the wheel is off the ground far enough to put a long bar under the wheel and then lift the wheel whilst observing where the seal on the top of the trunnion is to see any up and down movement.

Stuart.

[Z320]

1 hour ago, stuart said:

That wouldnt show wear up and down on the trunnion thread though. Jack up under the spring pan till the wheel is off the ground far enough to put a long bar under the wheel and then lift the wheel whilst observing where the seal on the top of the trunnion is to see any up and down movement.

Stuart.

Also a good idea!

Didn't we have a thread here not long time ago where the trunnion has been pressed off the vertical link by the coil spring?

Edited June 13, 2025 by Z320

[Casar66]

4 hours ago, stuart said:

That wouldnt show wear up and down on the trunnion thread though. Jack up under the spring pan till the wheel is off the ground far enough to put a long bar under the wheel and then lift the wheel whilst observing where the seal on the top of the trunnion is to see any up and down movement.

Stuart.

That I have done already at the beginning of my "front-clunk-trauma"

[Casar66]

2 hours ago, Z320 said:

Also a good idea!

Didn't we have a thread here not long time ago where the trunnion has been pressed off the vertical link by the coil spring?

In that case I would expect that it happens not only at braking at low speed?

[JohnC]

Hi Casar,

This must be *so* frustrating!

I confess I haven't been back through all of your previous thread (it's looong...), so please forgive me if you're sure it's not stub axle flex causing pad knock-back. For many years I suffered a clonk on the first application of brakes after leaving my driveway. It was cured by fitting a stub axle stiffening kit. I wonder: you say the clonk happens only at low speed. Does it happen *every time* you apply the brakes at low speed, or only the first time on a drive? If you take your car for a drive, are you able to cause the clonk by not applying the brakes at all (handbrake allowed!) until you have achieved a higher speed?

I fear I may be covering old ground, as you seem to have done everything short of selling the car, but worth a shot.

Cheers,
JC

[Casar66]

Hi John

I'm sure you're right, even I can't remember with 100% certainty what I've tried and what I haven't, hence the new thread.

Regarding your comments: I can only say that my axle (without additional stiffening) is without any abnormalities. Whether it flexes, I don't know, but if it did, I think the noise would fit.

I can't provoke the clunk without a foot brake. It also comes when I apply the footbrake with the handbrake on.

I can't always provoke it even when driving slowly. Often, but not always.

It happens the first time I stop after exiting, when I want to turn into the road and stop beforehand.

Or at the end of a tour, when I brake to almost zero just before entering the garage.

But not always. But when I do, I can repeat it many times.

Otherwise it doesn't happen. Never when driving in the rear gear.

[JohnC]

I want to say that sounds like pad knock-back, but your comment "But when I do, I can repeat it many times." doesn't fit. In my limited experience knock-back happens once, after tight manoeuvring and possibly after going over a bump, but it only happens once. After one application of the brake the slack is taken up and there's no more clonk.

But... If you've tried everything else, perhaps you should try either stronger stub axles (the originals can flex even if in perfect condition) or a stiffening kit like this. It's what I fitted and the clonk on my car was eliminated, never to return.

Cheers
JC

[Casar66]

Ok, could be my last exit Brooklyn.

Another approach:

What if the clunk is due the brakepad but not because there is too much play or too weak springs of the anti-noise-kits. But because that the pad is (slightly) too big?

That would match my impression that the clunk is relaxation-noise.

[Z320]

I‘m sure your clonk is from the pads, which have play in your calipers.

Please measure the gap with a feeler gauge and tell us.

[Casar66]

22 minutes ago, Z320 said:

I‘m sure your clonk is from the pads, which have play in your calipers.

Please measure the gap with a feeler gauge and tell us.

Haven't we sort that already out, Marco?

[Z320]

You sorted that out

[Casar66]

Yes, because there is no reason for it still. 

[Casar66]

Am I getting closer to the matter? In any case, I've come to a new conclusion:
The last time I tried everything to do with the brake pads, with or without springs or double springs, with or without anti-noise plates or double the number of plates, nothing changed. I even installed 3M pad tapes instead of the steel plates.

Today I noticed something that I hadn't noticed before.
Before: he clunk still comes when I roll/ride slowly and then stop. But not always. And not always when I want to provoke it.

But now I can always provoke it: I have to reverse first, not much, one meter is enough, then brake, then forward again and it clunks. Always. It's important to slow down to stop it reversing. Without braking when reversing, I can't provoke the clunk when driving forwards. 
Very rarely, it also clunks without having reversed beforehand.

Will this get me any further?

 

[Pete E]

In years gone by, used to get a clonk sometimes with brake shoes binding in the drums, that said no mention of handbrake being used so maybe another blind alley🤷‍♂️

Pete

[Casar66]

it is definitely from the front, not the handbrake.

[Steve-B]

Hi Cesar

Does the clunk happen all the time when you're driving so much that it distracts you or is it intermittent? If it is all the time, are there any speed ranges where it does OR does not clunk? Asking as you've done a heck of a lot and still have the clunk so I'm wondering if it has nothing to do with the wheels and possibly is something else?

[Casar66]

The clunk is only ( not only but nearly only) at the beginning or at the end of a drive. At very low speed. Not whilst normal driving ( and brakking).

It is not the wheel. I have changed the wheel. Even from centre-locks to standard ones.

[Casar66]

Another Idea: 

Do any of you also have the late brake calipers with the 3/16" pins and possibly a detailed photo? Maybe the holes for the pins are too big for me?

[JohnC]

You may be onto something here. The holes in the calipers, the pins, and the holes in the pads should all be the same size. If not, there will be movement. Could you possibly have the wrong size pins for the calipers? Of course that would mean you have early (Imperial) 16PB calipers which have holes for 1/4” pins, but are using 3/16” pins suited for late (Metric) M16P calipers (and I note you imply you have M16P). Or that the pad holes are for early pins but you have late caliper and pins (the photo is too blurred to tell).

Cheers,
JC

[Joestr8]

I’m not sure if it’s been covered already but I think the caliper retaining bolts have different shoulder sizes depending on which callipers are fitted.  If shoulder is too small it could be the caliper that has slight movement causing the clonk.

[jerrytr5]

18 hours ago, Casar66 said:

But now I can always provoke it: I have to reverse first, not much, one meter is enough, then brake, then forward again and it clunks.

Sounds like the pads are a very sloppy fit in the caliper. Your photo shows a very clean caliper. What it needs is a bit of corrosion & brake dust!

Try jamming the pads in with small bits of wood (not on the road of course) & repeat the test.

Jerry

[Z320]

Did I already ask you to measure the gap between pads (Trägerplatte) and caliper  „please“?

The pins do not hold the pads, they are too week to bear radial forces.

I had the gap on my green stuff pads only 0.5 mm —-> this was already too much and I had „good“ clonks

[Casar66]

3 hours ago, JohnC said:

You may be onto something here. The holes in the calipers, the pins, and the holes in the pads should all be the same size. If not, there will be movement. Could you possibly have the wrong size pins for the calipers? Of course that would mean you have early (Imperial) 16PB calipers which have holes for 1/4” pins, but are using 3/16” pins suited for late (Metric) M16P calipers (and I note you imply you have M16P). Or that the pad holes are for early pins but you have late caliper and pins (the photo is too blurred to tell).

Cheers,
JC

It should be all M16P stuff, the 3/16pin, the caliper and the pads. But I was wondering why is that much play nearly everywhere. The pins in the caliper are more or less loose, I can pull them out by Hand. Same with the pads, they are wider than the pins in any way. Yesterday I put some rubber hose from a fishtank over the pins so that there is no play with the pads. No change.