Intermittant rhythemic clack clack clack sound..

P

phil

New Member
Hi, this happens intermittantly when braking. It sounds like its coming from the rear but it may be transmitting. It is very loud and quite alarming. Braking effort isn't affected. Nothing seems loose and the discs are nice and shiny.

71 J reg, V8 auto.
 
How much material remains on the rear pads? Does the frequency of the sound reduce as the car slows down or does it stay the same?

Ron.
 
You will need to have a really good look about everywhere underneath using a nice bright light. Check your exhaust muffler 'O' rings and that the pipe is free from any excessive movement. Check for any contact between it and the tailshaft. Check the front brake shields that sit behind each disc for security. No movement should be possible. Remove the fibre board cover in the boot that hides the fuel tank and ensure that the tank is secure and free of any possible movement. Can't think of anything else at the moment...

Ron.
 
My instant reaction would be to have a very careful look at all the UJ's - including whether they may be fouling on something? Very difficult to diagnose without hearing it though.

Chris
 
I have a clackiing noise which i thought was brakes but looks like a uj is about to seize.

Other thing to check is the rear exhaust can hitting against the boot floor.

Colin
 
That is interesting. Would make sense, as the diff twists under braking.. Are the uj's replaceable like p4 ones or does the propshaft have to be overhauled by a specialist?
 
phil wrote,...
That is interesting. Would make sense, as the diff twists under braking.. Are the uj's replaceable like p4 ones or does the propshaft have to be overhauled by a specialist?
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How do you know Phil that the diff twists under braking? Where does it actually twist?

The tailshaft and half shaft uni joints are all removeable and replaceable with the normal tools. The only time you will run into bother is if the uni joint seizes and then the cups start to rotate within the yoke. The damage done can mean that the yoke needs to be replaced.

Ron.
 
On the rear outer pad there is a spring tensioner,that,if missing,or bent will not put pressure on the pad,allowing it to rattle on the 2 locating bolts that hold it in place,which in turn widens the holes in the pads backing that locate it thus making the noise worse.
Ive just replaced my rear pads,and noticed the tensioner wasnt doing its job,all it needs is the pad popped out,bend the tensioner in a bit and refit.
 
SydneyRoverP6B said:
phil wrote,...
That is interesting. Would make sense, as the diff twists under braking.. Are the uj's replaceable like p4 ones or does the propshaft have to be overhauled by a specialist?
Click to expand...

How do you know Phil that the diff twists under braking? Where does it actually twist?



Ron.
Click to expand...
It just seems logical to me that it would? The discs are mounted to the diff aren't they?
 
Phil wrote,...
It just seems logical to me that it would? The discs are mounted to the diff aren't they?
Click to expand...

Hmmm, doesn't seem at all logical to me... :?

Personally, unless proven otherwise, I don't think it would twist the diff (I assume you mean the case) at all.

The Rover's brakes are very heavily biased to the front, by comparison the rears do very little indeed.

Ron.
 
Well, imagine the wheel spinning and the brake mounted to the output flange on the diff, braking, the nose of the diff would try to go down as it takes the strain?? Maybe I'm wrong but that is how I imagine it happens.
 
Exactly so. Plus the UJ's in the drive shafts out to the wheels will be loaded in the opposite sense to when under drive.

Chris
 
phil wrote,...
Well, imagine the wheel spinning and the brake mounted to the output flange on the diff, braking, the nose of the diff would try to go down as it takes the strain??
Click to expand...

As you are including the pinion extension case, then I can see your line of thought. If there is a degree of flex between the tip of the extension case and the differential axis, then it would I expect need to be insignificant otherwise I imagine at some point there will develop a fatigue crack. If the magnitude of the force generated by the brakes is less than the force required to bend the diff + ext case, then it won't.

There is a lot of physics going on here, looking at the mathematics involved would be quite interesting.

Still I don't expect this has anything to do with the noise your Rover is making when you brake, unless of course one of the three flexible mounts needs replacing or has worked loose.

Ron.
 
Not sure if I should share this :roll: but I had an intermittent clack-clack occur on my last car - call it my P6 testbed - after failing to replace the lock tabs to the inner halfshafts after overhauling the brakes. The frequency of the noise rose and sank with vehicle speed. I had lost two bolts from the LHS one, as it turns out. Tightened the remaining two, ensuring they were in opposing positions first (they weren't), and limped to a screws supplier for replacements... :oops:
 
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