Brake Whine - Noisy brakes

P

p6jpe

New Member
I have recently had Rossini drilled and grooved discs fitted to my 1975 S2 V8 since these were a straight replacement for the standard ones and claimed better stopping power.

The improvement has not been great and there is now a continuous intermittent whinning noise which seems to come from the rear, particularly noticeable since I usually drive with the window down!

The installer has checked this out and insists that nothing is wrong; the discs themselves also appear to be working OK with no vibration through the pedal to suggest they are warped or faulty.

Am wondering if the cause may be wind noise as air passes through the vent holes causing an intermittent sound as the discs turn. There is no difference when applying the brakes and the noise is only heard when moving.

I have also spoken to the supplier who is unable to suggest anything but has said that some users have reported noise problems with these type of discs.

Grateful for any views or similar experiences......... :(
 
Have you tried putting the back of the car up on stands and running it in gear ? That might indicate where the noise is coming from
Does the pitch of the noise vary with speed ?
 
Drilled and grooved discs are notoriously noisy, friend of mine fitted some and complained about the noise, apparently grooved only are better, but not much, plus the drilling is supposed to weaken the discs.
 
Sounds like a good mod' for a race or rally car, and not so good for road use!
Regards, John.
p.s. I always thought the brakes on a P6 were excellent as standard.
 
Hello,

I have a similar problem on my '74 3500 which I bought in 2000. The rear brakes were always squealing a bit when operated. Two years ago I had all the system checked by a specialist, and he exchanged the rear pads. Since then the squeal is much worse, it even occurs during normal cruising, whithout braking that is. I wonder whether the mechanic forgot to reposition the anti-squeal shims, but amongst Roverists he has a strong reputation, working on P6s since they were new back in the seventies. Back then he told me the noise would disappear as soon as the pads are run in...

Any idea as to what could stop this annoying kakophony?

Cheers,
Klaus
 
I would have thought that if the pads are rubbing against the discs when you are cruising , they would have worn out rapidly
Is the handbrake releasing fully and are the callipers free to pivot ?
 
A common fault on MGB's is brake squeal. This is caused by the pad vibrating rapidly and is not the fault, as is comonly believed, of the disk.
The accepted solution is to put copper slip on the back of the pads.
 
A common problem with P6 rears is internal rotting of the flexible pipe to the diff, this causes a one-way valve type effect holding the pads against the discs.

I had this problem, replaced the pipe, and all was well again. I used some stainless braided hose to make my own pipe, but a standard replacement will be fine.
 
Thats worth knowing. imperial fittings I take it?

having loads of fun with my MGV8 conversion... Having hoses made up with imperial fittings one end for the MG bits and metric t'other end for the SD1 bits. hehe!
 
The brakes on mine tend to squeel a bit from time to time. I also get the annoying squeek from them when you are happily cruising at about thirty, and it sounds like you have got a deranged Hamster behind one of the wheels!! The strange cure for the brake squeel on mine seems to be throwing the anchor out the window at about 70MPH! :D Dunno why it works, perhaps it's just that the brake pads get glazed over, and start squeeking :)
 
Hi Chaps

Been down with a major computer crash (duff mother board).

I've got Rossini discs as well, albeit not yet turned a wheel in anger!

For about the last 10 years all my cars have had grooved discs and greenstuff pads fitted as the originals needed replacement.

Grooved discs make little difference with standard pads, but are essential with Greenstuff. The Greenstuff pads are based on a different formulation including Kevlar instead of asbestos. This formulation gasses heavily under load and the grooves are needed to vent it away and prevent the pad "floating" on the gas created.

Drillings serve a similar purpose provided you have vented discs, which of course the P6 Rossini's aren't!! They are the predecessor solution for racing / high performance use before grooving became possible. Major drawback is that the holes tend to act as stress concentrators and thence trigger fracture sites.

The Rossini discs are therefore rather flawed in their theory - but they are the only off the peg discs with grooves.

I've found the combination of grooved discs and Greenstuff pads absolutely superb. I've generally had VW Golfs as my everyday transport and these are notoriously underbraked. This disc pad combination absolutely transforms them.

There is a whine to put up with from the disc grooves, but in my opinion well worth it for the performance improvement released with the Greenstuff pads. Hence being prepared to contemplate it for the English P6.

In the light of knowledge gained the Thailand 4.6ltr P6 is now going to get vented discs care of Alan Ramsbottom. We are using his own discs with spaced P6 calipers at the front, Sierra Cosworth calipers and bespoke discs at the rear. All with grooves and Greenstuff pads. This car has 205 section high performance tyres to put the braking effort down. There'd be no point going to this trouble with the standard 185 section - you'd just lock the wheels rather easier!

Chris
 
Chris is right about grooved discs and better pad materials. A lot of small single seaters don't have venteds either and cross drilling is an alternative where permitted. There is an answer to the fracture problem but it is really boring to do. Place the disc face down on a flat surface, take one ball bearing about twice the diameter of the drillings, place in each drilling hole and strike it firmly with a hammer. This has the effect of peaning the sharp edges caused by driling and bingo no stress point. Can take hours to do a set though.
 
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