Topics and replies.

Re: Brake squeal

Postby Angus Munro » 22 Aug 2017 09:07

A lot of people are talking about soft braking causing glazing which then leads to squealing. I just don't buy into that argument. I cannot think of one single modern car with squealing brakes and yet modern cars are driven by millions of people all with different driving styles.
As a modern car ages and drops away from the main dealer network private individuals will purchase brake pads, possibly Mintex or EBC, and fit them in the driveway at home, without brake squeal resulting. For the MGB and the V8 variant there simply must be something wrong with the design of the calliper. I have spoken with owners who have one of the four pot systems and none of them report brake squeal. The snag with this alternative is that I have yet to find a four pot calliper that will fit within the standard Factory V8 wheel.
However, my new EBC discs and EBC soft pads will be fitted on Thursday with great care being taken with the orientation of the pistons. As I promised, I will report back with the result.
Angus Munro
 
Posts: 21
Joined: 18 Dec 2012 15:36

Re: Brake squeal

Postby Tony Lake » 22 Aug 2017 16:15

Angus makes a good point, modern braking systems rarely make a noise loud enough to become a talking point.
Just google: Resonant Frequency of Disc Rotors and you'll be able to see why.
There is a fascinating SAE paper by Honeywell that describes the measures development engineers take to dial out noise before a design is released for production. Scroll through to the fishbone diagram to get a feel for how many factors have a bearing on the problem.
I doubt that the B had that kind of focus back in the day, however I suspect that the interrupted piston perimeter was important in dealing with asbestos pads of the period.
Tony Lake
 
Posts: 33
Joined: 20 Dec 2012 15:46

Re: Brake squeal

Postby Martin Cridford » 22 Aug 2017 16:20

When I fitted EBC 'Greenstuff' pads to my MGTF (2004) they came with sticky backed rubber 'anti-squeal shims' to place between the pad and the piston. No squealing on that car.

I add a smear of copper grease to the back of the pads if no anti-squeal shims are provided which seems to work too.
Martin Cridford
 
Posts: 87
Joined: 20 Feb 2016 08:19
Location: Exeter, UK 1995 RV8 No:1422, 2004 MGZR 160

Re: Brake squeal

Postby Angus Munro » 22 Aug 2017 17:01

The MGTF is a modern car, as is the RV8. Last year I bought my partner a 2004 MG TF160vvc. No brake squeal on that.
Until recently I had an RV8 with silent brakes.

I forgot to mention that I also have sticky back 3M rubber to fit to the pistons on Thursday.

I will keep you all informed but, thank you all for your comments and interest thus far.
Angus Munro
 
Posts: 21
Joined: 18 Dec 2012 15:36

Re: Brake squeal

Postby John Hale » 22 Aug 2017 17:07

Hi

I have been following this thread with interest because my RV8 has had the howling banshee problem from the front brakes since I replaced the discs (oe spec from VAG) and Ferodo pads. Sorry Angus but this is a four pot system! I have tried with and without brake grease carefully placed at friction points, cleaned everything with cleaner and checked runout. I had two concerns with my set up one was a radial low point on the OS disc which caused the dial gauge to drop (about 1.5 thou". outside spec) and recover over a narrow area (I think that disc may have had a small piece of debris under the flange when it was machined), and against all advice I refitted the original pad retainer clips as the ones supplied were for a thinner non vented disc. I also did the heavy braking drive and came back with smell of hot pads but that didn't work for me.

The only mod I have subsequently done was to double up on the pad retention clips, I did this by fitting the outer ends of the spare narrow clips (cut down) between the split pins and the original clips to increase the retaining load on the pad backplate, which after a few miles bedding in seems to have reduced the problem to a "rare event" and still improving. I would also expect that the slight uneven disc surface has now worn flat so that may also be helping. I have since bought a new set of the vented disc retention clips but am a bit reluctant to disturb anything at the moment!

So that's my story on the RV8 so far, if I suffer with the awful howl again I think I would go down the shim route but I note that the old pads had a leading and trailing edge chamfer on them so perhaps that was an earlier fix. Regarding the MGB and V8GT 2 pot caliper, I have an old parts list (AKB 0039) and interestingly under the V8 it lists part number ASV 101 Anti squeal shims - set of 4. When I googled it I got to the MGOC site as here: http://www.mgocspares.co.uk/acatalog/MG ... B__49.html, see item 17. However, this seems to be an MGB page if you work through the menu via V8 and supersports to the front brakes page the shims aren't shown!

Perhaps for a £5.16 investment one of you GTV8 howlers might want to see if they fit?

Regards, John.
John Hale
 
Posts: 39
Joined: 06 May 2015 11:49
Location: Stratford, Warwickshire.

Re: Brake squeal

Postby Angus Munro » 22 Aug 2017 19:15

Thank you John,
It's a little too late for me to order the anti squeal shims in time for my Thursday appointment but, should the brakes remain noisy I will try them.
I'm sorry to hear about your RV8 having a similarly annoying problem. Sorry and a little surprised too. I know many RV8 owners and their cars and such a problem is a new one to me.
Your comment regarding the pad retention clips is interesting as this might keep the pads still. The problem might have something to do with pad movement although the recently fitted Mintex pads I have had to have their steel backs relieved slightly in order to get them into place at all. I mention movement only because others have cured the problem temporarily by the use of Teflon strips, pad steel back to calliper. Of course, the Teflon doesn't last long...
The very odd thing with the brakes on my car is that the noise worsens as the speed reduces, to its very worst just as the car stops. So far this amuses people waiting at traffic lights but my neighbours might be getting past the funny argument.
Angus Munro
 
Posts: 21
Joined: 18 Dec 2012 15:36

Re: Brake squeal

Postby Angus Munro » 25 Aug 2017 10:23

I am now able to report that the squealing problem has been solved and that, so far, I have completely quiet front brakes.
This has been achieved by the fitting of new standard EBC OE spec. discs together with EBC Ultimax2 pads.
I purchased the discs and pads as a set directly from BMH at Witney for £146 which was cheaper than buying the discs and pads separately by about £20.
I chose the Ultimax2 pads because they are the softest of the EBC range and appear to be free of metal within the pad material. I am hoping that the softer pad material will help to absorb any frequency vibration that may have contributed to the sound, the squeal.
BMH kindly included a packet containing thin sticky back 3M rubber strips for adhering to the steel backing plate of the pad separating the calliper piston from the pad backing plate. Interaction between the slightly floating pad steel back and the piston may have contributed to the squealing sound. This may go some way to explaining why some people have had success with the use of Copperease between the two surfaces, the Copperease acting as a lubricant of course. By using the 3M strip we did not use any Copperease. Should the rubber eventually wear through it will be a simple job to replace it as the kit supplied was more than sufficient for several application over time.
Comparing the old, less than 200 mile old, pads with the new EBC ones both had the same oddity. The steel backing plates were symmetrical about a horizontal centre line and yet the pad material is displaced with its own centre line, a slot in fact, a little above the backing plate centre line. What this means is that there is a greater lip of backing plate exposed at one end of the pad than at the other. So... which way is the right way up?
We had to make a telephone call to BMH at Witney to ask the question as, astonishingly, there is no mention of this in the instructions and no marking on the backing plate. The answer is the the longer lip is at the bottom.
The discs as supplied are coated with a black material which we were advised to leave in place. For the pads, I quote from the packaging, "The surface of the brake pads for street pad materials is coated with a red material known as BRAKE-IN. This coating helps your brake pads to 'seat' or bed in quickly. However pads should be used gently for the first 100 miles."

Once the two coatings, disc and pad, have worn away and I return to the real world of bare pad to bare disc I hope that even my gentle braking style will continue with silent brakes. As mentioned before, if it works for a ten year Golf using aftermarket pads.

I should mention that all four pistons were correctly orientated with the slot facing the centre of the hub.

I'll pop a photograph of one of the old pads that will clarify what I mean regarding the pad material/pad backing steel relative positions, together with a few observations in V8NOTE529. http://www.v8register.net/FilesV8WN/170 ... V8-AM4.pdf

I hope that this thread will have been of value and thank you to the various contributors and followers who have been with me along the way. Mostly though, many thanks to my super chum John Cumming who actually did the work for me yesterday. He just made it all look so very easy. Should anybody care to discuss any aspects of this work directly I am happy to be contacted by telephone. http://www.v8register.net/contacts.htm
Angus Munro
 
Posts: 21
Joined: 18 Dec 2012 15:36

Previous

Return to V8BB Messages

Who is online

Users browsing this forum: Bing [Bot] and 2 guests