Recommended Brembo supplier - Page 2

Rrawlings · 06-01-2022, 04:10 PM

I tried multiple different things to get rid of my evo brake pulse and the only thing that cured it was new discs I’m afraid.

Mr Gazza · 06-01-2022, 04:20 PM

In my experience of ABS it gives very rapid pulses and not the languid pulses you describe, but I don't know if the system can malfunction to give that effect? I doubt it.

If it were mine I would now be farging up a bracket to mount a dial gauge on the forks and then trying to find a hole free path round the rotor for the probe to run on.
Chances are that if the Italian tune up didn't glazebust the discs, then they are actually warped.. Sorry!

crawsue · 06-01-2022, 05:20 PM

Cheers for that, my Sprint ST has a warped disc (again) and it’s much more of a “shudder”, but I’ll sort out a disc check in the Spring, perhaps the MOT brake test will flag something up.........

slob · 06-01-2022, 05:54 PM

Quote:

Originally Posted by crawsue

I pm’d Vince (Luddite) earlier as I have a braking sensation similar to Mr Gazza, long pulses as I brake slowly to a standstill but perfect braking at speed. New fluid at last service, and Scotchbrited the discs ...to no effect. I’ll give Mr G’s tip a try on my next outing and report back. All bobbins have some free play, a warped disc gives a more of a shudder...this is a languid “pulse”....

I’ve had this with Galfer wavy discs, always used to get an MOT advisory despite them being perfect at 120+ mph on track. Oz had similar with another make of wavy discs, he removed the bobbins and checked the rotors on a surface plate, perfect. Since discovering this, I swap the left and right pads before MOT, it passes with absolutely no pulsing, which returns when the pads bed in again.

350TSS · 06-01-2022, 07:00 PM

^^^ Maybe I am overthinking this but could the pulsing result from the pad "falling into" /being pressed into the gap at the circumference of the wavy disc? I guess that the relationship between the length of the pad or rather the footprint of its swept area and the length/depth of the scallop in the circumference of the disc could be critical i.e. if too much of the pad is unsupported by the disc when the brake is applied it could lead to brake piston oscillating and pulsing on the lever.

slob · 06-01-2022, 07:17 PM

I think that’s exactly the problem, the brakes are a bit ‘grabby’ at low speeds, especially with p4 calipers. The problems with Mk2 Monsters is a little different though.

Dukedesmo · 07-01-2022, 11:40 AM

I'm not a fan of wavy discs although I confess to having such discs on the rear of my Monster but, for weight saving purposes and I hardly use it anyway but, it does make a strange pulsing noise (though can't feel any actual pulsing) if applied firmly at speed. I assume this is because of the change in friction area as the pads pass over the gap between the waves? Not sure if/how this affects pad wear?

As such I would think a pulsing would likely be present on twin, much larger discs applying significantly more braking power?

Darren69 · 07-01-2022, 12:33 PM

I've often wondered if wavy disks will produce a wavy brake effect and how can they be better than a circle one?

350TSS · 07-01-2022, 02:13 PM

If there is oscillation caused by the gaps in the circumference of the disc then two bad things are happening at the piston within the caliper bore
1. the piston is rocking within the bore
2. the seals are suffering a rapid forward and backward motion on the side where the piston has the most rocking movement i.e. the circumference of the disc (admittedly not of any great distance) but it cannot be doing the lip of the seal any good.
The only real benefits of a wavy disc is reduced rotating mass and un-sprung mass and a possible cooling benefit because of the increased surface area at the circumference.
Mine were purchased because they were cheap (Demon Tweeks) compared to OE or respected branded alternatives.

crawsue · 07-01-2022, 04:36 PM

My problematic set up is completely original, so no wavy discs. I have a suspicion that my “pulsing” issue is a pad problem, I can actually hear the pads gripping at low speeds,kind of “zing” sound, never been aware of this on other twin rotor ‘bikes. It’s only apparent in the final 20 metres or so of a gradual stop, e.g. for traffic lights.

slob · 07-01-2022, 06:55 PM

(double) check your steering head bearings?

crawsue · 08-01-2022, 10:59 AM

Head bearings were part of the big service , only 3k mls ago, it’s not a “grabby” sensation, just a kind of languid pulse as I coast to a standstill....all other braking is perfect ��

350TSS · 08-01-2022, 01:56 PM

Having had a close examination of my wavy discs I have decided I was talking complete bo**ox above. Sorry.
The missing bits on the circumference of the disc are:
1 not significant enough to cause the caliper piston to oscillate
2. too frequent at the circumference to cause a slow pulse at the lever

Mr Gazza · 08-01-2022, 02:03 PM

The new info you have given seems to have brought the issue back full circle to the disc "surface conditioning" rather than warping. It's a pity the hard braking or "Italian tune up" exercise didn't work but I could only advise persisting with it as there is nothing to lose provided it's done safely. (i.e. check your mirrors before braking on a straight empty road.)

I would recommend having the pads out and scrubbing them as clean as possible with a tooth brush and clutch and brake cleaner, then returning them to their original positions with a little coppaslip on the back. Make sure the pins are clean too. Also clean the discs with clutch and brake cleaner, just a soaked rag will do, but keep turning the rag to a clean bit.

I am sure that if you persist with this that the problem will resolve, you do sometimes have to stick at it. I am now in the habit of wiping my discs very often, especially just after a wash to make sure the discs are dry all round and free of any wax products from the wash/wax. Clutch and brake cleaner is hygroscopic so it works well for that.

It's not a bad idea to just push the pads off the discs if you're laying the bike up for while, such as Winter. I don't think I've ever bothered, but then I gently heat my workshop, so I shouldn't get any condensation in there.

One disc on my 750SS has a slight measurable warp but it is less than the movement that the bobbins allow and so they deal with it. I can feel no pulse through the lever or otherwise.

Wavy discs have the same area of contact by the pads at any given point otherwise they wouldn't work. Twin disc setups are staggered to negate any possible variation in this and give better balance. My three wavy discs work absolutely fine and have done for years.

For what it's worth I find Organic pads to be far better for feel, power and disc life. I haven't used a sintered pad on a bike for about 30 years or more.

crawsue · 08-01-2022, 02:36 PM

Thanks for all the above, I gave them a wipe with brake cleaner during this discussion last summer and before the “Italian Tune Up” exercise, but I do normally shove some wash ‘n wax in when washing my bikes ,so that could be a shout. I’ve spoken to my AJS pal ,he can sort out a dial gauge if required. I stopped using sintered pads at least 20 years ago, but I haven’t required to change the pads since I bought it, so they could have been fitted for the previous owner. I’ve resolved to do a calliper strip when measuring the discs , although I know that there is plenty “meat” left on them.
For what it’s worth, although I would describe my riding style as “brisk” I’m more inclined to use engine braking , especially on well known roads.....slow (ish !) in....fast out.

06-01-2022, 04:20 PM	#17
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,982	In my experience of ABS it gives very rapid pulses and not the languid pulses you describe, but I don't know if the system can malfunction to give that effect? I doubt it. If it were mine I would now be farging up a bracket to mount a dial gauge on the forks and then trying to find a hole free path round the rotor for the probe to run on. Chances are that if the Italian tune up didn't glazebust the discs, then they are actually warped.. Sorry! __________________

07-01-2022, 11:40 AM	#22
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,901	I'm not a fan of wavy discs although I confess to having such discs on the rear of my Monster but, for weight saving purposes and I hardly use it anyway but, it does make a strange pulsing noise (though can't feel any actual pulsing) if applied firmly at speed. I assume this is because of the change in friction area as the pads pass over the gap between the waves? Not sure if/how this affects pad wear? As such I would think a pulsing would likely be present on twin, much larger discs applying significantly more braking power? __________________ M900, 916, LeMans II.

07-01-2022, 12:33 PM	#23
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,095	I've often wondered if wavy disks will produce a wavy brake effect and how can they be better than a circle one? __________________ Roast Beef Monster! Termignoni and Bucci - Italian for pipe and slippers! S4 Fogarty, S4R 07T, 748, Series 1 Mirage

08-01-2022, 02:03 PM	#29
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,982	The new info you have given seems to have brought the issue back full circle to the disc "surface conditioning" rather than warping. It's a pity the hard braking or "Italian tune up" exercise didn't work but I could only advise persisting with it as there is nothing to lose provided it's done safely. (i.e. check your mirrors before braking on a straight empty road.) I would recommend having the pads out and scrubbing them as clean as possible with a tooth brush and clutch and brake cleaner, then returning them to their original positions with a little coppaslip on the back. Make sure the pins are clean too. Also clean the discs with clutch and brake cleaner, just a soaked rag will do, but keep turning the rag to a clean bit. I am sure that if you persist with this that the problem will resolve, you do sometimes have to stick at it. I am now in the habit of wiping my discs very often, especially just after a wash to make sure the discs are dry all round and free of any wax products from the wash/wax. Clutch and brake cleaner is hygroscopic so it works well for that. It's not a bad idea to just push the pads off the discs if you're laying the bike up for while, such as Winter. I don't think I've ever bothered, but then I gently heat my workshop, so I shouldn't get any condensation in there. One disc on my 750SS has a slight measurable warp but it is less than the movement that the bobbins allow and so they deal with it. I can feel no pulse through the lever or otherwise. Wavy discs have the same area of contact by the pads at any given point otherwise they wouldn't work. Twin disc setups are staggered to negate any possible variation in this and give better balance. My three wavy discs work absolutely fine and have done for years. For what it's worth I find Organic pads to be far better for feel, power and disc life. I haven't used a sintered pad on a bike for about 30 years or more. __________________

06-01-2022, 04:10 PM	#16
Rrawlings Member Join Date: May 2019 Location: Bradford Bike: M1100evo Posts: 175	I tried multiple different things to get rid of my evo brake pulse and the only thing that cured it was new discs I’m afraid.

06-01-2022, 05:20 PM	#18
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 278	Cheers for that, my Sprint ST has a warped disc (again) and it’s much more of a “shudder”, but I’ll sort out a disc check in the Spring, perhaps the MOT brake test will flag something up.........

06-01-2022, 07:00 PM	#20
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,422	^^^ Maybe I am overthinking this but could the pulsing result from the pad "falling into" /being pressed into the gap at the circumference of the wavy disc? I guess that the relationship between the length of the pad or rather the footprint of its swept area and the length/depth of the scallop in the circumference of the disc could be critical i.e. if too much of the pad is unsupported by the disc when the brake is applied it could lead to brake piston oscillating and pulsing on the lever.

06-01-2022, 07:17 PM	#21
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,736	I think that’s exactly the problem, the brakes are a bit ‘grabby’ at low speeds, especially with p4 calipers. The problems with Mk2 Monsters is a little different though.

07-01-2022, 02:13 PM	#24
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,422	If there is oscillation caused by the gaps in the circumference of the disc then two bad things are happening at the piston within the caliper bore 1. the piston is rocking within the bore 2. the seals are suffering a rapid forward and backward motion on the side where the piston has the most rocking movement i.e. the circumference of the disc (admittedly not of any great distance) but it cannot be doing the lip of the seal any good. The only real benefits of a wavy disc is reduced rotating mass and un-sprung mass and a possible cooling benefit because of the increased surface area at the circumference. Mine were purchased because they were cheap (Demon Tweeks) compared to OE or respected branded alternatives.

07-01-2022, 04:36 PM	#25
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 278	My problematic set up is completely original, so no wavy discs. I have a suspicion that my “pulsing” issue is a pad problem, I can actually hear the pads gripping at low speeds,kind of “zing” sound, never been aware of this on other twin rotor ‘bikes. It’s only apparent in the final 20 metres or so of a gradual stop, e.g. for traffic lights.

07-01-2022, 06:55 PM	#26
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,736	(double) check your steering head bearings?

08-01-2022, 10:59 AM	#27
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 278	Head bearings were part of the big service , only 3k mls ago, it’s not a “grabby” sensation, just a kind of languid pulse as I coast to a standstill....all other braking is perfect ��

08-01-2022, 01:56 PM	#28
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,422	Having had a close examination of my wavy discs I have decided I was talking complete bo**ox above. Sorry. The missing bits on the circumference of the disc are: 1 not significant enough to cause the caliper piston to oscillate 2. too frequent at the circumference to cause a slow pulse at the lever

08-01-2022, 02:36 PM	#30
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 278	Thanks for all the above, I gave them a wipe with brake cleaner during this discussion last summer and before the “Italian Tune Up” exercise, but I do normally shove some wash ‘n wax in when washing my bikes ,so that could be a shout. I’ve spoken to my AJS pal ,he can sort out a dial gauge if required. I stopped using sintered pads at least 20 years ago, but I haven’t required to change the pads since I bought it, so they could have been fitted for the previous owner. I’ve resolved to do a calliper strip when measuring the discs , although I know that there is plenty “meat” left on them. For what it’s worth, although I would describe my riding style as “brisk” I’m more inclined to use engine braking , especially on well known roads.....slow (ish !) in....fast out.