So, my 848 recently failed an MOT due to "Front Roller brake test indicates excessive fluctuation of brake effort (3.3.A1d)". Basically, a pulsing/gripping that you could expect from a warped disc, among other things. I can't actually feel it on the bike when I ride, so it's very subtle. However, I have felt a slightly pulse in the past when slowing down from ~10mph to 0. Looks like the problem has gotten better, or is intermittent. I tried cleaning the floating disc bobbins to see if that would free up the disc and fix the issue - retested on rolling road and the problem was much better, but he still said the issue was there (and therefore wouldn't pass the bike). Last night I decided to take the calipers off and give them a proper clean. I took a picture of one of the pads to note the OEM model number, as I might replace the pads too (though they still have ~4mm of material left, so I'm reluctant to change from Brembo HH OEM to EBC HH if there is no need). tl;dr: Anyway, today when looking at the picture I noticed that at least on that one pad (maybe others too), one of the piston impressions was severely misaligned on the pad. Is this normal?
Not sure how to double check that. Manual/parts list says the original item number should be '613.4.041.1A'. I got the bike used from a Ducati dealership, you'd think they'd have noticed if the pads were incorrect. Seem to fit into the calipers just fine though.
Give Ducati a ring and ask them if they are the right part. If they were in when the garage took ownership of the bike I doubt they'd have them out to check. Worth a phone call
It is very common with the semi floating front discs to fail the MoT and there is a quick fix using an M5 hex bolt and backing nut with a battery screw driver/drill. Put the bolt throught the centre of the button and lightly tighten the backing nut, then using the battery screw driver/drill, rotate the button. Repeat 10 times on each disc. You might need a ring spanner to undo the backing nut. IIRC, OE Brembo pads would have been SA not HH but that isn't an issue and I don't believe you have a misalignment problem. Cleaning the caliper should be a routine operation to minimise the build up of dust which cakes onto the pistons. I regularly blow out the calipers with an air line. Just had tp spend £300 refurbishing a set of M4s that were left too long. Andy
Just called them and the guy said he couldn't check that on the system, for some reason. He did say that it's unlikely that the incorrect pads would fit into the calipers though.
Yeah I tried the button/bobbin trick on the disc and it DID help (according to the rolling road machine there was less pulsing), but not quite enough. I didn't use a drill though, only by hand, so I wonder if I just didn't do it enough times.
You should be able to see the bobbins moving by grasping the disc and flexing it. You should be able to feel the disc move a millimetre or two. Andy
I used a drill and Cillit Bang degreaser until each bobbin would give an audible click when moved from side to side. You wouldn't believe how much crud came out... Took lots of mopping up with kitchen towels. Worth it though, brakes are sooooo much better
Nice, I'll give it another proper go when I get home. I think most of them are loose enough for finger movement already, but can't hurt to do it again...maybe that will make the difference between MOT pass or fail.
Okay - got an update. I lifted the front of the bike (don't own a gp stand yet, but I made it work with some ratchet straps and a squat rack). Spinning the wheel gives a definite on/off rubbing sound as one part of the wheel passes though the pads...so something is definitely off. Took off one caliper and spun, still makes sound. Put it back and took off the other...spin and still makes that sound - so it's not limited to one side. Took of both calipers and spun the wheel to find that I can hear a noise as the wheel rotates. It seems to be at the same point in the rotation every time. I made a video, you CAN make it out, but it's very faint...kind of a dull 'dunk' sound. So that rules out any brake issues, including warped discs. In my mind it leaves a bad wheel bearing or bad wheel. It has taken a knock during a crash, but I think the bearing is a lot more likely (unless anyone has other suggestions). Bearings seem to be ~ £15 on eBay so I guess pretty cheap to find out...though I'm running out of day for my free MOT retest! Edit: Didn't feel any sideways/loose movement on the wheel though, but still hoping it's the bearing.
I may be wrong but you need to check your wheel for a buckled rim and for roundness. Easy to do using a fixed pointer on the fork tubes and set close to the rim/tyre bead. If that is OK then see if when you spin it, it always stops at the same point it could be badly balanced. You can clearly hear the light clunking btw
Knock the wheel/bearing spacers out and before you reseat them (to test if they were installed wonky) turn the bearings by hand and see of you can find any roughness, If there's no play in the wheel when the wheel is fitted I'd check that before replacing the bearings.
Kind of like this video? I think that will show that there IS a wobble in the wheel - I'm just hoping it's because the bearings are acting up, rather than the wheel being buckled. I did consider bad balancing, but it seems to stop at a different place every time. There does seem to be a bit of resistance in the bearings though, probably enough to overcome any weight fluctuation that the wheel might have. I did JUST get new tyres fitted (and therefore re-balanced).
Yeah, sounds like a great idea to actually check the bearings before ordering new ones. I watched a video of bearing removal and I'm just slightly concerned about taking a chef's torch to my lovely wheel paintjob. Should be fine, but doesn't feel right
Heat gun. I got one of these, REALLY useful. Look at this on eBay 2000W HOT AIR GUN WITH 4 NOZZLES PAINT STRIPPER STRIPPING HEAT SHRINK POWER TOOL | eBay Freeze the new bearings before fitting.
Haha yes - much better idea! Not sure why the video recommended a blow torch in the first instance. :-/
You don't 'need' to heat them up to get them out, just go easy with the drift a little at a time and you'll be fine. Check the spacers first, I had a wheel supplied that had the spacers incorrectly fitted, luckily for me Final Edition found that problem!
