Emery cloth to a rotor? That should wear your brake pads down in a big hurry. Most auto parts stores carry brake parts cleaning solutions. It breaks down and removes oils and other crap that can build up on your rotors causing the pulsing that you are feeling. I don't think you are going to be able to see deviations in your rotor while spinning it on the wheel unless you can either lock the fork system down so it doesn't turn right or left, or take the wheel off and mount it in a trueing stand. As far as sanding a rotor smooth with an emery cloth, that's going to take a long while. Would be more worth your while to just buy a new rotor. Just go in and ask your garage mechanic what the process is in turning a rotor then ask him what he thinks of sanding the rotor with emery cloth. I'm sure he will laugh.

 

It actually works because it lets you re-bed the brakes. Not the same as turning rotors. And it's quite easy to check the runout while mounted using a dial caliper.

 

As you have said ., you didnt feel anything before you had the test and now after replacing rotors , pads and caliper shims you now feel a pulse .???
Thats very wierd i must admit ., so where do we go from here ?
1) i think we can eliminate any problems with the calipers as long as you feel they are mounted correcty etc.
2) the rotors are new and we can assume they are true ., did you clean the storage oil off the rotors before installing them ?
3) i think we can eliminate any problems with the new pads as long as you have cleaned the rotors as described in point #2 . If not , you will require new pads as they have been contaminated with the storage oil.
4) a brake pulse on a test dyno could also possibly be caused by other than a brake issue . Visually check your tire for any obvious weak spot and have a balance test done "on both tires" to verify that all is well there.
5) While having the tire balance test done , the shop should be able to test the wheel runout , wheel bearing condition etc. to help you eliminate these possible causes also.
Please let us know what you find here.

 

Thanks guys for you input, I purchaced a second set of rotors as the first new ones were warped. Booked it in to the garage for another mot. Whilst riding to the garage my heart sank!!! same as before - pulsing through the lever. The tester put it onto the machine and the reading for the front brakes was WORSE than the last set!!!!!!!!

 

What does the front wheel look like? I'm wondering if the front wheel is warped at the ub or there's trash there or something, and when you bolt the new rotor down, it is picking up the warp.

Pads, forks, calipers, transmission oil or brake lights will have no effect on a pulse. It has to be the pad to rotor interface pushing in and out. Now, why would new rotors warp? Were they warped when you put them on? Take them off and check for trueness. Put them on, put the front wheel up in the air and spin it and check with a dial indicator. Take it for a ride, come back and check it. Are these Genuine H.D. rotors or cheap Chinese crap?

 

Hi Dr Hess.
The wheels look good and there isn't even a hint of a wobble whilst riding the bike, you only notice any thing when you pull on the lever, even slightly. The discs are not from HD but they are from a reputable dealer - Motorcycle warehouse.
If the bearings were at fault, wouldn't I be getting some indication whilst riding? the calipers are central and the pads are new.

 

With the front wheel in the air and a dial indicator on the disks, spin the wheel and see what you get. Measure on all 4 disk faces if you can. Not sure about setting it up for inside, but see if you can.

With the wheel spinning, very lightly pull the brake lever, or preferably have a helper pull the brake lever. Are there easy and hard spots in the wheel rotation? Can you feel a pulsing in the handle? Some rotors only warp when they heat up. Actually, a lot of them. If you can feel the pulsing, try removing one caliper and blocking the pads/piston with something like a board, piece of steel, etc., and repeat. Still pulsing? If not, you found the side causing problems. If yes, try the other side.

Dunno about the bearings. I suppose it would be possible. I'm leaning towards cheap aftermarket rotors right now.

 

Just wanted to say thanks for taking the time to offer advice. Turned out that both sets of replacement rotors were warped!!!!
I managed to get hold of a set of s/h floating discs from a trusted source and the bike now FINALLY has a new MOT.
The pisser is the company that supplied the "new" discs have refused to refund my money because they say once they are fitted and "used" the problem must be a "fitment" issue.


Thanks again

 

Glad you got it fixed.


As for the company that provided the "new" discs I would put them on the never buy from again list as they sound like a fly by night kind of place!!

 

And that right there is why I buy Genuine H.D. parts whenever I can. There's good aftermarket stuff and there's a lot of crap aftermarket stuff, and I don't buy enough parts to know which are which, but a Genuine H.D. part will probably be OK.