[Resolved] [Technical] 'Soft' front brakes

[helloindustries]

Recently had a banjo fitting replaced due to a small leak. Brakes were bled, but now feel much less effective than before.
Granted; They were never at 100% as the rotors were bent before i got it. They were straightened out, which sorted as much deformation in the discs as possible, and the brakes were good enough.

All i can think of is that they might need re-bleeding.

Thoughts?


-

Resolved
Leak on right side due to worn washers.
Now replaced, re-bled at all points and back to where they were (which wasn't 100%, and wont be unless i buy new discs).

[darrsi]

Always thought discs were way too thin to be "straightened"?
Any warping of a disc will keep pushing your pads apart so your initial grab at the lever would feel unresponsive.
Other than that it can take a few goes at bleeding before getting them sharp.

[helloindustries]

Always thought discs were way too thin to be "straightened"?
Any warping of a disc will keep pushing your pads apart so your initial grab at the lever would feel unresponsive.
Other than that it can take a few goes at bleeding before getting them sharp.

Initially; I thought the discs were bent when i got the bike, turned out to be bent rotors, which i had straightened.

• Initially; I had the standard brake hoses, and the brakes were OK-ish.
• Then i got the hoses upgraded to braided and the brakes were crap.
• Investigation found the warped rotors, which were then fixed and the brakes were much better.
• Then i had a line leak on the left side so had to have the banjo replaced
• Now my brakes feel soft.

Likely as you suggest, and i suspect: They probably just need another bleed, though i don't expect to get them up to 100% without spending silly money on rotors, discs, callipers etc... but i'll never do that. Just not worth it considering the initial value and that it's a cat C, and the likely resale value -vs- investment.

[darrsi]

Personally, if i wanted to keep a low budget then i'd consider 2nd hand original discs.

[Tefer]

You can get brand new Ferodo discs for £108 each from M&P.

[helloindustries]

Personally, if i wanted to keep a low budget then i'd consider 2nd hand original discs.

The discs seem pretty straight, well under 1mm of wobble. And then there's no guarantee that 2nd hand discs are any straighter.

You can get brand new Ferodo discs for £108 each from M&P.

And this is why i don't want to spend on new discs.

[darrsi]

Kind of chancy 2nd hand, but if you buy from a breakers they will change them if they're not right.
I've bought them once before and they were fine.
Originals are definitely better to take a chance with though, and it is possible to get ones with lowish mileage on that will last you a good while.
Unfortunately new ones aren't cheap, same as the rear shock too.
Just need to keep an eye out for the bargains, they are out there if you persevere.
Regulars on here will know i had major problems years ago with juddering up front, and i replaced nearly everything, and my last final option was to change my braided brake lines and it turned out that they were the culprit. 
Still reckon that if you keep bleeding your brakes then it will improve things though.

[Tefer]

Personally, if i wanted to keep a low budget then i'd consider 2nd hand original discs.

The discs seem pretty straight, well under 1mm of wobble. And then there's no guarantee that 2nd hand discs are any straighter.

You can get brand new Ferodo discs for £108 each from M&P.

And this is why i don't want to spend on new discs.


Brakes are important and that's quite cheap as new OEM ones are about £200 each. Brakes and Tyres i would not scrimp on.


I know what you mean though, not easy.

[helloindustries]

Well, i'll see how i get on with bleeding, and work outwards from there, i guess.

[helloindustries]

Out of interest: What should the thickness of the front brake discs be, anyway?

[darrsi]

Out of interest: What should the thickness of the front brake discs be, anyway?

Don't quote me, but from memory 4.5mm is the limit, but with a 5mm disc.
The pads should do all the work.
I have 6mm discs on mine so "should" be good for a long time.
Saying that, i used HH sintered pads on a new rear EBC Pro-Lite disc and the pads ate it like it was made of cheese. Admittedly i was using the rear more because of my front juddering. Even still i expected better than that.

[darrsi]

Take off your front lever and clean and grease EVERYTHING, it can help too.

[helloindustries]

Take off your front lever and clean and grease EVERYTHING, it can help too.

Good idea.

[darrsi]

Another overlooked simple improvement is clean and oil under the pivot of the rear brake pedal.
Crud builds up due to shite weather, but once cleaned and maintained regularly can make the rear feel very snappy, and it takes seconds to do. 

[helloindustries]

Another overlooked simple improvement is clean and oil under the pivot of the rear brake pedal.
Crud builds up due to shite weather, but once cleaned and maintained regularly can make the rear feel very snappy, and it takes seconds to do. 

Rear is plenty snappy!
Noticed as much with all the extra rear braking i'm having to do to compensate for the lacking front.

[darrsi]

Another overlooked simple improvement is clean and oil under the pivot of the rear brake pedal.
Crud builds up due to shite weather, but once cleaned and maintained regularly can make the rear feel very snappy, and it takes seconds to do. 

Rear is plenty snappy!
Noticed as much with all the extra rear braking i'm having to do to compensate for the lacking front.

Clean the pivot anyway on a regular basis, you will notice the difference.
I either use brake cleaner, or WD40, then a bit of 3-in-1 oil, about once a month.

[darrsi]

Brake disc wear limit should be stamped on them somewhere by the way.

[ste131]

Have you tried back bleeding? Sometimes you get a small pocket of air in master cylinder banjo. Take top off and start flicking lever and move steering to full left. Don't forget cloth around reservoir in case it spits back. Sometimes works wonders 

[darrsi]

Another trick you can try is loosen the master cylinder cap then tying your brake lever back and leaving it over night with the bike on the centre stand.
You don't wanna spill that shit so put plenty of rags around it just in case.
It forces the bubbles upwards. I've done it many times before to give the brakes that final boost, it normally works very well.

[helloindustries]

I had the front brakes bled at both ends today, no air that we could see, but the brakes feel a bit better.

[His Dudeness]

Cable tie the lever closed overnight. It can force the air back up to the master cylinder. Do it a few nights in a row

[unfazed]

If the problem was not there before you changed the fitting then it is most likely air.

I presume you are bleeding them correctly.
Pump the lever, hold it, release the nipple, keeping pressure on the lever. do up the nipple, release the lever. Restart pumping the lever again.

If tying up the lever like His Dudeness says does not work try bleed the lines from the master cylinder down by loosening the banjo bolt like the bleed nipples.
If no success, remove the calipers one side at the time and push the pistons back fully, use a clamp or something to hold them in the fully pushed back position. Now bleed them again, you will need a helper to pump the lever, while you open and close the bleed nipple.

Sometime air can get trapped around banjo or in the calipers and this normally resolves it.

[helloindustries]

If the problem was not there before you changed the fitting then it is most likely air.

I presume you are bleeding them correctly.
Pump the lever, hold it, release the nipple, keeping pressure on the lever. do up the nipple, release the lever. Restart pumping the lever again.

If tying up the lever like His Dudeness says does not work try bleed the lines from the master cylinder down by loosening the banjo bolt like the bleed nipples.
If no success, remove the calipers one side at the time and push the pistons back fully, use a clamp or something to hold them in the fully pushed back position. Now bleed them again, you will need a helper to pump the lever, while you open and close the bleed nipple.

Sometime air can get trapped around banjo or in the calipers and this normally resolves it.

They've had a standard bleed at the garage which improved the feel, but i might well whip the callipers off and do as advised.

[helloindustries]

So; I cleaned my callipers/pads/pistons today.

Rear was all good, but the front right had one piston pop out, now my brakes are worse, and there still might be air trapped in the bridging line over the mudguard. Also discovered a leak on the double set of banjos on the right side.

Brakes work, but wouldn't like to have to use them in an emergency.

Back down to the garage in the morning for a proper look, new washers and some investigation.

[unfazed]

So; I cleaned my callipers/pads/pistons today.

Rear was all good, but the front right had one piston pop out, now my brakes are worse, and there still might be air trapped in the bridging line over the mudguard. Also discovered a leak on the double set of banjos on the right side.

Brakes work, but wouldn't like to have to use them in an emergency.

Back down to the garage in the morning for a proper look, new washers and some investigation.

Why are you bridging across the mudguard?  The best method for the fazer is 2 lines from the master cylinder, one to each caliper.