Brake bed-in?

[ZsZ]

Hi guys,

I just installed new front brakes (TRW pads and discs, FAG bearings) and the new set feels less 'biting' than the old set was (TRW pads and italian 'noname' discs).
I did change brake fluid too.

I already drove ~200kms. It slow the van fine, just not as sharp of a drag it was before.

After how long driving should I feel the correct braking power?

Or the chinese made TRW discs are not as good as the old worn thin italian ones?

[maxstu]

New brake rotors fitted to my camper (from Brickwerks) in 2022. I too thought there is little improvement here and doubted the gain. It took about 1000 miles before the real braking ability exposed itself.

But l drive with a very careful right foot and am extremely light on braking, driving A roads as if on a motorbike.....outside, apex, drift out again without letting foot off accelerator...... and use the auto box as if driving a manual on some steep descents and steep climbs.

Give it a few hundred clicks

[ZsZ]

Thanks Maxstu,

I also drive quite easy on brakes. The TDI have plenty of engine braking especially with manual tranny.

I hope it just needs a few hundred more kms.

[maxstu]

Cheers Zoltan

[ZsZ]

New problem:

After a week in storage today I went a small trip with the van.
The brake pedal is softer and seems to grab on lower than before. If I pump it up then it is OK for a few hundred meters then it sinks again.

Fluid level is fine, and I cannot see signs of brake fluid around the wheels or the master cyl.

The only thing I did last time was changed the pads and rotors and changed fluid (two person pump and bleed method)

What did I mess up.

[maxstu]

Nothing. A symptom of air still in the brake circuit in my opinion.
Re-bleed the system. Starting from furthest from brake fluid reservoir. So left rear if RHD.

[ZsZ]

Hmm...

I bled out around 0.25L at each wheel (LHD so startet RR) 1.5L fluid total. I thought it is enough.
The strange thing that it was fine last week.

I need a power bleeder to do it myself without the help of my brother.

I think I also need to check the rear drums.

[Burtybassett]

Just putting it out there....
Would temperature be a factor ?
It's been really warm, then really chilly and now warm again.
I only ask due to my Hope C2 Hydraulic Brakes on my Kona need bleeding regularly in the Summer months.

Just askin is all.

[ZsZ]

It was warmer than now when I did bleed the brakes.

[silverbullet]

Check the end-float of the front hub/disc is still 0.07mm (3 thou in old money) in case the bearings have settled.
Excess end float will knock the pads off and give a long and/or spongy brake pedal.
This will also apply to the rear brakes but you last worked on the front, so check there first.

[ZsZ]

Thanks!
I hope I installed the bearings as they should be (tightened fully while rotating and loosening the nut until the thrust washer just moves with a screwdriver), but I will check them
Might need new spindle nuts if the bearings are loose...

[ZsZ]

It must be the bearings. Today I drove the van again. First it was fine, then after a while it dropped again, then fine agajn.
It is significally worse after tight corners.

But then the thrust washer must be bent or the spindle worn. Or I nterpreted the "washer can be pushed with a screwdriver" method wrong

[ZsZ]

OK. The left side was fine it had just a little play with the wheel on, rocking 9-6 o'clock. Tightened it just a bit.
The right side however has some problems. With the wheel on it has clunking play even then the nut is tightened to where I cannot move the washer.
Either the washer is damaged or the spindle is worn on the inner bearing.

Now I tightened it to have just about the same play as the oher side. The pedal still drops after driving.
I stop with a fine pedal, then start moving forward and the pedal is lower after just half a meter or so.
It seems to be better than before but I will see after a longer trip later this day.

[ZsZ]

Did my 200km trip, and the right front wheel has play again

[silverbullet]

You must totally dismantle the right side hub to see what is happening. I suspect that the nut was too tight and now one of the bearings has failed.
The flat screwdriver test tells you nothing, the washer could move with only 0.01mm end float and that is far too little!