Pulsing brakes at my wits end

rob2489 · 28-10-2016, 12:52 PM

Quote:

Originally Posted by FLOORED

Process of elimination and if it was me i would change the front brake pads first as that was the only thing not done and the problem came back but dont use EBC Redstuff or Bendix as i have seen similar issues with this application. You will also have to skim the rotors again if possible.

Thank you for the advice
This time I will do it all myself so I know whats been done. So I think I will skim the rotors, new pads & while they are off I will do the front wheel bearing (hub) as well.This is just a to and from work ute nothing special - what pads would you recommend & how much? - you can pm me if you want.
These are Brembo 4 piston calipers & rotors
cheers Rob

**FLOORED** · 28-10-2016, 03:51 PM

Quote:

Originally Posted by rob2489

Thank you for the advice
This time I will do it all myself so I know whats been done. So I think I will skim the rotors, new pads & while they are off I will do the front wheel bearing (hub) as well.This is just a to and from work ute nothing special - what pads would you recommend & how much? - you can pm me if you want.
These are Brembo 4 piston calipers & rotors
cheers Rob

Project MU NS400 are a really good pad and priced well at $179 plus $18 freight.
Where are you located ?

MattSAU2XR8 · 31-10-2016, 02:00 AM

Easy way to work out if its front or back would be to take it to dyo place and put back wheels on rollers, run it up to maybe 150 (stability control turned off) and hit the brakes - if no vibration its probably not the rears. Cost < $50

Then to look at fronts:

1. Front wheel bearings can be checked for any play by jacking up car, removing wheel, removing and suspending caliper, clamping disc to hub using wheelnuts inside large sockets, bolting a piece of flat bar to caliper moints on hub, attaching dial gauge to flat bar and placing tip at edge of disc, and finally trying to tilt the disc in and out using a shifter (not too hard) with some card board packing in the jaws. Main point being to attach dial gauge to same part that bearing runs on, eg. Hub. Cost < $100 for dial gauge, 30 cms of 50 by 5 mm flat bar, 1/4 inch bolts and nuts and washers.

2. Assuming no play in hubs then consider runout. Now rotate disc which is still clamped up to hub by nuts inside sockets. If either surface moves in and out by >= 0.03 mm then likely warped but also given to developing DTV as high points get worn off. If you can get away with it access wise use the road wheel rather than wheel nuts snd sockets to clamp up the disc while you check the inner surface - potentially if wheel is very slightly crooked (or dirty) it could distort hub and disc. If you find disc has runout you could try indexing (rotate to different position and recheck). If still no luvk then on car machining ?$100 if you can find a place that does it and take car to them.

3. If no bearing play (or in spec) and no runout (or in spec) then another possibility is pad deposits, and (my theory only) pads catching on slots. Pad deposits could probably be cleaned off in < 1000 kms using an abrasive pad such as bendix ultimate at $120. Finally I can't help wondering if some slotted discs (eg RDA with very wide slots) either collect debris on the trailing edge of the slot, or actually catch the edge of the pad from time to time. I haven't tried it yet on my car but I'm quite tempted to try some non slotted discs....

4. Assuming no play in wheel bearings and no runout and no warped or dirty wheels that bend the hub/disc assy when bolted up, no pad deposits and no oversize slots I suppose its time to think about control arm bushes. Only caveat here is that if the car was fine for eg. 80 kkms, then you changed discs and pads and didn't touch the suspension, then 30 km later you have shudder, the timing is pretty much pointing at the brakes, no?

At this I'd be taking it to someone like Racebrakes unless another poster can explain how to assess the balljoints and control
arm bushes...

MattSAU2XR8 · 09-09-2017, 04:00 PM

Further to the above, I'm still procrastinating about my shuddering brakes, have bought a set of DBA 42107 without slots which I'll fit up when I have some free time as per the above.

Had another thought in the meantime - if the frequency of the shuddering is directly proportional to vehicle speed, i.e. nearly twice as fast at say 140 on a private road as it is at 80 on a public road, then this would strongly suggest it is related to wheel rotation.... So either pad deposits or disc thickness variation, or pad catching on slots or wheel bearing play, I think :-)

**FLOORED** · 11-09-2017, 10:22 AM

Quote:

Originally Posted by rob2489

Thank you for the advice
This time I will do it all myself so I know whats been done. So I think I will skim the rotors, new pads & while they are off I will do the front wheel bearing (hub) as well.This is just a to and from work ute nothing special - what pads would you recommend & how much? - you can pm me if you want.
These are Brembo 4 piston calipers & rotors
cheers Rob

rob2489 did you fix the issue?

Quote:

Originally Posted by MattSAU2XR8

Further to the above, I'm still procrastinating about my shuddering brakes, have bought a set of DBA 42107 without slots which I'll fit up when I have some free time as per the above.

Had another thought in the meantime - if the frequency of the shuddering is directly proportional to vehicle speed, i.e. nearly twice as fast at say 140 on a private road as it is at 80 on a public road, then this would strongly suggest it is related to wheel rotation.... So either pad deposits or disc thickness variation, or pad catching on slots or wheel bearing play, I think :-)

Is shuddering happening without the brake application?

rob2489 · 11-09-2017, 10:44 AM

[QUOTE=FLOORED;6000219]rob2489 did you fix the issue?

Hi Floored
Yes I did, I replaced the rotors with non slotted rotors , new pads & bearings.
I believe it was the rotors, as the grooves were quite wide and were catching the pads as I was doing sub 40kmh. Done approx 6000kms so far with out an issue.