Pulsing brakes at my wits end

[rob2489]

Hi Guy's
My FG ute has 4 piston Brembos on the front and standard brakes on the rear. I have had a low speed pulsing between 10-40 kph which is annoying as most of my driving is done in traffic. I don't push it hard or brake hard (after all it's a 6cyl E gas ) and as I said it gets me to & from work. So far in the last 10,000 km I have had the rears machined & new pads, then later had the front's machined but no pad replacement as they had 80% pad life left. After the fronts were done it went away so I thought it was all good. 1500 kms later its back. I read on here it could be control arm bushes but I have just had them checked and along with the ball joints they tell me it seems solid. (the control arms did have a little movement in them slight front to back not in & out) but he seemed to think it was ok. I measured the disc and it's 31.40 so it has plenty left in it. It almost feels like the groove in the disc that cleans the pad is catching the pad.I know it can't be that at 40 kph but I am trying to describe the sensation. The brake pedal doesn't pulsate either.
I have now noticed driving back I can feel it at 80 kph when braking lightly & slightly in the wheel
Any idea's or help would be great as I'm completely confused & don't know what to do next other than burn it??

[xr8cam]

I had exactly the same problem but mine was fixed when I replaced all four rotors, pads and both front bearings aswell as full set of new tyres. Bloody expensive fix but my car had driven 400 kms in 10 years so everything was plum ducked because it sat still for so long. I reckon yours might be just front rotors. Is the car new, how long have you had it, how many kms, what has been replaced if anything that you know of or has it been in a front end collision etc etc.

[Bez F6]

Do you feel/hear it more in low speed cornering?
If so, I'll say 99% its front wheel bearings...

[rob2489]

Originally Posted by xr8cam

I had exactly the same problem but mine was fixed when I replaced all four rotors, pads and both front bearings aswell as full set of new tyres. Bloody expensive fix but my car had driven 400 kms in 10 years so everything was plum ducked because it sat still for so long. I reckon yours might be just front rotors. Is the car new, how long have you had it, how many kms, what has been replaced if anything that you know of or has it been in a front end collision etc etc.

Had the car 2 yrs - the car itself has just done 105km and it's done 25km since I purchased it.

[rob2489]

Originally Posted by Bez F6

Do you feel/hear it more in low speed cornering?
If so, I'll say 99% its front wheel bearings...

Wheel bearings? not thought of that - how would it cause the pulsing??
would be good if it was just that

[xr8cam]

If you mean your car has done 105,000kms, definitely look at bearings, change rotors without fail and if you also meant it has been sitting around, you may have one or all of the issues I mentioned. A tyre shop will advise you if your tyres are out of round and the rest of the gear, me, I would replace it all at if it is all still factory at 105,000kms, but I often replace things before they are worn out, why wait till they fail or brake I say.

[FormulaFG]

What pads are you using?

[rob2489]

Originally Posted by xr8cam

If you mean your car has done 105,000kms, definitely look at bearings, change rotors without fail and if you also meant it has been sitting around, you may have one or all of the issues I mentioned. A tyre shop will advise you if your tyres are out of round and the rest of the gear, me, I would replace it all at if it is all still factory at 105,000kms, but I often replace things before they are worn out, why wait till they fail or brake I say.

yes the car has done 105,000 km the the rotors were changed along with pads just before I bought the car. They are brembo calipers & brembo rotors. I machined them at 92,000.
I will look into changing the wheel bearings but I assume I have to remove the brakes when doing so (not done wheel bearings in a long time) so I was looking at doing things together.
Seems the more I research the more confusing it gets, I have read it could be the above but also the lower control arm bushes as well, amongst a host of other stuff. plus leaving the rotors until everything else has been looked at first. Funds are not great at the moment so I can't afford to waste it on unnecessary replacements.

[rob2489]

Originally Posted by FormulaFG

What pads are you using?

I'm not sure what's in them I would have to check and come back to you.

[Peter B - CV8]

Might be resin deposits on the rotors (from the pads). What's your braking style like ? ie when stopping heavily at the lights do you engage the handbrake - or just leave your foot on the brake pedal (in certain cases, this can create a hot spot & cause resin from the pad to stick to the rotor. Can also cause a hot spot on the rotor & lead to rotor distortion).

[rob2489]

Originally Posted by Peter B - CV8

Might be resin deposits on the rotors (from the pads). What's your braking style like ? ie when stopping heavily at the lights do you engage the handbrake - or just leave your foot on the brake pedal (in certain cases, this can create a hot spot & cause resin from the pad to stick to the rotor. Can also cause a hot spot on the rotor & lead to rotor distortion).

Ok this has made some sense I have a couple of marks on the rotors and for the life of me didn't know what they were, resin deposits is what they look like (I will take a photo after work). I dont brake that hard but do get caught in a lot of traffic to and from work. I don't use the handbrake and yes leave my foot on the brake pedal. So yes it could of caused a hot spot.

[FormulaFG]

The fact the problem went away when you machined the rotors tells me there is nothing wrong with the other mechanicals of the car; ie wheel bearings, bushes etc.

The fact that it slowly came back suggests to me it could be resin on the rotor from the wrong pad/rotor combo.

[TRAU BLAU]

I had bad front pulsing until brakes were over-hauled.The caliper pistons were the culprits that caused the pulsing by not allowing the pads to release.

[FLOORED]

Pretty much all of the above could be the cause of this. I have had mechanics look at bushes and say there fine but customers replace them and the problem is solved.
One thing i would like to say is that when you machined the rotors and the problem went away it did come back, now yes it could be resin deposits but it could still be bearing hubs or something else and i will explain why.
When you machine a rotor you true it up but if the cause of the issue is still there ie bearing hubs OR even pad rubbing etc it will come back.What happens over a period of time of driving is basically a flat spot wears onto the rotor and after a few thousand km's this turns into a judder as it is uneven when the brakes are applied.

[rob2489]

Originally Posted by FLOORED

Pretty much all of the above could be the cause of this. I have had mechanics look at bushes and say there fine but customers replace them and the problem is solved.
One thing i would like to say is that when you machined the rotors and the problem went away it did come back, now yes it could be resin deposits but it could still be bearing hubs or something else and i will explain why.
When you machine a rotor you true it up but if the cause of the issue is still there ie bearing hubs OR even pad rubbing etc it will come back.What happens over a period of time of driving is basically a flat spot wears onto the rotor and after a few thousand km's this turns into a judder as it is uneven when the brakes are applied.

Ok thanks for chiming in - you guy's are the experts where would you start?
The brake shudder is driving me nuts now but I like most can't afford to just throw money at it so I would like to do things in a sensible order?
Thanks for all advice given guys

[aussiblue]

Also have a read of this: http://www.stoptech.com/technical-su...nd-other-myths

[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.

[rob2489]

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]

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]

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]

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]

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?

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]

[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.

[TRAU BLAU]

Yep,the shuddering pulsing front brakes FX were the symptoms of me wagon's(AU) brake caliper pistons not releasing properly.The other symptom was very hot to touch wheels.The brake garage said that Ford puts in a ceramic piston which decays & they replaced them with alloy pistons.With front disc machining also,no probs.after 3 years.

[MattSAU2XR8]

Hey guys,

This is probably my final installment on the topic of FG brake shudder

I've been having trouble on and off for a few years as follows:
- Bought a near new FG Ecoboost G6E in 2013, thought the brakes were a bit weak, and upgraded to RSA slotted fronts and Ferodo DS performance pads all round. Certainly stopped well but started shuddering almost immediately, and I could feed the pedal moving up and down a little as soon as they were installed.
- I had noted when putting the RDA's on that according to my dial gauge they were up to 7/100 mm out, i.e. surfaces not flat as they rotated, and so shuddered badly from 80 kms up
- After a while got some PBR slotted discs to swap the fronts out thinking that if Ford use them they should be good, i.e. minimal runout, at least initially. However not the case, as I recall at least 4/100 mm out and I think one may have been 6/100.
- Not wanting to buy more discs, and figuring I could gradually fix two problems which were (a) pad deposits, and (b) runout, I installed some Bendix Ultimates which are known to be a bit abrasive. 25,000 kms no shudder and the brakes are great!
- Given I'm selling the car now (have bought a VE SS - sorry guys) I finally installed some DBA 4000 plain rotors I'd bought on sale a while back. The result from the dial gauge - 1/100 mm runout on each of them as soon as I fitted them up, so good I didn't even bother indexing them!

So for me there are two morals to this story:
- Brake discs often do have runout when new, and this can cause shudder, regardless of what brake manufacturers say
- Top quality discs, i.e. DBA 4000s are less likely to have shudder

I can only imagine Ford used to machine all the PBR discs on the car as it was being assembled....

I'm wondering now how the DBA street series might go in future on the SS - seems that most of the problems I;ve been having are not related to overheating the brakes, just due to them having runout when new. The metal itself is probably good enough since they seem to improved with age...

[FLOORED]

Originally Posted by MattSAU2XR8

Hey guys,

This is probably my final installment on the topic of FG brake shudder

I've been having trouble on and off for a few years as follows:
- Bought a near new FG Ecoboost G6E in 2013, thought the brakes were a bit weak, and upgraded to RSA slotted fronts and Ferodo DS performance pads all round. Certainly stopped well but started shuddering almost immediately, and I could feed the pedal moving up and down a little as soon as they were installed.
- I had noted when putting the RDA's on that according to my dial gauge they were up to 7/100 mm out, i.e. surfaces not flat as they rotated, and so shuddered badly from 80 kms up
- After a while got some PBR slotted discs to swap the fronts out thinking that if Ford use them they should be good, i.e. minimal runout, at least initially. However not the case, as I recall at least 4/100 mm out and I think one may have been 6/100.
- Not wanting to buy more discs, and figuring I could gradually fix two problems which were (a) pad deposits, and (b) runout, I installed some Bendix Ultimates which are known to be a bit abrasive. 25,000 kms no shudder and the brakes are great!
- Given I'm selling the car now (have bought a VE SS - sorry guys) I finally installed some DBA 4000 plain rotors I'd bought on sale a while back. The result from the dial gauge - 1/100 mm runout on each of them as soon as I fitted them up, so good I didn't even bother indexing them!

So for me there are two morals to this story:
- Brake discs often do have runout when new, and this can cause shudder, regardless of what brake manufacturers say
- Top quality discs, i.e. DBA 4000s are less likely to have shudder

I can only imagine Ford used to machine all the PBR discs on the car as it was being assembled....

I'm wondering now how the DBA street series might go in future on the SS - seems that most of the problems I;ve been having are not related to overheating the brakes, just due to them having runout when new. The metal itself is probably good enough since they seem to improved with age...

DBA also have a very expensive dial gauge in a room that is temp controlled. They do various runout checks on there disc rotors whilst in production as to not have this issue.

[GO FURTHER]

I've replaced the front stock rotors in my XR6T twice now with DBA T2's and a new set of Bendix Ultimates with each change and never had a problem with shuddering. (Still running the stock rotors on the rears, but with new Ultimate pads).

I think it is very important that the hub is smooth, clean and free of any rust build up before installing new rotors. I feel a lot of brake places don't take the time to do this properly IMO.

The aggressive abrasive nature of the Ultimates soon sorts out any minimal runout issues that new rotors might have.