Stumped with shudder under brakes

[MilkmanDan]

Hi all,

Have had this issue for a while now and with priorities financially being spent on the house I haven't really gone too far in this.

Basically under braking I get a shudder, feels like a grabbing, similar to a warped disc. Now this was happening prior to and after doing front and rears at same time so have eliminated brakes.

Next was wheels or tires. Due for tires not long after brakes, new tires all corners had them check the wheels for out of round or damage also. All balanced up and free from damage. Front alignment done. Shudder remains. Eliminated wheels/tires.

So this afternoon did some more testing, doesn't happen when turning under brakes, also doesn't happen when rears are applied with handbrake so thinking a front end bush somewhere. Ran eyes over, nothing appears flogged out, keeping in mind I am putting the notes aside to refresh the front/rear in near future.

So I'm out of ideas, it's felt through the brake pedal and not the steering wheel, again another odd feature of the issue. Doesn't do it cornering with brakes and is more severe braking from freeway speeds. I'm stumped.

[har05l]

When you did the brakes did you only do the pads or discs as well?
I've got the same issue and replaced both within the last 12 months but I'm certain my discs are warped again.
The rears are useless imo and this puts the added strain on the fronts always.

[MilkmanDan]

Replaced all at once, DBA T3 slotted and QFM HPX pads, Protex drums and shoes

[GLRkenny]

I would suggest trying some bendix shoes in the rear. We've had a few cases of the cheaper shoes binding up to the point where the rear wheels were locking up, mainly on older Utes. We threw bendix shoes in and problem was solved. Also make sure the leading and trailing shoes are fitted in the correct orientation.

[MilkmanDan]

Yeah you did say that Kenny, was before I changed, after I changed and after you adjusted them. No change, and guessing how worn the rear shoes were when removed they were the stock ones from new.

Will pull the drums on weekend and check the shoes, if still no love I'll come down next time I'm in werribee

[snakesoup]

get some vise grips x2 and clamp on the rear brake lines, "rubber bit " in a safe manner to isolate them and go for a drive and see if it's still there, if it is still present then at least you know it's not from the rears.
process of elimination..

[MilkmanDan]

I knocked out rears bring problem using the handbrake

[Cowboy Dave]

Does the handbrake apply both shoes though? And it does it from near the bottom instead of via the wheel cylinders up the top. Maybe it's a valid test, I don't really know, but it doesn't seem like it would be 100% the same as normal braking to me.

[kxboss]

I have the same issue when coming down Mt Ousley a steep pass into Wollongong with an 80k speed limit, when I slow for my exit I get a shudder, put it down to tyres, BF Goodie atr standard size. MN 2012
so when I touch the braked lightly and I suppose they heat up then when I brake harder I get te shudder

Used to happen in olf EL falcon I replaced disc everything still happened.

[MilkmanDan]

Valid point snake, had another think about it after Daves comment. Still though it was before and after new brakes

[Crash486]

Had disc pads replaced and discs machined. No shudder for a few weeks then back again. Mechanic indicated its a result of the poor rears with heavy use of the fronts. I'd have hoped dab slotted rotors would fix this sort of issue .
Is it possible the abs is doing something too soon?

[MilkmanDan]

I thought I may have had the rears adjustment wrong, had it checked and readjusted with same issue.

Why it is so strange is the chances of the old drums/shoes being rooted and the new off the word go is so unlikely. Same with the fronts.

It feels like something is out of round, that's the feeling it has.

[Cowboy Dave]

I reckon I've experienced this too. I gave up trying to identify it. It feels like a shudder, only happens on heavy braking (usually for me pulling up hard at a red light or slowing sharply on a steep incline) and logically feels like the brakes are sort of grabbing then ungrabbing then grabbing again, a bit like if the rotors were warped, but to me the pulses are too far apart to be caused by that.

I too replaced pads and discs for no real change. i did think it was worse with the bendix HD pads on the front and swapped to 4wd pads but it is still there intermittently.

I came to the view that it was something Triton specific and gave up on looking for it in the end.

[Quinny]

Is it possible there's some grime buildup behind the disk putting it out a bit ? I just replaced disks / pads - dba standard non slotted + factory pads - just beautiful now ...

[coughy]

my challenger new sloted and drilled and new pads front and perfect as well
what pads did you use in the front???
i was talking to a bendix agent (he sells them it is a brake shop) and he states that bendix have changed there formula and they are crap now he uses a nother brand with very less or fewer problem
he dont like bendix at all no
i was like um ok but you sell them he said you give the dog a bone if you know what i mean.....

i have cheap shit pads euro dustless bla bla bla
but they pull up like a champ and my shutters...
lol i just looked up the pads u use and well F##K me they are the ones that the brake guy uses now and swears buy them

have you contacted QFM and asked them??

[MilkmanDan]

Is it possible there's some grime buildup behind the disk putting it out a bit ? I just replaced disks / pads - dba standard non slotted + factory pads - just beautiful now ...

Possible, I do hit the hubs with emery paper, when in checking the drums I might pull the front rotors and hit the hubs with a wire brush. Keep crossing things off the list

[MilkmanDan]

my challenger new sloted and drilled and new pads front and perfect as well
what pads did you use in the front???
i was talking to a bendix agent (he sells them it is a brake shop) and he states that bendix have changed there formula and they are crap now he uses a nother brand with very less or fewer problem
he dont like bendix at all no
i was like um ok but you sell them he said you give the dog a bone if you know what i mean.....

i have cheap shit pads euro dustless bla bla bla
but they pull up like a champ and my shutters...
lol i just looked up the pads u use and well F##K me they are the ones that the brake guy uses now and swears buy them

have you contacted QFM and asked them??

I've used them for years, previously bought off race brakes in Sydney but the QFM guys had a better pad for the Motorsport I was doing.

I'm thinking could be a bush issue, need to spend a good hour or so underneath it to diagnose, get it off the ground.

[snowman]

i was talking to a bendix agent (he sells them it is a brake shop) and he states that bendix have changed there formula and they are crap now he uses a nother brand with very less or fewer problem
he dont like bendix at all no

been through this as well. brake specialist in Blacktown now refuses to sell Bendix pads across the board as they are made in Malaysia and complete shit.

it was causing a shudder but only once warm. were perfect when colder.

[jimmyboy]

I was told that it's the ABS cutting in and out?

[snowman]

I was told that it's the ABS cutting in and out?

ABS operation is pretty different to a shudder. if you are braking really hard and the ABS operates - you will know about it. include the ABS unit making a racked under the bonnet.

shudder unfortunately comes in many shapes and sizes.

[coughy]

also the abs light comes on when this happens
i think it is still the pads or disks