Thump when applying brakes.

[perth_boy]

Hi all.

First time posting but been lurking for a while!
A month ago bought a 2013 MN GL-R and all has been well, this weekend the car started to make a thumping sound as the brakes are applied, it happens just as you begin to apply pressure to the pedal, just one thump which can be heard and felt through the brake pedal. It brakes just fine and does not make any other sound, and also only does this once or twice a trip I can brake 10 times with no clunk and then the 11th time there it is.

I'm taking it in to be looked at next week as it's still under its statutory warranty, but thought I'd ask the real experts before I got there!
Thanks in advance for your help and knowledge.

[WUNSIE]

One of the caliper bolts haven't come loose or seizing in the slide

[perth_boy]

IS that easy enough to check? I'm super confident when it comes to fixing my enduro bikes and could strip one down to all it's parts and put it back together again, but have never taken a spanner to a car, it's like speaking another language to me!

[perth_boy]

Hmmm Ok last night got the front wheels off and had a look, all caliper bolts were tight and nothing else seemed loose, but again I'm not really sure what I'm looking for.

[NowForThe5th]

Being able to feel the "thump" through the brake pedal suggests that it's being transferred via the hydraulic lines and is more likely to be in the brake system somewhere, rather than the more usual culprits like loose suspension or steering components.

[MrCozy]

Most likely, if the caliber bolts are tight, and the caliber is sliding well on its pins, one of the disc pads, probably internal one, the spring has broke which keeps it centered on the caliber piston, or on the outside pads, same which keeps from knocking against the caliper housing. The other circumstances could be in your suspension, and or wheel bearings, and may only happen when certain conditions occur.


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[perth_boy]

Being able to feel the "thump" through the brake pedal suggests that it's being transferred via the hydraulic lines and is more likely to be in the brake system somewhere, rather than the more usual culprits like loose suspension or steering components.

So once taking off the front wheels and putting them back on again, no thump for the last 3 days, what do you reckon the chances are of just having bumped something right and that's it's sorted?

[NowForThe5th]

Does it have steel or alloy wheels? Factory or aftermarket?

[Longranger1]

Original brake pads or aftermarket?

There is some rubbish out there that are dimensionally poorly made. These have excessive movement and can cause symptoms you describe.

[perth_boy]

Does it have steel or alloy wheels? Factory or aftermarket?

Alloy aftermarket wheels.

[perth_boy]

Original brake pads or aftermarket?

There is some rubbish out there that are dimensionally poorly made. These have excessive movement and can cause symptoms you describe.

No idea at all, might be worth just replacing them, the PO has taken great care of the Ute so I’d be surprised if he put crap in there.

[perth_boy]

Well took her for a little ride off road hoping the corrugations would shake something loose and show symptoms again before I get to the mechanic tomorrow, and what do you know, the issue's back, and worse than ever.

On first press of the brake pedal there's almost half the resistance of normal, however if I release and pump again it has full pressure, but the thud it then very noticeable.

Also and I'm not sure if this is related, after the off-road ride the handbrake needs about twice as much travel to hold the car still!

[NowForThe5th]

Broken rear brake shoe, mount or slave cylinder.

Be careful taking the vehicle to the mechanic. If whatever is broken or loose gives way completely you may have seriously reduced braking ability. Although it identified the area of the problem, your little off-road jaunt was probably ill-advised in a vehicle with a suspected fault, especially when you'd already booked in to the mechanic.

[perth_boy]

Broken rear brake shoe, mount or slave cylinder.

Be careful taking the vehicle to the mechanic. If whatever is broken or loose gives way completely you may have seriously reduced braking ability. Although it identified the area of the problem, your little off-road jaunt was probably ill-advised in a vehicle with a suspected fault, especially when you'd already booked in to the mechanic.

Appreciate the concern, and I wasn't rough enough or fast enough to put myself in any danger, I just really wanted to make sure the fault was still there when I dropped it off, they were quite clear that if it didn't present itself on a test ride that they would not start to look for faults.

Anyway the update is... Needs a new master cylinder and new brake shoes, and then all the bleeding etc. that comes along with that.
Also just booked it in with Pedders to have the whole suspension and brake system given a once over!

[NowForThe5th]

Good to hear the brakes will be sorted.

Pedders? That will be expensive. I bet that they'll find something wrong with the brakes.

[perth_boy]

Good to hear the brakes will be sorted.

Pedders? That will be expensive. I bet that they'll find something wrong with the brakes.

They charge $28 for the full check up with no obligations and in my case the more they can find wrong the better as it's still under warranty!

[NowForThe5th]

Yes, I've been sucked in by their "low cost, no obligation" inspection. As have quite a few others here.

The kinds of things that they're likely to list are things that are not covered under warranty. For suspension that would include bushes, under-performing shocks and so on. Things that Mitsubishi would class as wearable, and be excluded from warranty. For example, a shockie that fails completely would be covered under warranty but one that "isn't performing to standard" would not. They really are very good at it.

[perth_boy]

Haha that's good to know, thanks for the heads up!

[explorer.dave]

What suburb of Perth are you from Perth_boy? Only asking because there are other options out there apart from Pedders.

[perth_boy]

What suburb of Perth are you from Perth_boy? Only asking because there are other options out there apart from Pedders.

I'm in Shelley, SOR

[perth_boy]

Update: So after 3 days at the workshop, they can't figure out why the brakes are still not working

This is after a new master cylinder and a full bleed and new fluids!

[WUNSIE]

3 Days They've probably only spent an hour on it, to stick the new master cyl on, or the apprentice had to go to tech

[RHKTriton]

I'm wondering whether the abs unit is probably the culprit?

[perth_boy]

I'm wondering whether the abs unit is probably the culprit?

100% yesterday got a call to say that they're replacing the ABS module, then later the workshop called to say that it's ready tp pick up.
Apparently the fluids were contaminated and had done a heap of damage to the master cylinder and ABS unit. Supposed to be good as new... we'll see....

[greybeard]

Of course the fluids did heaps of damage to the master cylinder and ABS unit, how else could they get you to pay for them