Vehicle pulses when braking - NOT warped disks.

[geopaj]

Hi Geoff,

Have you tried the multiple very hard applications of the brakes yet. Do 5 or 6 full braking stops from 80kph and get the brakes nice and hot, just so you can smell them and then go for an easy drive with to let them cool down. If it is pad material deposit on the rotors this should wear it off.


OJ.

X2

I also had this as a re-occurring issue. OJ’s suggestion will improve it but it will come back.
Are you running Bendix 4x4 pads with the OEM disks? I can’t explain why but that combination caused issues in my NT. I ran Bendix 4x4 pads in my last Pajero (NL) with OEM disks but never had an issue too??

[gemster]

Hey Justin, When I was doing my last brake job I installed slotted Rotors and the Bendix 4x4 pads... About 3 days after doing this on a downhill mountain run I ran out of brakes... Never happened before so I took it into a brake shop to ask for advise... First Q they asked was what pads im using.... After a bit of thought they swapped over the pads to the SUV/4x4 ones and I can now stop on a dime... They told me that there is something with the 4X4 pads that causes some issues with heat in certain circumstances ... It certainly made a big difference to 'Mitzy'.... I also found the 4x4 ones created a lot of brake dust...... Far happier with the SUV/4X4 pads...

Gemster.....

[GHendo]

Hi Geoff,

Have you tried the multiple very hard applications of the brakes yet. Do 5 or 6 full braking stops from 80kph and get the brakes nice and hot, just so you can smell them and then go for an easy drive with to let them cool down. If it is pad material deposit on the rotors this should wear it off.


OJ.

Hi OJ

No, haven’t tried that yet – I try not to do hard braking – ha ha, and it would be a very long time since I’ve hit them that hard that I could smell them !

If you really think it will help I’ve give it a go over the weekend – better not take the wife along though – I’d probably end up with a screeching nose coming from the passenger’s side of the vehicle !!

Cheers
Geoff

[old Jack]

Hi Geoff,

If is is friction material deposit on your disc it is because you are a "light footed braker" but using heavy duty pads. Do you read this article in full before?

https://www.dba.com.au/main/tech-article-to31-friction-material-deposits/

Nothing to lose from a good hard braking session, it may just save you having to machine the discs.

On Bendix 4wd Blue Stripe Pads, I got a bad batch that only lasted 40,000kms, current set have 30,000kms and still plenty of pad left. I got 80,000kms out of factory pads but I do use my brakes and are always close to or over GVM.

OJ.

[gemster]

GHendo, that's exactly what im running too.... DBA Slotted.... Could be an issue with that combo? I do remember that the boxes the pads came in was quite faded and torn up a bit... Old stock or the bad batch that has been mentioned before, im not too sure....

Gemster....

[mongoose]

On my NS I had a lot of brake issues, tried DBA rotors and they failed in short order. I then went and bought EBC disks and never had a problem again, not sure if that helps.


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[gemster]

The plot thickens... Interesting, as the brake shop said that they don't like DBA too....

I had to replace my rear brake callipers as dumbo mechanic said that they were seized and with-out asking, Proceeded to Drill out the bores to get them going with a drill bit, or something like that anyhow. I was too peeved to listen properly . Outcome was little to no brakes in the rear.. They wanted to fix their mistake for free but I have never taken the car back to them since .. I cant trust anyone with my Paj anymore...

Gemster...

[mongoose]

I tend not to trust anyone to do anything on my cars these days.


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[shawty950]

One other option to try if heavy braking doesn't completely fix it and before machining, is to remove the rotor, put it on the bench and use wire brush wheel on grinder / drill to clean both surfaces.


Use to do it on road bike rotors.


One way to try and stop the pad material building up in the hot spot when stopped, is to go to nuetral and release the brakes...one cant do that all the time, but it cuts the transfer of material to disc and saves replacing rear brake light bulbs as often

[pajflareo]

A slight bend in a caliper slide gave me a sensation similar to warped disks.

But you shouldn't have a bent caliper slide unless they were in pretty bad nick when you rebuilt them.

[erad]

Not sure if anyone has suggested this, but possibly one of the caliper slide bolts is sticking. This would mean that the brakes are being applied not square to the disc face. The effect would be a wedge being forced onto the flat surface of the disc, and maybe tat could cause a minute shudder. It wouldn't take much to cause some flutter in the brake pedal.

[GHendo]

There is no ‘flutter’ with the brake pedal or any sort of shudder. The best way of describing what is happening is probably to say it’s a bit like the brake is grabbing and releasing (very slightly) about once or twice a second – it is only slight but certainly detectable.

I’m going to do some hard applications of the brakes as suggested by OJ and others – just haven’t had a chance. Every time I’ve been out in the last week or so the wife has been with me and doesn’t like those sort of manoeuvres. I might get a chance this weekend.

Cheers
Geoff

[Lance]

Are the new pads grooved ?
Could the grooves be clagged up with dust or anything else that allows too much heat to build up ?

[Scouter1]

Hi Geoff,

I just went through a similar exercise with my NT exhibiting same symptoms as your vehicle. I have DBA slotted front rotors, standard rears & Bendix SUV/4WD pads all around. Previous service I had mentioned to mechanic the brakes were pulsing, front rotors were machined and all seemed well. About three months later the problem came back with greater severity to the extent that I nearly locked up a wheel a couple of times when having to stop suddenly (have to love driving in a big city...) This last service I told the mechanic the problem had come back, they changed rear pads & machined discs, problem has been completely resolved.

Cheers,
Stephen

[Tripplec84]

That is really interesting – we have a lot in common. I installed DBA slotted rotors and Bendix pads (pretty sure they were 4WD ones) AND I rebuilt the callipers at the same time. The pulsing is slight and only noticeable when slowing down at low speed. I've done around 60,000km. since I installed them however.

When I get around to it I’m going to pull the rotors off and get them machined – the local guy tells me he can take a minimal amount off them. If that doesn’t fix the problem I will at least be able to dismiss that theory.

Cheers
Geoff

Hi Geoff,

Did you manage to get your problem fixed up? I managed to find the issue with mine, it was the rear brakes.

About 2 weeks ago I noticed a scraping noise coming from the rear wheels and eventually traced it to the brake pad wear indicator, the little metal bracket the pads come with which you can clip onto the edge of the pad which I forgot I had installed.

So anyway I got my rear rotors skimmed and fitted new rear pads and the surging/pulsating effect is completely gone and my brakes feel smooth as!

My front breaks were originally done the same time as the rears but they still have a fair bit of life in them, seems like the rears get worked down quicker.

I still think there is something fishy with the DBA rotors or Bendix pads (SUV/4x4) or maybe the combination doesn’t work all that great together in the long run. I think the next time I look at getting new rotors and pads I will go original as that is what was in before I changed to the DBA & Bendix combo.



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