Brakes.... Or lack of them..

[Scaredycrow]

Question: Did you make sure you cleaned the DBA rotors before putting them on. I know mine had quite alot of oil on them when I installed. I decent brake cleaing product and a clean rag clened them up nicely.

I have exactly your setup. And my braking performance is now *better* then when I bought the car, that said initial bite does feel a bit less than stock but the stopping power is definitely there. No spongy feeling from the pedal either. Did you change brake fluid when you put the new rotors on?

[AndyMPS]

Rotors cleaned with brake cleaner.

The original brake fluid was clean with no bubbles. So I did not change it at the start. Though after the braking being so crap I changed the brake fluid, with no positive results.

Maybe something is up with the master cylinder??

[Scaredycrow]

Rotors cleaned with brake cleaner.

The original brake fluid was clean with no bubbles. So I did not change it at the start. Though after the braking being so crap I changed the brake fluid, with no positive results.

Maybe something is up with the master cylinder??

I'm no expert on these things but if you get the opportunity I'd heat those breaks right up. Go for a fang through some twisties and see what happens. Especially take note of the performance when they're hot versus when they're cold. If they still aren't good when they're hot, you may have a dodgy set of pads. I had that exact experience with some HAWKS pads, leading me to try the QFM's which I've had no complaints about.

That said, I've heard nothing but rave reviews about the ceramics. If you think that's where you'll end up anyway get them now, before you get any rotor wear. Otherwise you may have a hard time bedding the ceramics properly. (without machining the rotors)

[gslrallysport]

The pedal is really spongey

That's not pads. Pads, not matter how cheap or nasty, don't go soft and spongy. Friction material, regardless of compound or brand, won't cause a 'spongy pedal'. There's some other (most likely fluid) issue here.

The pads just don't seem to bite very well (completed bedding cycle as per described at the following site: Instructions for bedding in your brakes)

That bed in procedure is how you would bed in full on race pads, and NOT street pads. I'd say you've toasted the original fluid during that 'bed in' and there's now vapor lock somewhere in the system. Any bed in procedure that says the pads are going to 'fade' is a bit questionable. The idea of bed in is to transfer an even layer of pad material to the rotor, and NOT to put any sort of heat cycle through the pads etc. Attached is our recommend bed in procedure for QFM.

The brake pedal is now like a squishy ball.....

Again, fluid. You can't physically describe a pad problem as 'squishy'. The lack of bite comes from the lack of proper pressure in the hydraulic system. It would only be a pad problem if you had a lack of bite, and a firm pedal.

[TUFMPS]

Very true. However if you have given up and feel the need to change don't go bendix. I couldn't even get the abs to work with them lol

[AndyMPS]

Thanks for all the help guys.

gslrallysport: Looks like the incorrect bed in process could be the problem (I wish they included bed in instructions with the pads).

The fluid has been changed by bleeding the system. But the clutch hasn't been bled. Would getting a pressure bleed done at a store perhaps fix this possible vapourlock?

Also do you think my pads and/or rotors have been affected from this incorrect bed in process? (apart from wear)

Thanks in advance.

[gslrallysport]

Very true. However if you have given up and feel the need to change don't go bendix. I couldn't even get the abs to work with them lol

Quoted for truth! Yep, there's far better pads on the market than Bendix, especially for the dollars. I'm not that biased, we supply them, and continue to to a couple of specialist SAAB workshops that refuse to even try anything else. But if you've lost faith in the QFM, then the other pad I woudl highly recommend is a European performance brand called Resma. Good for 650 degrees (or 100 degrees better than Bendix Ultimate), and what's used in alot of performance euro cars from factory. Remsa is a subsidery of the TRW Group (who manufacture most of the drive line hardware used in European cars), so the quality is exceptional. Remsa is what we supply to a few specialist Audi/VW/Porsche specialists.

They're also relatively cheap for what they are too, MPS fronts are $139 per set, and MPS3 rears are $95 for the set. MPS6 rears not available yet. They also come standard with anti squeal shims on the back, which is why we use them as a replacement pad where noise is an issue in particular applications, particularly opposed pistons calipers.

The fluid has been changed by bleeding the system. But the clutch hasn't been bled. Would getting a pressure bleed done at a store perhaps fix this possible vapourlock?

To be honest I'm not really familiar enough with the MPS's to know how sensitive the system is to just being gravity fed. I know alot of VW Group cars need the computer to work the ABS pump during bleed, but I'm not sure if the same would apply to the MPS's.

Also do you think my pads and/or rotors have been affected from this incorrect bed in process? (apart from wear)

Rotors provided there's no vibration (DTV) will be fine. Pads, I'd personally rip them out and give them a light rub on some smooth concrete, and go through another bed in process. It's pretty hard to genuinely cook pads below the exterior face.

[Dark Authority]

Interesting thread.

I also had a similar problem. Not with QFM pads but another brand. I installed then without bleeding the brakes and the initial bite was just EPIC fail. I bleed the brakes thinking there was air in the system.. with still the same results. Seemed like i had to push the brakes deeper to get the car to stop and even then, it was no match for the standard OEM pads. It had a spongy feel. I decided to try and put stock pads back on and the braking was back to normal.. weird..

So although the posts above suggests its the fluid, my personal experience from the last month points straight at my pads.

I got fed up and decided to go MPS calipers with OEM rotors and OEM pads and bled the brakes AGAIN.. and its very much better. WAY better than stock, but then thats expected as they're quite alot larger than the standard rotor/caliper of a 2L mazda 3

[AndyMPS]

Thanks for the help again gslrallysport. I will try rubbing the pads back and rebedding tomorrow.

The brakes have started to feel a bit better, and so has the pedal.


Dark Authority: I know what you mean about the stock brake setup. It is awesome. I was hoping the aftermarket gear would be an improvement. I'm not so sure now.

The price of a set of front pads from Mazda is $345 though..... Is it me or does that seem a little steep?

[bd581]

Read dads (rd415) opinion on the qfm pads he fitted to his 6.
Under emergency braking it will now eject the CD
So there is nothing wrong with the pads, they are a vast improvement over stock, which even stock I think is quite impressive, it's the first thing anyone who has driven mine comments on.

Don't know what it is, but I do think whatever is wrong is no fault of the pads.

[rd415]

The rear calipers are a FORD product and have the crapiest handbrake adjustment. If you accidently wind the piston in too far on the rear caliper you will have a lousy pedal until the stupid thing self adjusts.

Definitely not a brake pad problem, soft or hard pads or any pads won't effect pedal feel, they may not stop as well, but will always self adjust to give the same pedal feel. The ABS control can be a pain at times if it gets air in the system - very difficult to remove. Quite often only a vacuum bleeder can remove the air.

Did you let fluid out by cracking the bleeder open to push the pistons in - if so you have probably aerated the fluid.

How good are Bendix ???? They don't evem make rear pads for the MPS6

My QFM HPX pads after 10,000km are still just superb and as previous post, they work so well they eject the CD when the ABS works hard under emergency braking - I don't believe I'd still have the car if it wasn't for the the superb braking ( Mexican Taxi driver did a "U" turn on a freeway right in front of me)

[gslrallysport]

Thanks mate, appreciate the feedback!

[AndyMPS]

An update on the brakes issue.

I have not been able to take the pads out and give them a rub down on concrete and a re-bed(correct).

However the more I have driven the car, the better the brakes have become. The pedal now feels a lot better. However the brakes still don't have much bite compared to the stock setup (may be fixed by rubdown and rebed).

[rd415]

Still sounds to me you have managed somehow to get air in the system. The brakes sound as if they are slowly, very slowly letting the air bubbles to rise back to the master cylinder and self bleeding.

Technically brake adjustment of any sort (including clearance) can be pumped out of the pedal, a few quick pumps and the pedal becomes solid. Air cannot be pumped out and the pedal feels spongy until all the air is evacuated.

Before any - one comments
1. yes the booster evacuates and makes the pedal firm.
2. Gravity is a wonderful thing and brakes can self bleed - but it takes a long while - also depends where he air is trapped

Seen some funny things bleeding brakes - MK1 Zephyrs - to get the air out had to raise the rear of the car higher than the master cylinder. Looked hilarious with the rear wheels backed onto the hoist with the front still on the ground.
Did a Volvo once where as soon as I put the pressure bleeder on I lost pedal. Used a vacuum bleeder got a pedal, put on pressure bleeder, lost pedal. Ended up vacuum bleeding to a reasonable pedal - warned the owner and within a few days the pedal came good.

An update on the brakes issue.

I have not been able to take the pads out and give them a rub down on concrete and a re-bed(correct).

However the more I have driven the car, the better the brakes have become. The pedal now feels a lot better. However the brakes still don't have much bite compared to the stock setup (may be fixed by rubdown and rebed).