Braking System Stiff?

[DECIM8]

Hey guys

Recently took the car for a spin through a mountain range .. within speed limit but heavy braking with alot of 25km/h corners by the return to sydney the brakes felt like I had 0 pads left.. But they are 70-80% still

Straight to the mechanic .. Lucky I was booked in for the day and we went into the night with a few mods..

Anyway ..

Bleed out fluid - Refilled

Machined discs Rears only fronts are fine

However underbraking now feels like its a old kingswood with stock booster and a wicked braking system .. I press down on the brakes slightly and get awesome braking if I push harder to slow its very hard to press and without much result.

Now im assuming this is because the mechanic filled the fluid up past the full mark right to the top with no air in the system but would this cause such strange braking?

I also feel the high heat and stock pads caused maybe a glazing over of the pad and its not working efficently any more? Could this happen?

So in short..

1* Remove the overfilled fluid?

2* Sand the brakes down?

Cheers

[djr81]

Would suggest:

1: Re-write post so that is atleast sounds coherent.

2. Invest in a brake master cylinder stopper from someone like Cusco to stop the firewall flexing.

3. Don't worry about the level of fluid - as the pads wear it will lessen.

4. Depending on how much braking you are doing it may just be fade, ie pad gets hot, pad loses friction coefficient.

[DECIM8]

but it worked fine before and now it works shit house basically.. but before i.e after mountains I had the foot close to the floor with little/no brake?

And yeah I tend to blab on sorry, grammar isnt my strong point either.

Do you think the pads will wear "back to normal" or will they be forever shocking? i.e until I get new pads

Edited June 25, 2007 by DECIM8

[GTS4WD]

Would suggest:

2. Invest in a brake master cylinder stopper to stop the firewall flexing.

Ok.. excuse the noob question.. but how does this work?

How does the product work and how does it stop flex in the the firewall? I take it it stop flex as in twisting under extreme conditions?

Mechanical explination?

thanks mate =]

[djr81]

but it worked fine before and now it works shit house basically.. but before i.e after mountains I had the foot close to the floor with little/no brake?

And yeah I tend to blab on sorry, grammar isnt my strong point either.

Do you think the pads will wear "back to normal" or will they be forever shocking? i.e until I get new pads

Well if your foot was close to the floor you probably boiled your fluid in which case replacing it should make the problem go away.

With regard to the pads - well some types come back after they get too hot, but others are stuffed for ever more. It depends on what they are made of.

If you want an opinion I would spend the $200 or whatever on some new pads. They are after all some of the most important parts on your car.

[djr81]

Ok.. excuse the noob question.. but how does this work?

How does the product work and how does it stop flex in the the firewall? I take it it stop flex as in twisting under extreme conditions?

Mechanical explination?

thanks mate =]

It stops the master cylinder from moving forward by placing a mechanical stop in front of it (tied to the shock tower)

See the photo.

If you want to get an idea of what is going on lift the bonnet & watch the master cylinder whilst a mate presses on the brakes...

[DECIM8]

thanks alot I deff think I boiled the fluid but i drove home on the freeway for a good hour in 10 degree temps at 100+km without touching the brakes .. it was then I realised they had been rooted...

So ill give it a go for another week or so .. they stop but just harder .. might buy some new pads .. they are only nissan stockers anyway

[tacker]

do yourself a favor and do as you say, new pads & fluid and you should be good as new

[MrStabby]

Standard pads are hopeless for track use - try Ferodo DS2500s. Also use high temp brake fluid, like Motul 600.

Heh, if you're anything like me you didnt notice they were rooted on the track because you were pumped with adrenaline and using huge force on the pedal without realising!

[Ronin 09]

could have farked the seals on the calipers as well...

[DECIM8]

Seals are ok, Got them checked cheers tho..

Really think its just the pads which are rooted.. Will investigate the Ferodo DS2500s or whatever its called .. anyone suggest a cheap place to pick them up?

Edited June 25, 2007 by DECIM8

[skylinecouple]

100% brake pads.Bendix ultimates for price or ferodo 2500 for less wear on rotors but a little more expensive.I use bendix but I wash my car every week so no problem with brake dust.

[DECIM8]

Well drove it for about 3 days now and seems its just glazed over the pad, seems theyve over heated and put a slippery surface onto the top of the pad.. I assume so anyway because they are back to normal maybe a little better..

Will be buying new pads still just for safety

[JimX]

It is burned/glazed pads. If the fluid boils it will be a momentary thing and your brake pedal will go to the floor while it's boiling. It will also do this if the fluid has absorbed water and the water boils. You can take the pads out and sand the glazing off, basically when they get too hot they can form a glassy like layer on the surface (at least the ones I've seen have done so, racing compounds might be different) and then it doesn't bite into the pad properly. But if you sand it back and re-bed the pads they are usually ok.

I would still replace the pads as you are going to do anyway, because once they're over heated that much I wonder if the pad material will become brittle and and start to break off. Also you may have put hot spots on your disc but you will probably not notice that for awhile. The hot spots will start accumulating more and more pad material and then you'll get a shudder under brakes. It is what most people think are warped brake rotors but it's just excess pad material accumulating in the hot spot.

Changing fluid to a better grade can also help, I'm not sure what the consequences of boiled fluid are but I imagine it's not good. It will probably make the brake pedal more spongy after it cools down. I've only experienced boiled fluid in a mate's car but it had absorbed a lot of water so not really the fluid boiling. So after we nearly died after losing all brake pressure, I detoured slowly to buy brake fluid and then to my place and I changed his brake fluid. He owes me big time!