Jump to content
SAU Community

Recommended Posts

On my 93 R33, the brake pedal has a really bad habit of knocking you back or holding you in a spot if you apply pressure to fast, for example in a panic brake situation. This is BEFORE you even reach the initial bite point of the brakes. It has resistance with zero actual braking force and its totally dependant on how fast you apply pressure.

Lets say if you try slam on the brakes while you are driving down the road and see something, the pedal will get rock hard, completely keeping the pedal from getting to the point where the brakes bite. It will hover here no mater how hard yo press, the harder you press the stiffer it gets. After a few seconds it will start to move down again at its own rate (kind of like a shock absorber) and get into the point where the brakes bite normally. IF you ease the pedal slowly down during the first parts of the movement, getting past the initial movement slowly, you can then slam it down and it wont lock up on you.

What exactly is going on here.

The brakes are strong and dont have a lot of pedal travel otherwise.

Edited by sonicz

Something is f**ked.....

Are you able to pull the master cylinder and booster off?

If not take it to a brake place asap. That's some dangerous shit right there.

  • Like 2

Doesn't matter.

Has to be taken apart and fixed regardless. It could be the pivot point.

Doesn't change the fact it's extremely dangerous and a chat on a forum won't fix it.

  • Like 1

Maybe it came across a bit too dramatically. Its not scary bad, its just a bit strange and the brakes otherwise feel like they are working easily and normally. The car recently passed rego and a average driver they probably would not even notice it. I guess I could describe the brakes using the common "mushy" or "spongy" terminology, but only at the start of the pedal travel and then they bite down really well and strong. Normally when brakes a spongy they are spongy throughout.

I am going to change the brake fluid as I think it could be air in the brake fluid making things mushy. Use any Dot 5.1 grade right? Its ABS equipped.

The perfect analogy would be the shock absorber on your computer chair. Take the chair all the way to the top, then hold the handle which allows you to go down again and sit on it fast from a height whilst holding the handle. You'll notice it wont let you just slam the chair straight down, but rather resist you plenty initially, then ease of holding you back and let you go down at a faster pace

Edited by sonicz

Just changed the pads and fluid and its much better now. Looks like it was related to air and water in the old possibly never changed brake fluid. It still has about 30% of that stiffness left however so I wonder if it was done right.

Yea most of the old stuff out, though obviously some residuals would be left in reservoir tank and lining of components. I think the order was rear left rear right front left front right.

I had/have no idea that you cant mix synthetic and mineral based. Have no idea what the previous owner had. I used dot 5.1 from supercheap.

How come all the "good" stuff seems to be dot 4? Is that ok to use? I think dot 5 is the one not to use, correct?

I still feel like there is air in the system somewhere that gets pumped around, maybe stuck in the ABS unit, how on earth do you bleed that.

Edited by sonicz

Dot 4 is fine mate, wasting your money on 5.. You can't use dot 4 when the system recommends dot 5 as the seals won't like it..

But you can go away the other way as far as I know,

That order was correct

I still feel like there is air in the system somewhere that gets pumped around, maybe stuck in the ABS unit, how on earth do you bleed that.

I had a lot of issues bleeding our brake systems, until I bought a vac bleeder. First time every time now and it's a one man operation.

Sounds like the seal is shot in your booster. Just grab another. I have an auto one here... (The manual booster is smaller I am told, to fit the clutch slave cylinder.)

Thanks for the tips guys. I don't think anything is wrong with my seals or components, at first I suspected it may be the case, but now I'm pretty sure it was just air in the system as they are a lot better now.

At the moment its ok, but still I don't feel it was done 100% right. IT seems the Skyline brake system is not an easy one to bleed, something in the design makes it that if you're not spot on and know exactly what to do you will have problems, certainly more so than other cars like mazdas I've owned.

Scotty, any info on where to pickup a cheap vac bleeder?

Edited by sonicz

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Latest Posts

    • Which solenoid? Why was it changed? Again, why was this done? ...well, these wear..but ultimately, why was it changed? Did you reset the idle voltage level after fitment? I'm just a tad confused ~ the flash code doesn't allude to these items being faulty, so in my mind the only reason to change these things, would be some drive-ability issue....and if that's the case, what was the problem? Those questions aside, check if the dropping resistor is OK ...should be 11~14 ohms (TCU doesn't throw a flash code for this) ~ also, these TCU designs have full time power (to keep fault code RAM alive), and I think that'll throw a logic code (as opposed to the 10 hardware codes), if that power is missing (or the ram has gone bad in the TCU, which you can check..but that's another story here perhaps).
    • Question for people who "know stuff" I am looking at doing the new intake like the one in the picture (the pictured is designed for the OEM TB and intake plenum), this design has the filter behind the front bar, but, the filter sits where the OEM duct heads into the front bar, and the standard aperture when the OEM ducting is removed allows the filter to pulled back out of the front bar into the engine bay for servicing, a simple blanking plate is used to seal the aperture behind the filter This will require a 45° silicone hose from the TB, like the alloy pipe that is currently there, to another 45° silicone hose to get a straight run to the aperture in the front bar Question: how will it effect the tune if I move the MAF about 100-150mm forward, the red is around where my MAF is currently, and the green would be where it would end up Like this This is the hole the filter goes through  Ends up like this LOL..Cheers    
    • Despite the level up question, actually I do know what that is....it is a pressure sender wire.  So check out around the oil filter for an oil pressure sender, or maybe fuel pressure near the filter or on the engine. Possibly but less likely coolant pressure sensor because they tend to be combined temp/pressure senders if you have one. Could also be brake pressure (in a brake line somewhere pre ABS) but maybe I'm the only one that has that on a skyline.
    • Pull codes via the self-diagnosis procedure. As far as I can tell this is just a sign of transmission issues but not a code unto itself.
    • Hi All, putting the engine back together and everything is perfect except have this plug left over.. any ideas what it is for and where it goes? Is on cold side under the intake plenum *note not a stock plug, as everything has been modified Cheers
×
×
  • Create New...