Abs Problems?

[worldwalker]

Hi there, I've been having an odd brake/abs problems with my 03 MT coupe and wonding if anyone knows what it might be?

During normal driving the brakes are 100% I could comfortably lock the wheels with less than 2inch of peddle movement.

As soon as I drive the car "spiritedly" I start getting problems but I'm terrified to attempt to replicate them. I only drive like this with VCD off as I find it more of a hinderance than assistance.

The times I seem to notice that it has happened is roughly between 70-100 with relatively light (feathering) braking through right hand sweeping corners while coasting in 4th or 5th gear downhill.

As I'm braking I hear the ABS kick in the peddle shudders and the brakes start pulsing momentarily (as if I'd hit the brakes too hard just clipped that ABS threashold) without my foot on the peddle.

I'm also finding that the ABS is very trigger happy and cutting in way before locking.

I havn't really checked anything yet but any help or ideas would be great.

Cheers,

Nick

[whtbox]

your cars stock standard?

[180 wanabe]

this might sound dumb but is ur brake fluid low?

[Touge Kyousou]

I had ABS problems too but different to what you're experiencing.

Though it may be related.. i cleaned the ABS sensors on the front and no problems since. Use a wet rag to clean the sensors then jam a bit into where the sensor sits and use your hands to spin the rotor so it cleans the rotor surface too, you'll have to do this a few times as there is alot of gunk in there.

If no go after that, you might need to do your rear sensors.

Not saying this is the solution but it was for my abs problems and hopefully it works for you (easy diy fix).

GL.

Ps. A guy on G35 forums had same abs issues as me and this fix worked for him too. Took us ages to figure it out lol.

[worldwalker]

pw350gt - Yeah its stock other than bilstiens

180wanabe - its 3mm under the full mark cold

touge - Thanks for that. I thought that might be the case as i had a similar problem with my MR2 when the bearing shattered and damaged the sensor... Scary when it happens on the way down King Lake spur.

[scathing]

Stock tyre sizes?

[grae35]

Thanks for the ideas guys because I too get the abs going off prematurely on some occasions. Had thought it just a characteristic of the car but will clean my sensors and see if any change. Mine is a 6MT 2004 sedan.

When on the skid pan with VDC off I always get weird abs style vibrations and longer pedal travel after spinning the car, ie as I am braking going backwards. Its never a big problem cos by that stage car is going at a low speed (generally) but feels weird.

Also when I first bought car it had stuffed (worn to undersize) front std rotors. I hear a common problem on G35's as well. Decided to upgrade to slotted rda's and QFM A1RM performance pads for the odd track day. They are great but before changing from the stockos I did an experiment to see how much the std set up would fade in simulated track use on the road. So I did over twenty 100kph - okph consecutive stops on a nearby vacant bit of highway and found bugger all fade but what I did get was interesting. After about the third or fourth stop it felt like the abs was going off even though wheels did not seem to be locking and unlocking and braking distance did not change much, still very short. I put it down to older brake fluid but may be something to do with those abs sensors.

With the whole system rebuilt for a track day at QR in July everthing worked well and I used Penrite Sin brake fluid as an upgrade from std stuff. I still got weird rear axle braking as trail braking/coasting into turn one which gave me a bit of a fright first time it happened. Car was sliding mid corner at about 125kph just after coming off the brakes from the front pit straight. It only happened in that small window of time between braking and getting back on the throttle but was a distinct unsettling braking action of the rear wheels one side first then the other. VDC was off of course for the track but I had read that you cannot totally shut off traction control and so assumed that this must be what was happening. But perhaps it was just the ABS sensors playing up.

Any one else had similar problems or know of a solution?

[scathing]

  grae35 said:

When on the skid pan with VDC off I always get weird abs style vibrations and longer pedal travel after spinning the car, ie as I am braking going backwards.

That symptom is characteristic of the car. The Z33s do the exact same thing.

I had an "oh shit" moment when I was doing some drifting on a motorkhana course. I was straightening it up to go into the garage when I hit the picks, and nothing. Dead solid pedal, with ABS vibration. No give at all, and no deceleration. I almost ran over the timekeeper on the way in, and almost shot through the other side and into a curb.

I've been told by a friend who has done a lot of research into fixing it that its pad knock-back. I've got no idea what that means, so maybe someone can chime in?

  grae35 said:

VDC was off of course for the track but I had read that you cannot totally shut off traction control

Did you press it, or hold it? The only way to completely disable VDC is to trigger a fault, either by holding the button down or unplugging something.

When the dash lights up and the button doesn't toggle the VDC (which can also happen if you spin out enough, all the weird readings freaks the computer out), its permanently off until you restart the car.

[DAS KAMU]

throw abs out

[scathing]

  DAS KAMU said:

throw abs out

True. Who needs insurance?

[grae35]

Hey Scathing

Sorry to not reply earlier. Been busy at work.

Yes I always just push VDC button once for skidpan work. Didnt realise you could hold button in and get a more permanent result. Must try it next time.

All of us v35 owners at gympie skid pan seem to get the same SLIP warning light staying on after multiple spins. Its does not always happen, seems related to the number of times you get more than 90 degrees to direction of travel and not necessarily how often you keep the car in a less pronounced drift.

Will research pad knock back and see what else I can learn . Thanks

Graeme

[scathing]

  grae35 said:

Yes I always just push VDC button once for skidpan work. Didnt realise you could hold button in and get a more permanent result. Must try it next time.

Try it when you go outside, before you leave. Hold it down for 8 seconds.

When you give it an instantaneous press it should only light up the VDC light. If you hold it down for long enough, the SLIP light stays on too (I can't remember if any other lights come on).

  grae35 said:

All of us v35 owners at gympie skid pan seem to get the same SLIP warning light staying on after multiple spins. Its does not always happen, seems related to the number of times you get more than 90 degrees to direction of travel and not necessarily how often you keep the car in a less pronounced drift.

Same here with my TCS-equipped Z33.

If I can keep the car drifting with a "forward" momentum nothing happens. If I spin hard (a big spin in a very tight area) then it tends to shit itself. I can spin out reasonably regularly on a race track without the unit going nuts, but on the skidpan if I wipe out its more likely to drop into failsafe.

  grae35 said:

Will research pad knock back and see what else I can learn

MR RIZK on 350Z-Tech has been getting chronic cases of this problem on his car.

[grae35]

MR RIZK on 350Z-Tech has been getting chronic cases of this problem on his car.

And from what I have read that he has tried in fixing the problem it seems pretty difficult to eliminate.

Track corners are predictable so not a real issue to tap brakes before a corner. I suppose it is only the unpredictable nature of drift spins that will catch me out and hopefully not some poor marshall in the finishing area of a motorkana event . Thanks for the info.

Graeme