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G1en

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Right then, after the zed today binned me into the gravel and tyre wall for the second time i need to get to bottom of why its happening. 

 

When i slammed on the brakes at around 65mph (on rev limiter in 2nd) the abs light and car skidding light came on and the brakes lock up sending me straight on to certain death (ish)

 

Traction control is always off as its during hillclimbing/sprints. Any ideas whats happening. When i restart the car all lights come on (TC, ABS, Skid car (SC?) and stay on then go off when i pull away. 

 

 

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Doesn't SC = Stability control ??

 

Also if the TC light is coming on and going off TC is not disabled - it stays on if its disabled. If you are switching it off with the button I don't think it's completely off any way. I think that's why they say to pull the fuse or use the Mod that @cs2000 does.

 

Any way to answer your question I think your just overloading the system and it can't handle it, TC on a 350 is pretty much just an engine cut it's not a refined racing aid, The car has some clever electronics stability control and abs that "try" to interpret an issue and correct it. hard acceleration then hard braking and cornering deliberately (all be it with good reason) is probably beyond it's comprehension, add to that no doubt upgraded brakes both disks and pads and the cars "corrections" or attempts at it appear to do more harm than good. That's just a guess mind you but I'd start by turning more on board control off.

 

Hope that helps point you in a good direction :)

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This happens when i am braking full on in a straight line. The brakes seize and stay seized even when i release pedal. I dont know if the car has some sort of G meter that thinks i am in a crash or something as i have uprated brakes and semi slicks and this braking zone is uphill so im going from 65 to 25 in about 10mtrs. As you say i may be overloading the system. I would much rather do the braking myself anyway as abs very rarely kicks in which is why i think something or some sensor may be faulty. 

Which fuses do you pull for the ABS/TC/SC on the HR?

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Yikes - That really sucks in a straight line :scare:

 

As I've never  used the fuse trick I can't answer that - a search on here may help - hopefully some one who knows will post up soon.

Weird that they stay locked, you would think that has to be some sort of  valve  in the ABS holding it but I've never come across it unless it's in the ABS unit itself.

 

Here's an off the wall thought for you - Off throttle so TB closes, engine braking starts meaning the inertia of the car keeps engine at high RPM which creates large (than normal) vacuum in Plenum, Brakes are servo assisted meaning the vacuum in the plenum is holding the brakes hard on even when you release pressure with your foot. - That's just a well somethings doing it type thought that may be worth looking at.

 

I managed almost the opposite with my SC - dump throttle SC still turning at high RPM creates positive pressure before (sticky) blow off valve dumps it - result in very poor brakes going into a bend due to no servo assistance - that was a bum twitch moment!

 

EDIT: - or a faulty servo? - I have spare if you want to test that theory :)

Edited by Keyser
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It all works fine when i re-start the car though, its just strange that its happened at the same place twice and only there. The track was slightly damp on both occasion as well. 

Do you know if abs is front wheels only? 

As on other occasions the rears seem to lock way before the fronts, this may be to do with the 2-way diff, CL6 pads on rear, little weight on rear or prob all 3. 

Think i need to pull the fuses and try it out or the abs module (if there is such a thing) may be faulty as it feels like instead of pulsing the brake pedal (releasing, reapply releasing) it applies then fails (light comes on) then cannot disengage. 

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12 hours ago, G1en@waxandshine said:

It all works fine when i re-start the car though, its just strange that its happened at the same place twice and only there. The track was slightly damp on both occasion as well. 

 

I think the system can be shocked into failing. I don't know how exactly - maybe a sensor or a wire vibrates or gets hit by dirt, rubber or whatever. Doing donuts usually triggers it after a bit for example. 

 

How much kerb did you run at Orchard? 

Only thinking this because it happened just after there twice. And the only time it failed on me was there too. I used to really whack the kerb there looking back at the vids but it only failed once in a few hundred runs. So its either that or its the Bermuda Triangle round there.

Luckily it was dry for me and the light came on on the straight so I had fair warning and made it around your bend... Was on for a record though so kept pushing and binned it in the tyres at the next instead. 

 

I hope I'm wrong and its something concrete that can actually be fixed. Its too much of a liability otherwise and it would be better running without .. 

 

Edited by Kieran O'Quick
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It's your stability control kicking in. You cannot turn this off via the switch as that only deactivates the traction control.  A member trader sells a kit on here that will turn SC and TC off, I have it and I never drive with them on

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Yeah, i will have to try that kit, stability control i could understand on a corner but going in a straight line? I just think its the abs as i cant recall it ever triggering and i can do some last minute braking, but when i leave it too late the rears seem to lock up first, if i am starting to turn this usually results in a 180/360 spin. If abs was working correctly i would understeer yes?

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Thanks for the recommendations guys, we're chatting in PM now about my mod.

 

From my point of view. One thing stands out. If you stamp super hard on the brakes and engage ABS, the TCS/Slip lights stay illuminated on the dash. The slip light should blink whilst ABS is functioning, but it should go off.

 

The only way you can get those lights to stay on is to do a donut. Some weird combination of high wheel RPM readings on one axle along with a weird sideways G load causes the TCS/VDC computer to go into fault mode and disable itself. It only gets re-enabled when you re-start the car and the wheel speed sensors register "normal" values (such as just driving in a normal fashion.

 

Just from that symptom alone, im fairly confident its the TCS/VDC system getting in your way, but it is weird that you say your brakes seize and stay seized even when you release pedal. You are correct that if abs was working correctly you would under steer (to a point anyway). SOme very odd symptoms, but your current build, setup and use-case is way outside of anything Nissan would ever expect the computers and sensors would have to deal with, so these things are expected i guess.

Edited by cs2000
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  • 3 months later...

To update this:

been having more braking issues of late to a point:

good news is i fitted the module from cs2000 and i haven't had a recurrence of all the lights coming on (well they are on anyway when the module is activated) but my brakes have been getting worse and worse over last few months:

i have changed pads 

cleaned and filed pads

changed discs

changed fluid

all made little to no difference,

 

when braking in a straight line now i have no issues, car stops brilliantly very little locking. 

When i try and brake on a bend or slight angle when weight is say 70/30 to one side ABS kicks in, brake pedal pulses and it takes an eternity to stop meaning i have been going off cutting the grass at harewood more often than the staff. 

Couple of questions for those that track the zed or know more than me!

1- if one wheel is unloaded and you brake does the abs kick in for all wheels or just that one?

2- Why does it seem to take twice the stopping distance with abs in the zed than regular threshold braking?

3- if i pull the fuse for abs, does it effect anything else? Im thinking i would rather be in control of the brakes and with semi slicks i think in the dry locking up would still stop me faster than abs braking. 

4- why did i not have this issue until recently?

has the module above made abs more sensitive as TC/SC is now disabled?

 

Answers on a postcard. 

Cheers

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