Tuesday, August 17, 2010 - 09:31 pm, by: Trent Linnell(Tlinnell)
I have a V8 and recently replaced my front rotors and calipers from a Supra. Driving the car afterward, everything was fine. Just took the car to get new Power Steering Rack Bushes and when I come to stop at the traffic lights, between 15-10kms the brake pedal will kick up (as though the abs was kicking in) and then the pedal will depress as normal and come to a stop.
I removed the front wheels to see if there was an brake fluid leaks but everything was fine there. I then removed the ABS fuses to see if there was any change and the problem went away. I then put the fuse back in and did a diagnostic check (but couldn't understand the flashing sequence) and this came up on the dash.
Wednesday, August 18, 2010 - 08:41 pm, by: Nathan Richardson(Richtheblack)
I don't want to really take a stab in the dark here because my comment my be factually floored, but I believe there has been issues in the past with the ABS, particularly with Soarers with smaller calipers, that there is too much travel on the brake pedal.
This should result with a soft feel also. I have heard braided brake lines may resolve this.
Thursday, August 19, 2010 - 04:05 pm, by: Andrew La'Brooy(Andyttr)
You shouldn't get longer pedal travel with the Supra callipers as the piston volume is the same as the original V8 brakes. The Supra 2-pot callipers are also identical to the Soarer TT callipers. Both early JZA80's, V8 and TT Soarers use the same master cylinder. If you do get longer pedal travel then something else is wrong in your system.
Trent, you'll have to come show me what it is doing because I don't understand the description. lol Does the car pull to one side when this is happening?
The only way the pedal can come back up is if pressure from the ABS pump is going backwards through the modulator to the master cylinder. It shouldn't do this. When you get an ABS intervention the pedal feel should go 'hard' and then down when the modulator stops building pressure.
My money is on bung seals in the ABS modulator or MC.
As a side note, its pretty common for MC seals to go after the system is bled for the first time in a long time. Crap builds up at the end of the piston stroke, then when you bleed the system you drag the seals through the accumulated crap...
Thursday, August 19, 2010 - 04:16 pm, by: Matt Petersen(Mattmannz)
The early model JZA80's had the same brakes as the TT's but the laters had the four pot calipers and a larger master cylinder.
Not sure if anyone would swap the early 2 pots over, everyone I have heard swaps the 4 pots on which is what I did and got a slightly longer pedal travel.
During an ABS event it can seem like the pedal is coming up but as you say the pedal will go hard then soft then hard as the ABS pulses on and off.
Thursday, August 19, 2010 - 04:29 pm, by: Andrew La'Brooy(Andyttr)
Even the JZA80's with the 4/2 setup use an MC with the same bore, but the front to rear proportioning is different IIRC - hence the slightly longer pedal throw.
Its fairly common for UZZ30/31 owners to upgrade to the JZZ30 / JZA80 2/1 piston setup. The stock V8 brakes use the same pads as an old Camry or Celica... scary stuff for a car that weighs ~200kg more. :p
The TT brakes are a good upgrade as they have slightly larger rotors and bigger pads than the stock V8 ones. The rear callipers are identical, just the rotors and anchor brackets are larger to suit.
Trent, if the pedal is not actually coming up when you're braking there's a chance you're just having over-sensitive ABS issues caused by the different tyre sizes on your front axle compared to your rears. Come grab the rear 16's and see if it fixes the problem?}