A summer of brake woes (long rant)
09-14-2010, 02:41 PM
#22
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Okay one last question for you then. Obviously obtaining the correct balance through the properly sized pistons is preferred. What about using a proportioning valve? The adjustability could be nice to have when at the track and experimenting with different pads, tires, etc.
09-14-2010, 02:58 PM
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Prop valves can be an option but can be complicated when running modern systems with ABS and other systems. We have a lot of info on prop valves and how they should be implemented on our site here:
http://www.stoptech.com/tech_info/wp...g_valves.shtml
http://www.stoptech.com/tech_info/wp...g_valves.shtml
09-14-2010, 03:38 PM
#24
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Good read! I suppose no one makes a mechanical tandeum master cylinder as shown in the article for our cars? At least without being totally ridiculous. I pretty much only track my car but I do occasionally drive to around so I don't want to go through huge hoops to install it, but that seems like the way to go, being able to adjust on the fly.
09-15-2010, 08:38 AM
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Most dual master systems are a custom deal. We have a customer doing a full race car build with his STi, you can see some of the parts (pedal box, master cylinders) he is using on his build thread here:
http://forums.nasioc.com/forums/show...921025&page=13
He also has some custom billet spindles with integrated caliper mounts and our Trophy BBK:
http://forums.nasioc.com/forums/show...921025&page=13
He also has some custom billet spindles with integrated caliper mounts and our Trophy BBK:
Last edited by StopTechErik; 09-15-2010 at 08:47 AM.
10-04-2010, 07:24 AM
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If you had the 03-05 rear kit, you would not have any issues as the car would be too front biased and you are reporting a clearly rear biased condition. My guess is that you have the 03-05 front kit since you reported noticeable rear pad wear and fade with the front only kit installed. The added efficiency and heat capacity of the rear BBK appears to have made the condition more noticeable, which is why you ended up swapping ends in the brake zone on track. If you have the means, shoot me a PM with the piston sizes (info on how to measure them without removing them is available here http://www.zeckhausen.com/How_to_Measure_Pistons.htm) or even the lot number which would be stamped on the caliper body between the pistons.
On a related note, I think I may have a ABS control unit module issue. I can hear the solenoid pump (I think) firing occasionally. Sometimes when I turn the car off it runs for several minutes, other times it will fire when I just turn the key to the run position. Bimmertech and I have been trying to trouble shoot this a little, but we used Cipher software and none of the wheel speed sensors were bad.
10-04-2010, 07:31 AM
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PS, this makes me say things that would make Glen Quagmir blush
Most dual master systems are a custom deal. We have a customer doing a full race car build with his STi, you can see some of the parts (pedal box, master cylinders) he is using on his build thread here:
http://forums.nasioc.com/forums/show...921025&page=13
He also has some custom billet spindles with integrated caliper mounts and our Trophy BBK:
http://forums.nasioc.com/forums/show...921025&page=13
He also has some custom billet spindles with integrated caliper mounts and our Trophy BBK:
10-09-2010, 04:30 PM
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I'm definitely subscribing to this thread.
I went to big brake kit in the front of my car. Wilwood 6 piston bbk with 13x35mm rotors running BP20 pads. I havn't done anything to modify the rears. They are the stock 2006 rotors and HP+ pads
WITH abs the rear will engage ABS way too early!
WITHOUT abs the rears totally lock up. Doesn't make sense right, it should be front biased (unless there is no braking proportioning/distribution when ABS is disabled) I disabled the abs via fuse just to see what the issue was. The rears lock up under about half pedal travel.
However I believe without ABS (when it's disabled) we do not have any EBD either.
Therefore, I THINK there is equal pressure being sent to all 4 wheels since the 350z relies on electronic brake distribution instead of proportioning valve. Under weight transfer, weight will lift off from the rear and cause it to lock up and will get snap oversteer because the setup is too rear biased.
I don't mean to steal your thread at all but I think the info from my case will help you as well. I think if you get your ABS working functionally (as you stated your ABS light is on) again all will be well since you are running a BBK front and rear, but without ABS I'm pretty sure you need a proportioning valve to adjust the current equal pressure that is currently being sent to front and rear.
It's the only reason why I could think my rears are locking up so damn easily without ABS, and ABS engaging in the rears way too easily with just front BBK.
To the guys at stoptech, does this seem valid? Do I need to buy a rear BBK to prevent rear abs engaging when using ABS and EBD?? It's the only reason why I could think my rears are locking up so damn easily without ABS, and ABS engaging in the rears way too easily with just front BBK.
I went to big brake kit in the front of my car. Wilwood 6 piston bbk with 13x35mm rotors running BP20 pads. I havn't done anything to modify the rears. They are the stock 2006 rotors and HP+ pads
WITH abs the rear will engage ABS way too early!
WITHOUT abs the rears totally lock up. Doesn't make sense right, it should be front biased (unless there is no braking proportioning/distribution when ABS is disabled) I disabled the abs via fuse just to see what the issue was. The rears lock up under about half pedal travel.
However I believe without ABS (when it's disabled) we do not have any EBD either.
Therefore, I THINK there is equal pressure being sent to all 4 wheels since the 350z relies on electronic brake distribution instead of proportioning valve. Under weight transfer, weight will lift off from the rear and cause it to lock up and will get snap oversteer because the setup is too rear biased.
I don't mean to steal your thread at all but I think the info from my case will help you as well. I think if you get your ABS working functionally (as you stated your ABS light is on) again all will be well since you are running a BBK front and rear, but without ABS I'm pretty sure you need a proportioning valve to adjust the current equal pressure that is currently being sent to front and rear.
It's the only reason why I could think my rears are locking up so damn easily without ABS, and ABS engaging in the rears way too easily with just front BBK.
To the guys at stoptech, does this seem valid? Do I need to buy a rear BBK to prevent rear abs engaging when using ABS and EBD?? It's the only reason why I could think my rears are locking up so damn easily without ABS, and ABS engaging in the rears way too easily with just front BBK.
10-09-2010, 04:39 PM
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Say for example, would this situation be correct?
Say with ABS and EBD,
when 2000 psi of pressure is being sent to the front brakes, EBD will calculate the bias and send something like 1000-1500 to the rear to adapt for weight transfer, load, etc.
But without ABS and EBD and no proportioning valve:
then there will be no proportioning whatsoever, and front and rear pressure being sent is the same, lets say 2000 psi front and 2000 psi rear. This I think would most likely lock up the rear brakes under weight transfer and the proportioning valve will allow to restrict the rear brake pressure down to like 1500 psi so it won't be locking up the rears.
I think what I just said is true (please anyone correct me if I'm wrong), but what about my current situation with ABS and EBD, and FRONT BBK and the rear ABS actuating way too early? Is the ABS trying to compensate for the larger amount of pressure being sent to the fronts now by sending more pressure to the rear as well? Say if it was sending 2000 psi and 1500 psi in stock form, after BBK for the front only, would EBD be sending something like 2500 psi to the front, and then 1800 psi to rear to try and compensate and keep the pressure bias? If this is true, then it would explain why my rear puny stock brakes are engaging ABS so easily.
Say with ABS and EBD,
when 2000 psi of pressure is being sent to the front brakes, EBD will calculate the bias and send something like 1000-1500 to the rear to adapt for weight transfer, load, etc.
But without ABS and EBD and no proportioning valve:
then there will be no proportioning whatsoever, and front and rear pressure being sent is the same, lets say 2000 psi front and 2000 psi rear. This I think would most likely lock up the rear brakes under weight transfer and the proportioning valve will allow to restrict the rear brake pressure down to like 1500 psi so it won't be locking up the rears.
I think what I just said is true (please anyone correct me if I'm wrong), but what about my current situation with ABS and EBD, and FRONT BBK and the rear ABS actuating way too early? Is the ABS trying to compensate for the larger amount of pressure being sent to the fronts now by sending more pressure to the rear as well? Say if it was sending 2000 psi and 1500 psi in stock form, after BBK for the front only, would EBD be sending something like 2500 psi to the front, and then 1800 psi to rear to try and compensate and keep the pressure bias? If this is true, then it would explain why my rear puny stock brakes are engaging ABS so easily.
10-10-2010, 01:01 PM
#30
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Ideally the bbk manufacture should compensate for the additional torque from the larger diameter rotor by adjusting the diameters of the pistons in the caliper. Or at least get close. In the case of my old car, Lexus SC300, I used a larger rotor and caliper from a Lexus LS400, this created a huge amount of rear bias because I not only increased the rotor diameter adding more torque, but I added more pistons without adjusting the area ratio from the master cylinder to the front pistons.
So adding a front bbk only does not guarantee bias one way or another.
So adding a front bbk only does not guarantee bias one way or another.
10-10-2010, 01:29 PM
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Ideally the bbk manufacture should compensate for the additional torque from the larger diameter rotor by adjusting the diameters of the pistons in the caliper. Or at least get close. In the case of my old car, Lexus SC300, I used a larger rotor and caliper from a Lexus LS400, this created a huge amount of rear bias because I not only increased the rotor diameter adding more torque, but I added more pistons without adjusting the area ratio from the master cylinder to the front pistons.
So adding a front bbk only does not guarantee bias one way or another.
So adding a front bbk only does not guarantee bias one way or another.
Engineering and development does cost money, which is why the better brake systems cost a little more. If an owner wants to save some coin, he certainly may do so, but he also shouldn't be surprised when the results need more work to dial it all in. This can be done with engine mods or maybe even some basic suspension stuff, but it is a bit more scary when it comes to brakes. The resulting failure could be very hazardous to the health of many involved, not just the occupant(s) of the car in question.
Chris
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