Dual Piston Front Brakes = Change in Bias on an ABS Car?
- Thread starter Zazzn
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Zazzn;1346034 said:
Considering what you've been told and your responses the past couple pages...it's highly amusing watching you flip-flop around.
(sorry if it offends you)
Perhaps you should call "Steve" up again and you two figure out what to do
(that fits your unique view of these brakes and their operation)
Good Christ Almighty. I'm gone for a day and this is what I come back to?
LOL!
As the creator / designer / engineer of this brake kit, let me go ahead and clear some air.
In ANY non-ABS car, you MUST have the fronts and rears matched as closely as possible in fluid displacement vs prop valve to maintain proper bias.
You've installed a MUCH larger than stock setup in the front, and retained the tiny rear setup. You've destroyed the bias. FIXING your ABS WILL fix the bias in a very specific instance - at front lockup. Once the ABS kicks in the front, the rears THEN get additional pressure vs the front (the fronts begin to divert, the rears do not)
You don't have to slam on the brakes - if you had working ABS, Zazzn, you would know this.
For all of your asking of JDub if HE has this kit or not, YOU have not driven in an ABS equipped car with these brakes.
Jeff's car has ABS, and these were designed with ABS in mind.
Tekdeus, you're right - the MKIV TT rears are slightly too big in regards to bias vs these specific fronts. That's why the rear setup I'm building is a 12.6" single piston caliper. I'm hoping to have more details later this week about them.
Zazzn, you have two options - upgrade the rears to get proper non-ABS bias back, or fix your ABS. Honestly, you should fix the ABS first anyway, and do the rears later.
LOL!
As the creator / designer / engineer of this brake kit, let me go ahead and clear some air.
In ANY non-ABS car, you MUST have the fronts and rears matched as closely as possible in fluid displacement vs prop valve to maintain proper bias.
You've installed a MUCH larger than stock setup in the front, and retained the tiny rear setup. You've destroyed the bias. FIXING your ABS WILL fix the bias in a very specific instance - at front lockup. Once the ABS kicks in the front, the rears THEN get additional pressure vs the front (the fronts begin to divert, the rears do not)
You don't have to slam on the brakes - if you had working ABS, Zazzn, you would know this.
For all of your asking of JDub if HE has this kit or not, YOU have not driven in an ABS equipped car with these brakes.
Jeff's car has ABS, and these were designed with ABS in mind.
Tekdeus, you're right - the MKIV TT rears are slightly too big in regards to bias vs these specific fronts.
That's why the rear setup I'm building is a 12.6" single piston caliper. I'm hoping to have more details later this week about them.Zazzn, you have two options - upgrade the rears to get proper non-ABS bias back, or fix your ABS. Honestly, you should fix the ABS first anyway, and do the rears later.
:runaway:
^^^ LOL...be careful John, you don't want to attack or belittle anyone. You're going to be accused of being an arrogant asshat with an attitude if you keep talking like that
(blunt facts are not what some of these guys want to hear - it's offensive after all)
^^^ LOL...be careful John, you don't want to attack or belittle anyone. You're going to be accused of being an arrogant asshat with an attitude if you keep talking like that
(blunt facts are not what some of these guys want to hear - it's offensive after all)
jdub;1346137 said::runaway:
^^^ LOL...be careful John, you don't want to attack or belittle anyone. You're going to be accused of being an arrogant asshat with an attitude if you keep talking like that
(blunt facts are not what some of these guys want to hear - it's offensive after all)
You've got 15-20 years of battle history on the books that I don't have yet... I'm still young enough and naive enough to think I can teach someone something new
if its not a track car just fix the abs should be easy enough. if you want to install a after market proportioning valve its really simple. although you need to know that OEM style proportioning valves are not linear, so a after market proportioning valve is going to behave differently
Wouldn't an aftermarket proportioning valve allow you to adjust and "reduce" the current stock restriction to the rear? Allowing more braking force to the back?
Doward, yes I would LOVE to put on some rears to balance the car again. A few people have said here the system will not actively provide more pressure to the rears when the fronts lock it would have to be me doing this. When I hit ABS I tend NOT to press harder, I have 3 cars that I track and it's hard to change the way you drive under reaction situations depending on which car you drive.
The Aristo and TT perform and act the same way that my mk3 did. Not anymore however...
We have established that
-Yes the ABS would HELP mask the problem (not really actually fix the problem)
-Bias is skewed as I originally though
-I would like to upgrade the rears to return the car back to balance
this is why I've been asking for the piston sizes so we can calculate what I need. Since I can't wait for a BBK for the back's for years. I'm going to have a spare set of mk4 NA rears that I wanted to calculate out.
I do track the car and I've already explained why I do not like the stock ABS system. I may have to fix it to help with this issue but I'd rather resolve it by actually resolving the bias issue.
Jdub - This is my last reply to these childish antics.
-I have and have had nothing against you
-I have always valued infomation that you have provided even if it was not the solution I was looking for.
-I believe you were wrong for the way you acted, you ignored my PM regarding this subject
-Editing/deleting many of your original posts to mask information or why I had made my comments doesn't make them any less valid.
-I have issue with anyone who thinks they are superior because they are "in the know". Replying in a condescending way or belittling someone.
SM was supposed to be the safe haven form SF crap that admins allowed on SF. Please lets keep it civil, clean and healthy after all we are all here learning and upgrading our supras buying form the community.
Doward - Now that we have identified there IS a problem IF you are running a car WITHOUT ABS, I'm just trying to improve on what you have provided by fitting my whole car with better breaks. After all this kit doesn't provide more stopping power, because I could already lock up all 4's on the stock system. I purchased this kit to help with repeated high speed stops. I know you are working on a kit for the rear, but working on doesn't help me because I need a kit now! Which is why I was asking for Piston diameters so that I could calculate what I could use. IE Mk4 NA rears or something similar.
Supraguru - we already established that a prop valve will not be beneficial since it's not rear biased but front biased.
The Aristo and TT perform and act the same way that my mk3 did. Not anymore however...
We have established that
-Yes the ABS would HELP mask the problem (not really actually fix the problem)
-Bias is skewed as I originally though
-I would like to upgrade the rears to return the car back to balance
this is why I've been asking for the piston sizes so we can calculate what I need. Since I can't wait for a BBK for the back's for years. I'm going to have a spare set of mk4 NA rears that I wanted to calculate out.
I do track the car and I've already explained why I do not like the stock ABS system. I may have to fix it to help with this issue but I'd rather resolve it by actually resolving the bias issue.
Jdub - This is my last reply to these childish antics.
-I have and have had nothing against you
-I have always valued infomation that you have provided even if it was not the solution I was looking for.
-I believe you were wrong for the way you acted, you ignored my PM regarding this subject
-Editing/deleting many of your original posts to mask information or why I had made my comments doesn't make them any less valid.
-I have issue with anyone who thinks they are superior because they are "in the know". Replying in a condescending way or belittling someone.
SM was supposed to be the safe haven form SF crap that admins allowed on SF. Please lets keep it civil, clean and healthy after all we are all here learning and upgrading our supras buying form the community.
Doward - Now that we have identified there IS a problem IF you are running a car WITHOUT ABS, I'm just trying to improve on what you have provided by fitting my whole car with better breaks. After all this kit doesn't provide more stopping power, because I could already lock up all 4's on the stock system. I purchased this kit to help with repeated high speed stops. I know you are working on a kit for the rear, but working on doesn't help me because I need a kit now! Which is why I was asking for Piston diameters so that I could calculate what I could use. IE Mk4 NA rears or something similar.
Supraguru - we already established that a prop valve will not be beneficial since it's not rear biased but front biased.
I know its been said already, but have you verified the ABS system is free of blockages (particularly to the rear of the car)? If you've got a malfunction that is blocking or impeding pressure to the rear, a larger set of rears isn't going to help anything.
Zazzn;1346257 said:
Zazzn - the only thing that has been established is you will not listen. ABS would in fact fix the problem...the guy that designed these brakes even said so (among others).
Your attitude toward me, both in this thread and in the PM you sent me is/was condescending from the start...a passive aggressive attempt to to make me seem like the bad guy. That is the reason I responded the way I did and deleted my posts. You do not want to hear the answer, you do not want to learn, all you want is to keep yourself from looking ignorant or stupid. You are putting up quite the smoke screen that's doing a far better job of illustrating your ignorance than I ever could.
Kinda funny from a guy that quotes "safe haven from SF"...the same guy that is a moderator over there. I guess you are never a problem, huh Zazzn.
If you think that locking up all 4 brakes is the fastest way to bring this (or any car) to a stop...you really are clueless. The extra capacity provided by this kit will stop the car as well or better over a longer periods of brake use. It's really getting old, your repeating the same incorrect BS.
Zazzn, I think you are misunderstanding how the stock ABS system works. To use your example:
600psi to lock up the rears, 400psi to lock the fronts:
1) @ 400psi, you're locking the fronts, the rears have 266 psi.
2) ABS kicks in, bleeding fronts back down to 350psi (not exact, I have not measured, this is just to illustrate)
3) You press on the brake further to 500psi
4) ABS is still going, fronts are bled from 500 to 350, and the rears are at 366psi.
5) You press on the brakes further to 650psi
6) ABS going, fronts bled back down to 'unlock' (350psi in this example) and the rears are bled back to 550psi (as the rears lock @ 600psi)
Obviously, this pulses. I don't know the exact drop, but this illustrates how the ABS system will passively bias the brakes for you.
Since you refuse to fix your ABS, you are locking your fronts up pre-maturely. My new rear setup will go a long way toward fixing that.
600psi to lock up the rears, 400psi to lock the fronts:
1) @ 400psi, you're locking the fronts, the rears have 266 psi.
2) ABS kicks in, bleeding fronts back down to 350psi (not exact, I have not measured, this is just to illustrate)
3) You press on the brake further to 500psi
4) ABS is still going, fronts are bled from 500 to 350, and the rears are at 366psi.
5) You press on the brakes further to 650psi
6) ABS going, fronts bled back down to 'unlock' (350psi in this example) and the rears are bled back to 550psi (as the rears lock @ 600psi)
Obviously, this pulses. I don't know the exact drop, but this illustrates how the ABS system will passively bias the brakes for you.
Since you refuse to fix your ABS, you are locking your fronts up pre-maturely. My new rear setup will go a long way toward fixing that.
Zazzn - John's post pretty much spells it out. Since you seem to have all the info you need, you seem to have your game plan laid out, and do not want to accept any input from anyone that disagrees with your view...this thread is closed. It was amusing while it lasted...and, will be the last reply period. Do not PM me on this issue again.
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