BBK bias discussion
- Thread starter Zazzn
- Start date
Poodles;1360145 said:
Well if diameter of the master cylinder piston is the same, base bias would also be the same.
Not exactly as there are springs and what-not that could put more stress on the front or back part of the master (two chambers).
My main point is, why would they have changed the master for the ABS cars? There must be a reason and quite frankly it may be a failsafe built in to push more to the front if the ABS system fails...
My main point is, why would they have changed the master for the ABS cars? There must be a reason and quite frankly it may be a failsafe built in to push more to the front if the ABS system fails...
i am current non abs with a abs master cylinder and i dont have any issues. i think i have a spare non abs master cylinder if i find it ill take a look inside to see if i can see any differences
Lots of info getting thrown around 
So far looks like it's mainly good stuff.
I use the brake pad area combined with the coefficient of friction of the pads to help determine brake rotor torque.
Zazzn, smaller pistons in the front would have less bias toward the front. Larger pistons would have more bias toward the front.
We've determined your car was originally ABS, right? Do you have a non-abs prop valve in place, or not?
So far looks like it's mainly good stuff.I use the brake pad area combined with the coefficient of friction of the pads to help determine brake rotor torque.
Zazzn, smaller pistons in the front would have less bias toward the front. Larger pistons would have more bias toward the front.
We've determined your car was originally ABS, right? Do you have a non-abs prop valve in place, or not?
looks like the MC might be the same http://www.cygnusx1.net/Supra/Library/EPC/291420/catalog.aspx?F=4702&P=1 unless the "W/*66" means ABS?
Remember mine is a Canadian edition if that matters but I don't think it does according to the TSRM.
I havn't changed any valve or master. It's all original....
I havn't changed any valve or master. It's all original....
I will this weekend when i get home i'm acutally going to have time to work on it for the first time in a long time.
I was out lapping with the mk4 today... I guess the oil cooler isn't enough I need some ducting as well.. 140ish C Oil temps are cooking and the breaks need some good fluid... was cooking them too
Lapping is so damn fun.
I was out lapping with the mk4 today... I guess the oil cooler isn't enough I need some ducting as well.. 140ish C Oil temps are cooking and the breaks need some good fluid... was cooking them too
Lapping is so damn fun.
Bringing this up from the dead, i'm revisiting my breaks as my car was sitting for a few years since I moved to cali and finally shipped it here.
Ciff's since thence
-ABS is working again
-Breaks still lock up very easily on the front (activate ABS) in a panic stop (jab the break fast)
-No leaks
-About to change the rear rotors and pads.
-Still on stock rear rotors and calipers going to use stoptech performance pads have the same ones for the front that will install as well (also have a set of ceramic for the front since they usually tend to have less bite)
Since I see doward is banned from the forum (don't know why) is there any rear kits still available anywhere?
Ciff's since thence
-ABS is working again
-Breaks still lock up very easily on the front (activate ABS) in a panic stop (jab the break fast)
-No leaks
-About to change the rear rotors and pads.
-Still on stock rear rotors and calipers going to use stoptech performance pads have the same ones for the front that will install as well (also have a set of ceramic for the front since they usually tend to have less bite)
Since I see doward is banned from the forum (don't know why) is there any rear kits still available anywhere?
U might want to start here: http://www.ebay.com/itm/Big-Brake-K...Parts_Accessories&hash=item233248669b&vxp=mtr
On the front the car is using their front 13 inch slotted rotors, Wilwood BBK, shod with Porterfield R4-1. On the rear, the stock MK3 rear calipers and upgraded, slotted rear rotors from Driftmotion, shod with stock Sumitomo metallic pads. The brake fluid was flushed and filled w/ Castrol SRF.
I ran this set-up on my lightened car (3164 Lbs curb weight), w/o any brake fade or lock up all day long at several NASA events. My car is a non-ABS model MK3. Suspension is RSR linear springs (rated front/rear at 700/400), Tanabe Sustec anti-sway bars, and KYB shocks. It was running with 255/40/17, BFGs G-force Sport Comp2, which are not very soft tires, but allowed a smooth transition from 135mph down to 60 w/o any fade or tire squirm, into turn 10, at PIR, a high speed corner.
HTH
On the front the car is using their front 13 inch slotted rotors, Wilwood BBK, shod with Porterfield R4-1. On the rear, the stock MK3 rear calipers and upgraded, slotted rear rotors from Driftmotion, shod with stock Sumitomo metallic pads. The brake fluid was flushed and filled w/ Castrol SRF.
I ran this set-up on my lightened car (3164 Lbs curb weight), w/o any brake fade or lock up all day long at several NASA events. My car is a non-ABS model MK3. Suspension is RSR linear springs (rated front/rear at 700/400), Tanabe Sustec anti-sway bars, and KYB shocks. It was running with 255/40/17, BFGs G-force Sport Comp2, which are not very soft tires, but allowed a smooth transition from 135mph down to 60 w/o any fade or tire squirm, into turn 10, at PIR, a high speed corner.
HTH
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Had to freshen up a bit on this thread as it's so old.
If you're locking the fronts, your tires aren't good enough. Front bias is a good thing as if you lock up the rears, you're going ass first into what you're trying not to hit.
If you're locking the fronts, your tires aren't good enough. Front bias is a good thing as if you lock up the rears, you're going ass first into what you're trying not to hit.
Zazzn;1983161 said:
Arizona Performance has had their kits for sale for quite a while. Revolution Brake also has quite a few kits for the MKIII Supra on their website.
Nick M;1358435 said:
For the record, you just described the definition of 'dissipation', the point you were trying to refute, while simultaneously saying it will 'make' more heat (which if I were nitpicking like you were, I'd say that's impossible due to Newton's First Law).
Normally I'd ignore this as it was three years ago but when someone gets preachy about engineering or thermodynamics and is completely wrong it needs to be corrected
Poodles, I understand and I think I mis-represented what I mean by front bias....
Vs stock the front and rear seems balanced front is going to dive and as I press the breaks hard it will stop harder until you lock up.
Cobra setup, seems that the front will give the same amount of breaking force with a 1/3 the effort of the stock pedal push. Meaning I push 1/3 as much as I used to, to arrive at the same breaking power as I did before (from the front).
I understand I want a lot front bias, as I don't' want the car to slide around like a BMX bike.
What I don't understand is why the breaking power has increased so much if the calculations were all supposed to be right.
To me a BBK should add enough capacity that will allow the car to slow from speed server times without fade because of a larger rotor (heat sink). To accommodate this larger rotor you generally have to change calipers, which in this case we use the mustang caliper which provides 1.4% more breaking than the stock breaks (according to the old doward threads)
So the way I see it, I should only have lost 1.4% of rear breaking power on the rear as the front is doing more work. (no problem)
However, this does not seem like the case for me, and I don't know why. It seems that when I press the breaks I only need a 1/3 as much pedal distance to achieve the same rate of deceleration, leaving me 2/3 of the pedal which will lock up the front 245/40/18's.
This also means that since the pedal is only 1/3 pressed, the rear breaks are 2/3 less effective as I'm not pushing as hard on the pedal to activate the rears equally.
Make sense what i'm talking about now, I don't know how else to explain it.
I was talking to Zach, and was thinking of switching to the willwoods, but I still would like to replace the rear rotors with something bigger in size and a caliper that will offer the same balance that I had stock.
Vs stock the front and rear seems balanced front is going to dive and as I press the breaks hard it will stop harder until you lock up.
Cobra setup, seems that the front will give the same amount of breaking force with a 1/3 the effort of the stock pedal push. Meaning I push 1/3 as much as I used to, to arrive at the same breaking power as I did before (from the front).
I understand I want a lot front bias, as I don't' want the car to slide around like a BMX bike.
What I don't understand is why the breaking power has increased so much if the calculations were all supposed to be right.
To me a BBK should add enough capacity that will allow the car to slow from speed server times without fade because of a larger rotor (heat sink). To accommodate this larger rotor you generally have to change calipers, which in this case we use the mustang caliper which provides 1.4% more breaking than the stock breaks (according to the old doward threads)
So the way I see it, I should only have lost 1.4% of rear breaking power on the rear as the front is doing more work. (no problem)
However, this does not seem like the case for me, and I don't know why. It seems that when I press the breaks I only need a 1/3 as much pedal distance to achieve the same rate of deceleration, leaving me 2/3 of the pedal which will lock up the front 245/40/18's.
This also means that since the pedal is only 1/3 pressed, the rear breaks are 2/3 less effective as I'm not pushing as hard on the pedal to activate the rears equally.
Make sense what i'm talking about now, I don't know how else to explain it.
I was talking to Zach, and was thinking of switching to the willwoods, but I still would like to replace the rear rotors with something bigger in size and a caliper that will offer the same balance that I had stock.
Hi guys, I know about the other kits out there, but I want to work with what I have if I can, if it's a trash kit I'll give up, but many seem to have loved this kit when they bought it a few years back.
Erik, you have a proportioning valve in the system now it's just biased for the Stock Callipers, if you workout the Piston area front to rear this will give you a ratio that the stock valve works in, to return the car to "normal" bias you need to increase the rear piston area by the same amount as the new front callipers, this will get you "close" discounting the increase in front rotor size/leverage.
Or you could delete the stock valve and substitute an adjustable valve.
When I built my BBK for the Mk3 I went with option A and it worked perfectly, did this again on the new project car even though it has ABS and in theory should sort itself out I still wanted it to be close so there's no surprises.
Or you could delete the stock valve and substitute an adjustable valve.
When I built my BBK for the Mk3 I went with option A and it worked perfectly, did this again on the new project car even though it has ABS and in theory should sort itself out I still wanted it to be close so there's no surprises.
88suprat - I very much am, but I was wondering, about the ISF setup that was spoken about a little while ago by Sethron, since i have an ISF, would make things pretty simple for new parts.
IJ - problem is I don't know the sizes for the pbr cobra breaks, nor do I know what the stocks are... Anyone have this info handy? Also what are the EVO calipers like what size is the piston?
IJ - problem is I don't know the sizes for the pbr cobra breaks, nor do I know what the stocks are... Anyone have this info handy? Also what are the EVO calipers like what size is the piston?