Dual Piston Front Brakes = Change in Bias on an ABS Car?
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Agreed IJ, I did it mainly to allow more heat to be soaked up in the front rotors. My stock breaks could lock up all 4's no problem, it's just that they would overheat the rotors after a few sessions.IJ.;1345437 said:
We'll I'll upgrade the rear if that's what it takes but Doward we are waiting on you buddy.T701jz;1345440 said:
2 stops from 200+ Kph would kill my stock Rotors, I got 55 stops on the test track before I cooked up the current set up and boiled the fluid, changed it to RBF600 and installed DBA 5000's on the front in place of the 4000's I had on it previously and have noticed they run MUCH cooler but didn't get a chance to do the track again before I took it off the road.
I did a few hard 200+ to 50 in a row and they're fine and haven't changed the heat paint at all.
I did a few hard 200+ to 50 in a row and they're fine and haven't changed the heat paint at all.
Zazzn;1345455 said:
MK4 rears are a relatively cheap, easy upgrade for the rear.
(I say easy assuming you have access to a machine shop to make some simple inserts)
So you like the DBA's with the paw pattern? Any suggestions IJ on fixing my solution other then abs? That leaves me to the valve right?
The DBA's are great rotors just a bit EXE
In order that I'd do it.
Fix ABS
Bigger rears to get the balance back to where it should be
Messing with a Prop valve isn't going to change anything as they work by reducing rear pressure and this is the exact opposite of what you need.
In order that I'd do it.
Fix ABS
Bigger rears to get the balance back to where it should be
Messing with a Prop valve isn't going to change anything as they work by reducing rear pressure and this is the exact opposite of what you need.
IJ, wouldn't the prop valve resolve 2 issues that I now face?
#1 pedal travel before locking the front is about 1/3 of what it used to be
#2 could send less pressure to the front so that #1 it locks later, and #2 allows the rears to provide more braking force before they lock?
I agree ABS will be a good fix when I get around to it...
Adam, what inserts? I just upgraded my mk4 to mk4 tt calipers form the NA ones that come on the JDM cars.
#1 pedal travel before locking the front is about 1/3 of what it used to be
#2 could send less pressure to the front so that #1 it locks later, and #2 allows the rears to provide more braking force before they lock?
I agree ABS will be a good fix when I get around to it...
Adam, what inserts? I just upgraded my mk4 to mk4 tt calipers form the NA ones that come on the JDM cars.
Prop valve works by reducing the force to the rear not the front, it shouldn't have any effect on the front circuit.
Sounds more like a mismatch between the Master cylinder bore size and the Calliper piston size and pedal effort should be close to stock.
I haven't done the math for a Mk3 and just based my current system on a "guesstimate".
Sounds more like a mismatch between the Master cylinder bore size and the Calliper piston size and pedal effort should be close to stock.
I haven't done the math for a Mk3 and just based my current system on a "guesstimate".
Is anyone with this kit finding the same results as me?
Can you explain how to calculate the correct sizing or stock sizing vs the PBR's?
Can you explain how to calculate the correct sizing or stock sizing vs the PBR's?
I would think it's dependant on a ratio of pressure to various pistons. Like take the size of the brake master cylinder piston compared to the size of the front/rear/left/right calipers. It would also change depending on the number of pistons per caliper, like the stock fronts are a large single piston, and the new Doward calipers are 4 (?).
Edit: check this out, might be helpful: http://tceperformanceproducts.com/brake_bias_calculator.html
Edit: check this out, might be helpful: http://tceperformanceproducts.com/brake_bias_calculator.html
For your interest, the previous owner of my '87 removed the ABS. I swapped in Mk4 TT rears at the same time as the Doward kit so I never noticed such a huge difference in Bias. In fact, under extreme braking, my TT rears will begin to lock before the fronts do(even with 295 rears), but the bias feels close to balanced. I will just be very careful until I either install a prop valve or get 14" fronts later on.
I picked up an old jakespeed bolt-on kit for my rears. The inserts are the little parts that the bolts go into. The rotor also needs a shim. Adampecush had these parts custom machined for his install so Eric you might have to do the same if you don't want to drill out your Mk3 hubs for the larger Mk4 bolts.
I picked up an old jakespeed bolt-on kit for my rears. The inserts are the little parts that the bolts go into. The rotor also needs a shim. Adampecush had these parts custom machined for his install so Eric you might have to do the same if you don't want to drill out your Mk3 hubs for the larger Mk4 bolts.
IJ.;1345437 said:
I had the same results, cracked one of my rear rotors and they turned nice and blue in spots lol.
Zazzn- I have these brakes, and have put the most miles on them, they are no where near the numbers you pulled out of your ass, I DO HAVE THIS KIT, and I HAVE DRIVEN ON THESE BRAKES, so stop trying give jdub a hard time he is one of if not the most knowledgeable person on this board, that's why your asking the questions and he's HELPING with an answer or solution.
7mBoost - So what numbers are they? Exactly the same numbers I pulled out of my ass. Lets resolve this so read down....
I'm not here to bash on JDUB or anyone else and I don't believe I've done so. Stop acting as if I have. I've been more then amicable to everyone! JDUB got me a little razzed when he was calling my fix a “ghetto”. While IMO his suggestion of fixing the ABS would mask the problem not resolve the problem, which I believe was the ghetto fix.
THANK YOU JDUB I appreciate the insightful input, sorry if you feel offended. I did NOT START THIS THREAD TO BASH ANYONE especially you.
I want to find a solution to the problem that has been created by upgrading my front breaks only. This is one of them hidden "bugs" that you find with may upgrades which people do not talk about very often.
I just got off the phone with Steve Jarvis form supraforums, we talked for about 4 hours! Initially I called him for his expertise on wheel fitment on the mk4 for road racing and we some how got talking about breaks.
He informed me that he did a BBK on his MK4 on the front only and ended up with worse stopping distances and challenged me to try a test with my new BBK vs a stock system to do a full stop form 60MPH and assured me the stock system would stop sooner. He then upgraded to the Rotorex 14" all around and could not believe how much difference it made.
He completely agrees with me that just upgrading the fronts will cause you problems because of the breaking bias. Also a prop valve will not work in my case as IJ has said. He also agrees that ABS would just band aid the situation.
If you don't know who Steve is check this out
http://www.geocities.com/steve_jarvis_me/
He's an Instructor at VIR and he's done plenty to his supra to make it go fast around the track.
So lets end this squabbling about numbers out of ass controversy. Can someone who measure the stock calipers break piston diameter since I'm not in the same city as my mk3.
I need the diameter of the mk3 front piston, and the same for the rear caliper piston.
I will then be able to calculate the change that has occurred and we can see just how much this has changed the dynamics of the car.
AGAIN i'm not bashing anything or anyone here just want my upgrade to actually perform like an upgrade.
I'm not here to bash on JDUB or anyone else and I don't believe I've done so. Stop acting as if I have. I've been more then amicable to everyone! JDUB got me a little razzed when he was calling my fix a “ghetto”. While IMO his suggestion of fixing the ABS would mask the problem not resolve the problem, which I believe was the ghetto fix.
THANK YOU JDUB I appreciate the insightful input, sorry if you feel offended. I did NOT START THIS THREAD TO BASH ANYONE especially you.
I want to find a solution to the problem that has been created by upgrading my front breaks only. This is one of them hidden "bugs" that you find with may upgrades which people do not talk about very often.
I just got off the phone with Steve Jarvis form supraforums, we talked for about 4 hours! Initially I called him for his expertise on wheel fitment on the mk4 for road racing and we some how got talking about breaks.
He informed me that he did a BBK on his MK4 on the front only and ended up with worse stopping distances and challenged me to try a test with my new BBK vs a stock system to do a full stop form 60MPH and assured me the stock system would stop sooner. He then upgraded to the Rotorex 14" all around and could not believe how much difference it made.
He completely agrees with me that just upgrading the fronts will cause you problems because of the breaking bias. Also a prop valve will not work in my case as IJ has said. He also agrees that ABS would just band aid the situation.
If you don't know who Steve is check this out
http://www.geocities.com/steve_jarvis_me/
He's an Instructor at VIR and he's done plenty to his supra to make it go fast around the track.
So lets end this squabbling about numbers out of ass controversy. Can someone who measure the stock calipers break piston diameter since I'm not in the same city as my mk3.
I need the diameter of the mk3 front piston, and the same for the rear caliper piston.
I will then be able to calculate the change that has occurred and we can see just how much this has changed the dynamics of the car.
AGAIN i'm not bashing anything or anyone here just want my upgrade to actually perform like an upgrade.
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rears are about 38.4 mm. (good thing I've had a rear caliper sitting in my office for the last year...)
Jdub what is the point of posting stupid emoticons? Thanks adam, you woudln't happen to have the fronts?
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