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When will people learn to read. The Wilwood kit is designed to use a standard mc. Its on the TTT site FFS.
how big are the s13 rotors tom? are they the turbo or non-turbo ones? are they similar to the R31 brakes?
When will people learn to read. The Wilwood kit is designed to use a standard mc. Its on the TTT site FFS.
Seeing as how you know everything about brakes Ill keep it in your condescending tone.
In my experience, a caliper with more pad area has a greater amount of force needed to overcome the extra friction of the larger pad. Rotor size serves only as a leverage increase.
So to this end, when you upgrade front brakes the rears often lock early as a result, since you are applying more force through the braking system to make the front effective, the rear will lock. Ive never seen it go the other way.
90/10 sounds odd, its more like 40f/60r with a big front brake setup. To this end, you need to limit the force going to the rears. With a bias adjuster you can only limit the pressure, not increase. I don't know how your comments reflect this.
On to my next point. I hope you got the hoppers kit built around a strut with a larger stub axle and bearing than ae86 or you've just missed out on the one main potential advantage of the kit. The weak point in AE86 front suspension is surely the tiny wheel bearings, which resent deeply the extra forces of big front brakes. I believe the kit includes CNC hubs and adapters, which they can make to suit any stub axle and bearing you want to run. If you didnt start with an XT130 strut then you missed out on the only real advantage of the kit over the Wilwood upgrade. The hoppers kit is a lot heavier and more expensive too.
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quoted directly from techno toy tuning website:
"Big Brake Kit for AE86 Corolla
This Big Brake Kit is a direct bolt on for the AE86 Corolla and features 280MM crossdrilled rotors, Wilwood Forged Dynalite Calipers and stainless steel lines. You can choose pad choice from street/sport to full race.
Blank rotors available by request.
These rotors have been tested under the most grueling road race and rally conditions and have the heat dissipation capabilities required for all your needs.
This kit is available for any vehicle using AE86 struts and requires 15" or larger wheels. Please call or email us with any questions."
littleredspirit you should take some of your own advice, and learn to read.
i have had this kit on my car for 12mths. and the fronts do more of the brake than the rears. ive neve once had my rears lock up at all...
and you just confirmed everything i said, as you need more pressure to apply the clamping force on the brakes as they have a larger diameter. but the friction is still the same its just applied over a larger area, so in essence it would be harder to lock the brakes due to the larger friction surface area. also most of your braking is done by the front, so i still dont know how the hell you can lock your rear brakes as you claimed to see, when most of the force is always applied to the front. and if you have a larger surface requiring less friction to stop, the fronts rarely lock as well.
I don't know what experience you have with brakes, but what you said above about the rear will lock up before the front when you upgrade to a bigger front brakes is simply not true. People with big front brakes please comment.
When you upgrade your front brakes to something bigger like the Hoppers kit you increase the effective caliper piston area (larger pads) and the rotor effective radius (bigger rotors) which equal to increased mechanical gain giving you more braking power to the front wheels for the same amount of pressure from the master cylinder.
To prove my point, my car used to lock the rear first everytime after I installed a rear disc setup from a Jap ae86. This is no longer the case after I installed the Hoppers kit. Now the car will lock the front first everytime. This is the reason why I am installing bigger S13 rotors to the rear to restore brake balance.
xero S13 rotors are 259mm turbo and non turbo appeared to use the same size rear rotors. Don't know how that compare with R31 setup.
My mistake on the Wilwood Kit and the site saying that you need a standard MC, it was an email from Gabe that told me to use the standard one. It doesn't say change it though does it? But it just plain doesn't specify.
My experience:
Add Wilwood kit to an AE71 with std drum rear. Rear locks first, everytime, feels much unsafe.
Change ADM diff to Kouki LSD and keep std bias valve. No braking force to the rear, certainly nothing like a lock up.
Change to JDM Bias Valves, close to perfect brake force distribution with no bias issues.
Ive had soo many discussions with my mechanic about brakes, and he agrees that when big front brakes are added to a system it usually leads to locking rears. He even told me to have an adjuster handy to dull down the rears when the fronts go in, just in case I needed it.
The Wilwood kit has only a slight increase in pad area over a standard AE86 pad.
Id be curious to know what the complete braking systems in your cars comprise, as it seems to have a lot to do with having the correct bias valves for the setup upon reflection.
I still say you two are the only two people who I've heard have front lock-up issues from this type of upgrade. What rears and bias valves were you guys running when the fronts were locking?
Ive done a lot of reading now about this issue. The difference between our situations seems dependant not on pad area, but on piston area, as the area that the fluid contacts on the piston is the only quantifiable thing as far as fluid pressures go. Pad area is irrelevant and misleading to speak on as its a small detail next to the fluid behavior in the system, and pads vary wildly in design and area from caliper to caliper.
Assuming we have the same braking system except for our fronts, if your calipers have a smaller total piston area, they will lock first.
Use this formula to check for yourself:
Pressure = force / area
(think stilettos vs slippers on a lawn - smaller stiletto easily pushes thru, slippers stay flat on top. Same force applied due to same person wearing both, but the stiletto punches thru cause its under greater pressure due to the reduced surface area)
If you increase the front piston area above standard, the rears will always lock first using this rule. A greater amount of pressure is required to displace a larger piston, so as you add more piston size, you need more foot pressure to do the same braking. As you increase the pressure in the system the rears reach the amount of pressure they need to lock before that threshold is reached for the front.
This is science you cant argue with it. My simplified explanation above wasn't that good, but I think this does it.
I found a thread on Toymods where you, Tom86, are asking about rear brake upgrades due to this same issue and someone even posts the same anecdotal evidence as I have observed about the rears locking. So why you telling me its BS? It happens on every upgrade that increases front piston size. Thank physics for that. 8 months go by and you've still got issues? Good to see you can get to the bottom of things when you put your mind to it.
Here's the thread so people can verify:
I think you have a unique problem with your setup, firstly, you possibly bought a brake upgrade with a reduced piston area over standard. If this isn't the case then perhaps your front tyres are bad, maybe some nice sticky front pads and some shagged rear brakes combine to give you this issue, there's also an extra 10mm of leverage thanks to a 290mm rotor.
Or possibly you went ahead and changed the master cylinder, bias valves, front calipers and rotors all at once and you have no idea which of these is contributing most to the issues your having.
I did a good 9 months research on which upgrade to get, and I must say, I'm glad I chose the Wilwoods. It works awesome. What decided it for me was the quality of the Wilwood product. Shits all over a twin piston BA caliper, weighs less too. The good thing about the hoppers kit is the money stays in australia, but honestly, with results like you guys are having, they dont deserve a cent.
You guys never answered me whether you used bigger stub axles, cause a 290mm rotor locking all the time isn't much good for tiny 86 wheel bearings.
Anyhow Id like to know what your full setup is.
You might try changing to an adm ae71 rear pressure limiting valve, like the one i discarded to make my brakes work, since you have the opposite problem.
Last edited by LittleRedSpirit; 2nd January 2009 at 10:05 PM.
yes all the nissan masters have the same bolt spacing, as in you can use the S13/S14 silvia;s also. S14 looks very much like a R33 item anyway.
if you want a new booster then the brake booster from any of these nissans will also bolt up and is the same pattern as the toyota 4 bolt.
If ur using a nissan master, then dont use that shitty toyoya brake proportioning valve, use the nissan one.
I have a question related to master cylinders, hoping someone can answer it for me.
Im just wondering if anyone has a picture of a kouki AE86 master cylinder with its angled stud pattern. All installed in the car is ok, as long as I can see which way the angled pattern goes and I can find out the centre to centre spacing of the studs.
Please Help Kouki AE86 owners!!!
If all goes well I might have a solution for running long stacks on an adm 20v!!
I'm doing FC/FD front brakes, with rear drums from a tarago (just part of my diff...)
What master cylinder/booster/proportion stuff should i run?
On another note, a friend of mine put an S13 booster in, has two ports for the front brakes, and one for the rear, i think he was saying something about removing the proportioning valve thing altogether?? It was new years day though, so i was fairly hungover
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