I'm trying to figure out the pros and cons of upgrading my front brakes. Car is an 82 datsun 280zx. I do hpde.
I am looking at wilwood dynalite-m calipers with 300zx rotors. They'll bolt up with an adapter bracket and some shims. This is for the fronts only... I don't have plans to change the rears from stock.
Compared to stock the wilwood piston area is about 20% larger. What will this mean in terms of pedal feel? Stopping ability? Will the stock proportioning be messed up?
If you can already lock up all four wheels on the tires you've got, increasing brake output won't do a dang thing.
if your fronts currently lock but your rears don't, increasing front output will just make that situation worse.
if your rears currently lock but your fronts don't, then increasing front output is the right move.
Increasing caliper piston area decreases the pressure required to lock up a brake. So it decreases the force you have to put into the pedal.
however, increasing caliper piston area increases the amount of fluid the caliper takes to build pressure, so it increases the distance you have to push the pedal.
what performance deficit are you trying to overcome? What the car needs determines where to throw the money.
Going from a factory floating caliper to a fixed caliper may improve feel as well.
Wilwood is also considerably lighter.
I am trying to overcome what I think is a heat issue, ultimately to gain confidence. Progressively throughout the day, the pedal gets softer and softer - though the car continues to stop. I'm running Porterfield R4S pads and relatively new calipers, with ATE fluid.
Are you ducting air from front fascia area toward the center of the front rotors?
Pads will last longer and probably be cheaper!
Switch to R4E pads unless the car sees primarily street use. The R4S is a good street pad and autocross pad, but it's not stellar for HPDE even on something that's feather light.
Additional heat management capabilities are good even if you don't "need" it. Especially if after you get comfortable and skill level increases that you change other parts to go faster....which immediately is going to work the brakes harder.
I have built/fabricated my own big brake kits now for both my Cutlass and a Prelude. Just finished the brackets for the Prelude yesterday in fact. Prelude changes that I would also recommend to you or others is rotor upsize, caliper upgrades, and pads. I this case it was a stock 10.75 (or close to that) rotor and I swapped to a 12.6. Went with the Wilwood Dynalite 4 piston 1.75bore calipers and BP-30 pads for track use. What I'm expecting in terms of feel/change from this is a faster acting/initial bite both in pedal travel and pressure applied. Once I'm into the brake I will have better modulation due to the significant increase in bore area (requiring more fluid and therefore travel) and only slight increase in pad area.
As AngryCorvair stated above being able to lock them up not won't gain anything....yes and no.
Nothing will be gained on a one time stab the brakes. 20min later at the end of your session when everything is HOT I say there is a gain. But most of all is that "feel" or your interaction with the pedal that will benefit most (provided you end up with a nicely balanced brake system). Great example here is my Cutlass. I went from stock 10.5 x 1 rotor and big bore stock calipers with good pads to 12.81 x 1.25 Cryo treated Stoptech rotor, Staggered 4 piston calipers 1.625/1.75, and larger but same compound pads. One variable in here is going to a wider tire at the same time 245 on small brakes to 275 on big brakes, same tire line. Small package could lock up brakes all day and hang for the 20min session but there was a little "less" at the end. Big brakes.....What a difference!!!!! So much more stopping power and massively reduced brake zone distances. Why? 1. the variable of more tire plays a factor. 2. The bigger brakes: First off that initial bite at low pedal travel and pressure was so much more effective and faster (keep in mind that this is nowhere near lockup). Secondly was the increase in pedal travel from zero to lockup made is much easier to modulate the brakes. Resulting in being able to brake harder with out locking up and easier to do it every corner. This means I can spend nearly my entire brake zone at 95-99 percent of useable tire traction with confidence vs being more like 85-90 percent to keep from that over step to lockup. Third with all that additional heat capacity the brakes feel the same out lap to cool down with zero changes in between. Also don't forget the rotor diameter increase. Not only is it more surface area for heat management but it is also a leverage increase which decreases the required pedal pressure you need to input at all levels of braking.
Its widely agreed that Tires are the single most beneficial performance upgrade to any car. I would argue that brakes are the second...especially on older cars with pedestrian brake systems.
It may not be just as simple as calipers and rotors. Master cylinder change and bias adjustment may be needed as well. If you don't have disc brakes on the rear of your car I can't recommend that enough either. A rear disc swap has been a huge difference on every vehicle I've installed them on.
Long and the short of it is you simply need to get cooling air to the brakes.
It may be as simple as removing the dust shields (if they are still there). You may have to fabricate up some ducts that aim airflow towards the inside of the wheel. If you are running an airdam make sure is has some holes in it for cooling air.
Fitting larger rotors and calipers to the front will change the brake balance towards the front. The smaller bore master cylinder relative to the larger caliper will result in an increase in pedal travel. You may or may not even notice these changes, you won't know till you do it.
My advice is save your money and fix the brake cooling issue.
Many/most of the big brake conversions are done for bragging rights not performance. I agree - optimize your stock brakes before resorting to anything more drastic and expensive. There are a few cars where stock disc set ups are deficient (old style Cooper S, Sunbeam Tiger with 13" wheels) but not too many.
Like they said, between pad choice and making sure some air gets at the brakes you can probably improve you set up.
wspohn said:Many/most of the big brake conversions are done for bragging rights not performance. I agree - optimize your stock brakes before resorting to anything more drastic and expensive. There are a few cars where stock disc set ups are deficient (old style Cooper S, Sunbeam Tiger with 13" wheels) but not too many.
Like they said, between pad choice and making sure some air gets at the brakes you can probably improve you set up.
If you track frequently, the cost of consumables is often lower purely on price, but also by way of the discs/pads lasting longer as well.
Tons of good advice here (as usual), thanks all!
I have done some brake cooling improvements but will do something more significant - then, if necessary, change pads - and see how it is.
If you drive on the street at all, make sure you get calipers with dust boots. Wilwood makes calipers with boots and without. The ones without are really supposed to be rebuilt on a regular basis.
It may have been mentioned, but changing pads on non floating calipers is like a 10 minute job. That alone is worth it imo
I ran KVR ceramic pads (dating myself here) on my 280zxt for lapping days, changing back to street pads for regular use... The biggest issue I encountered was overheating the brake fluid but changing to dot4 helped... Increasing air flow to cool the brakes would definitely help...
Good luck
Gordon
AngryCorvair (Forum Supporter) said:If you can already lock up all four wheels on the tires you've got, increasing brake output won't do a dang thing.
if your fronts currently lock but your rears don't, increasing front output will just make that situation worse.
if your rears currently lock but your fronts don't, then increasing front output is the right move.
I disagree with this. I can easily lock up all four corners of my 67 LeMans with four drums. That doesn't mean it has good braking. Nearly any braking system can provide a peak brake torque that locks the wheels, it's how you get there. It's all about modulating the peak forces immediately BEFORE lockup that are the key. Something like small drums offer a pathetic amount of brake torque and then unexpectedly lockup. Switching to 12" discs would give me all of that "in between" braking that makes control possible.
Even switching from 10" discs to 10.5" discs can be a big difference because of where in the radius you're providing the friction. The further out you are adding the friction, the more control you have over how much brake torque you can apply before lockup.
A lot of good responses in this thread, and as noted it's not just about one stop power.
I have a 'big' Wilwood setup on our NA Miata, and it's totally overkill for the current power level. That said, it's got the best braking feel of any car I've driven. And it's capable of handling anything I ever plan to do with the car. I spent quite a bit of time researching to ensure everything I was doing would work in concert, and chose components to be part of a system rather than on the most impressive individual specs. For everything to work together, you'll probably need to upgrade both ends of the car at the same time. I don't remember what the ZX had on the rears, but if they're discs, you may get away with just a pad change in the rear to balance the front...?
All that said, Wilwood is far from perfect... I don't like the NPT brake line connections on most of their calipers, and their parts catalog is a dumpster fire. One of my master cylinder reservoirs was leaking from a joining line in the plastic part, and even their tech line gave me the wrong part # as an upgrade/replacement. I ended up ordering a couple of different parts to find the right one piece replacement reservoir.
Another thing to consider is pads... the pads that are perfect on track will most likely suck on the street. Fortunately, pad swaps are easy. It takes longer to jack up the car and remove the wheel than it does to swap pads.
Curtis73 (Forum Supporter) said:AngryCorvair (Forum Supporter) said:If you can already lock up all four wheels on the tires you've got, increasing brake output won't do a dang thing.
if your fronts currently lock but your rears don't, increasing front output will just make that situation worse.
if your rears currently lock but your fronts don't, then increasing front output is the right move.
I disagree with this. I can easily lock up all four corners of my 67 LeMans with four drums. That doesn't mean it has good braking.
show me again where the OP is asking to improve the performance of his four-drum lemans?
AngryCorvair (Forum Supporter) said:Curtis73 (Forum Supporter) said:AngryCorvair (Forum Supporter) said:If you can already lock up all four wheels on the tires you've got, increasing brake output won't do a dang thing.
if your fronts currently lock but your rears don't, increasing front output will just make that situation worse.
if your rears currently lock but your fronts don't, then increasing front output is the right move.
I disagree with this. I can easily lock up all four corners of my 67 LeMans with four drums. That doesn't mean it has good braking.
show me again where the OP is asking to improve the performance of his four-drum lemans?
Even switching from 10" discs to 10.5" discs can be a big difference because of where in the radius you're providing the friction. The further out you are adding the friction, the more control you have over how much brake torque you can apply before lockup.
I'll let that go without smarmy reply because I'm confident you're not directing that to me.
I just disagreed with your initial assertion that being able to lock up brakes means that he couldn't improve his braking. Not a personal attack, just a disagreement.
AngryCorvair (Forum Supporter) said:Curtis73 (Forum Supporter) said:AngryCorvair (Forum Supporter) said:If you can already lock up all four wheels on the tires you've got, increasing brake output won't do a dang thing.
if your fronts currently lock but your rears don't, increasing front output will just make that situation worse.
if your rears currently lock but your fronts don't, then increasing front output is the right move.
I disagree with this. I can easily lock up all four corners of my 67 LeMans with four drums. That doesn't mean it has good braking.
show me again where the OP is asking to improve the performance of his four-drum lemans?
Even switching from 10" discs to 10.5" discs can be a big difference because of where in the radius you're providing the friction. The further out you are adding the friction, the more control you have over how much brake torque you can apply before lockup.
I'll let that go without smarmy reply because I'm confident you're not directing that to me.
I've got to jump in here to defend Curtis. He has a valid point. Braking ability can actually be better with good drums than disk brakes.
What? Yes that's right. Drum brakes can have a servo effect that disk brakes lack. Without, rpt, without power brakes. Drums can even have dual servo effect. Basically what happens is the leading edge of the brake shoe wedges into the drum. Disk brakes on the other hand are just pinched by the caliper without any sort of mechanical assist.
In reply to Curtis73 (Forum Supporter) :
Edited to remove smarm.
Still, the OP asked if adding 20% to his front piston area, plus IDK how much to his rotor effective radius, would make his brakes better. Assuming the factory set it up with some amount of front bias -- which was and still is required by law -- adding 20+% to front with no other changes to the rest of the system will make the car even more front biased, and therefore achieve less decleration when the fronts are at their threshold.
In reply to frenchyd :
I think you should reread what Curtis said. He didn't suggest drums could be better than discs.
280ZXs are 4 wheel disc.
My 1200 uses 280ZX calipers on the front, when I originally added the set up I had exactly what Angrycovair describes, there was a mismatch that was less than optimal. Now it was better than the pathetic stock front calipers. The stock calipers created the exact situation Curtis spoke of; the stock calipers could lock the fronts but the pedal effort was not linear. You'd get 75% of the front tires traction then you'd double the pedal effort without any increase in braking then bam the wheels would lock.
Yes a 280zx is disc both front and rear. The rears are an integrated parking brake and the pistons twist to adjust that.
The 'big brake' setup would be 274mm vs 250ish diameter rotors coupled with the change in calipers. And i still would have some figurin' to do... Wilwood specs 0.85" maximum rotor thickness whereas z31 rotors are 22mm... 0.86". I was hoping that was close enough. Companies like silvermine motors and techno toy tuning sell kits that are the easy button for this. I don't know exactly what rotor they include but maybe they solved the thickness issue and probably build any centering spacers into the brackets
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