Low Dollar Brake Upgrade unsprung weight reduction
 

-Update at 10:26 PM CST- Braking Distance 60-0 MPH dropped by 8 feet. I tested this by setting cruise at 60 mph using line spray painted on the road on a bump that can be felt to insure that I'm starting the braking at the same point. In 5 repeated stops letting the rotors cool to 115 degrees each time I had a Deviation of stops of only 4 feet from shortest to longest stop. The ABS Engagement feels just like stock. Same method I've used 3 times previous when testing to see if coil overs and rims and tires added to shortening stopping distance. This test has given consistent results each time. I'd guess the improvement in stopping distance is the new pad composition being better. I actually gained a better reduction in stopping distance when I upgraded my wheels and tires.

So, looking around on the Internet I stumbled upon DifTech.com and seen they make brackets for putting wilwood calipers on stock rotors. I've already Cut Almost 8 Pounds a corner off with the 16' wheel and tire combination I'm looking at almost 8 more pounds of unsprung weight with this upgrade. Next will be a set of 2 Piece rotors but for now just the caliper.

The parts I used for this was the Diftech brake caliper adapter, Wilwood 350z rear braided brake lines which are 1/2 longer than what wilwood uses for the brake kit for a 86, a set of 1.62" wilwood 4 pot calipers from speedwaymotors which were on sale and than a set of Brake pads from wilwood I used the BP10 pads for now since the car is daily driven. All said and Done I'm sitting at $660.

https://photos.app.goo.gl/qm5JqFDa93VHr14m6

https://lh3.googleusercontent.com/wP...=w1081-h608-no

https://lh3.googleusercontent.com/Zi...o=w493-h657-no

This was the brake with pads and Cable Connected The scale only goes up to 11 pounds the other caliper without brakes or brake line was to heavy for the caliper to read. On a less Accurate Scale I was 13 pounds heavier holding the stock caliper with pads and brake line attached.

https://lh3.googleusercontent.com/lK...=w1168-h657-no

On the Car,

https://lh3.googleusercontent.com/2d...=w1168-h657-no

what's the bent pieces of aluminum for?

i hope that's not the new mounts!

Lol I would hope not.

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Unless it's some drag racing build (for which twins make bad match), i'd care more about braking capability and keeping brake bias, then blindly trying to reduce weight and retrofit calipers from other cars ignoring hurting main function to gain in secondary one. And if weight savings are your goal, worth going to two-piece rotors too, not just lighter calipers. But by then it was more then worth to go right away to some BBK kit designed natively for twins, instead of having $660 spent on interim solution with serious flaws.

Proper weight reductions for a 86:
Sell car.
Buy a Miata.
Problem solved.

Do you understand the Difference between sprung and unsprung weight? I don't think you do.

The stock brakes have a 1.68 piston the brakes i installed have a 1.62 piston the new calipers brake feel and function identical to the stock brakes.

Please list the aforementioned serious flaws.

They are because the brake lines I got don't have a mount so I bent the pieces of aluminum and totally forgot to take a picture of how I used that to hold the brake line.

take some pills
grow boobs
have a sex change

sorry you missed the last three steps thought I'd finish that thought process for you.

I know not even that difference, but also that two piece rotors i mentioned (pitty that only ones i know of for stock brakes are very expensive DBA ones) are unsprung rotational weight, reduction of which should be most effective out there :P
Then again often impact/gains from that weight reduction by lighter wheels/brake assembly or even lugnuts are overstated, and it certainly is wrong if one hurts other more important areas for sake of enhancing less important ones, eg. if one puts too overlightened wheels too much at expense of their rigidity/strength, or if one chooses less grippier tires only because they are lighter, and same with brake caliper retrofits from other cars with different suspension, different weight, different weight distribution.
You have done all homework properly before doing swap? Is pad area same? Is pad area geometric center at same distance from center? Similar piston area is just one of many variables affecting resulting brake torque. I'm guessing that you have no access to brake dyno, bet have you done skidpad tests on both stock & retrofit calipers? Have you enough track experience and consistent enough driver to trust your "feel"/"butt dyno" to properly gauge "feel and function identical"? Do you want based on your current experience put enough trust trailbraking from 200kmh into corner with small runoff zone till wall?
In my eyes from retrofit from other cars at most i'd consider willwood 4pot for wrx (of course, full kit, including rotors of specific diameter), with stock rears for lighter weight, as twins stock fronts are same as wrx's (rears from legacy gt), so i'd expect similar bias. As to why it's important to retain brake bias, simply with it too far off one way car stability/handling safety under heavy braking will be affected, and to other end of spectrum - fronts (which do most of braking) will be underbraked, thus braking distances will grow. Also if one still uses some nannies, they are designed with specific bias in mind i guess.

I don't have two piece rotors, only mention that I'm going to get some at some point. Once I find them in the right price range.

I can tell you right now Cutting 9 pounds per corner of unsprung weight is in no way understated.

I'm not weakening my wheel hub or any other structure. Are you saying there's an occurrence where decreasing unsprung weight without decreasing the structural integrity of my wheels and brakes would cause the car to loose performance or handling? Can't say I've ever heard of someone tuning in the suspension on a track by adding sprung weight..

Yes, within 3% area, Yes same distance. No access to brake dyno? Skid padding the car tonight on the same section of road I always use. On the way home tonight the G-meter in my phone was showing more declaration forces going from stock pad material that's not hard. Experience to properly gauge yes.

I don't have a track where that scenario happens here, however I know that trail braking at 70 MPH with the fully stock setup wasn't as good as my RX8 or my 914, but those were very different cars and had no boosters or ABS. Which will probably be one of my next modifications to this car. I can stop a car much faster than the ABS in this car. The ABS in this car I would say is particularly poor. The brake booster in this car does a great job at eliminating all pedal feel.

Also the place where I'm running my car for the most part is a winding road with a very uneven asphalt surface lots of dips. It is in the middle of nowhere so I can run it pretty hard. The look of the road Reminds me a lot of the road you see in the MOTORing Touge videos from back in the day. If you run down it with some heavy springs your rear end will bounce and slide mid corner.

I'm not the first person to do this setup. It has been tried and proven. There's a fellow who I copied the setup from that autocrosses over in San Diego california and he's rather good driver and runs his car rather fast. Compared to some overpriced off the shelf Big Brake Kit this is just a far more reasonable way to lower unsprung weight, while maintaining braking. Losing the unsprung weight gives the car more consistent and better handling on the surface where I'm primarily running the car at. Not the first car I've done this to. As I move forward with more brake system modifications it gives me the options to get calipers that will drop in that I can tune the braking by changing caliper piston sizing, and having more options with superior pad materials.

RyuGuy2: examples on wheels are for example something like forged wheels vs overlightened (to same weight) kosei r4. Yes, later are among lightest and dirt cheap .. but then again on this forum i've heard of several cases of them breaking or bending eg. when driving over kerb or some potholes when DD. Or test of Enkei where their RC4, focused on rigidity not the very lightest wheel performed a bit better on track vs lighter one that flexed a bit and robbed a bit of handling. Wheels have to be sufficiently strong (for use. Of course, for example rally use, with those insane jumps, cutting corners over ditch, or being able to finish with flat tire, requirements are a bit higher :)) and then lightest, how much budget allows, while retaining that strength.
As for weight reduction efficiency .. there are many loud opinions of how efficient is weight reduction, how even more of unsprung weight and most of all unsprung rotational weight .. and yes, racing teams with high budgets of course can fit expensive forged (maybe even magnesium) wheels, but still, and rest being same, where even hundredths or tenhs of seconds may decide winner, but more down to earth, at enthusiast trackday warrior level biggest difference is from nut behind wheel, and usually later makes up tenfold or more difference in time then what lighter wheels or brakes may net imho.

solidsnake11: including same master cylinder bias on those camaros? As for abs on twins, doubt it. After all, there are also ones driving with abs fuse pulled. What may differ rather, stability control, working individually on wheels, but that is among nannies, most switch off on track. And imho you have got it a bit wrong. I'm not hater, i'm just speaking about possible ill-effects, and so that people that are lazy and judge mods just by budget, would be more careful with modding something as important as brakes, instead of blindly bolting on calipers from different cars (though in most cases not for weight saving, but just for bling purpose, just to get brembo branding on them). There are already enough such that blindly put on STI/Evo/Cadillac calipers on twins for bling :/

What kind of drugs are you on? None of this are relevant to what is going on here. I put on brakes. Why are you talking about rims? Please stop commenting.

The ABS does bias the brakes. I intend on going manual brakes with a manual brake bias adjustment. I've done this mod on several cars. Little different to get used to the pedal if you've never had a car with manual brakes. It's also a pucker moment the first time you're doing 80mph and you lock them up. Once you get the pedal feel it's way more comfortable to brake as late as possible, and more consistently. Also it's nice to be able to adjust the brake bias.

EBD bias brakes, if it's off due eg. pedal dance procedure, leaving just basic ABS, then if anything, ABS will change brake action closer to optimal bias by delocking wheels on end with too much bias that locked first while other end still underbraked .. at expense of longer then could have been braking distance.
Having brake bias adjuster is indeed nice thing to have on competitive racecar, as at different grip level different mass (and grip) transfer happens and different bias-es are optimal. The less the grip (in wet, or in winter on snow/ice, or on gravel) the closer to 50:50 "optimal bias" is, the more the grip (dry / slicks / lot of downforce) > more mass transfer > more bias to front "optimal".

As for drugs i'm on, sorry, if i dared to reply in more details to your questions in post before that on "structural integrity" about wheels aswell. But yes, if arguments evolve to personal insults to ones having different opinions, it's not much of interesting discussion to keep participate in.