TheDrip

BIG BRAKE UPGRADE PROJECT

25 posts in this topic

Big Brakes for the Little Spark

---------------------------------


before-after-316mm.jpg


Here I lay down the tale of how I toiled night and day for weeks on end, simply to equip my spark with (unneeded) larger brakes, or, how I learned to love the bomb.


**NOTE: Sorry for the giant pictures, this board won't let me specify image dimensions for thumbnails, it will take some time to go through and replace them all. Give me a day or two!


These are me memories of the last 3 weeks or so, working for a couple hours each day on the weekends, and the few minutes I could sneak in on week days after work. I think writing this thread took almost as long as all the CAD work put together!


But really, I thought i would lay out the process I used and went through fitting larger brakes to my spark. With no specific purpose other than to do it. The Spark's brakes are exceptional, and put it in braking territory of sports cars of recent years past. Motortrend gave the spark a 60-0 stopping distance of 116ft when they tested a '13 model. This puts it on par with early mid 90s Corvettes, Acura NSX, RX-7s, and all but the newest Miatas. Not the best of the best now, but certainly more the sufficient for an economy car.


So why do it? Because I think I can.


My basic approach was this:


Using the stock caliper, just pushed 'out' from the rotor centerline to account for the larger disc.


Find a rotor with the same wheel bolt pattern (4x100), and a large enough increase in diameter to make the relocation bracket design easier.


Mock up designed with 3d printed plastic parts to verify fitment.


Produce the design in steel once it was verified.

Edited by TheDrip

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SUNDAY MORNING


The first step was some exploratory surgery. I remove the wheel, and started poking around the brake setup to see how the caliper was mounted to the bracket, bracket to the spindle and so forth. I took dozens of pictures so I could think and refer to them while drawing the first design.


I determined the caliper would have to stay bolted to the bracket as-is, and that I would be moving the bracket mount points outward. Based on the below pictures, I decided a simple design of two plates would work best. One that bolted to the spindle where the bracket should go, and a second plate welded on, inboard of the first so that the caliper bracket would mount in the exact same plane as stock.


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While I was under the car, I took the one measurement I knew was important (there were two that were important, more on that later), the distance between the mounting bolts for the caliper bracket to spindle. I took a few others that weren't as critical, but would make designing a bracket easier.


I rushed inside and opened up a CAD program. Know I would be going through a number of revisions, a quick sketch in CAD seemed more efficient than a hand drawing with hand edits, then transfering to CAD.


My first design was quite simple, as I wanted to verify clearances. I made both halves of the bracket identical. You can already see the 3 holes in the center however. the center hole drilled through both pieces of clamping them together when welding, pls a single hole to each side, opposite each other, for plug welds.


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I printed the design out to lifesize and trimmed the pieces for a quick test fit/mock up. It was quickly approaching that time of day when my wife returns home and demands her warm, dry parking spot inside the garage doesnt have my car in it, so I hurried back outside and without taking the time to document anything with my potato camera. I took out a couple printed versions of the templates I could sketch on as I found interferences, and ripped out little pieces until the brackets fit.


I put the car back together and came in for the night to think about the bracket design and begin searching for a rotor.
Edited by TheDrip

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SUNDAY NIGHT ... and the week following.


I sat down to do some deep thought, research, designing, and internet forum browsing.


Over the next few days I poked and prodded at my brain trying to kickstart some activity.


My first stroke of genius was realizing my wife's car had the same bolt pattern as a Spark. I started looking for a database of rotor dimensions to narrow down possibilities.


First I found a drawing for a Chevy Spark rotor, measuring 236mm in diameter. Included in the drawing I found were overall height, hub thickness, center bore diameter, and other useful dimensions.


Next I started poking around rotors related to my wifes car, a 2005 Mini Cooper S. And yes, the Chevy Spark is our large 4 door family car. I knew from my initial measurements that an offset of at least 28mm was needed to allow the caliper to move directly outboard from the stock mounting point. This meant an minimum overall diameter of 292mm.


I quickly found two possibilities, a 02-06 John Cooper Works edition Mini with a 294mm rotor and approximately the same height/thickness, or an archaic Renault application that is 300mm. Being practically minded for such a ridiculous project, I quickly found the Renault rotors would fit perfectly, but cost $125/side and were essentially unavailable.


It was getting toward the next weekend, so I moved forward with the Mini cooper rotor and ordered one from an online vendor to have ready for fitup.


Here is the stock Spark rotor vs the Mini rotor


20160109_113437.jpg?m=145237393120160109_113411.jpg?m=1452373920


I fired up my CAD program and got to making my design work with the car's parts. I couldnt have two identical parts, so I split into caliper side and spindle side designs.


These are the paper templates I printed out to test out the next day. The top is the caliper side, or rather the piece that bolts to the caliper bracket. The middle is the piece that bolts to the spindle, and the bottom is the two combined, so I could see if one interfered with the other in any way.


20160124_203633.jpg?m=1453689432


I was happy enough with the design to save a couple of 3D renders as well.


caliper%20bracket%20-%20caliper%20side.Pcaliper%20adapter%20-%20spindle%20side.Pcaliper%20adapter%20-%20assembled.PNG?m=


I moved on to comparing the details of the two rotor drawings. I wanted to make the centerline of the thickness of the rotor match the old rotor since I was only moving the caliper out from the spindle. I decided that I only needed an offset of two MM. I drew up a 2mm thick spacer that also included a spacer ring to adapter the Spark's hub diameter to the rotor's center bore. For good measure, I also included little index rings around each wheel stud to the the larger holes in the new rotor.


Capture.PNG?m=1451671889


I put down my thinking cap for the rest of the week and waited for the weekend.
Edited by TheDrip

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SATURDAY MORNING


With the energy that accompanies good initial progress on a new progress, I headed back out into the garage first thing in the morning, armed with the latest paper templates. Everything went smoothly. I got the car into the garage and the drivers front corner stripped down in no time at all.


I made sure to take the time to photograph the fitup this time. I knew I was getting close, but that any minor dimension changes would be easier to get right with pictures to refer to.


First I tried the fitment against the caliper bracket. The half of the adapter which will attach to the caliper bracket first, followowed by my template showing both halves to see if anything would interfere. Fitment was good with a millimeter here or there that needed tweaking.


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I did the same with the spindle side of the adapter. First the half that bolts on, then the combined print.


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This fitment went even better. The only changes needed were changes already in line from the caliper bracket side fitting.


I called it a (very short) day in the garage, cleaned up and set about my honey-dos for the weekend. Later in the evening, I sat down and finalized revision one of the bracket design.


The changes were so minor I didnt even save my renderings, I couldn't see a difference. I sent files out to a couple good friends with 3D printers, and planned on a new round of mock-ups the next weekend with plastic brackets and a real rotor.


I wasn't going to make any progress beyond this on sunday, so I let the whole project rest.
Edited by TheDrip

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MID WEEK


My 3D printed mock-up parts arrived late in the week and I felt like it was Christmas day. I took really poor excuses for pictures of the parts I had in-hand.


20151231_215606.jpg?m=1451671840yrQa2Go.jpg?m=1451707756


The black ring is the rotor adapter, the grey plastic is the two parts of the adapter bracket. They were printed at 4mm thick to save material. I can't thank these guys enough for the help on this project. Theres nothing like having parts in hand quickly for doing this kind of work.


I fitted up the rotor adapter inside of the new rotor and managed to slow down to take (too many) pictures. As you can see, all my measurements for the rotor adapter were perfect.


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Edited by TheDrip

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SATURDAY MORNING of broken hearts...


A warning before hand, you may cry from empathy for how I felt 20 minutes after walking into the garage Saturday morning. I woke up cheery, ate a good breakfast. Ready to get out there and see how terrific everything looked. I got the car in the garage, stripped off the same corner, and got to work.


I started with the same approach as the paper templates, each side individually, then glued the brackets together to check for interference from the overlap.


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A great day so far, I tried out the rotor without adapter. Again, fitment looked perfect except for some minor interference with the dust shield. 3 screws fixed that problem, and I had the rotor on with the adapter this time with one minor change. The Spark's spindle has a step from 57.1mm where the wheel indexes to 59.1mm where the brake rotor indexes. No problem, scrape some plastic out and we're back in business. I wonder why the rotor drawing didnt show the correct center bore?


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Feeling the confidence of a boxer with his opponent on the ropes, I bolted the adapter on and the caliper to that, and slid on the rotor adapter. The world is a great place this morning!


20160109_115511.jpg?m=1452373977


Let's carry this through all the way so we can get to the celebration right? Heres the 294mm rotor installed, with the caliper hanging off the plastic bracket. I am the greatest engineer in history. I have conquered nature, made metal and plastic bow to my whim. See where this is going yet?


20160109_120317.jpg?m=1452373986


That looks fantastic! That looks terrific! That looks... wait, why does that caliper seem to be stock way to far out?


WHAT HAVE I DONE?


With my victory stolen from me by an unknown foe, I calmed down and started measuring parts, double checking my drawings, questioning every part of my design.


I found the problem.


Remember back at the beginning when I found a drawing of the Spark rotor? It wasnt for a current generation Spark. I broke out my meauring tape, and sure enough my car didnt come with 236mm rotors. It came with 256mm rotors. So that 20mm difference in diameter means 10mm for the caliper offset. No wonder my caliper stuck out to far.


Back to the drawing board. My design was based on caliper at least 56mm larger than the OEM one to simplify the bracket design. I would have to start all over again!


I put the car back together, packed up the rotor to go back to the vendor, tucked my tail between my legs and sulked around the house for the rest of the day.


My design had worked perfectly, I made one major mistake at the very beginning: I didnt measure the stock rotor. I made an assumption, and I made an ass out of me. I don't know where the U went, but it doesnt matter.

Edited by TheDrip

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SUNDAY of redemption.


OK, that title is a bit dramatic, but I did get over myself long enough to at least find the close end of the tunnel, hoping there would be light at the other end. Fewer pictures now, and more badly written words.


I started by going back over my inital math. Now it was a 256mm stock rotor, plus the same 56mm for enough offset. 312mm at a minimum. I thought I would start with the same vehicle, a Cooper Mini. The John Works packages cars always came with bigger brakes, so maybe a later year car would have even bigger brakes. I managed to dig up that an 08-12 Mini JCW car had 316mm rotors, with otherwise identical dimensions to the 294mm rotor. Not only did I find the tunnel, there was light at the end of it after all!


I headed back out into the garage yet again, quickly tore the brake rotor off the car and measured for depth, thickness, offset and sketched it out to match my Mini rotor drawing. I should have done this the day before, but I wasn't thinking straight out of frustration with myself.


The rotor adapter wwould work, it just needed to be 4mm thick instead of 2mm thick. An easy enough change. I went back into the house, and sat down for a few minutes of CAD. I added a couple things to the rotor spacer. A hole that correlated with the retaining screw hole in the Mini rotor. A hole that correlated with the retaining screw hole in the Spark rotor. I also added two holes that would line up with these positions but were only drawn at 3mm so that I could use a 1/8" diameter center punch to mark the hub face, or rotor to be drilled out later.


Capture-1871896555.PNG?m=1452482270


I also revampled the relocation bracket design. I went from pushing the caliper out 29mm to pushing it out 30mm, an easy enough change. I also changed the alignment and plug welding holes in the center. WHen gluing the plastic halves together, I realized one bolt is a terrible way to hold parts in alignment. I laid out a 5 bolt pattern. the two outermost holes were in the spindle side of the bracket for plug welds, the center hole in the caliper side for the same reason, and two more holes that would be threaded on one side to use bolts to align and clamp the parts together for gluing or welding.


Capture2.PNG?m=1452460229Capture1.PNG?m=1452460229


I sent off my designs to my friend at Multirotor Superstore who printed them up for me. MRSS doesn't do 3d printing for their business, but they are a terrific vendor of Multicopter (drone) and other flying R/C hobby parts.


logo.png

Edited by TheDrip

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LATER THAT WEEK...


When they arrived I opened the package and thought I was being attacked by Smurfs. Here are the parts, followed by the bracket halves tapped and bolted together.



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These parts fit great, so I tried the rotor adapter with the new 316mm rotor I had ordered.


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Once again I was excited for the weekend when I could try these out on the car.

Edited by TheDrip

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SATURDAY MORNING


...again, or HURRAH! depending how you think this will go.


I slowed things down, and tried to be a little more methodical. First I compared the old rotor to new. This seems better, looks like a little more than an inch extra material on each side. Good so far!


20160123_143828.jpg?m=1453582973


Next I tried the new rotor adapter on the hub, again looking good. You can see that the small hole for the rotor retaining screw is in the right location, the retaining screw fit like it should. Then I tried the rotor on the adapter, after removing the same dust shield as before. It occured to me that this was a sizeable brake rotor. The last time I had a 12.5" rotor on a vehicle, it was rated to 14k GVWR. That is a lot of brakes for a car that weighs 2300lbs.


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One more step before we get too excited, I bolted the relocation bracket in place. Thats a lot of smurf blue. I think I will paint the final parts something other than bright blue.


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And then I got too excited. I removed the caliper, fit the rotor, and put the caliper on. I will need to grind about 1/8" of material off for a perfect fit, but its 1/8 of steel coming from a piece thats over an inch thick. This will work. Finally, THIS WILL WORK! I forgot to take a picture. I got the wheel on and bolted up and all of a sudden, it was picture time like your mom watching you leave for the prom.


First, to remind everyone what this looked like when I started, followed by the glory of my work.


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What a difference! The crowd goes wild! And then I found the problem. My car doesnt have 4mm to spare in the wheel well. 17x7 wheels with 205/40R17 rubber. The wheels have +38 offset. If they had +42, I would have been ok. As it is, I have a feeling there is barely a hair between the fender and the sidewall when I go over bumps as my car is also lowered.


It works. I know moving the caliper out 30mm from the centerline is perfect, I just need to figure out how to save 4mm in width. I'm sure someone out there is yelling the solution at their computer screen, but it took me the rest of the day (in between chores) to commit myself to a new design.
Edited by TheDrip

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I would keep the outline of the caliper adapter pieces, I would keept their drill hole locations. I could move the wheel in by removing the rotor adapter, and move the caliper in the same distance by adding a spacer in between the caliper adapter halves. For strength reasons I didnt want a 3rd piece, so I added the 'spacer' to the spindle side of the adapter.


I mocked up the adapter with a spacer, that looked good. I drew up modified adapter halves in CAD, they looked good. I changed from a 5 hole center pattern to a 3 hole center pattern where all 3 would be bolts. Through holes in the narrower piece and threads in the thicker piece with the 4mm bump.


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And that's almost the end of the story, you have almost caught up to me. I designed one last thing. During the last fitup and trying to figure out how to fix the 4mm spacing issue, I may have used some pieces from unneeded 3d prints to try and solve the issue. The end result was that my smartly engineered rotor adapter with the locations for drilling the rotor with a retaining screw hole was no longer usable. Knowing I would need to mark and drill any future rotors on this car, I designed up a little drill template. It keys into the center bore of the rotor and a single wheel stud hole. This is enough to locate the correct location for the retaining screw hole. Another good friend printed this for me. It's in the mail somewhere, but he sent me a picture before sending it.


Capture2-1328007872.PNG?m=1453692131MM1akj3.jpg?m=1453688989


A last single simple detail. With no rotor adapter, I now no longer had a way to center the rotor on the hub. A quick websearch found me a vendor who carries a hubcentric ring with the odd dimensions of 59.1x64.1mm. Perfect to center my BMW rotor on my Chevy car. A fun side note about the rotors I ended up ordering. They're from AC/Delco and have a GM parts number. I can buy my 12.5" rotors for my Spark at my Chevrolet Dealership!


And that is all. You're caught up. My design is finalized. I have some parts in the mail. A bag full of 12x1.25 10.9 bolts for the final bolt-up. All I need to do is have the final relocation bracket design cut from steel. I have a vendor that can do it with a 1-2 week lead time, but its quite a bit of money. It gets a lot cheaper per set if I have more than one made, but how big is the market for Spark brake upgrades? I'm guessing about 1 person.


I will leave a post or two reserved for final pictures. In the meantime, don't hate on my write up too bad, and don't tell me why this whole thing was a useless idea. I know. It won't improved brake performance 60-0. It will probably hurt my 0-60 times from the extra rotational weight. I'm never going to track the car. I did it to see if I could, pure and simple!


Thank you for reading through my 20 pages of ramblings. This wasn't a terribly hard project. If you wanted to you could make the brackets needed with an angle grinder, a drill and a tap. They wouldn't be pretty, but they would work. I just hope that new guys who would never think of a project like this can realize that its not rocket science and everyone should try a project to stretch their limits now and again. Its amazing what you can do with a measuring tape a pencil and a napkin!

Edited by TheDrip

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Reserved for future updates

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If anyone is further interested in this project. I have DXF and STL files of the adapters, and measurements on everything. I'm a little wary of sharing them publicly, as someone will surely think they can actually drive with 3d printed plastic brake brackets and then blame me.

I am looking for someone with a CNC mill to cut these out of steel. I'd rather support a hobbyist I can really explain the important parts of the maching work to than blast drawings off to the shop and hope what I get back is what I meant. The needed machining can be done completely one sided, though some creative fixturing would be needed to keep from having to refixture halfway through the process.

Shoot me a PM if you're interested in finishing up this project with me. Also if enough people want brackets (at their own peril!) it may become financially reasonable to have a larger shop produce them.

Edited by TheDrip

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I'm practically speechless..OK..not quite... That is one of the finest examples of a proper, precise and professional ways to do a mod. Having spent time in 'Nam flying and fixing heli's and later as aircraft mechanic then onto pilot, I can appreciate the work that went into this one man project. We could have used someone with your ingenuity and ability to think 'outside of the box' back in 'Nam when parts were scarce and we had to use scavenged parts from damaged heli's and had only one guy with the knowledge and tools to make the odd part...no CAD, just a drafting table and some machining equipment.

The logical way you went about that mod is exactly how these things end up being successful. Nice work!

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Nice work! Only downside is you probably have to run 17" wheels and 14" snows wouldn't be an option for us Yankees in the north lol

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One of the nice parts about using the stock calipers and an adapter bracket is that I can revert to stock brakes just as quick as I can do a normal brake service job.

Edited by TheDrip

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I am assuming you removed the rust and dried grease from the hub surface and re-greased it? If not you may run into shimmy from the raised area of the dried grease or bolt loosening. This is a step most often dismissed by DIY and even mechanics in a hurry.

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And we finally have some progress! I found a friend who was willing and had the time to machine the parts from steel. Here is a better rendering of the assembled product (minus bolts) from Fusion 360.

caliper%20bracket%203d%20render.png?m=14

And photos from my friend of the raw pieces fresh off the Mill! I will be tapping the 12-1.25 holes when they get here, as well as painting.

There are a few notches in the outline, they were run using off-cuts, and the outline just barely intersected with holes in the material.

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He also posted a machining video of cutting the outer profile of one of the pieces. I'm geeking out over all this. I figure maybe one other person in the entire world would be interested in this product, so it definitely won't be going into production, but I will hang on to the drawings just in case.

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Nice job on this big project. Very well thought out..

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We're getting close now. I receive the machined steel brackets in the mail, looking terrific.

The brackets were not completed, I still needed to tap the holes to 12x1.25. I practiced some on scrap steel to get a reliable tapping setup. Using my cheap Chinese drill press as a tapping stand worked great. I used a c-clamp to prevent rotation, and a couple of spring clamps to hold the bracket down, but allow it to self center on the tap. A pair of channel locks to turn the drive pulley made the work easy, and I installed the drive belt crossed over on itself to drive the spindle in reverse. Manual tap, but power un-tap saved quite a bit of time. The end result was 10 very straight, very nicely tapped holes.

Primer and paint is next, then on the car. I should be driving around the only 12.5" braked Spark this weekend. I also slapped new tires on this morning to give the best first impressions of the brakes that I can.

My tapping rig. 100% pure potato camera used.

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And the brackets themselves, bolted together as they will be in the car, and all lined up letting the cleaner flash off before primer and paint.

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Nice..very nice work. Are the new brackets stainless or graded steel? A nice touch might be red painted calipers..now that you have them off anyway?

Edited by Retired old Gearhead

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The brackets are just 1018 steel. Plenty strong for this application. As far as painting the caliper red, they're not actually coming off the car. One of the great things about just relocating them out, I never touch the hoses, so no bleeding at all. If I ever get a wild hair, its really not much work to get this car apart and paint the calipers.

I still don't know that this will drive well and may end up having to take it all back off. With the donated prototype printing and machining and finding rotors at a discount, I'm only into this project for $75. $150 if you include all the tooling I bought along the way, but that was all things I should own anyway.

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THEY'RE ON! I DROVE IT!

With the 205 rubber, the OEM brakes wouldn't lock up enough to trip the ABS on clean & dry pavement. These new brakes STOP THE CAR. with ABS activation, I leave witness marks coming to a stop from 60.

I had a little more grinding to do on the caliper bracket than I initially thought, just to clean the outside diameter of the rotor, nothing structural.

I have one expected issue, and one put-the-OEM-back-on for now issue.

The expected issue is a low pedal. The full thickness of the replacement rotors just barely falls into the minimum thickness spec of the OEM rotors, so its like driving around with worn rotors as far as pedal position is concerned. Brand new pads and only using them to 1/2 wear would fix this right up, or 1mm spacers behind the brake pads.

The put-it-back-to-stock issue is a different story. Not expected. The rotors are "squirming" just a hair off center under hard braking. Even with a concentric ring to keep the rotor centered up (the center bore is larger than the chevy part) the rotors are moving just a hair. The concentric rings are plastic and I'm betting that when I pull it all apart tomorrow, they're smooshed out of shape. Easy fix is metal rings, but the dimensions are odd. I'm going to whip up a drawing for an integrated spacer for the rotor and spacer for my aftermarket wheels. Also I will machine out some little spacers for around the studs. The mini rotor has 16mm holes around the 12mm studs, too much play.

All in all, quite successful. Minor hiccups are addressable!

5 Miles on the brakes, and a few 45-0 and 60-0 panic stops to test it all out

The picture is *after* driving the car. Hoorah!

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Ya..the low pedal can be corrected with a brake fluid top up...just be very sure you drain enough/same amount out if you put the OEM rotors back..reservoir is easy access but you gots to be very careful with that stuff..identical fluid type/make and not one spec of dirt or other crap.

I'm sure you also realize that you are looking at some rotor warping issue due to the pads not covering the whole radius of the big rotors and the fact that the rotors are thinner, single sheet unlike the wider ribbed OEM's. Still, you sound very knowledgeable on what you are doing so you are probably aware of these issues. I have a lot of respect for people that take on a project like this and take the time to template and do this stuff right. Too many times I see people buy some kinda kit or parts to increase engine output etc with practically no knowledge of the principles involved in their project and run into all kinds of issues..Not just the Spark, but other cars and even seen some bizarre shit done to a few boat outboard and in-board engines without a thought to what they are doing.

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The rotors are still vented like OEM, just 2MM narrower overall. Two "discs" with ribs in the middle. The maximum disc thickness for the new rotors is the same as the minimum thickness on the OEM rotors.

I'm taking it off today and putting it back as stock until I can address the issue of the disc wandering axially under heavy braking. Working on a new drawing for integrated concentric rotor and wheel adapters.

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This is the sh*t that gets me excited to get a Spark. I hope this week. Really enjoyed reading this thread.

I have access to a Northwoods CNC machine if I can help at all.

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