Custom front and rear big brake kit

Suspension and other discussion

Custom front and rear big brake kit

Postby gt4rcdude » Sun Feb 24, 2008 9:05 pm

A few weeks ago I ordered some discs from Wilwood. I wanted an affordable big brake kit that included the rear. In order to save money, time and headache I decided to use the stock calipers. The mechanical advantage of the larger rotors combined with the added thermal capacity should net a big improvement.

Major progress the last few days. Went up to NJ to help with the machining. The first picture is the stock front rotor on the lathe being turned down to make it into a rotor hat.

First cuts were to get to the proper outside diameter to fit inside the new disc.

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Now cutting down the back of the rotor:

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Internal cooling fins: (yes, these were nearly new Brembo rotors) :eek:

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This is the new rotor on it's new hat before we drilled the mounting holes:

327mmx25mm

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The rear rotor was cut down the same way. Here we are cutting down the back of the rotor to give the new disc a true surface to mount.

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On the milling machine getting the mounting holes:

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The holes all done. This is when we realized the bolt heads interfered with the bell of the rotor:

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Back on the milling machine for some sexy slots for clearance:

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This is a crummy shot of the trial fit of the rear disc. The rear rotor is only 1/4 of an inch larger than the stocker, however I now have a 2 piece rotor with a replaceable $66 disc.

ADDED: These discs ended up not working out. They foul the dust shield too much.

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We did both sides of the car simultaneously. Of course grade 8 bolts will be used. I'll probably end up just painting the hats. Powder coat would add too much thickness and anodizing isn't an option. Next engineering feat will be the caliper mounting system.

More to come. . .
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Last edited by gt4rcdude on Thu Mar 27, 2008 12:24 pm, edited 2 times in total.
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Postby Meurz » Sun Feb 24, 2008 9:16 pm

Damn, that looks very nice man, good idea! :D
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Postby Corey » Sun Feb 24, 2008 9:32 pm

Nice ! 8)
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Postby Azonic » Fri Feb 29, 2008 7:20 pm

and where did you get the replacable rotors?
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and how many MR2's did I have? I forget..
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Postby gt4rcdude » Wed Mar 05, 2008 4:29 pm

Wilwood.
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Postby gt4rcdude » Wed Mar 05, 2008 9:31 pm

Well, looks like the stock caliper isn't going to work. The OEM caliper is going to foul the inside of the wheel. Oh well, it's only money.


Ordered 4 Wilwood calipers, 4 sets of pads and two rotors today. All to the tune of $700. That brings the total so far to $1100. The only thing that remains is brake lines as the Wilwoods use an NPT fitting for the fluid input instead of a banjo bolt. Brake balance should be close to stock. Here's the breakdown. . .

Front OEM caliper is 2.25" diameter for a total of 3.97 sq. in.
Wilwoods at 1.62" diameter X2 for a total of 4.12 sq. in. Part no#120-8465L & R. Forged Billet Superlight.

Rear OEM caliper is 1.37" diameter for a total of 1.47 sq. in.
Wilwoods at 1.00" diameter X2 for a total of 1.57 sq. in. Part no#120-9706 Billet Dynapro Lug Mount.

While other big brake kits use larger front pistons, some owners note longer pedal travel, which I want to avoid. Some say they can modulate the braking better, but I'd rather do it myself. I'm more concerned with keeping the brake bias correct. I want to leave the stock master cylinder in as well.

Updates as progress continues. . .
Last edited by gt4rcdude on Sat May 17, 2008 4:01 pm, edited 2 times in total.
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Postby gt4rcdude » Wed Mar 19, 2008 11:07 pm

New update!

Went to NJ this passed weekend to try to button up the brake system. Would have had it done but we ran out of steel. The good news is the front system is finished and just needs hardware. I'll hopefully be picking up some AN hardware tomorrow at the local aircraft supply store.

Front mockup. I still need to bead blast and paint the hats. . .

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Do these brakes make my wheels look phat? :)

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Here's a mockup of the rear setup. The brackets for the calipers should be finished by the end of the week. In this setup the bolts enter the hat from the rear into the threaded holes of the disc. The venting is hung over the inside to pull the rear caliper out for mounting clearance. This also prevents any modification to the dust shield.

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ADDED: In order for these discs to slide down the parking brake drum, we had to machine down the outside of the drum a few thousandths.

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Next up is the brake lines. As soon as I can fully mock up the fronts (I need grade 8 bolts) I'll be grabbing the brake lines. More to come. . .
Last edited by gt4rcdude on Thu Mar 27, 2008 12:26 pm, edited 1 time in total.
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Postby Corey » Thu Mar 20, 2008 1:37 am

Nice !
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Postby robolt » Thu Mar 20, 2008 2:27 pm

Nice job!

What Wilwood rotors did you end up with front and rear? P/N?

You could get the hats you machined zinc chromate plated.
Or even something like JetHot.

I had done a number of parts in the past zinc chromate plated (zinc plated chromate dipped).

I have ST205 calipers for the F/R, did the ST205 rear rotor. And was going to to the hats and wilwood rotors for the front. Mock up a hat from an original rotor.

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Postby silence » Thu Mar 20, 2008 5:44 pm

gt4rcdude, can you post your findings on the brake line adapters you are using. Im guessing if you already have stainless lines all you need is an adapter to fit the line to the caliper...that is all i will need when i finish mine.
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Postby gt4rcdude » Thu Mar 20, 2008 7:29 pm

Rear Rotor: 160-5844
Front Rotor:160-7597 & -7598

Calipers have a 1/8-27 NPT hole. No real way to "adapt" them to OEM style braided lines. If you were to cut off the banjo fitting to install an adapter, the line would be too short. Especially since the caliper is farther away due to the larger diameter of the disc. Any local hydraulic line making shop could make the lines. However NO shop will make them if you tell them it's for a car. Race car, street car or any car. Just bring in your lines, tell them you need them 3" longer with a 1/8-27 NPT on the end. If they ask, remember, it's not for a car. Period. Of course I'll want an adapter on the end of the line so I don't have to pull the fitting out of the caliper every time I want to remove it.

On a side note. I weighed the front calipers. The OEM's weigh 11.5 lbs. The Wilwoods weigh 6lbs.
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Postby camry90 » Fri Mar 21, 2008 12:57 am

how did you proceed to mock up a bracket for the caliper? what part number are the front caliper? do you have a picture of the bracket? thanks
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Postby gt4rcdude » Mon Mar 24, 2008 11:17 pm

Update!

Spent some more $$$ today. Aeroquip fittings, paint, AN bolts, Grade 8 bolts. Got enough to do a full mock up on the front to measure required brake line lengths. It's so nice living in a big city sometimes. DOT braided lines? In stock in multiple sizes. 1/8-27NPT to AN-3? In stock, 10mm/1mm pitch to AN-3? In stock. Grade 8 bolts? What size and length sir?

Here's the front brackets after paint. The two inner bolt holes are threaded for a little extra security between the two welded pieces. After paint. . .

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Before paint and the initial mockup.

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My hand should give you an idea of how big these calipers are!

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On the car after paint. . .

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Mockup on the car with the caliper. . .

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Painted hat and all mounted up!

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With the wheel. Still have 3/4" of clearance on the caliper to wheel distance.

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It was starting to get dark. This is the last pic before clean up. The pics don't do it justice on how big that disc and caliper look!

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Up tomorrow is the rear. Although I still haven't received the rear caliper brackets yet, but I can get the rotor/hat assembly mocked up. The AN hardware should be here Thursday. Got some safety wiring to do when it gets here!

Stay tuned!
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Postby Luni » Mon Mar 24, 2008 11:33 pm

John did you retain your use of your emergency brake?

Big issue to some peeps when doing a big brake kit.
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Postby gt4rcdude » Mon Mar 24, 2008 11:46 pm

Luni wrote:John did you retain your use of your emergency brake?

Big issue to some peeps when doing a big brake kit.



Of course, did you expect anything less!


The rear rotor hat is the OEM unit machined to accept the disc. Parking brake system is unaffected. :D
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