Inexpensive DIY Big Brake Kit

[GotBRZ1691]

Originally Posted by 200hp/tonne

If you end up making money on these hundreds, could you send me a couple? The taper on the water jet cut screwed up the holes on one of my pieces (the guy stacked my 2 work pieces and made 1 cut), so my 10mm holes have to be 11mm on that one piece for everything to line up properly. I haven't done GD&T at all on this thing...

By the way, the piece is 3/4" thick.

We cut up to almost an inch for our processes, somethingg li 14 or 15\16th.

surprised about the water jet screwing up. if time allows we always run the water jet because it will yield a high quality hole but takes longer. holes cut by the plasma need to be touched up with a dye grinder.

ill pm ya and maybe we can work something out

ill be at work for a little bit later today

[wparsons]

Originally Posted by 200hp/tonne

120-11782-bk costs 300$ PER CALIPER. These are essentially the same as the WRX calipers in terms of pistons, piston area and pads, and only cost 125 per piece. Brake bias seems to be a concern for a lot of us including me, but i am confident that similar rotor diameters and piston areas as the Wilwood FRS kit will provide a similar net result.

The calipers you linked to have pistons 0.5" larger in diameter than the ones AP uses (which is almost 50% larger diameter). There's simply no way the bias is going to be the same.

They also need a thinner rotor (or thinner pads), 0.8" vs 1.1".

[200hp/tonne]

i meant the WRX kit from Wilwood, as well as the FRS kit from Wilwood.
It is almost the exact same caliper as the WRX kit from Swift996's post, only difference is radial mount vs normal mount.
I don't have data from AP racing kits.

[DustinS]

You could try the 120-11133

It has the same piston area w/ a larger pad for only about $20 more from Amazon. I have these(well I have a set with a larger piston size because I ordered the wrong set, fixing that after the holidays)

These are sitting on a set of DBA STI rotors. They are heavy, but they work well till I get 2 piece set worked out. Trying to use wilwood rotor has and rings.

[Canehda]

Originally Posted by DustinS

You could try the 120-11133

It has the same piston area w/ a larger pad for only about $20 more from Amazon. I have these(well I have a set with a larger piston size because I ordered the wrong set, fixing that after the holidays)

These are sitting on a set of DBA STI rotors. They are heavy, but they work well till I get 2 piece set worked out. Trying to use wilwood rotor has and rings.

So would these work on the same bracket that op has proposed?

[DustinS]

No. These have a smaller mounting distance (3.50 off the top of my head, compared to the 5.25 or whatever is on the OP Calipers)

These would need a new bracket, but I imagine He might be able to use the ones he has already made. I haven't checked to see the differences.

Edit: OP Caliper is 5.25" Mount center (distance between center of mounting holes) and 2.03" mount height (distance between center of mounting hole and top of pad). Calipers I am using have a Mount center of 3.50" and Mount height of 2.85"

[CSG Mike]

There's more to bias than just piston area...

[200hp/tonne]

What else affects brake bias?

On an unrelated note, I drove on my new setup to bed the pads in, so far so good...

[finch1750]

I am no expert so please someone correct me if I am wrong. I took some info from the $600 BBK thread with Z32 calipers and simply replace with the Wilwood specs according to this calculator (Credit to @eikond)

Stock:
front piston size (inches) = 1.685 and 1.685 (42.8mm)
front pad cf I left at .48 (street performance example)
front rotor diameter 11.575
front pad height (I left at 1.875.. not sure how to calc this so I left it at the prefilled value)
rear piston size = 1.49999 (38.1mm)
rear rotor diameter = 11.42
rear pad cf = .48 (same as above)
rear pad height = 1.25 (left at prefilled value)

Result = Front brake bias 0.697 or 69.7% to front.

Wilwood brakes from OP:
front piston size (inches) = 1.620 and 1.620
front pad cf I left at .48 (street performance example)
front rotor diameter 12.190
front pad height (I left at 1.875.. not sure how to calc this so I left it at the prefilled value)
rear piston size = 1.49999 (38.1mm)
rear rotor diameter = 11.42
rear pad cf = .48 (same as above)
rear pad height = 1.25 (left at prefilled value)

Result = Front brake bias 0.706 or 70.6% to front.

Edit: Just to clarify this is with stock rear brakes

[Racecomp Engineering]

Cool project!

There is not much of a change in bias from stock.

One concern is that the rotor is thinner than stock at 20.6mm vs. 24mm. That combined with a larger rotor diameter would make me nervous at the track if rotor temps got very high.


EDIT: The rear FHI 2 pots shift bias forward. Front FHI 4 pots have no effect on bias.

- Andy

[200hp/tonne]

Originally Posted by Racecomp Engineering

Cool project!

There is not much of a change in bias from stock.

One concern is that the rotor is thinner than stock at 20.6mm vs. 24mm. That combined with a larger rotor diameter would make me nervous at the track if rotor temps got very high.

- Andy

Thanks, and my thoughts exactly. I will probably get better rotors for the track if i ever get to visit one, but my main aim is weight reduction and an enjoyable experience on the street.

[200hp/tonne]

it took me forever to clean out and repair my pressure bleeder ( I hate ATE Blue with a passion now) so i have not updated thread with any installation pictures. If i can find the time, i will update later tomorrow. to everyone for all the appreciation, support and even skepticism.

[200hp/tonne]

Ok so i spent all of Sunday on waiting for my bleeder to completely dry out and then bleeding the system and finishing up the install.

The Old setup about to be removed:


Rotor and caliper removed from wheel carrier. If the Rotor is too stubborn, get 2 M8 bolts and tighten them in the 2 small threaded holes on the rotor hub. It will pop out as you tighten them.


Remove Caliper hose by loosening the flare fitting on the fender wall after taking the clip off. I used the Conversion fitting from the wilwood line kit to cap it up. If you have removed the pre-requisite bolts for strut bracket and the ABS sensor wire bracket, the caliper comes off.



The rotor (with assembled Hat) goes up on the wheel hub. Now to install the Caliper.
Attach the Caliper to the bracket using M10 bolts. You will need some combination of shims/spacers to get the caliper in the right AXIAL position.
Its RADIAL position is handled by the bracket.
RADIAL:


To attach it to the Wheel carrier, use M12 bolts. I do not trust threads in Aluminum which is why i decided to have a lock nut on the other side.
As i said before, The Axial position can be adjusted by the use of shims or spacers.
AXIAL:

This is the view of the top of the driver side fitment. The bracket mounts BEHIND the wheel carrier mounts as opposed to Stock Caliper, which mounts to the front. This is because there is no space to create a strong bracket with enough thickness to resist crushing stresses at the bolt holes. The back side had Machined RECESSES on it, which is why we need a shim/spacer between the wheel carrier and the caliper mount bracket. Then we need to adjust the axial position of the caliper by adjusting the thickness of the spacer on the M10 side. My Combination is:
M12 Spacer : 1/8" Thick
M10 Spacers : 2.5mm Thick + 1/8" Thick

This brought the Rotor smack in the middle of the caliper, with pads inserted there was exactly the same air gap between pads and rotors on both sides of the rotor. YMMV

End result:


Now Remove the bracket the was on the fender inner wall and remove the abs sensor wire clip. The large oblong hole in this bracket is just a little too small for the wilwood fitting to pass through. you can file it with a round file if you have one, or you can do it my way, hammer the sucker flat. This also makes it easier to insert the fitting clip later. I forgot to snap a picture of this, sorry.

Stainless line attached and all fittings tightened.


Fitting clip inserted:

[shiro]

Looks amazing buddy! Love the project! Looking forward to read more.