Installing Square Brakes - Front rotors and calipers all around

[Harley818]

I've been driving my 818S for 3 summers now and love the way it drives, but hate the way it brakes.
I've been following a number of the brake threads, but ultimately I'm following Bob n Cincy's solution using the front calipers on all 4 wheels.
I'm using the same rotors on all 4 as well, where Bob used the Australian DBA rotors that retained the parking brake internals.

Its not a difficult installation, and its cost effective. Rock Auto for calipers and rotors.

However, this mod does delete the stock parking brake that the DB rotor solution retains.
I am planning to ultimately add one of the hydraulic drift brakes on the rear wheels to add a parking brake.
Basically when you pull the brake lever, it interupts the fluid to the rear calipers and pressurizes them ..... locking the rears.
I don't often park in an area where I need a parking brake, and I can usually just leave it in gear. The brake is an extra safety.

I designed a 1/4 in thick mounting plate to take the place of the backing plate and dust plate.
The 4 mounting holes for the backing plate are not centered on the hub centerline (who would have thought?) so I had to do a bit of cutting and grinding to make it fit.
I'm happy to share my ACAD drawing and dwg file.
I had it water jet cut from 1/4 in plate (straight from the .dwg file) at a local shop, and then had it machined 3mm deep for spotfaces for the 4 bolting locations and around the center hole to clear the casting.
It interfered with the hub casting a bit still - so a bit more grinding until it fully contacted the bolting locations.
Sorry, I didn't take pictures of the finished plate before installing it.

Installed Plate from the front, and from the back.
122079122080

I didn't want to take the hub apart, so I cut the backing plate off with my angle grinder and cutoff blade.
It was a little tricky to avoid the hub casting, but wasn't too bad.

Once the caliper and rotor were installed, I had to shim the rotor out by 1mm so that it would align with equal clearances to the rotor.

View from the top, and from the bottom
122081122082

All assembled
122083122084
122085

Comparison of rotor size - but its the two pistons that make it work much better.
122086

All good now... just need to test it - but Bob says the double pistons per caliper work well on all 4 wheels.
Thanks for the info to get me started Bob.
PM me if anyone wants the ACAD and .dwg file. I will post those in the next post when I mark them up with my grinding mods.

[Harley818]

Saved for ACAD and markup drawings.

[NAZ]

You know, there are block valves made for hydraulic parking brakes. Here's one: https://www.speedwaymotors.com/Search?query=hydraulic+parking+brake+valve

[flynntuna]

Thanks Naz. Just what I need, another reason to redo my brake lines. :p Even though this will do away with the emergency brake feature of the parking brake, I could get rid of the parking brake handle and cables. The simplicity of this
Would free up space on the center console. Win win? I think so. The only downside I can think of is running th brake line inside the cabin. I'm rambling now, am I thinking clearly on this

[NAZ]

Not a problem running the brake lines in the driver's compartment -- just need to keep to them away from feet and seat sliders. Even NHRA allows brake lines in the driver's compartment without running them through protective tubing.

I used this very same valve so that I could run smaller profile calipers with the large rotors and still use 15" wheels on the rear. Press the brake pedal then the block valve and let off the pedal, parking break is set. Press the pedal again and the spring loaded valve handle releases unlocking the brakes. It's common to find these on aircraft for parking brakes. Makes a clean and economical way to add parking brakes in difficult builds.

[Ajzride]

The other option is an electric parking/emergency brake. Most Tesla's have a stand-alone caliper for the e-brake and there are lots of options out there for controlling them. I retrofit a set on my 65 mustang, Hydraulic brake caliper at 9 o'clock and electric caliper at 3 o'clock.

[Harley818]

You know, there are block valves made for hydraulic parking brakes. Here's one: https://www.speedwaymotors.com/Search?query=hydraulic+parking+brake+valve

Naz thats awesome...... I'll use one of those instead. Perfect solution.

[20boxer]

We had a company in the Uk? make a set of rear e brake shoes for our set up. Retains the STI stock rotor, stock e brake set up.

[20boxer]

122172122172122172

[Harley818]

122172122172122172

Thanks 20boxer, I knew about that option, but the DBA rotor is expensive, the shoes are expensive, and I thought I could do it cheaper with just duplicating the front brake set up.
I'm happy with my solution, and any wear/replacement parts will be cheap.
Just thought I would share so everyone had all the options.

[67 Car Guy]

Hi Harley 818;

I'm currently planning my 818 project. I like the idea of using the stock front rotors all around. What did you do for your master cylinder? Is it manual or power assisted? Are you happy with the results? I used a really small master cylinder bore (5/8" IIRC) on my last project car build and it worked well with Fiero Calipers (Fiero suspension parts on a homemade chassis). The pedal had a fair amount of travel but I could easily lock up my wheels and the pedal would never bottom out. I used the EBC green pads which also helped.

[Harley818]

Hi 67,
The square brakes have been great. I've been driving the car all summer.
I wish I had done this mod earlier.

I used the stock 2002 master cylinder, de powered rack, and stock 2002 rotors and callipers all around.
Initially using the stock rear brakes, pedal effort was massive and I had difficulty locking up any brake.
Now, with the square brakes, pedal effort is "normal" like it would be for any non-power assisted brake. It is much easier than pedal effort with the stock 2002 rear brakes.
I used standard pads on the new brakes in the back and still have the EBC yellows in front. I might replace the fronts with standard pads to avoid all the brake dust from the yellows.
I haven't added the line lock yet as suggested by Naz above, but I did buy it and intend to install this winter.
I also haven't balanced the front/back yet but it stops pretty quick. I'll tune that soon as well.



Hi Harley 818;

I'm currently planning my 818 project. I like the idea of using the stock front rotors all around. What did you do for your master cylinder? Is it manual or power assisted? Are you happy with the results? I used a really small master cylinder bore (5/8" IIRC) on my last project car build and it worked well with Fiero Calipers (Fiero suspension parts on a homemade chassis). The pedal had a fair amount of travel but I could easily lock up my wheels and the pedal would never bottom out. I used the EBC green pads which also helped.

[67 Car Guy]

Thanks for the reply, that's good to know. I'd prefer not to have to add the vacuum booster. Sounds very easy. Did the front calipers mount up directly in the rear, or did you have to make an adaptor plate to hold the caliper in the right position?

[Harley818]

Yes I made an adapter plate out of 1/4 plate.
I describe it in post #1 above, but for some reason the pictures don't show up.
I'll have to go look to see if I can find the pics.
I should be able to find the .dxf file and send it next week.

[67 Car Guy]

Sorry, I guess I got distracted with all the discussion that followed that I didn't realize that's what started the post!

Yes, If you have either the DXF file or just a PDF of the drawing that would be great. It'll be a while before I get to that stage but hopefully in the next few months!