Brembo Racing Brakes (my own design)

[Vulcan Grey]

So I bought these along time ago with the intention of designing the hats and brackets and parking brake myself and then probably having somebody else manufacture them for me.

Well I started the design and then didn't finish do to having too many hobbies and most of the racetracks in Colorado closed, and then I did an engine rebuild...

So now I'm back at it!

So I bought these on ebay (talked the seller down a bit too )

While I was arraigning to buy the calipers only, I asked about pads, and then rotors, and then bolts for the hats to rotors.

Well, he threw in a full set of new pads, and 6 slightly used rotors (no cracks or really any wear), and all of the rotor fixing bolts that are required for a fully floating Brembo rotor (they charge $300 for the bolts alone!).... He threw all that in for the price of shipping!

These calipers normally go for ~$2900 each for the fronts and ~$2300 for each rear! The bolts, as I said $300. The rotors are approx $500 each, and the pads.... I'm not sure, but they are 1" thick!

Calipers

calipers and 2 sets of front rotors

Front caliper and pads

So I bought a Wilwood proportioning valve and a brake pressure gauge, some braided brake lines, and some Wilwood parking calipers.

You can see the size difference between the original Lotus rotor (top) and my new Brembo rotor 328mm x 35mm (bottom)

and the rear solid rotor (top) vs the 313mm x 25.4mm (bottom)

These brakes are designed to fit into a 15" forged wheel, and they fit fine in my 17" and 18" AWI's from the '97 Esprit V8.

But it's fairly close in the front

The calipers are aluminum (front is monoblock) with vented titanium pistons. They are very light.

So I measured everything on my car and made some 3D models that I could use to create the mounting hardware.

the orange bracket and blue rotor hat

Rear assembly with separate parking caliper

After designing everything in CAD, I wanted to make sure that my measurements and offsets were ok, so I prototyped everything in plastic

front rotor assembly with plastic hat (real hat will be aluminum)

my piece of plastic was too small, but it served it's purpose

Rear rotor prototype assembly (also an aluminum hat)

Plastic caliper mounting bracket prototypes

Bolting the rear caliper mounting bracket in place. This will move the rear caliper to a leading position (Esprit caliper is in a trailing position) but this design is based on the X180-R and Sport 300 (which have phenomenal braking performance)

from this

to this

Checking the wheel clearance (plenty with my 18"x10" AWI rear wheel.

Front bracket (maintain trailing position)

front rotor, mounted behind the hub as in all Esprits prior to the Brembo S4 and V8's

Caliper and rotor

with 1" pad

With wheel

So everything fit, and I am starting to make the metal parts as I type this.

Rear Chrome-moly bracket

[lotus4s]

It oughta stop now.....

[Jonathan]

LOL, cool how long have you 'ad them now ? hehe

[Bibs]

Very cool, nicely done

[Simon350S]

They are awesome mate.

Those pads will last you the next 10 years..!

Really liking your car. You binning the servo and original master cylinder etc and going for dual cylinder adjustable bias etc?

[Vulcan Grey]

Starting off with the standard master (my 89SE doesn't have ABS).

I'll add a proportioning valve if needed.

And it that doesn't work then it'll be fairly easy to change the master cylinder later or go to a dual master (no servo) with a balance bar.

[rocket63]

Very nice.

[Petrol feet driven]

Well done that is truly an amzing job.. Very impressed.

[Iconic Ride]

Travis, when you say your are "making" the "metal parts," are you actually doing this in your own "shop," or having it outsourced? The CAD depictions and plastic "trial" parts were impressive enough in their own right, but if you're also manufacturing the final results yourself, I'd really be interested in seeing [pics of] the "tools of the trade." (even if you farmed the work out)

When you finally complete the mod, I'd be especially interested in your unofficial stopping figures comparison to the stock numbers (Road and Track distances?). Looking at the size of the new rotors/calipers/pads, you're gonna' need a full-restraint driver harness.

[Vulcan Grey]

Made some more progress today.

I finished making the 4 metal final versions of the caliper mounting brackets. I machined them myself out of 4140 Chrome-moly steel at the machine shop at work (bandsaw and milling machine) I dodn't know how to use the CNC so I did everything on the manual mill. I'm not too worried about nice finish so I am roughing these out with a roughing mill. The chrome-moly doesn't like a normal end-mill, it tends to work harden very fast, especially when trying to plunge or do a conventional cut. SO I had to make my designs to match my capabilities, and with all climb milling in mind (one pass each time in one direction of feed only).

SO here are the completed caliper brackets. I added some lightness from the previous picture!

Test fit

Fits great!

All parts are symmetric, so I just have to make 2 copies of everything.

Here it is with the rotor (you can see my new JRZ Race double adjustable suspension that I am also installing at the same time)

See my other thread for the JRZ suspension install.

[USAndretti42]

Looking good, Travis. Be interesting to read how well it stops and handles with all the new bits.

[Vulcan Grey]

more progress today.

Started machining the front rotor hats.

Fly-cutting a flat surface

Cutting the other side of the plate to proper thickness, before fly-cutting one last time for a nice parallel surface on both sides.

Drilling all the holes at once so they are perfectly in position relative to each other.

Rough milling the hub-centric center bore before finishing with a boring bar.

Center bore done

Holes done. I also finished the 2nd hat. Now I just need to make them round.

[Passmore928]

Great work!

[Jonathan]

Nice 1 Travis, you're lucky to have that kinda machinery there at your disposal - are you getting paid to do this at work ?

Dunno what it is about bright shiney machined metal....some peope look at Rembrants and so on, but watching a slab of metal turn into a work of at on the table infront of you is well satisfyng.

You gonna anodise them hats yeah ?

[Vulcan Grey]

Thanks!

Yea, I will have them anodized. I would rather have hardcoat grey but I'll take black.

[Vulcan Grey]

Made some more progress since last update.

Gunter asked me if I had done the FEA analysis on the design as well.

And I have. Not in a absolute "yes they will preform exactly a certain way", that is a bit misleading with the FEA software. You'd really have to know exactly the types of loading that you'll see.

The software is very good for comparison of two different designs, and I use it at work often to improve a design concept (usually to tweak how much a titanium spring design will yield and the force it will provide). But I always check it by a mechanical test.

In the case Of the brakes, I don't have mechanical test equipment that can test these things (I work with hearing implants). So I have chosen to compare my design to an existing design that I have based my design on.

The Esprit X180-R and Sport 300 have a very good AP Racing brake setup with a Brembo parking caliper.

The X180-R has a flat 6mm plate, and the hardware is not floating so the hat gets distorted where the growth of the hot rotor pulls the bolts within the aluminum hat.

So I ran an FEA simulation of the X180-R hat (after measuring my friend's). Then I ran the same simulation settings on my design.

X180-R flat plate

My design is thicker, different offset, and dished for stiffness.

With all parameters the same, my design saw ~1/2 the stress that the X180-R hat saw.

Here is an X180-R rotor and hat after ~13,000 miles, many hard laps on the track! And almost 20 years.

So by that comparison, and with the Brembo floating rotor hardware... my design should be fine.

So here's my progress!

turning the hat from a square blank into a round on the turntable.

almost done, need to the the front side now

[Vulcan Grey]

Someone asked me about the "floating rotor design".

Most cars have cast iron brake rotors that are one piece. hat and hub are integral, usually a dish shape.

The problem is that the rotor area, swept area where the pad grabs the rotor, heats up more than the center hat portion that is bolted to the hub and wheel. So as the brakes get hot, the rotor and hat deform into a bowl or tulip shape. This causes problems with the pads getting pushed to the side, and distortion in the rotor.

Racecar engineers need to minimize weight, so they replaced the heavy center section of the rotor with aluminum and bolted the rotor to the hat (a 2-piece fixed rotor design). But the rotor still sees more heat and the rate of thermal expansion is different between cast iron and aluminum. So the rotor grows and it drags the bolts along with it. The aluminum hat doesn't see the same kind of heat so it doesn't grow as much, even though it's rate of thermal expansion is higher than cast iron. SO you still get distortion, with the hat bolted to one side it still grows into a bowl shape, or it would if the aluminum wasn't weaker than the iron.

So now they use a 2-piece floating rotor design, where the bolts ride in oval shaped slots, and the rotor isn't bolted firmly to the hat. There is actually a small gap between the rotor and the hat. This design uses special bolt hardware with small antirotation D-shaped bobbins that are taller than the total thickness of the hat+rotor mounting flange. Then there is a bolt and a washer.

The rotor is free to grow radially with the heat, and the hat sees less stress.

Take a look at this Champ Car rotor and hat assembly. The bolts are in U-shaped grooves at the edge of the hat. The rotor is still radially fixed but free to expand a bit.

Here are the bolt hardware (also shown is a McLaren anti rattle spring). The spring is used sometimes on every other bolt, usually on road cars only. These floating rotors can squeak and make a lot of noise sometimes.

My brakes use this floating hardware, though I do not have the anti rattle springs...

[Rich H]

Nice work, I wish I had access to that little lot of machinery.... That damage to the x180 top hat is a bit scary!

[Vulcan Grey]

Thanks. It is a good benefit to have!

Finished a front hat last night.

[Simon350S]

Put it on your head for a photo then. Your first home made hat

[Iconic Ride]

"(I work with hearing implants)."

Impresssive results, using equally impressive machining tools, Travis. Leading me to ask, just how big are your "patients" ears?!

[Simon350S]

Was thinkin exactly the same!

My grandad had big ears but I struggle to imagine anything machined in a workshop fitting inside of them!

[Vulcan Grey]

We most of our parts are made by CNC mill and lathe vendors, but we have a small shop with a few CNC mills, a manual mill, lathe, band saw, grinders...

[Iconic Ride]

Maybe this kind of "ears"?

Travis, this is my big chance to ask another "great mystery of life" question. Some rotors (discs) have (for lack of a better term) "scoops" on the outer circumference, others have a solid edge, yet I have sometimes heard both types referred to as "ventilated discs." I've been told that even the "scoopless" discs are hollow. Is this what is meant by "ventilated"? And along those lines, is the function of the "slashes" on the swept area strictly for additional cooling, or do they serve some other purpose as well?

Cheers,

John

[Vulcan Grey]

A vented rotor is one that has basically two plates separated by pillars or cast in vanes. The vanes may be straight or curved, making a kind of turbine effect to move air through the middle of the rotor.

A solid disc is one plate, no gap between the friction surfaces.

The slots on the side of the rotors like mine serve to scrape the pads and clear the gasses so the pads are basically always fresh and not glazed. The drilled holes in some rotors are supposed to do the same, but generally increase the thermal stresses and do not scrape as well.