The Lotus Cars Community banner
1 - 9 of 9 Posts

·
Vendor
Joined
·
3,655 Posts
Discussion Starter · #1 ·
Brakes on the Lotus is a long, long story…….

The original brakes were designed for Naturally aspirated 190HP car and aero drag co-efficient of (all the drags). The brakes were light 2 pistons units in the front with super-heavy cast steel , single-piston slider in the rear. The rear caliper is actually the same as the E-Brake Caliper on a Dodge Viper!

These brakes are adequate for the base car OEM use-case.
They do suffer from some issues:

The front brakes don’t have anti-knock back springs so be prepared for your foot to go to the floor at the end of a long straight until you learn to pump them a bit to come back. It is a high sphincter-factor event!

As you start to go faster, heat becomes a problem. We have stainless pistons to help reduce heat transfer but ultimately the limit is the small pad these calipers use. They don’t have enough area and mass to keep the temperatures down in higher than stock power vehicles.

The rear calipers integrate the e-brake, however, the single piston setup tends to drag which puts more heat into the brakes!

Wheel Tire Vehicle Car Hood


We uncovered these issues when we ran the Optima Ultimate Street Elise. My wife was driving that car(still the only Lotus and only woman to outright win an Optima event!) She was boiling the brakes every session on the track! I thought she was riding them. Chatted with Phil at BOE, he said she was using the brakes too much. We were both wrong, she was right. Here is the thing: Higher horsepower cars go faster(higher Vmax) but the Optima car is on street tires which keep the cornering speeds low(low Vmin). So the speed delta the brakes were required to deliver was off the charts!

Wheel Automotive tire Locking hubs Vehicle brake Alloy wheel


Current solutions solve different issues or miss the mark:

Lotus did a Big Brake Kit(BBK) with the cup brake option on some Exiges
These made the already bad overly front biased brakes WORSE.
- Use a larger 308mm disc that doesn’t fit 15” wheels which are very popular for track cars
The 308 disc is heavier, has more rotating mass. The stock 288mm wasn’t the issue.
- The 308mm disc is stupidly expensive to replace!


Some folks look at locating an extra set of front calipers to the rear with a bracket.
A couple of issues here:
  • Brake bias is 50/50 which is much too far the other way!
  • The fluid volume of those pistons is too large and results in a very long pedal!
The problem was not the disc, the problem was the energy absorption/transfer capability of the pad!
 

·
Vendor
Joined
·
3,655 Posts
Discussion Starter · #2 · (Edited)
When we started this project 2+ years ago we had a set of requirements we thought would fit the use case of most Lotus owners looking to upgrade their brakes:

1. Fixes the problem! Don’t just throw parts at it, solve the friggin’ issue!
2. Uses high quality and cost effective components
3. Is plug and play, no cutting required!
4. Fits 15” wheels for best wheel and tire options.
5. Wide pad selection (common pad shape)
6. Uses stock 288mm sized disc. Many options from street to full race and reasonable prices.
7. Is fully modularized and upgradeable. For example, we designed our ultimate front uprights to accept these calipers! Upright customers have a lower added cost if they want to upgrade their brakes!

Components:

Calipers:

Ultimately after looking at what was available and fitments etc. We selected Wilwood as our caliper! Their Forged Superlites radial calipers are 4 piston flow-forged from aluminum alloy billets. Flow forging aligns the metal grain structure which eliminates stresses and interruptions to the grain structure that occur from machining directly from block billet.

The piston sizes are such that the bias shifts 5% rearward for optimum braking! We’ve been doing this with with different compound pads for years to get the bias correct. Now we are baking it into the system!

These Calipers has stainless steel pistons standard to reduce thermal transfer to the fluid from the pad. Additionally, they have anti-knockback springs to keep the pads close to the disc on track!

The crossover tubes are internally machined into the calipers which prevents track debris from causing damage. Lastly, there are 2 piece bleed screws on each side AND each end to make bleeding the brakes super easy and fast.

Wheel Rim Bicycle part Automotive tire Disc brake


Brackets:

We’ve designed our own brackets with extensive Finite Element Analysis (FEA) for stress. We’ve designed them to have FOS (Factor of Safety) well over 1 so that they are the strongest brackets available anywhere! The front brackets use the same Exotic Aerospace 7075-T7351 we use on our uprights. They have stainless steel threaded inserts so they can be used and re-used for a long time.

Hoses and hardware:
Our hoses are stainless braided hoses custom-fit for the Lotus application. Caliper bolts are ARP Nickel plated 12 pt bolts.

Bicycle part Rim Auto part Bicycle drivetrain part Automotive wheel system


System and Modularity:

Front-Only:


4 Piston Caliper (Small Piston) Wilwood Forged Superlight weight calipers

BWR front caliper brackets(unless you already have our Ultimate Uprights)

Hoses, fittings, bolts, and Wilwood Polymatrix E Street/Track Pads.

5% brake bias shift to the rear.

Can upgrade to full system later!

Wheel Tire Automotive tire Motor vehicle Vehicle


Front and Rear

4 Piston Caliper (Large Piston) Wilwood Forged Superlight weight calipers

BWR front caliper brackets(unless you already have our Ultimate Uprights)

4 Piston Caliper (Small Piston) Wilwood Forged Superlight weight calipers

BWR Rear caliper brackets

Hoses, fittings, bolts, and Wilwood Polymatrix E Street/Track Pads.

5% brake bias shift to the rear.

Notice if you start with the Front only, you can move those calipers to the rear later and just get the larger piston front calipers later!


E-brake

We mount the caliper on the front side of the rotor so you can just leave your rear caliper in place for E-brake duties if you wish.

For cars and drivers, you may choose to just remove the stock rear caliper altogether. It is heavy and you can put the car in gear vs using the brake.

For folks that want the ultimate of the ultimate, we have a billet aluminum spot caliper for each side that weighs-in at half of the stock caliper and looks the business! Completely bolt-in solution.

Wheel Tire Locking hubs Automotive tire Vehicle brake


We’ve been testing this system in various cars for well over a year. It finally has face-planting performance under braking even from triple digit speeds. Straight, true stop after stop, lap after lap. The Lotus finally has supercar braking performance to match the rest of its upgraded capabilities.

Intro Deal:

We are ready to launch however we are waiting on our production front Brackets to come in. So I figured we will launch with a big discount on Black Friday with a deposit to commit to Fronts, Fronts and Rears, Ebrake etc. The deposit is non-refundable unless for some reason we can’t deliver in which case everyone gets their deposits back. This helps us know quantities to prepare etc. In exchange you get the best deal anyone will ever get.

I expect we will be delivering by end of the year, though realistically with the holidays and Covid, that could push into January.

When everything is gathered and ready to ship, I’ll reach out to invoice you for the balance.

Intro Pricing:
Front: $1795 (If you already have our uprights the fronts are only $1295!)
Rear: $1795
E-Brake: $695


To place a deposit for Blackwatch Real-Deal Ultimate Brakes
 

·
He's on fire!
Joined
·
3,538 Posts
What backing plate size for the pads? Also, do the calipers have dust boots against the pads like the stock rears, or are the seals internal only like the stock 2pot up front? What's the pad thickness front and rear? Pad change procedure? Thanks

Sent from my SM-G950U using Tapatalk
 

·
Registered
Joined
·
1,006 Posts
Pad backing plate number is 7416 for front and rear. Total pad thickness is 16.5mm. Backing plate is 4.84mm thick. Just pad material is 11.66mm thick.

The calipers have internal seals only, no dust boots.

The pads are changed by removing the bridge bolt and bridge bolt sleeve. Once removed, the pads slide out radially. Requires about 5 minutes per caliper.
 

·
Addict
2007 Lotus Exige S
Joined
·
1,673 Posts
What about for those with brake bias adjustments. Would you still go with the smaller pistons in the rear or would having the same calipers front/rear be better?
 

·
Vendor
Joined
·
3,655 Posts
Discussion Starter · #7 ·
What about for those with brake bias adjustments. Would you still go with the smaller pistons in the rear or would having the same calipers front/rear be better?
Simple answer is that I would go with the smaller pistons in the rear since the native bias is closer to ideal, then fine tune the balance with the adjuster. In reality you could probably make both work as there is alot of range in the dual master setup. If you have a prop valve, definitely get as close to ideal piston sizing as possible.
 

·
Premium Member
Joined
·
138 Posts
What we experience on hard braking during autocross is that the car does not brake as well as most cars we have driven. Occasionally we would have a lack of the majority of braking which we assume is an ice mode. Our last change was to change to softer pads in the rear to solve the brake bias problem like Fred mentioned above. Since then, we realized that neither of us has had an ice mode event. [fingers crossed] But I would still not describe the braking as good as a Miata or an S2000. We do a left foot braking which helps with getting the car to handle better.

For an autocrosser what kind of change would we see?

I haven't done a track day in a year. The much longer braking events make it much easier to play around and generate a lot more heat. Even very good fluid we will loose most of the braking by the end of a 20 minute session at COTA. We have the hatted rotors and semi-race pads in the front but no stainless piston or any of the other brake changes. For a track car this seems like a possible solution.
 

·
Vendor
Joined
·
3,655 Posts
Discussion Starter · #9 ·
What we experience on hard braking during autocross is that the car does not brake as well as most cars we have driven. Occasionally we would have a lack of the majority of braking which we assume is an ice mode. Our last change was to change to softer pads in the rear to solve the brake bias problem like Fred mentioned above. Since then, we realized that neither of us has had an ice mode event. [fingers crossed] But I would still not describe the braking as good as a Miata or an S2000. We do a left foot braking which helps with getting the car to handle better.

For an autocrosser what kind of change would we see?

I haven't done a track day in a year. The much longer braking events make it much easier to play around and generate a lot more heat. Even very good fluid we will loose most of the braking by the end of a 20 minute session at COTA. We have the hatted rotors and semi-race pads in the front but no stainless piston or any of the other brake changes. For a track car this seems like a possible solution.
I think the braking is far better on our Optima car for having the full BWR setup. I haven't autoXed it but Alex has and she concurs. We haven't had any ice mode but we are using non-stock wheel sizes and the sample size is small.

There are alot of things less than ideal with the Lotus brake solution. This addresses the balance, heat capacity, and feel. I think it helps with ICE mode, but Lotus ABS is certainly not Porsche GT3 ABS!
 
1 - 9 of 9 Posts
Top