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2021 Champcar E30 Brake Kit - Polling Interest


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Hey everyone,

 

With the advent of the 2021 "2x" brake rule going away, there is finally an opportunity for the E30 to upgrade to a low-consumable-cost brake option for the front.

 

With my experience operating e30's in this series for many years, I have had great success on the OE brakes.  My current setup is Stock Girling calipers with Zimmerman rotors.  Condor supplies my brake lines, and I use PF08 or ST43 pads.  This setup has weaknesses:

1.  Rotors - The rotors last about 14 hours at most tracks, even with massive 3" custom cooling ducts.  We have cracked rotors on many occasions, leading to some pretty hairy moments having to finish a race with a terrible braking vibration.  Luck kept us from "exploding" a rotor and having a big issue

2. Consumables Costs - The rotors get changed after ever weekend on the track, including doing "testing" or "DE" days.  Pads are good for 1 Race weekend, and the left overs get used for testing and DE.  The rotors are $30 each (FCP helps with this), and the front pads are $200/set.

3. Component Sourcing - The Caliper brackets are NLA new.  The guide pins are currently NLA and have been for a year or so, and I just used up my last NOS set of those plus swapped my last set of good brackets from left to right (One pin wears faster than the other).  The calipers require frequent rebuilds to replace the seals, which have been intermittently available.  At least this stuff is cheap when it is available.

 

Looking to improve upon this, and minimize risk of rotor failure in longer races, I have designed a custom kit to fit the E30 front and work with the stock E30 rear.

 

The kit is designed, as much as possible, around off-the-shelf Wilwood (a champcar supporter!) components.  It's primary concern was minimizing ongoing consumables costs and maximizing ease of service.

 

Components:

Wilwood Caliper 120-13232.  Forged Superlite 4 Radial, 4 Piston, 1.25" Pistons

Wilwood Rotors 160-2898 (RH) and 160-2899 (LH).  11.75x1.25 with a 8x7 mounting pattern.  Many other rotors will also work (for example HAWK HR8002R and HR8002L)

Wilwood Bobbins and Bolts 230-14845 (qty 2 required).  5/16 x .750.  Locktite and Safety Wire recommended.

Pads - Any '7420' pad shape, which is an extremely common shape.  Almost any compound can be had for <$200 in this shape.

Lines - The Wilwood caliper is supplied with 1/8-27 NPT female threads.  The kit will come with an adapter to allow use of the stock E30 brake lines (M10x1.0 DIN)

 

Custom Components:

Hats, Machined from 7075-T6 Aluminum, with black anodize Type 3

Adapter Brackets, Machined from 4140 Steel, with black powder coat

 

Costs:

I would like to offset some of the manufacturing setup costs by selling hats and brackets to other E30 teams.  Getting one part made and getting 10 parts made is pretty much the same costs when you request custom CNC work.  Therefore, I don't know the exact cost of hats and brackets at this point.  I would like to sell them in pairs, and I would suggest a team buy one pair of brackets, and 2 pairs of hats to have a spare set.  

My best estimate for costs if I can sell QTY 10 of each is

$300 for the pair of brackets

$200 for a pair of hats

Brake Line Adapters are ~$15 ea, but I am still looking for a source of these in stainless instead of brass

Caliper Mount Hardware - 3/8-16 for the bracket, 3/8-24 for the nut, plus some 12-point nuts.  Titanium stuff would be $80, steel would be much less but I have not found a source of appropriately graded hardware at this time.

I am not looking to profit from this - Just offset some of the costs for my own kits.

 

Fixed Costs are for the Wilwood components, which you would buy direct from your preferred source:

Calipers - $500

Rotors - $100

Bobbins - $100

Pads - $200

Lines - You have these already

 

Brake Bias:

With stock brakes, the torque bias (assuming equivalent pad compounds) is 67.6% front.

With this kit in the front, and stock rear, the torque bias is 66.8% front. 

 

The pedal feel will be marginally softer due to the smaller front piston area.

 

 

Weight:

The rotor is 9.6 lbs per Wilwood

The caliper is 5.4 lbs per wilwood

The adapter bracket is 1.2 lbs

The hat is 1.2 lbs

Total = 17.4 lbs per corner

 

Stock Rotor = 10.5

Stock Caliper and Carrier = 8.8 lbs 

Total = 19.3

 

 

 

image.thumb.png.1eb3f9a398162bff3de77404ff4a23a0.png

image.thumb.png.29b924911bbc6d08cce51052b98cc62a.png

 

 

Don't worry, it has been thoroughly scienced, and I am more than happy to explain the process if there is concern.

These von-mises stress images have the deformation scale multiplied ~75x for visibility

image.thumb.png.7c4d9043cbe06cb4b5838a492d941efc.png

 

image.thumb.png.822077258863e84dc5fe8977cb31e00e.png

 

Timing = The prototypes are on the 3d printer now, so within a few days I should be able to test-fit to a car.  I still need to order a rotor and caliper for this purpose.

Once that confirms fitment, I will need to source the components.  I have a local source for USA made stuff, but the price is about 2x the overseas costs. Lead time is probably 6 weeks from order, so getting this done for Road Atlanta next year is possible but unlikely.  More likely March 2020 delivery to anyone who is intersted.

 


If you are interested, shoot me a pm.  If you have concerns or questions, post them here and I will do my best to address them.  

Edited by Huggy
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Impressive design work, although I disagree that your pedal will feel the same. IMO it will be noticeably softer.

Stock is single piston 1.89", correct?

Also, I'd consider do the adapter out of aluminum too, machining will be much cheaper and you don't have to shave off a bunch of material, could just be a large block and probably the same weight. You could do steel thread inserts if you were concerned about that.

Edited by Slugworks Paul
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11 minutes ago, Slugworks Paul said:

Impressive design work, although I disagree that your pedal will feel the same. IMO it will be noticeably softer.

Stock is single piston 1.89", correct?

Also, I'd consider do the adapter out of aluminum too, machining will be much cheaper and you don't have to shave off a bunch of material, could just be a large block and probably the same weight. You could do steel thread inserts if you were concerned about that.

 

You are correct, the pedal effort will be a bit softer.  Stock area is 2.8", and to keep the bias close the wilwoods are 2.45"

 

I considered aluminum, but prefer steel.  After considering threaded inserts (4 per part) the pricing and labor is a wash.  Some of the shape is for clearance to ABS sensor, Backing plate/cooling duct, etc. so a big square block is an issue.

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1 minute ago, Huggy said:

 

You are correct, the pedal effort will be a bit softer.  Stock area is 2.8", and to keep the bias close the wilwoods are 2.45"

 

I considered aluminum, but prefer steel.  After considering threaded inserts (4 per part) the pricing and labor is a wash.  Some of the shape is for clearance to ABS sensor, Backing plate/cooling duct, etc. so a big square block is an issue.

Fair enough. You could also do a thru-hole and nut on the inside maybe?

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4 minutes ago, Slugworks Paul said:

Fair enough. You could also do a thru-hole and nut on the inside maybe?

Also considered that - but thanks for the suggestion.

 

I decided against it because of the tight tolerance.    Re-using the stock bolts to thread into a threaded bracket mimics the stock method and makes it more "normal", although using the radial mount caliper means these bolts should hardly ever need to come out.

image.thumb.png.8aee3404b8bb4bad8920b39f3768dbca.png

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2 hours ago, Huggy said:

Hey everyone,

 

With the advent of the 2021 "2x" brake rule going away, there is finally an opportunity for the E30 to upgrade to a low-consumable-cost brake option for the front.

 

With my experience operating e30's in this series for many years, I have had great success on the OE brakes.  My current setup is Stock Girling calipers with Zimmerman rotors.  Condor supplies my brake lines, and I use PF08 or ST43 pads.  This setup has weaknesses:

1.  Rotors - The rotors last about 14 hours at most tracks, even with massive 3" custom cooling ducts.  We have cracked rotors on many occasions, leading to some pretty hairy moments having to finish a race with a terrible braking vibration.  Luck kept us from "exploding" a rotor and having a big issue

2. Consumables Costs - The rotors get changed after ever weekend on the track, including doing "testing" or "DE" days.  Pads are good for 1 Race weekend, and the left overs get used for testing and DE.  The rotors are $30 each (FCP helps with this), and the front pads are $200/set.

3. Component Sourcing - The Caliper brackets are NLA new.  The guide pins are currently NLA and have been for a year or so, and I just used up my last NOS set of those plus swapped my last set of good brackets from left to right (One pin wears faster than the other).  The calipers require frequent rebuilds to replace the seals, which have been intermittently available.  At least this stuff is cheap when it is available.

 

Looking to improve upon this, and minimize risk of rotor failure in longer races, I have designed a custom kit to fit the E30 front and work with the stock E30 rear.

 

The kit is designed, as much as possible, around off-the-shelf Wilwood (a champcar supporter!) components.  It's primary concern was minimizing ongoing consumables costs and maximizing ease of service.

 

Components:

Wilwood Caliper 120-13232.  Forged Superlite 4 Radial, 4 Piston, 1.25" Pistons

Wilwood Rotors 160-2898 (RH) and 160-2899 (LH).  11.75x1.25 with a 8x7 mounting pattern.  Many other rotors will also work (for example HAWK HR8002R and HR8002L)

Wilwood Bobbins and Bolts 230-14845 (qty 2 required).  5/16 x .750.  Locktite and Safety Wire recommended.

Pads - Any '7420' pad shape, which is an extremely common shape.  Almost any compound can be had for <$200 in this shape.

Lines - The Wilwood caliper is supplied with 1/8-27 NPT female threads.  The kit will come with an adapter to allow use of the stock E30 brake lines (M10x1.0 DIN)

 

Custom Components:

Hats, Machined from 7075-T6 Aluminum, with black anodize Type 3

Adapter Brackets, Machined from 4140 Steel, with black powder coat

 

Costs:

I would like to offset some of the manufacturing setup costs by selling hats and brackets to other E30 teams.  Getting one part made and getting 10 parts made is pretty much the same costs when you request custom CNC work.  Therefore, I don't know the exact cost of hats and brackets at this point.  I would like to sell them in pairs, and I would suggest a team buy one pair of brackets, and 2 pairs of hats to have a spare set.  

My best estimate for costs if I can sell QTY 10 of each is

$300 for the pair of brackets

$200 for a pair of hats

Brake Line Adapters are ~$15 ea, but I am still looking for a source of these in stainless instead of brass

Caliper Mount Hardware - 3/8-16 for the bracket, 3/8-24 for the nut, plus some 12-point nuts.  Titanium stuff would be $80, steel would be much less but I have not found a source of appropriately graded hardware at this time.

I am not looking to profit from this - Just offset some of the costs for my own kits.

 

Fixed Costs are for the Wilwood components, which you would buy direct from your preferred source:

Calipers - $500

Rotors - $100

Bobbins - $100

Pads - $200

Lines - You have these already

 

Brake Bias:

With stock brakes, the torque bias (assuming equivalent pad compounds) is 67.6% front.

With this kit in the front, and stock rear, the torque bias is 66.8% front. 

 

The pedal feel will be marginally softer due to the smaller front piston area.

 

 

Weight:

The rotor is 9.6 lbs per Wilwood

The caliper is 5.4 lbs per wilwood

The adapter bracket is 1.2 lbs

The hat is 1.2 lbs

Total = 17.4 lbs per corner

 

Stock Rotor = 10.5

Stock Caliper and Carrier = 8.8 lbs 

Total = 19.3

 

 

 

image.thumb.png.1eb3f9a398162bff3de77404ff4a23a0.png

image.thumb.png.29b924911bbc6d08cce51052b98cc62a.png

 

 

Don't worry, it has been thoroughly scienced, and I am more than happy to explain the process if there is concern.

These von-mises stress images have the deformation scale multiplied ~75x for visibility

image.thumb.png.7c4d9043cbe06cb4b5838a492d941efc.png

 

image.thumb.png.822077258863e84dc5fe8977cb31e00e.png

 

Timing = The prototypes are on the 3d printer now, so within a few days I should be able to test-fit to a car.  I still need to order a rotor and caliper for this purpose.

Once that confirms fitment, I will need to source the components.  I have a local source for USA made stuff, but the price is about 2x the overseas costs. Lead time is probably 6 weeks from order, so getting this done for Road Atlanta next year is possible but unlikely.  More likely March 2020 delivery to anyone who is intersted.

 


If you are interested, shoot me a pm.  If you have concerns or questions, post them here and I will do my best to address them.  

How much more life do you expect from consumables on this setup compared to stock?

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4 minutes ago, enginerd said:

How much more life do you expect from consumables on this setup compared to stock?

Hard to say.  

 

The pads are 20m thick (so only 4mm more) but have 2x the surface area.

 

The rotors are significantly more sturdy, and offer a larger "target" for my brake cooling to aim at.  

 

I'm hoping to have rotors last multiple races.  Pads already last 40-ish hours so that will hopefully increase as well, hopefully to a point I can feel comfortable running two weekends on the same set.

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1 hour ago, Huggy said:

You are correct, the pedal effort will be a bit softer.  Stock area is 2.8", and to keep the bias close the wilwoods are 2.45"

Trying to understand here...

 

Press the brake pedal with some amount of force and you create X psi of line pressure. If that acts on a BMW piston, you get Y pad pressure. If X psi acts on a the Wilwood pistons, since they have a smaller area, you get Z pad pressure where Y > Z

 

So doesn’t this mean you have to press the pedal harder with the new setup to get the same force between pad and rotor? ( I assume because of friction = Fn * mu, equal force means equal braking even with larger pad) 

So for equal braking, slightly shorter throw, with slightly more force required by your foot, for the new setup. 

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17 minutes ago, enginerd said:

Trying to understand here...

 

Press the brake pedal with some amount of force and you create X psi of line pressure. If that acts on a BMW piston, you get Y pad pressure. If X psi acts on a the Wilwood pistons, since they have a smaller area, you get Z pad pressure where Y > Z

 

So doesn’t this mean you have to press the pedal harder with the new setup to get the same force between pad and rotor? ( I assume because of friction = Fn * mu, equal force means equal braking even with larger pad) 

So for equal braking, slightly shorter throw, with slightly more force required by your foot, for the new setup. 

The new pads are farther away from the center of rotation and therefore have more leverage.

 

Stock calipers at 1600psi make 4675 lb clamp force resulting in 1980 lb wheel torque

Wilwoods at 1600psi make 4100 lb clamp force resulting in 1900 lb wheel torque

 

 

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Definitely interested. Did you consider an off the shelf rotor hat to save on machine work. Not sure what your offset is on your setup. Wilwood makes a rotor hat with a 1/2” offset for half the cost and no custom machine work. Similar to what Miata big brake kits are made with. Couple other manufacturers out there. Caliper to spindle adapter is part that needs to be custom made for sure. maybe lug style caliper to save on radial mount cost as well.
https://www.tssfab.us/product/universal-brake-hats/

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So, as someone running for the BOD and wanting to keep costs low, are you proposing a $1300+ brake package to your specific model vehicle that has already proved to be a top choice?

 

I understand that the rules now say you can, but are those rules not counter to what all of the criticism of the series has been as far as money spent?  Heck, we have a huge thread on saying we need to ban certain tires.....

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10 hours ago, hotchkis23 said:

So, as someone running for the BOD and wanting to keep costs low, are you proposing a $1300+ brake package to your specific model vehicle that has already proved to be a top choice?

 

I understand that the rules now say you can, but are those rules not counter to what all of the criticism of the series has been as far as money spent?  Heck, we have a huge thread on saying we need to ban certain tires.....

 

Total FRONT brake consumables cost for 2020, for 1 car:

 

Races:

VIR-S, VIR-F, VIR-N, Barber:

Pads = 4 x $200

Rotors = 8 x $32

Total = 1056

 

Forecasted cost with this kit:

Rotors = $100

Pads = 2 x $200

Total = $300

 

Difference = $756 (not including extra rotors used for track days)

 

Payback = 1.5 - 2 Years depending on total kit cost

 

That doesn't even take into consideration the brake rotor issues we suffer from (and have suffered from since 2015 - so no, its not "speed creep" causing it)

6N3Ep5B.jpg?1

wYa8EMn.jpg?1

These are after 12 hours of hard racing...  

 

 

 

There were no viable economical brake upgrades for the E30 under the 2x rule.  Options existed, but due to the extremely low rotor offset there were no off-the-shelf US 4x100 rotors to donate affordable consumables to.  Upgrading the caliper was NBD, but the only rotor option was the VW Corroado rotor, which was only marginally larger and still straight-vained, plus front-cooled if you order the affordable versions, and unsuitable for track use as a result.

Raybestos Brakes Disc Brake Rotor 1990-1992 Volkswagen Corrado 1.8L-96122R  - The Home Depot

 

Consequently, the options would require ordering rotors from europe, putting the spacer behind the rotor, re-drilling the rotors, or modifying the spindles, none of which I was willing to do for various cost or safety reasons.

 

So No, I do not think this is counter to champcar.  I think this is exactly a chumpy way of going about it.  I didn't just break out my wallet and order poop from google, I designed it myself, using parts from a series sponsor, I am offering it at a reasonable cost to other teams.  

 

IMO you come off as a bit of a jerk as a result of your post.

 

This is a perfect example of how sometimes spending a little more up front saves money in the long run.  

 

 

 

Edited by Huggy
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6 hours ago, Huggy said:

The new pads are farther away from the center of rotation and therefore have more leverage.

 

Stock calipers at 1600psi make 4675 lb clamp force resulting in 1980 lb wheel torque

Wilwoods at 1600psi make 4100 lb clamp force resulting in 1900 lb wheel torque

Thanks for explaining!

reduced pad force with increased pad area and thickness and more cooling sounds like a great recipe for increasing pad life.

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10 hours ago, Huggy said:

There were no viable economical brake upgrades for the E30 under the 2x rule.  Options existed, but due to the extremely low rotor offset there were no off-the-shelf US 4x100 rotors to donate affordable consumables to.  Upgrading the caliper was NBD, but the only rotor option was the VW Corroado rotor, which was only marginally larger and still straight-vained, plus front-cooled if you order the affordable versions, and unsuitable for track use as a result.


This is exactly why I had been assembling information to upgrade the brakes on my car. I don’t have the same problem Huggy has mainly because I’m not as fast and don’t generate the brake temps he does. I do see that pad and rotor wear is still significant. I had been getting ready to make this upgrade to reduce the cost of rotors and pads. Over time I believe I would save enough to pay for the upgrade in time saved rebuilding the brake system. Rotors would last more than one weekend, pads depending on compound would also last more than one weekend, and calipers would go more than a year without rebuilding. And when things needed replacement I would have options. 

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11 hours ago, Huggy said:

 

6N3Ep5B.jpg?1

wYa8EMn.jpg?1

These are after 12 hours of hard racing...  

 

 

 

Yep.  Got a stack of rotors that look EXACTLY like that.  I was able to improve the major cracks when I switched to Centric high carbon rotors.  I now get 2 races on the rears but the smaller cracks are all over the place up front after a 14 hour and must be replaced.  I'm paying about double on rotors than you are currently but to have less fear of a complete split in the rotor is worth it to me.  Not saying it won't happen but I haven't had a one split like that in about 3 years now, but then this year was an anomaly as we only ran snowpocolypse and the recent tropical storm (thanks Covid).  

 

Depending on what the team plans are with this car, we might be interested.  I'll know more before Road Atlanta.

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