HD12 Front Brake Kit
This is being re-posted to replace the previous thread. Some links and pictures are lost--will try to get it all working again.
Originally posted March 5, 2008 (with updates)
GM B-BODY HD12 FRONT BRAKE ROTOR KIT
Pricing and specifications of HD12 Rotor Kit and price, specifications or availability of any special offers subject to change without notice.
If you have followed the Impala SS Forum for awhile, you are probably aware that a true “upgrade” of the stock front brakes was one thing that was frequently coming up short of the hype.
The HD12 Front Brake Rotor Kit changes all that, and is the missing link in the “Bolt-On” front brake upgrade category. The development of this brake kit has been a long-term goal that has finally come to fruition. The prototype kit has exceeded all expectations, and the project has moved to production status.
In addition to it's use in competitive events where lots of braking is involved, this kit is ideal for our heavy cars, and especially for wagon, Fleetwood, and 9C1 applications when the smallest OEM (15") wheels are being retained.
NOTE: Fit & clearance are verified ONLY for the identified OE iron calipers when HD12 rotors are used with OE 15" steel or aluminum wheels - all other combinations of aftermarket aluminum calipers with HD12 rotors are the responsibility of the vehicle owner or installer to confirm proper fit & clearance.
The HD12 Front Brake Rotor Kit is rotors & hats ONLY, and does not include hubs*, calipers, pads or tone rings (more tone ring info in Q&A post below)
*Requires use of KORE3 HD Billet Hub Kit for GM tall-spindle - PN 10149. Hub kit may now be ordered at same time as HD12 kit as a single purchase, or hubs may be purchased separately by calling 800-357-5467 or online at www.kore3.com
See combined rotor/hub kit pricing information below.
HD12 FEATURES MORE MASS WHERE IT COUNTS, IN THE PAD PATH
- 32.5mm DBA** rotor versus 26.5mm OE rotor – 23% greater thickness (ie., stock rotor is 81% of HD12's thickness)
- 302mm, same diameter as OE rotor
HD12 FEATURES SUPERIOR VENTILATION
- Directional vane design versus OE straight vane rotor
HD12 ROTOR SURFACE TREATMENT
- Plain or slotted (extra charge)
HD12 FEATURES BILLET ALUMINUM ROTOR HAT
- Slip-on design, separate from hub for easier brake servicing without disturbing wheel bearings
- Correct offset for GM caliper mount
- Reduced weight, improved thermal characteristics
- Hat & Rotor assembled with 12 NAS fasteners
- Black anodized finish on hat
- HD Rotors are pre-assembled and ready for installation on KORE3 hubs - ABS tone rings transfer from take-off rotors
- Clears all OE 15” or larger wheels used in 91-96 production – 5x5 pattern is standard, or 4.75” pattern available special order
- Fits all 91-96 GM B-body and D-body vehicles with ABS, also fits 1990 and earlier 12” rotor GM “tall knuckle” applications
- Plain rotors are black zinc plated for anti-corrosion and pre-finished for proper break-in using the “Flex-Hone” process and GWR finish treatment mini-kit included with HD12 kit.
The HD12 Front Rotor Kit REQUIRES use of:
- Calipers from 93-96 Cadillac Fleetwood Brougham J55 heavy duty (wide caliper/wide rotor) brake system (limo & commercial chassis)
- See Q & A in next post for specific caliper PN information
- Brake pads meeting FMSI D614 (Impala SS spec) or FMSI D52
- Link to Wilwood GM III caliper - PN 120-5289
- Link to Wilwood GM D52 dual-piston caliper - PN 120-10936 - <<<NEW INFO, added 12/17/09
- Link to twin-piston caliper for HD12 and standard rotor fitments - MUST inform supplier of rotor width being used--for HD12, use WIDE version of this caliper
NOTE: 9C1 calipers for 94-96 Caprice MAY work, however pad choice can determine whether they fit or not--these are same casting as Fleetwood J55, but use a slightly taller piston, which reduces pad to rotor clearance. Any pad with shims, which includes the majority of all DOT-approved pads, will not likely work in combination with a 9C1 caliper on an HD12 rotor.
Wilwood has D52 pads with no shims (primarily for race use when noise isn't a consideration) that may allow 9C1 calipers to be retained with the HD12 rotor. This has NOT been confirmed.
The replacement of 9C1 calipers with the "correct" J55-spec calipers listed is a quite inexpensive option--see PN's in the Q&A post of this thread, linked vvv below vvv.
See the >>>"Question & Answer" page<<< below for more detailed information.
For photos, please contact me directly, until I can post any new photos to Forum.
HD12 ROTOR and ROTOR/HUB KIT COST:
(pricing in US Dollars)
- $525.00 for HD12 kit (add $40 for slotted rotors)
- $839.50 for combined HD12/KORE3 HD hub kit (add $40 for slotted rotors)
- additional individual component price information listed in Question & Answer section
NOTE: HD hub kit - combined kit price based on use of ARP M12 wheel studs, includes stamped steel dust caps, new wheel bearings and grease seals. Billet dust caps and ARP 1/2" wheel studs are optional - inquire.
Contact Bill Harper for full ordering details:
- Direct E-Mail [email protected] (preferred)
- Phone 770-359-9207
- PM on ISSF Navy Lifer
- Two options
1. Full payment prior to delivery includes free shipping
2. Pay 50% of total--deliver kit, with payment of balance extended for up to 6 months, with shipping cost added.
- Personal check or Money Order (US Dollars) accepted. PayPal available with additional 4% processing fee.
No warranty, expressed or implied, is applicable to the HD12 Front Brake Rotor Kit. Suppliers of the components that comprise the kit have their own policy with regard to warrantable conditions. Any issues arising from a claim for any defective HD12 brake component will be evaluated and responded to on a case-by-case basis.
**Rotor rings are supplied by Disc Brakes Australia
Questions & Answers About The Hd12 Front Brake Kit
QUESTIONS & ANSWERS ABOUT THE NEW HD12 FRONT BRAKE KIT
DOES THE HD12 KIT INCLUDE HUBS?
A. Hubs are normally purchased separately - the hubs ship from KORE3. It is (now) possible to order the HD12 kit and hubs together, from me, for a special price.
IS ABS FUNCTION MAINTAINED (91-96 B-BODY APPLICATIONS)?
A. Yes, the ABS tone ring from an existing stock rotor must be transferred to the HD12 hub. The ring can be installed with Loctite or equivalent Sleeve & Bearing adhesive, or modified to secure to the hub with set screws (drawing available). Modified rings from KORE3 require customer-supplied core tone rings that are suitable for modification (i.e. not damaged).
DOES THE HD12 KIT AFFECT VEHICLE FRONT TRACK WIDTH?
A. No – the hub and hat are designed as a package to maintain stock front wheel positioning.
WHAT GM CALIPERS WILL FIT THE HD12 ROTOR?
A. 1993-1996 wide-body calipers from the Cadillac Fleetwood HD (RPO J55) brake system will fit the HD12 rotor.
RPO J55 - Cad Fleetwood (D) limo chassis (HD brake system - "wide body" with thick rotor, no ABS)
ACD Durastop reman
19140904*- CALIPER (L)
19140905*- CALIPER (R)
includes caliper bolts, sleeves and bushings, pad clip, hose seal gaskets
*has core charge
242-2044* or SE4678*- CALIPER (L)
242-2045* or SE4677*- CALIPER (R)
includes caliper bolts, sleeves and bushings, pad clip, hose seal gaskets
*has core charge
(pads not included with any of these calipers)
- Reference to "no ABS" for J55 Fleetwood calipers refers to the production application--NOT whether the ABS function is maintained on B-body....IT IS, as long as the tone ring is transferred to the new hub and ABS system is intact and functional before upgrade.
- Minor clearance grinding of caliper or knuckle REQUIRED with some Fleetwood caliper / knuckle combinations.
- SSBC Quick-Change aluminum calipers are NOT compatible with the HD12 Brake Kit.
ARE SLOTTED OR CROSS-DRILLED HD12 ROTORS AVAILABLE?
A. HD12 rotors are offered plain, with an exclusive ‘X-SLOT’ pattern, or with the DBA 6x6 Wiper Slot pattern - there is no cross-drilled version offered
The HD12 Brake kit is intended to place maximum mass in the pad path at stock rotor diameter. Cross-drilling reduces mass unacceptably, and creates greater potential for stress-crack propagation, and WILL NOT be an option for the HD12 kit.
Good photo of HD12 X-slot rotor installation
WHAT BRAKE PADS ARE COMPATIBLE WITH HD12 ROTORS?
A. Any brake pads that are defined as fitting the 1994-1996 Impala SS (FMSI 7492 D614 spec) are acceptable for use with the HD12 rotor. Any FMSI D52 spec pad will also fit.
What is more critical is that the pad choice reflects the intended vehicle use, as it will have a significant effect on brake dust, noise, and potential for accelerated rotor wear.
WHAT HD12 BRAKE KIT SERVICE PARTS ARE AVAILABLE?
A. The following parts are available:
- Rotor (RING ONLY, NO HAT) – Left/Right, directional-vane, includes new lock nuts & washers
a. PLAIN $210 per pair (black zinc plated)
b. X-SLOT $250 per pair
c. 6x6 Wiper Slot $250 per pair
- Rotor Hat $165 each - fits standard KORE3 HD GM "tall spindle" hub
- Rotor Hat with modified/dual pattern $170 each - for 4.75" stud pattern, using special order KORE3 hub
- Rotor Hat with thicker flange & modified pattern $175 (for 15" OE steel wheels when using Wilwood D52 calipers)
(See "Other Kit Options" below)
- Fastener kit (new nuts & washers only) $17.50 for 2 rotors (hat bolts are reuseable)
- Hat bolt kit (new bolts only) $2.25 each, $25.00 per hat (12 bolts)
- Tone rings, modified with set screws, $50 per pair (Requires core tone rings - $20 credit)
NOTE: Order from KORE3
CAN HD12 ROTORS BE USED WITH OTHER HUBS?
A. No, correct caliper/pad/knuckle alignment requires the use of the KORE3 billet hubs which the HD12 Brake Kit was designed to work with.
ARE LONGER WHEEL STUDS AVAILABLE?
A. Yes – pressed-in or threaded stud options are available.
Threaded wheel studs are ½-20 instead of M12-1.5 thread. All studs are supplied by ARP. Standard 12mm studs included in the KORE3 hub kit are longer than production wheel studs.
WHAT OTHER KIT OPTIONS ARE AVAILABLE?
A. The HD12 Brake Kit can be used on any GM “tall knuckle” application, with either 5” or 4.75” wheel stud pattern. 4.75” stud pattern and hub pilot diameter hubs for the HD12 kit are available by special order from KORE3. HD12 compatibility requires knuckles from any 12” rotor application – B-body wagon or police vehicle (5x5) from 1977-1990, or any 1991-1996 B-body.
This means that the HD12 system can also be used on 70-81 F-body (Camaro/Firebird), 75-79 X-body (Nova and similar), 73-77 A/G body (Chevelle, Monte Carlo and similar) with the proper knuckle conversion. Wheel size must be 15" minimum, and wheel clearance is, of course, the responsibility of the buyer. Thicker rotor hat may be required depending on caliper and wheel being used.
IS ANY MODIFICATION REQUIRED TO INSTALL HD12 BRAKES?
A. No - HD12 hubs are installed exactly like stock rotors. The rotor/hat assembly slips over the hub, followed by the caliper/pad unit.
WHAT IS THE MINIMUM THICKNESS LIMIT OF THE HD12 ROTOR?
A. The discard thickness is 30mm (1.18”).
ARE HD12 ROTORS SUITABLE FOR TRACK USE?
A. Yes- HD12 rotors are suitable for track event use.
WHAT IS THE BENEFIT OF USING THE HD12 ROTOR KIT?
A. The HD12 rotor offers significantly greater thermal management capacity over ANY existing OE B-body rotor. Temperature at the pad/rotor interface remains lower due to more effective and efficient heat transfer, which in turn keeps brake caliper and brake fluid temperatures lower, significantly raising the brake fade threshold and extending the brake performance envelope to ensure the car stops as well the tenth time as it does the first.
With the HD12 Rotor Kit, more aggressive pads (for track use as an example) which can easily overwhelm stock brakes due to extreme heat in the rotors, pads, calipers, and fluid, can now be used to far better advantage. For street use, this translates to having extremetly durable brakes under virtually any conditions that may arise.
Please post your questions that may not be addressed here!
What kind of clearance does the HD12 kit require? Other KORE3 kits provide a template, not sure if there is any other way to specify that required clearance.
From post #1
- Clears all OE 15” or larger wheels used in 91-96 production with OE (iron) calipers – 5x5 pattern is standard, or 4.75” pattern available special order
HD12 isn't a KORE3 kit - it does use parts produced by KORE3.
Since it uses an OEM caliper, there are no wheel clearance issues that would warrant a checking template.
Trouble is I'm looking at using a non-OEM rim. Perhaps I should take this offline.
They are 18x9.5 with a -4mm offset and 5.031" backspace, might even go with 18x8 with a +2 mm offset and 4.517" backspace up front though if clearance is going to be an issue with those I'll just ditch the staggered approach altogether.
Well, if the wheel can be checked on your car with stock brakes and clears, it will clear with HD12, too. In other words, the caliper profile is the same as production B-body front brakes.
Backspace and/or offset isn't the real issue, with the numbers you're citing--it's inboard-side (ie. back of wheel) center/spoke shape that has to be dealt with.
updated caliper applications for HD12
Wilwood has introduced a twin-piston floating caliper for direct fit to both 1" and 1.25" rotors.
Just another option for the B-body, with either standard or HD12 front brakes--front application piston diameter is 2". Like other Wilwood products, no dust seals, but there are enough Wilwood calipers in use today to demonstrate that they are street-worthy, just not full DOT "spec".
Current information indicates the standard finish is red, optional colors TBD.
PN info in thread - universal mount, same caliper used on both sides
NOTE: 100% fit/clearance checks on B-body knuckle have not been verified--if there are ANY issues, it would only be a matter of minor clearancing for use with 15" wheels - this is a buyer responsibility.
thicker hats for 15" OE wheels available
As mentioned in this post, the use of OE steel 15" wheels has presented a potential fit issue if someone decides to combine HD12 brakes with Wilwood D52 twin-piston calipers.
To accomodate such situations, a limited number of thicker hats are being produced for those who intend to run 15" steel wheels. Depending on demand, more can be produced, but it appears that most who may use this combination of rotor & caliper are already using larger wheels, which would call for the standard-thickness hats now used on the HD12 kit.
Cryogenic rotor treatment for HD12
Currently available are a limited number of HD12 rotors in all 3 variants (plain, standard DBA 6x6 slotted, and X-Slot). A total of 18 rotors remain from the cryo batch just processed.
Cryo treatment adds $50/pair to current cost of any HD12 kit.
Rotor rings are available separately to existing HD12 owners--special pricing for replacements runs to end of October.
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