# Sticky  Rear Brake Enhancements and Upgrades for the GTO (Holden)



## Xman (Oct 31, 2004)

Overview

This thread has been established to help owners obtain maximum performance from the OEM GTO braking system. It applies to the rear brakes of all models of Monaro-based GTOs and will cover the following topics.
1.	General
2.	Emergency Brake
3.	Brake Pads - Rear
4.	Rotors - Rear
5.	OEM Rear Brake System Upgrades for the 2004
6.	HSV OEM Rear Brake System Upgrades
7.	Dust Shield Modification For Improved Cooling
8.	Painting Rear Calipers OEM Red for the 2004

Dealing with corrosion, torquing wheel nuts, brake fluid suggestions, brake bleeding, and other general tips can be found in the companion thread on Front Brake Enhancements and Upgrades. 

Front Brake Enhancements and Upgrades for the GTO (Holden) - Pontiac GTO Forum


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## Xman (Oct 31, 2004)

*General*

This is worth repeating. Safety first!! Always block wheels, use jack stand to support a raised vehicle, and common sense. If you do not feel comfortable performing these maintenance actions, you should not hesitate to take your project to a qualified mechanic.

One of the first things I had to do learn with my GTO was how to lift it off the ground. This was my first vehicle with an independent rear suspension (IRS). I had a Camaro Z-28 before this and had learned the trick of driving the front wheels up on ramps to get enough clearance to get my floor jack under the limited ground clearance afforded at the front end and still have some room to pump the handle. Lifting the GTO rear end off the ground is different. Unlike a live-axle vehicle, the differential of the GTO’s IRS is not designed as a lifting point. I’ve included a picture provided by diverdan that illustrates the GTO’s jacking points. The yellow points are the centerline lifting points. There is a cast black stub just behind the rear differential that is the jacking point if you intend to take both rear wheels off the ground. As far as a sequence of steps, drive the front wheels up on the ramps and then jack/lift the rear first if the intention is to get all four wheels off the ground. The green points are the frame points suitable for jack stands. If your jack stand does not have a broad contact surface with the vehicle, consider using a block of wood between the frame and the jack behind the front wheels. My frame showed some slight deformation the first time I rested the front end on jack stands. The rear jack points are stout. I rarely jack or lift the car from the green points because it puts a twisting stress on the body. If you don’t have a high-powered impact wrench, don’t forget to loosen the wheel nuts before you get the wheels of the ground. 



I mention stainless steel brake lines a couple of times in this thread but do not address them specifically. Many aftermarket rear upgrade kits come with stainless steel brake lines but only include two for the rear. This practice has caught many GTO owners by surprise when they perform the install and find out they are two lines short. There are four flexible brake lines for the rear; two from the body to the IRS (usually not included) and two from the IRS to the brake assembly. Upgrading to stainless steel brake lines provide a definite safety enhancement from stock making the brake lines more durable and less prone to failure under demanding use. However, if you feel your brakes are not performing adequately with the 2005 or later brake system, bleed your brake lines to ensure all air has been removed before you make any determination you need stainless steel brake lines to improve pedal firmness. The GTO is notorious for being delivered from the factor with air in the brake lines and the bleeding process may have to be repeated 2 to 3 times to remove the air bubbles and restore pedal firmness. Bleeding the brakes is part of the companion thread covering the front brake system. 

There is also a wealth of brake system knowledge that can be found on the StopTech website for those that want to get into the details. 

http://www.stoptech.com/tech_info/tech_white_papers.shtml


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## Xman (Oct 31, 2004)

*Emergency Brake*

Call it the hand brake, parking brake, or emergency brake if you like, I’ll use the term eBrake. The GTO’s eBrake is a cable operated brake-shoe system located inside a drum machined into the large “hat” of the rear rotor. It is independent of the hydraulic rear caliper. Typically, the eBrake shoe friction material should not wear because they are applied when the vehicle is not in motion. It is common for there to be a significant amount of travel in a GTO’s eBrake lever. Sometimes an owner will pull the hand lever up & back significantly and the eBrake still hasn’t engaged. It still has to be pull up & back further to make effective contact. There is only one adjustment available to reduce the hand lever’s travel. There is a 10mm nut at the base of the eBrake’s under the flexible cover. Pull the lever up part way and pull the cover back to see it. It best to use a 10mm deep socket and the nut turns very easily. I did not have a 10mm deep socket so tried using a 10mm wrench. There wasn't much room between the console and the seat but I could slowly work it tighter. I found a 3/8" deep socket held just enough to turn the nut also. You don’t want to tighten the nut all the way down, so the 3/8” deep worked for me. After a couple of rounds of tightening, I found the engaged eBrake lever’s position to be much improved. 

A couple of things to note about the eBrake. I’ve tried to engage the eBrake while slowly moving. One of my shoes engages a click before the other. Also, I often get a loud popping sound upon engagement but the eBrake keeps on functioning. Most important, if your brakes are hot, e.g., having just dropped anchor from high speed or just come off the track, don’t set the eBrake. It can wrap your rear rotors and damage the ebrake shoes. Park on a flat surface and let the transmission hold the car while the brakes cool.


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## Xman (Oct 31, 2004)

*Brake Pads - Rear*

Unlike the front brake pads, which are interchangeable with Corvette C5/6 pads, the GTOs rear pads are unique and you must buy GTO-specific replacement pads. This is not bad news as the rear pads on the GTO are actually taller, longer, and thicker than the Corvette rear pads. Though the selections are fewer, there are several good options available. If you expect to be performing multiple high-speed brake applications, your pad choice becomes more important. The GTO’s rear brakes generate a substantial amount of heat. Getting the right pad compound that has a wide temperature range is critical. The stock GTO pads, the 2004 models in particular, are not suitable for high-speed haul downs. I was getting friction material build-up on the rotor surface which can cause wrapping of the rotor is not removed. The heat generated from a track session can be intense. After two 20-minute track sessions in the rain - even with the cooler temperatures and water coming off the track, my rear brakes were toasted. They smelled, smoked, were hotter than the fronts, and the rotors turned steel blue. The heat generation would have easily combusted paper that came in close proximity. After the track session, I inspected the pads and found them burnt and cracked. I could scratch ash-like material off the pads with my fingernail. Some owners have reported that their stock rear pads totally disintegrated from track use. If you track, you will also need to inspect your calipers frequently. The brake piston seals in the OEM calipers are not specifically designed for the high heat build up from track use (I’m not aware of replacement seal kits designed to withstand high temperatures). Some owners have reported melted seals on 2004 models. Converting to the vented 05 or later rear rotors can help with the heat generation as well as considering removing the dust shields (covered in later sections). Several owners in the US and Oz that say the performance gain from just going to the vented rear rotor and good pads is significant and will work adequately at the track. 



I am now using Axxis Ultimate pads on the rear. Stoptech.com has them reasonably priced. They have a wide temperature range and work well when they are cold as during normal street use but also are able to stand up to the heat generated from high-speed haul downs. Dedicated racing may require pad with a compound that can sustain high temperature operations. Racing pads actually have to be heated to their higher operating temperature before they work effectively and would be dangerous to have installed for everyday street use. The Axxis Ultimate pads are working well for me but are generating more dust than the stock or other ceramic pads. The extra dust, however, is easy for me to deal with considering the gain in stopping power. There are other performance pads out there. Make sure you do your research including using the search function on the forum. 

One aspect to be aware of when you are purchasing rear brake pads for the GTO is pad thickness. All GTOs use the same rear caliper but the 04s have a solid rotor that is 16mm thick and the 05s and later GTOs have vented rear rotors that are 18mm thick. Some manufactures list the same rear brake pad for all applications. Some know there is a difference and build the pad thinner to be compatible for all model years – some don’t know there is a difference. If you have the vented rear rotors, you may find fit a problem. Several 05 owners have fit 04 rear pads with no problems. I found the Axxis Ultimate pads were very tight. I used a clamp to get the caliper piston all the way in and then hit the caliper with the heel of my hand to get it over the pads. The wheel turned so I drove the car cautiously at first and checked for heat build up. I could feel the drag but the heat generation during normal driving did not get too high. After 3 days and 100 miles, the mpg readings went back up and I could feel the rear brakes were free-wheeling again. I was a bit concerned at first but now am glad with the choice. Since all parts are built with variation, be prepared for this issue. The GM part no. for 2005 and later rear pads is 92175205. For the price GM charges for the stock pads, consider buying a performance aftermarket pad. This will save yourself some money and give you better braking.


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## Xman (Oct 31, 2004)

*Rotors - Rear*

All Pontiac GTO OEM rear rotors are 286mm in diameter (11.2 inches) and activated by the same single piston caliper. The 2004 models are equipped with a 16mm thick solid rotor that is adequate for normal street use. The 2005 and later GTOs come with an 18mm thick vented rotor that is more effective at dissipating the heat generated by high-speed haul-downs. Even though the vented rear rotors are thicker, they do weigh less than the solid rotors, 27.5 vs 30 pounds for the pair. Rear rotors, even though smaller, can often cost more than the fronts because the rotor has an integral drum for the emergency brake. If you need to replace your solid rear rotors, consider purchasing the vented rotors for the performance gain. The OEM vented rotors (part# 9216-8567) from GM list for over $200; however, they can be purchased from several GM parts suppliers for under $150 a rotor including shipping. If you want more options and can wait a few months, DBA and PowerSlot are supposed to be coming out with 05 replacement rotors by the end of the year (2005). However, with the number of GTOs being limited, aftermarket manufactures have to give other vehicles with higher production numbers more priority. So don’t be surprised to see the availability of aftermarket rotors for the GTO sliding right due to the economics of supply and demand. 



If you upgrade your front brakes to a larger size, don’t assume you need larger rotors in the rear. The rear brakes contribute about 15-20% of all the braking force the vehicle. A more effective front brake system will cause increased weight transfer to the front and actually reduce the need for rear braking power on a GTO that remains with a stock suspension set-up. Even upgrading to tires with more traction will reduce the amount of braking the rears do because the tires will improve braking effectiveness and cause more weight transfer to the front end as a result. 

The following sections will discuss performance rear brake upgrades including converting 04 GTOs to vented OEM rotors, installing the larger OEM rotors used on the HSV Monaros, and removal of the dust shields for better cooling. The aspects of slotted and drilled rotors are covered in the companion thread on front brake upgrades.


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## Xman (Oct 31, 2004)

*OEM Rear Brake System Upgrades for the 2004 GTO*

For 2004 GTO owners, it’s an easy upgrade to the vented rotors used on the 2005 and later models. Alls you need is a pair of vented rotors. I was unsure that the thicker vented rotors would fit without modification. I was lucky to have a friend with a 2005 GTO come over and let me matched rear brake parts and do a rotor swap. Both vehicles had the same part numbers on the caliper and bracket castings with the only difference being the 05 GTO rear calipers are painted red and the brackets black. The 2 mm thicker vented 05 rear rotor fit on the 04 with all the 04 parts, had the same clearances as the 05 GTO, and still had plenty of space between the bracket and the 18mm 2005 rear rotor.



Your options for vented rotors are to buy new from a GM parts supplier, used from a salvage yard, or from aftermarket suppliers when they finally come to market. I upgraded my 2004 GTO’s brakes with used components and have watched the prices of used 05 GTO brake parts from salvage yards climb. The salvage yards are waking up and realizing that our "sleeper" cars have Corvette-based brakes. I have gotten quotes for as high as $500 an axle. $500 for the front is still a bargain compared to aftermarket brake upgrades. Paying $500 for the rear, however, does not make financial sense. With the 04 rear calipers being the same as the 05 (except for the paint color), you only need the rear rotor for improved performance. Finding vented rotors in a salvage yard can also be a challenge because they want to keep the IRS a complete unit for the hot rodders. If you find a yard that will let them go, you may have to pay as much or more than the front rotors, put still less than new. BTW, even if you buy new OEM rotors they will show rust after a few miles and look like the ones you get from the salvage yards. You can look for used parts on http://www.car-part.com/ and on http://www.ebay.com/ . I also know that many of the 2005 GTOs damaged in trail wrecks earlier in the year ended up in mid-west salvaged yards. You can try these companies to see if they have any components left. 

http://www.nordstromsauto.com/
http://www.gandrautoparts.com/
http://www.clevelandpickapart.com/

If you upgrade your 2004 front brakes to the 05 OEM brakes, see the last section in this thread on an inexpensive way to paint your existing rear calipers to match the GTO’s OEM Red. If you want a larger rotor in the rear, check the HSV OEM set-up in the next section.


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## Xman (Oct 31, 2004)

*HSV OEM Rear Brake System Upgrades*

The high-end Monaro GTOs from Holden’s performance division, HSV, come with 315mm diameter (12.4-inch) vented rear rotors compared to the 286mm (11.2-inch) rear rotor for our US GTOs. Many may have seen this upgrade from JHP which comes with calipers, stainless steel brake lines, and rotors. The calipers in this upgrade, and the ones used by HSV, are the same rear calipers used on our Pontiac GTOs. The bracket is different to allow the caliper to be positioned further from the center to mate with the larger diameter rotor. You can also buy the 315mm rear rotors from DBA - Disk Brakes Australia (www.dba.com.au) via a US distributor like www.Man-a-Fre.com (part # DBA049). Man-a-Fre also carries the bracket to use your OEM caliper to mate with it (part # BKT049). Prices for this combination are $110 to $170 for each DBA rotor, depending on the grade and surface configuration, and about $180 for the brackets. 

 

The HSV rotors are a bolt-on install. The only issue that has to be considered for this set-up to work are the brake lines - they now have to reach 0.6 inch further out. You have three options; purchase longer rear brake lines from an Australian supplier, special order stainless steel lines from StopTech.com, or continue using stock brake lines. There is already slack in the stock brake lines to account for caliper removal when changing brake pads. If you unclip the brake line from its mounting bracket on the dust shield, you will have enough play to get the caliper over the rotor and onto the bracket. You may have to bend the metal tube slightly toward the mounting plate to reinstall the clip.

I choose not to go with the 315mm rear rotor as my first upgrade step. I wasn’t sure I needed the increase performance. Other GTO owners have reported adequate performance with the OEM rear brakes and, even though Corvettes are lighter vehicles, the C5 Z06s have 11.5 inch rear rotors so I felt the OEM 2005 vented rotors should be suitable. I concluded if I found out later that I needed the larger diameter rear rotors, I could add them the next time I needed new rear rotors.


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## Xman (Oct 31, 2004)

*Dust Shield Modification For Improved Cooling*

Both the front and rear rotors on the GTO have dust shields. The front dust shields are minimal, don’t cover the rotor very well, are flimsy, and take about 30 seconds to remove. I’m not sure why Holden even bothered to install them in the first place. The rear dust shields are just the opposite. They cover the rotor like a glove and are stout. If you look at the relationship between the output vent in the rear rotor and the rear dust shield you will notice that they are in close proximity. From a thermal dissipation perspective, this is not an efficient design. The intake for the rotor’s cooling vents is in the inside center of the rotor. The dust shield blocks the intake area causing the cooling air to be drawn in next to the outside diameter where the rotor vents. This sets up a condition called hot air ingestion. It’s not critical for normal street use but removing the rear dust shields can dramatically increase rear brake heat dissipation if you track you GTO or need maximum brake performance during other high speed situations. Corvettes and F-Bodies don't have shields around their vented rear rotors either. I wanted every braking advantage I could get from my GTO so I set out to figure out a way to remove the shields. 



Removing the rear dust shield is not a wrench turning modification and will require about a half day of your time. It wasn't hard to do and I was able to do it without taking off the emergency brake components and hub. You will have to remove the caliper and bracket to allow the rotor to be removed. As shown in the pictures, I used a hand-held saber saw with the base positioned at 45-degrees for the initial removal step. Tilting the base was important because it allowed the saw to rest against the shield and facilitated cutting. The only part I had to be watchful of was the cable on the bottom going to the eBrake and the brake line on top. I placed a rag around the hub to reduce the chance of getting metal debris around the axle seal. You need to leave the 12 o’clock portion of the shield to support the brake line. After I cut dust shield off, I used a file to clean the burrs up a bit. This step is really all that is needed for improved performance. 





I wasn’t satisfied, however, and wanted to get a cleaner mod by getting the entire dust shield off down to the rotor’s intake vent. I accomplished this with an air impact hammer and a chisel bit. After sharpening the bit, I found the rest of the shield came off clean and easy, like using a can opener. The closer I had cut to the inside edge of the shield the easier the chisel trimmed the excess. What was really nice is the chisel action folded the exposed lip down against the shield backing and left no sharp edges. This mod turned out better than I expected. I had considered using a high-speed grinder to remove the lip but the air hammer worked cleanly on the first try. 



I never had an issue with my Camaro not having rear dust shields nor have I with my GTO since the mod. I don’t have the shields on the front either. This modification also contributes about a 2-pound savings to anyone's weight reduction activities.


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## Xman (Oct 31, 2004)

*Painting Rear Calipers OEM Red for the 2004*

This section applies to 2004 owners that desire to paint their rear calipers to match the color of an OEM 05 or later front calipers. Note, this is an aesthetic only mod and obviously not done for performance. If you are just using your car on the street, this should work fine. If you track your GTO a lot, you may want to skip this mod as the paint may darken from high heat exposure. 

I purchased 3 cans of paint to do this job. To match the later GTO paint scheme, the brackets should be black and the calipers a dark red. I used black engine block paint for the bracket – Dupli-Color High Heat Black DH1602. This paint has a ceramic additive and is advertised to be good to 1200 degrees F which is much higher than the typical 500-degree engine block paint. For the caliper, I used two coats of Dupli-Color High Heat Red DH1602. It is still a bit brighter than the GTO red but I used it as a base coat. I found International Harvester Red is a close match to the GTO red and used it as a top coat to the Dupli-Color Red. Krylon makes an International Harvester Red (Krylon 1818) for farm equipment that I purchased at O'Reilly's. 



I painted just the outer, visible section of the caliper to make the job easier and to have less clean-up if I needed to remove the paint later because it darkened from the heat generation. Besides less to paint, painting only the visible outside of the caliper made the job easy because I could paint the caliper on the car and did not have break the integrity of the brake system. I used a large section of cardboard to shield the car and taped the caliper to the cardboard as I masked it. Make sure you let the paint on the caliper dry several hours, at least 4 if not overnight. Otherwise, the finish will get nicked very easily when you reposition the caliper while finishing your brake work. So far, this paint combination has done well.


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## GTOooo (Feb 5, 2006)

Awesome posts! I'm shocked nobody else has replied before me. Keep it up, I love reading these kinds of posts. I have an '06 so I don't have a lot of the issues that the '04s had but this post convinced me not to upgrade the rear pads. I'll be looking in my other posts for more advice on front pads. 

Thanks Xman!!!


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## Tacmedic (Feb 24, 2006)

*That was...*

.. heck of a post. Thanks. It was worth the read just for the ebrake info. I am headed to the garage to get my 10mm socket and a wrench:cheers


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## 1gto (Dec 3, 2006)

Thanks man that was intense reading great job.


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## michaelescobar1606 (May 28, 2009)

awsome post man!! thanks alot for the info !!!! keep up the good work


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## bluefox (Jul 29, 2010)

Great post thanks!


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## firebird (Feb 6, 2011)

great post!!

for the eBrake, can we take that round plastic cover off, which is located between the passanger seat, and how?? 

also do 05/6 have an adjuster knob at the rear under the rotor like most vehicles??


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## billyjack2 (Oct 21, 2011)

I know I am bringing an old post back, but where can the rear brake caliper bracket be found today? I have been searching and cannot find one.


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## Aussie_Cruiser (Nov 2, 2012)

The pics aren't working for me?


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