Catera Braking Upgrades

UPDATED 11-21-2011

The Catera's brakes are good and compare well with equivalent sport sedans of its day but they can be improved. Luckily the last ever Pontiac GTO and the Catera share some Opel ancestry. The dual piston front brake calipers, mounts, & hoses from the 2004 Pontiac GTO are a direct bolt-on to the Catera. Buy only the 2004 calipers. The GTO's front brakes were redesigned for 2005 thru the end of production and will not fit the Catera. Those cars got bigger, more powerful brakes to cope with all that LS V8 HP. Still, the stock 2004 GTO dual piston calipers are a big improvement over the Catera's smaller single piston units.

Load them with C5 Corvette (1997-2004) high performance brake pads. The Corvette pads provide a larger friction zone than the GTO's pads. We learned of this from the GTO crowd. The choice of pads is up to you. Their pros & cons are too varied to cover here. No mods to the calipers, their mounting brackets, or the steering knuckles they attach to are necessary as they are an exact fit. The GTO's front brake hoses are needed though because they're longer. The location of the larger caliper's hydraulic fitting would cause the Catera's shorter hoses damage at full steering lock.

The GTO's front discs will not fit the Catera due to differences in their hubs. Their lug bolt patterns are different and would mean adapting the Catera wheels to fit the GTO hubs, or visa-versa. Besides, the GTO discs are no bigger diameter-wise than the Catera's so there really would be no mechanical advantage, ergo no performance gain, by adapting them.

When first used on racing cars the cross-drilled brake discs were a great improvement over the standard solid or vented discs. But when used on street cars they would frequently fracture. During a race these special discs are used hardest before entering turns. Luckily they get a chance to cool on the straights, fed air by ducts directed at them. They were often used for one race and then discarded. Hot-Rodders would imitate the pros and drill their own discs at home but found that they would often fracture under use. At first they used solid discs. Drilling the later vented discs, which have internal passages through which air passes and help cool the discs, brought a new wave of fractures. DIY drilling of both types would compromise their structural integrity if drilled in the wrong spots. Not expert with material they were drilling they spaced the holes too closely, or in a pattern pleasing to the eye but structurally unfeasible.

Another reason for the fracturing was the disc material itself. Hot-Rodders would use junkyard parts or in today's parlance, recycled parts. Not necessarily junk but to say used factory pieces. Parts already stressed from street use. Believe it or not, street driving is harder on brake components than racing. Stop & go driving builds heat with little time for cooling. Standing in traffic with the brakes applied concentrates heat on the disc area under the pads, super-heating the discs at that spot. These used street discs, already having gone through countless heat cycles, would expose hidden stresses when drilled, leading them to warp and fracture.

Also, drilling obviously means less metal to absorb the generated heat. This excess heat would be transfered to the calipers and boil the hydraulic fluid in the calipers resulting in reduction of line pressure. Brake fluid is hygroscopic, meaning it absorbs water. Brake fluid hot enough to boil will cause any trapped water to turn into steam bubbles, which compressed when the pedal was depressed, lowers the line pressure at the discs. Remember pumping the brakes? We used to do that because of boiling brake fluid. With ordinary smooth faced discs, repeated hard braking will super-heat the pads creating a super-hot gaseous layer (aka plasma) between them and the disc surface. This gaseous layer eventually lifts the pads off the disc contributing to the "brake fade".

The aftermarket saw a hole in the performance braking niche and filled it with new racing inspired discs.  Vented cross-drilled discs are very efficient since the holes allow the plasma to exit through their internal passages. Computer designed hole patterns reduce the chance of fractures and internal vane patterns are designed with drilling in mind. Another benefit is the aggressive texture the holes present to the pads. They give the pads something to "bite" into. An added plus is a reduction in unsprung weight that helps by reducing the inertia of the tires, wheels hubs, and control arms. Doesn't sound like it would be much but every gram helps.

Performance discs come in different flavors:

• A drilled disc allows plasma to escape from between the pads and the disc's surface. It's drilled clean through from the outside to the inside face. With a solid disc the gases expand into the drilled holes and escape after the pad is cleared. In the case of a vented disc these gases exit via its internal passages.
  

• A slotted disc has radial trenches that extend from its center to the edge, across the face of the disc. Some in a scythe shape, others straight. They expel plasma and prevent the pads from hydroplaning on the disc's surface when braking in the rain by siphoning water away.
  

• Dimpling is a partial drilling that doesn't fully penetrate the disc. It leaves a surface similar to a golf ball with a drilled look yet still allows some space for the plasma to expand, helping reduce brake fade. Less efficient at water and plasma expulsion than holes or slots but better than smooth discs.
  

• Combinations exist, including drilled & slotted, and dimpled & slotted which might seem better than drilled or slotted or dimpled only but the jury is still out regarding any improvement over them.
  

Drilled, dimpled, and slotted discs give the pads a more aggressive surface to grip. Slotting and dimpling's advantages over holes are that they maintain the discs' structural integrity. The holes, slots, and dimples all clean the brake pads by scraping them of any glazing. Of course, they also wear the pads faster making replacement intervals shorter. After all, you don't get something for nothing.

The Catera's rear brake calipers use dual opposed pistons that, with premium brake pads, are probably better than the GTO's rear single piston calipers which are similar, if not identical, to the Catera's fronts. Midway through the Catera's 2001 model year her rear discs were upgraded from solid to vented. Vented discs aren't the same as drilled performance discs. The venting is internal and radial. The vents work with the discs' rotation to force air from center to edge. "Wide mouth" rear calipers are required to accommodate the new vented discs' extra thickness. These were factory parts and will fit all model year Cateras. Able to run cooler under hard braking they will fade later than the stock brakes. High performance rear discs, solid or vented, drilled, slotted, or dimpled are also available from the aftermarket, as are the "wide mouth" calipers.

Now honestly, all these holes, slots, and dimples aren't really necessary. Today's OEM discs can handle more heat than ever before without damage. Their iron alloy has come far in its ability to handle the disc's quick heating and cooling cycles. New brake pad compounds (metallic, organic and ceramic) handle higher temperatures and the latest hydraulic fluids have higher boiling points. The pad material itself is slotted to further improve cooling and vent plasma. So why upgrade the brakes? Lets be honest, we all want to modify our cars, put our stamp on them, make them better than the next guy's. It sounds silly but I'm a late-braker and get a secret thrill showing other drivers on the road how deep I can go into a sharp turn or full stop before showing them my brake lights.

Want better feel at the brake pedal? Order aftermarket steel braided brake hoses. Our cars' vacuum assisted brakes dull some of the feel but braided hoses can help. Stock hoses are made of Nylon or Teflon reinforced rubber that swell when braking pressure is applied. The steel sheath surrounding braided hoses resists swelling for a better feel at the pedal and more pressure to the calipers. To set up your entrance into the next turn on that twisty mountain road or at the track you need to finesse the brakes. Maintaining your speed into that entrance means late braking and trailing them through the first part of the turn. You need your foot to feel how much pressure the brakes are under and how close you are to the ABS threshold. The braided hoses provide the pads with exactly the pressure you want them to have, while giving your foot the feedback you need. Definitely overkill for most of us but those original rubber hoses are pretty old by now and need replacing anyway so why not upgrade?

Now we come to the braking system's weak spot. The Electronic Brake/Traction Control Module (EBTCM). It's the computer which controls the ABS and Traction Control functions of the brakes. Its failure causes the ABS and TC systems to quit and activates their dashboard alarms lights. The OBDII code is U2108 and in addition to the ABS and TC its failure kills the speedometer, odometer, cruise control, and power steering's low speed variable assist all of which take their speed and distance readings from the EBTCM. The Sport mode will also be affected. The loss of speed and distance data will let the engine hit the redline cutoff without shifting to the next gear. The module can be removed and sent to repair with no affect to normal braking but it's a bear to remove. Module Masters fixed my unit and added a patch to prevent the original failure from occurring again. Until it's repaired an alternative to the speedometer will be necessary or you'll just have to slow down. I used my GPS unit which displays my speed on its map.

As I said at the start, The Catera's brakes are already pretty good. While my was ABS down I had occasion to practice my old school braking technique during some emergency stops. Since the ABS isn't normally able to be disengaged I had the rare opportunity to compare unassisted versus ABS braking. I'm not totally impartial where the Catera is concerned but I am very partial to living. When a U-Haul truck pulled out of a side street in front of me I laid on those unassisted brakes for all they were worth, pumping the pedal when the tires felt close to locking up. No contact but it was a close thing. I'm pretty sure the ABS would have given me a wider safety margin but I know that without the GTO calipers and dimpled & slotted discs I wouldn't have been able to drive away from that one. Thankfully the EBTCM has since been repaired and reinstalled.

Even if you have no interest in "spirited driving" and only use your Catera for family transport and commuting isn't it still worth it to improve your stopping power? The GTO calipers alone could save you from an accident by reducing your stopping distance by a few yards. Two things I never skimp on, whether for my car or motorcycle, are tires and brakes. My tires keep me pointed where I want to go and my brakes stop me when I need to. To me they're the most important parts of any vehicle.

Another Brake Upgrade report. I've made some changes to the front brakes again. My 2001 Catera Sport still has the 2004 GTO calipers but I've gone back to the performance discs (this time just slotted), and the C5 Corvette pads. Brake Performance was having one of their many sales and since I needed new pads I splurged and bought the slotted discs too. I went with their Premium Semi-Metallic pads. Dirtier and rougher on the discs but I prefer avoiding collisions over longer disc/pad life and clean wheels. The stopping power is quite amazing and a big improvement over the Catera disc and GTO pad set-up I had been using. I highly recommend them.