1994-2002 [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
Folks,
I've recently replaced the rear rotors and pads on my wife's 2007 9-3 Sport Combi at 24,000 miles. The many posts I've found on this topic, plus the responses to my initial queries are greatly appreciated.
Herewith are some lessons learned during and subsequent to the experience.
1. The caliper is attached by 2 E-18 Torx bolts that are torqued to approximately 100+ lb ft and locked with Permatex Loctite Ble. While you might be able to break torque and unscrew the bolts using a 15 mm wrench with a closed, 12-point racheting end, I recommend that you plan ahead and order the E-18 Torx socket with a large (1/2 inch) drive. Plan on waiting a day or two to get the socket, because it is likely that the parts shop will have to order the socket from a warehouse.
2. It is very likely that you when using the E-18 Torx socket on the upper caliper bolt, you will not be able to get good tracking on the bolt unless you use one or more wobble extensions. There are two obstacles to using a wrench wither directly on the socket, or to using regular extensions. The first is a trailing arm bolt that sits almost directly above the are where the E-18 socket drive end needs to be. The second is the rear spring. Any socket extension has to pass through the rear spring, which almost guarantees that a coil will be in the way of a straight extension.
3. If you don't have a brake piston retraction kit, forget about the job. Those little cubes that operate off a 3/8" socket drive do not fit the holes in the ATE caliper piston. Some auto parts stores will rent you the retraction kit. If you're planning on keeping the car awhile, spend the $50 and get the retraction kit. You can find them on major mechanic's tool sites, eBay, and Amazon. Prices vary.
4. Whenever the rear pads go out, you'll probably have to replace the rotors. The mechanics at my local SAAB dealer told me that they routinely replace the rotors because the rotors are so thin that turning them usually puts their thickness below minimum. Besides, there are no wear indicators on the rear pads, so by time you hear the grinding, your rotors are probably scored and in need of replacement.
5. The parts manager and the mechanics at the local dealer also told me that the accelerated wear on the rear pads is due to their involvement in the passive rear wheel steering and stability control. While there has been much discussion on whether and under what circumstances the rear wheels castor towards or away from the direction of the turn, there appears to be agreement that the rear wheels toe in under hard braking to provide addition traction. Judging by the position of the calipers (rear of rotors) and the wear pattern of the pads (inner pads wear out well before the outer), this seems reasonable. Indeed, the parts manager called me "old school," when I stated that the front pads should always wear out before the rears if the braking system is designed and is working properly. I have also heard from colleagues who have other vehicle makes with stability control and passive steering who have similarly experienced early rear brake pad wear, and who have been told by their mechanics that this is due to the involvement of the rear brakes in traction and stability control.
6. After many years of working on the junky old Teves-designed front calipers on my 1985 900T - I would say that everyone should have that experience at least once, but I'm not that sadistic -- I figured that never again would I have to deal with calipers that use a secondary piston on the main caliper as the parking brake. I suppose that in my world, "never again" translates to 22 model years. ugh.
posted by 70.187.23...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
