Now that my 900 has bigger and wider rims.. I want to look into upgrading the brakes. I know they are old and probably not as good as they once were.. so rather than flushing fluid and changing pads, I might as well upgrade.
I have heard that brakes from the 9000 are larger and will fit the 900 (it is the same basic suspension) but what do I need? There is a 9000 in the local yard I can pull parts from.. but I need to know what to grab
Well, I get flamed by the internet experts for writing this on Saab forums, but I don't think it's worth it, even for a track car. I did this on one of my cars, in part, because I found a set of 9000 rotors/calipers at the pull-a-part that were barely used/very cheap, and my car was in a million pieces already so doing the swap was pretty easy. Driven back-to-back, my 9000-caliper-equipped 86 provides no advantage over my stock 89 on the street. When I autocrossed both cars, I never felt like I needed more brakes, even at practice events with multiple runs with short cool-down periods. (The only trouble I had was with rear lock-up. I mostly solved it by running Axxis MetalMasters up front, and Ultimates in the rear.)
If for some reason you are overwhelming the brakes, you could fit thicker 9000 rotors (more below) and better pads for less money, weight, and effort. I assume you're installing some sticky tires??
But if you really really want the 9k stuff...
You need the later style brakes (90+??) -- see eEuroparts for the cut-off: early 9000 calipers were the same as 88-93 calipers. Note that ALL 88-93 rear calipers are identical to ALL years of 9000 rear calipers, so don't bother grabbing the rears from a donor unless yours are trashed. (BTW, c900 and 9000 rear suspensions are basically the same design, but the fronts are totally different: double-wishbone on the 900; struts on the 9000. Presumably, it was cheaper for Saab to spec the 9000 front calipers on the 900 in 88, when they abandoned the front e-brake configuration.)
You will need to cut the rotor backing plate to accommodate the larger caliper. If you use c900 brake lines, you run the risk of rubbing them against the rims during parking maneuvers if they're not routed properly, so figure that out. Longer lines will also need to be kept from the rims.
If you have 15-inch rims and they are balanced with lead stickers, you may run into clearance issues: the caliper will quickly remove the lead!
If installing new pads, a tip from a Saab indy: grind the leading/trailing edges down to a 45* angle and consider slotting them down the middle, ~75% into the pad material, perpendicular to the length of the pad, with a cut-off wheel. This helps to cut down on squealing.
Here's some more info (a cut/paste of something I wrote some time ago):
9000 Brake Retrofit to c900
Some facts:
9000 calipers are 3.6 pounds heavier per corner -- that is, caliper and rotor. (This can vary a bit depending on which rotors you have.) This is all unsprung weight.
9000 calipers and Aero/Super Aero rims add 43 pounds to your car, all of it unsprung and a lot of it rotating mass. (Noted because lots of people like the Aero rims...)
The heaviest 9000 rotors, by Balo and Brembo, weigh 14.95 and 14.88 pounds, respectively; meanwhile, the lightest rotors, by Zimmerman, weigh 14.5 (their cross-drilled rotors weigh 14.0 pounds). The heaviest 900 rotors, by Brembo (which is OEM, I believe), weigh 14.2 pounds, whereas the lightest, by ATE, weigh 13.44 pounds.
The stock c900 donut spare tire does not fit over 9000 brakes: if you get a flat up front, you'll have to swap a good rim from the rear to the front, then put the donut on the rear.
Installing 9000 calipers requires an adjustment to the master cylinder to compensate for the longer pedal travel. This travel is due to the larger piston size in the 9000 brakes. (For some reason, I did not have to do this on my 86, which has a different cylinder than 88-93.)
Installing 9000 calipers and rotors requires the use of washers on the caliper bolts; without them, the bolts will rub against the rotors. (900 rotors are 278mm x 23.5mm thick, while 9000 rotors are 280 x 25mm thick. If you purchased "9000" rotors that are 23.5mm thick, then you were sold 900 rotors being sold as 9000 rotors.) Sorry, I don't recall the washer thickness needed.
Here's a FAQ from someone who used to be on forums pretty regularly:
http://www.twinsaabs.com/900_repair/brakes/9000_brakes.asp
If you already have an '88-'93 900, I wouldn't bother, personally. Mine feels great on track with stock-sized but more aggressive pads and rotors, even with the 15x7s wrapped in Z1 Star Specs. It feels great when I throw out the anchor...
If you're dealing with an '87 or older, I think it is totally worth it to swap to the '88+ setup. I did it on my '87 Airflow when I had it and it was a night and day difference in ease of service and performance. I may do the same swap with my 99 eventually.
EDIT: I just remembered seeing your post about putting the 9k Aero wheels on, so I know you already have the later bolt pattern and brakes. I'd just get some good pads and rotors and be done with it.
it was just a thought as there is a 9000 in the yard near me. I will stick slotted rotors, pads, and some braided lines on the brakes I have then.
I did the 9000 up grade and was very happy. It has been years but I seem to remember the 9000 pads were larger and it was easier to find track pads. The rotors being thicker is not that big a deal.
mad_machine wrote: it was just a thought as there is a 9000 in the yard near me. I will stick slotted rotors, pads, and some braided lines on the brakes I have then.
If you haven't bought the rotors yet, I could not tell any difference between plain-jane and slotted rotors. Per a very old forum post by a long-time Saab tech, he's had the best experience with Balo rotors. Not available from eEuro but you should be able to get them via a WorldPac reseller (I've used ips-parts.com out of Idaho with good luck but pick yer favorite.
The Carquest near me has access to WorldPac parts. I assume they all do.
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