SO one of the neat stock features on my '96 STi is the turbo cooling timer. That's a nice trackday feature IMO. My only problem with it is that the timer function is setup to be on when the parking brake is engaged. That is definitely not a good idea after running hot laps on the track. The result is warped/cracked rotors. My plan is to reverse the switch to be engaged when the parking brake is disengaged. That way I can use the feature on track! SO I was wondering if anyone has done this before? I'm guessing it's a simple microswitch on the parking brake lever but it may be more complicated than that... If nobody else here has done this, I guess I'll be the first to find out.
Sorry if this is a dumb question but how would the parking brake shoes (that aren't generating heat while driving) cause the rotor to warp or crack when applied to an area of the rotor that's also not really being "used" while driving?
I KNOW my question is dumb...do all Subarus use a drum style parking brake that is separate from the main calipers/rotors? I know my '05 Legacy was that way, but I have no idea how many other Subarus are set up that way.
Yeah, no problem. I don't think any questions are dumb. The problem comes from the pads/shoes creating a heat sink that causes uneven dissipation while the rotor is cooling. It is more pronounced in applications that apply the caliper for the parking brake vs. a smaller hub drum like we have but it is still possible. In fact, I actually did manage to warp a rear rotor on my SRT-4 in this way (they use a similar small hub drum) when I accidentally set the brake just after a 20 min session. It's also just good practice trackside to not use the parking brake (for me...). Although to be totally fair, I was in the habit of VERY aggressively braking in that car on track. That said, I felt so think having done that and shortening my really fun track day that I ended up pulling the shoes and just not having a parking brake. I actually don't know the answer to that one. Anyone else know off hand?
As far as I know any car that has a handbrake lever or foot pedal will have drum-type brakes since it's operated by cable and has to be separate from the hydraulic calipers. On a car with an electronic parking brake (like my '15 Legacy for example) it does use the calipers, where if I'm not mistaken small electric motors extend the pistons in a screw-like fashion to apply pressure. Obviously if you install a hydraulic handbrake this eliminates the cable-operated system so that's a unique exception, but either mechanical or electronic handbrakes can cause the same hot spots on the rotors if engaged after heavy braking.
I would assume you should be able to bypass the circuit pretty easily and fool the turbo timer into thinking the brake is engaged. There should be a plunger switch that extends and closes the circuit when you lift the lever, so the one thing to do would be just to unplug it and add a jumper wire so it's always closed. Alternatively you could remove the switch from the bracket it's mounted on and just have it loose under the console. Either way the only downside would probably just be that the brake indicator light on the dash would light up, so a minor annoyance but you could always pull the bulb out. Also if there's a level sensor in the brake master cylinder that uses the same light you'd lose that functionality.
Stock turbo? If so, IMO save yourself the hassle and just don't use it or uninstall it. A turbo timer is not necessary for water cooled journal bearing turbos. Letting the car idle for ~30 seconds after spirited driving provides sufficient cooling. Just as much as it won't really help anything, it won't hurt anything either however
That's fair. I'm guessing it is water cooled since I was using water cooled turbos on my '86 GLH and that thing was a dinosaur. I'm probably still going to use it but you're point is totally valid. Also, I've decided that the first thing on my list (after the floppy side mirror problem) is going to be the floppy and vague shifter. WOW it sucks. I'll start a new thread about that. Thanks for your feedback, team!
Definitely a worthwhile repair/upgrade. I replaced all my shifter bushings with new ones from Kartboy, very tight and solid feel now with zero play.
Ok so here's an update. I dug into the switch in the console, found a brown wire sorta jammed into a crack. Hmm that's not stock. So I pull off the lower dash cover under the steering wheel and find that half-ass backyard wiring is apparently an international pass time as well! Neat. I'd always wondered what this dash antenna was. I figured it was a special aerial for the radio or something. NOPE, apparently it's for this Japanese aftermarket remote starter unit with a built-in turbo cooler circuit. SO that settles my turbo cooler project. I'm not gonna have one! LOL! I chopped it out: Then cleaned up the wiring and buttoned it back up: Ahhhh that's better. Project finished. SO on to fixing the grounds on this boost gauge so it works. It was also mickey mouse'd into the wire nest with the 'turbo timer'. That's next up...
