Bleeding ABS Brakes, Hints, Tips, Tricks? |
Bleeding ABS Brakes, Hints, Tips, Tricks? |
Dec 16, 2003 - 2:42 PM |
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Enthusiast Joined Nov 25, '03 From Mizzeri Currently Offline Reputation: 0 (0%) |
I am about to change the brakes on my '94 GT, and was wondering about the ABS system.
Now, a lot of ABS systems are of the closed loop variety, which means that in order to completely bleed the system, you have to do one of two things: either take it to a dealer to get them to hook up a snorkelator which electronically activates the ABS, allowing access to the normally closed ABS loop (or perhaps have one of these snorkelators yourself and know how to use it).. which is the preferred route; or you can bleed the brake lines, take the car out on the road, and slam on the brakes and activate the system (which in theory will flush new fluid into the loop), then bleed the brakes again. The latter doesn't really strike me as a very good way of doing this, as you are never sure of the fact that you got all the old fluid out. Typically, on these closed loop ABS systems, the bleed steps are different than what you would normally expect from your plain jane brakes (i.e. you don't start at the wheel farthest from the master cylinder and work towards the closest). Looking at the Factory service manual, though, it says that the bleed steps for ABS are the same as non-ABS. So my question is whether or not the ABS system on the '94 GT is a closed loop variety, or if a regular bleed is going to accomplish a complete flush of the system. Logic kind of points to the fact that it will, but I was wondering if any of you have some input on this. I am replacing the bleeder valves with SpeedBleeders, and going to Hawk HP Plus pads on the front. Stock Toyota pads on the rears. Fluid is SuperBlue. For those of you that bleed your brakes yourself, and haven't tried SpeedBleeders and/or SuperBlue fluid, I can't recommend the stuff enough. The bleeders let you do it yourself, and the fluid is electric blue, so you KNOW when the lines is completely flushed. ~Mark |
Dec 18, 2003 - 3:19 AM |
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Enthusiast Joined Nov 25, '03 From Mizzeri Currently Offline Reputation: 0 (0%) |
Synthetic brake fluid is not completely useless, but for all intensive purposes, it is not advantageous to use it. The reason is, as mentioned above, that is does not absorb water. One of the functions of brake fluid is to absorb and disperse the water in your brake lines. This is the main reason people should bleed their brakes every year or so, to flush out the old fluid that has absorbed water (which is a good thing, since it is not corroding your lines). As the fluid absorbs water, its boiling point goes down, again, another reason to bleed your brakes. Under normal conditions, your brakes will never heat up to a temperature such that this will even matter. An emergency stop from 100+ mph won't do it. A lot of autocross runs back to back *might cause you some grief, but probably only on neglected systems in the first place. Track days, on the other hand, willstress you brake system, and likely cause boiling unless you are on top of things. The people who get benefit from synthetic fluid are race cars or cars that do extensive lapping on road courses. I guarantee you that most, if not all of these people bleed their brakes after every single session on track. Humbug! you say?! I think not. Ever use SpeedBleeders? They are flat awesome! I can bleed my entire brake system in 20 minutes, by myself. Water hasn't a prayer of forming in the lines, and therefore the risk of corrosion is nominal. Like you mentioned, one the fluid exceeds the biolign point, in becomes less consistent. Another reason the track guys bleed so often. I know I would. I am pretty sure this was what he was referring to when he said it was completely useless. I would never use it, and I autocross extensively. I simply don't reach those temperatures, even under those conditions. I think the best bet is a very good DOT4 fluid. It has a high boiling point andabsorbs moisture. I bleed my brakes about twice a year, but that is probably overdoing it. I am not telling you not to use synthetic fluid. I am telling you that you should be aware of the consequences of doing so. I don't think you need it, I know I don't, but ultimately you have to make up your own mind about this. Bear in mind that one drop of water near your caliper will boil at 212 degrees fahrenheit. I bet your synthetic fuild won't boil, but the water it won't absorb will... |
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