Bleeding ABS Brakes, Hints, Tips, Tricks? Options

[ConeTrouble]

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

[SpedToe169]

haha, I wasn't trying to OWN Joo! There are a number of reasons we don't use it. First of all, the AP fluid is designed to be compatable with the seals used in their calipers. Other stuff would probably work, but in racing probably isn't ever good enough. Second, as you mentioned the synthetic fluid doesn't absorb water. Whenever you take the cap off the system the ambient air fills any space in the resivor not occupied by fluid. In a racing system the fluid gets very hot, well over 100deg while on track. As a result the fluid expands. We run our fluid levels lower than you would in a street car because of this. Thus, more air space and more moisture. Its better to have the fluid absorb it than have it alone in liquid form (later in a gas form). Anyway, we don't really need the additional boiling point afforded by the synthetic fluid. If your fluid is getting hot enough to boil then your disks are alredy over temperature and you need to revise your brake ducting. We've got this trick thermal paint we put on the rotors, so we always know how hot they're getting. Its really interesting how the ducting setups vary from track to track. Some tracks don't hardly need any. Some tracks need a lot of air on the rotor, others need more on the caliper.