Brake Question
03-22-2007, 12:12 PM
#46
Race Car
Thread Starter
There is a lot more brake pedal travel required on Turbo S cars than n/a cars (same master cylinder but much larger caliper piston/cylinder volume), so the Turbo S pedal will feel spongy or soft compared to the 944S. I always much preferred the brake pedal feel of my S compared to the Turbo S. If you can access to another Turbo S, try to get an opportunity to drive it to compare the brake pedal feel to yours.
If there is anyone with a turbo S who can replicate the test I did I would appreciate it (car at idle. turn wheels from end to end and back to center. Step on brake and see if pedal sinks lower then usual. Hit brake again to check height, turn wheels again end to end to center and check height).
Different pad compounds will affect pedal effort/feel.
Brake bleeding. Can never be ruled out as a potential cause of brake problems. Cars with the ABS system are even more prone to bleeding problems, because of the much more complicated line routing through the hydraulic unit. If the car exibits any symptoms of brake lockup, instead of or initially before the ABS kicks in, its very likely air in the lines.
Master cylinder seals. If the seals in the master cylinder are worn, the brake system can slowly depressurize past the MC piston seals, back into the reservoir. This would cause a soft pedal when initially engaged, but pressure could be built up by the second push (if the seal are not completely shot, you can pump up pressure faster than it leaks past the seals).
Sorry, I did not read through this entire thread thoroughly; did you mention the mileage on the car, the type/brand/age of pads, fluid and when last changed?
Just an mid-thread thanks for the help. Keep it coming. this is getting frustrating.
03-22-2007, 03:37 PM
#47
Rennlist Member
I agree the Turbo S has more pedal travel than its NA brethren -- my old '87 NA had EXCELLENT brake pedal feel.
But, as I mention in a previous entry, I had a rear wheel bearing go south on me, so I know what it feels like with the pedal goes waaaay down while you're doing a buck-forty.
If, after you're driving around a bit and doing some turns, the pedal goes way down and your first thought is "oh ****", and then on the second pump the pedal is fine, there's something wrong with the car...
Stepping on the brakes in a turbo S shouldn't scare you (your passengers, perhaps, as they dangle from the seat belt, but not you). From your description, I believe something is amiss.
But, as I mention in a previous entry, I had a rear wheel bearing go south on me, so I know what it feels like with the pedal goes waaaay down while you're doing a buck-forty.
If, after you're driving around a bit and doing some turns, the pedal goes way down and your first thought is "oh ****", and then on the second pump the pedal is fine, there's something wrong with the car...
Stepping on the brakes in a turbo S shouldn't scare you (your passengers, perhaps, as they dangle from the seat belt, but not you). From your description, I believe something is amiss.
