Subaru Impreza GC8 & RS Forum & Community banner

1 - 9 of 9 Posts
H

·
Guest
Joined
·
0 Posts
Discussion Starter #1
OK so tonight (on an undisclosed private (of course!) road) I was messing around and did a brake check from about 115. The results were pretty scary. The first 1/2-1 second the brakes grabbed hard and the tires squealed as I slowed down to about 80, but after that they felt way mushy and didn't seem to have the same grip, and I slowed down way slower (115-80 was fast, 80-50 was sloooow). Would this be fade caused by out-gassing? Stock rotors/pads, SS lines. Could it be cured by getting better pads and slotted/drilled rotors? I had the brake pedal mashed to the floor, and the ABS wasn't pumping, so I know that wasn't the problem.
 

·
Registered
Joined
·
744 Posts
I would say any kind of ventalation on the rotors would do A LOT in that kind of stop. Anything to keep the brake pads cool, would help you.
 

·
Registered
Joined
·
3,614 Posts
what was the ambient air temp/elevation/elevtation change? also, keep in mind the stock system is not designed to go from 115-0. also, what tires do you have, its possible they got overheated (hence over pressured) and lost some of their contact patch, resulting in less decelleration force.
 

·
Registered
05 LGT limited
Joined
·
405 Posts
The stock pads don't handle heat well. After 3 20 minute sessions on Gigermann Raceway on open track night, I noticed my brakes really sucked (I couldn't activate the ABS in the rain!)
When I finally got around to checking it out, I found that the front pads had chunked, ie big pieces of pad material MISSING! The rears had also, but not as bad.
I now have NAPA (Raybestos Brute stop) ceramic pads in front and Applied Engineering semi-mets in back, (SS lines too) and the brakes are awesome. They actually get stronger as they heat up
 
H

·
Guest
Joined
·
0 Posts
Discussion Starter #5
air temp - ~35 degrees F
elevation - ~ 200' ??? (Dunno really)
elevation change - slightly uphill, maybe 10' up over the 1/2 mile
tires - Dunlop Sport SP5000s
weather - wet, but no standing water (snowed the previous day, not sure about that morning, but it mostly melted off)

I've got ~27k on the car, it might be time for new pads. :)
 

·
Registered
Joined
·
6 Posts
You could try stainless steel brake lines. Also IIRC they make a brace for the master brake cylinder that'll stop some of the fade/flex.

Or I could just be doing too many drugs.
 

·
Registered
Joined
·
3,614 Posts
You could try stainless steel brake lines
in his initial post he states that he has ss lines already, though they serve the purpose of increaseing brake feel and don't influnce fade at all, same with the brake cylinder bracket. his instance sounds like he was just asking too much from the stock system (or he already had some air in the fluid) and thus pads would probably be the best solution, though i have been quite happy with the stock system. of course, i don't try and stop from 115 either :)
 
H

·
Guest
Joined
·
0 Posts
Discussion Starter #8
Hmm. I thought stainless lines prevented some fade due to the rubber hoses heating up and stretching.

Either way... it's entirely possible that I need a new set of pads. :)
 

·
Registered
Joined
·
3,614 Posts
if they do its negligible. the main purpose of the SS lines is to deflect less when you pressurize the brake fluid then the stock rubber ones. this produces more resistance when you apply force to the pedal, since the SS lines move less, thus allowing the fluid to reach higher pressures sooner. thus it improves the "feel" of the brake pedal, but has no real effect on performance of the brake system. it can also decrease the risk of brake line failure from a rock or something along those lines. to reduce fade, you have to either increase heat tolerances of the brake components or increase the heat disappation rate. mods along these lines are cross-drilled/slotted rotors, larger rotors, higher performance pads, more calipers, ducting, higher performance brake fluid, etc. also, if you brake hard alot or if you ever fade the brakes, even just a little, make sure to bleed the fluid.
 
1 - 9 of 9 Posts
Top