Horrible brake feel

[BlindAssassin111]

I have had my 13 SHO w/PP for a few years and it has always had fairly shit brake feel and takes a lot of pedal travel to really stop. I somewhat recently had the fluid flushed and replaced with much nicer fluid thinking maybe it was just due to fluid age (it was most likely the original fluid) but after a few weeks it honestly doesn't feel much different. What I am unable to find out is what could be causing the issue or if this is actually just how it always has been.

Could this possibly be a bad master cylinder, booster, or something else I am not thinking of? It doesn't feel like the pedal sinks while held, but it takes literal inches of movement to have any usable amount of braking. Prior to the fluid flush, I was able to bottom the pedal out and it isn't too much better than that now. When pumped, it doesn't build pressure to the point the pedal becomes hard (when the car is on). When the car is turned on the pedal drops a bit and becomes much softer than right before the button is pressed.

Sadly I don't know anyone local with an SHO or have a dealer with a used one on the lot to get a reference from so hopefully someone here can chime in with some helpful info.

 

[kryptto]

So a brake booster when bad would create a very hard pedal. So not that.

New fluid should be replaced based on quality and it absorbs moisture from the environment. I live in a swamp and my humid environment requires me on all cars replace my fluid every 15k in general. Should not be causing that issue.

Dropping to the floor, master cylinder is my best guess. Why? The rubber O rings around the piston can leak fluid. You didn't state how old the car is. Age will cause those gaskets to slowly degrade, and having bad fluid with a high water dilution will cause the fluid to boil and also corrode the parts on the calibers and master cylinder.

There still can be a vacuum issue, so check the one from the charge pipe to the brake system.

If your lines were leaking you would see leaking brake fluid and you would have zero brakes.

If calipers were siezing, they sieze open or closed, and you would feel it in the steering wheel, or fish tailing etc.

Only other issue could be anti lock brake module/system - however that would throw a CEL hopefully.

My guess - master cylinder.

 

[BlindAssassin111]

So a brake booster when bad would create a very hard pedal. So not that.

New fluid should be replaced based on quality and it absorbs moisture from the environment. I live in a swamp and my humid environment requires me on all cars replace my fluid every 15k in general. Should not be causing that issue.

Dropping to the floor, master cylinder is my best guess. Why? The rubber O rings around the piston can leak fluid. You didn't state how old the car is. Age will cause those gaskets to slowly degrade, and having bad fluid with a high water dilution will cause the fluid to boil and also corrode the parts on the calibers and master cylinder.

There still can be a vacuum issue, so check the one from the charge pipe to the brake system.

If your lines were leaking you would see leaking brake fluid and you would have zero brakes.

If calipers were siezing, they sieze open or closed, and you would feel it in the steering wheel, or fish tailing etc.

Only other issue could be anti lock brake module/system - however that would throw a CEL hopefully.

My guess - master cylinder.

It is a very early 13MY build (so just over 11 years old). I know the brake fluid was a dark amber when it came out so probably damaged the o-rings just enough that it has issues but doesn't lose a noticeable amount of pressure while held? Thank you for at least walking through each issue as I wasn't 100% sure it would be the master cylinder and haven't personally dealt with any of the other issues either.

Going to just try and have that replaced along with some other issues that came up recently and hope that the car will be back to how it felt long before I got it.

 

[kryptto]

It is a very early 13MY build (so just over 11 years old). I know the brake fluid was a dark amber when it came out so probably damaged the o-rings just enough that it has issues but doesn't lose a noticeable amount of pressure while held? Thank you for at least walking through each issue as I wasn't 100% sure it would be the master cylinder and haven't personally dealt with any of the other issues either.

Going to just try and have that replaced along with some other issues that came up recently and hope that the car will be back to how it felt long before I got it.

well take what I gave you - and now have a logical discussion from the shop. make sure they share any codes/errors in the ECU, if you question what the code means - feel free to ask.