Chrysler 300M Enthusiasts Club
  • Mushy brake peddle.

  • Repair Questions and Answers.
Ocean City 2019 Banner

Membership Banner

Repair Questions and Answers.

Moderator: Moderators

 #380718  by StealthM
 September 15th, 2019, 10:52 pm
Howdy gang. I have a mushy brake peddle. I have replaced all the brake lines, calipers, brake hoses. Rotors and pads. Flushed the system with new fluid. But still mushy peddle. Master cylinder??
User avatar
 #380719  by LUNAT1C
 September 15th, 2019, 11:29 pm
I’ve never had the issue myself, but I’ve seen this solved in the past with a master cylinder, the booster, or both. My first thought would be booster.
User avatar
 #380720  by M-Pressive
 September 16th, 2019, 7:07 am
Ryan ended up doing the booster and master cylinder to fix the issue.
 #380723  by StealthM
 September 16th, 2019, 12:50 pm
Well ordered the master this morning. Booster seems to be working properly. Guess we will see... ugh.
User avatar
 #380724  by Sneke_Eyez
 September 16th, 2019, 1:55 pm
I fought a mushy brake pedal for a long time on the Special after doing my brake lines last year.
It turned out to be a bad booster and a bad master. In the process, I went to the bigger bore master cylinder, which seems to have helped as well.
 #380726  by StealthM
 September 16th, 2019, 11:05 pm
Bigger bore? Please school me...
User avatar
 #380727  by Sneke_Eyez
 September 17th, 2019, 8:16 am
So Autozone (and possibly others, but I bought mine at Autozone) sells a 1'' bore "heavy duty" master cylinder for our cars, versus the 15/16 they originally came with:
https://www.autozone.com/brakes-and-tra ... 2558_89618

I believe Brian (Mottman) mentioned it to me in a brake thread I had posted, but I cannot locate where he talked about it.

However, I installed it on my Special, which in my opinion has had poor braking performance since I purchased the car in 2013 with 86k, and it seems to have helped.
One thing that you need to make sure you do is adjust the pedal travel on the master - that will control brake feel to some degree.