Author Topic: Rear Brakes Locked Up Badly in Emergency Stop Today  (Read 1180 times)

Offline Road_Runner

  • Sr. Member
  • ****
  • Posts: 1825
  • Mopar Owner & Standard Bearer Since 1974
Rear Brakes Locked Up Badly in Emergency Stop Today
« on: May 06, 2010 - 07:54:09 PM »
So I'm out driving the Barracuda today for the first time in a while and 5 mins from the house a lady in an SUV did her best to hit me head on!!  It happened on the road in front of our local high school so the speed limit was only 30 mph.  I was heading one way and a line of cars/SUVs were heading in the opposite direction and the 3rd or 4th SUV in line just veered into my lane about 100 feet in front of me.  I saw her crossing the line and hammered the brakes, good news the Cuda stopped fairly quickly but the weight shifting to the front of the car locked up the rear brakes and the car acted like it might try to swap ends.  It didn't, and I know I've gotten used to modern anti-lock 4 wheel disc brakes, but I just wanted to ask others here if their cars are as prone to locking up the rear so automatically on a panic stop.  Story ends well, I think my car locking up & making so much noise actually alerted her that she might want to whip it back into her own lane.  Thanks to me stopping so quickly she had room and at least she waved as she drove by!!   :swear: :stomp:

I may play with the front/rear brake balance but any other suggestions would be appreciated!

Thanks, Jim
1970 383 Roadrunner Tor Red
1973 318 Barracuda Mist Green
2014 Mustang GT/CS Convertible All Black




Offline quapman

  • Resident
  • *****
  • Posts: 2350
    • Auto-Grip on Facebook
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #1 on: May 06, 2010 - 08:29:55 PM »
You might have the common rear axle seal leak which leaves rear end lube on your shoes making them act like this. Might be worth a look. It's usually on the right side.
My name is Steve and I'm addicted to Challengers...


Offline Road_Runner

  • Sr. Member
  • ****
  • Posts: 1825
  • Mopar Owner & Standard Bearer Since 1974
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #2 on: May 06, 2010 - 08:39:15 PM »
You might have the common rear axle seal leak which leaves rear end lube on your shoes making them act like this. Might be worth a look. It's usually on the right side.

Thanks, that's a great point.  I've had that same issue a few times through the years on my Roadrunner, but I've usually been able to spot some leakage on the inside of the tire but if its been leaking for a while which it could have since I just got it, the grease is only coating the inside of the drum(s).  I never really connected the leaks with the rears locking up since I always fixed it quickly and cleaned out the brakes, but the previous owner of the Barracuda may not have been so diligent.

Thanks again, Jim
1970 383 Roadrunner Tor Red
1973 318 Barracuda Mist Green
2014 Mustang GT/CS Convertible All Black

Offline Changin Gears

  • Sr. Member
  • ****
  • Posts: 1011
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #3 on: May 06, 2010 - 08:56:41 PM »
Every e-body I have had with disc/drum was just like this.  I've even seen vitage road tests where e-bodies were swaping ends during brake tests.


By default, I now always install a proportioning valve on the rear brake line.


The goal never changes - Stop the 60' timer with your back tires

Offline Road_Runner

  • Sr. Member
  • ****
  • Posts: 1825
  • Mopar Owner & Standard Bearer Since 1974
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #4 on: May 06, 2010 - 09:05:48 PM »
Every e-body I have had with disc/drum was just like this.  I've even seen vitage road tests where e-bodies were swaping ends during brake tests.


By default, I now always install a proportioning valve on the rear brake line.

I wondered if this was a normal trait of the car, definitely something to be aware of!  I thought it would have had a front/rear bias valve from the factory, my 70 Roadrunner does but I need to check the Cuda to see if it does too.

Thanks, Jim
1970 383 Roadrunner Tor Red
1973 318 Barracuda Mist Green
2014 Mustang GT/CS Convertible All Black

Offline acudanut

  • Full Member
  • ***
  • Posts: 928
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #5 on: May 06, 2010 - 10:04:46 PM »
Every e-body I have had with disc/drum was just like this.  I've even seen vitage road tests where e-bodies were swaping ends during brake tests.


By default, I now always install a proportioning valve on the rear brake line.
I don't get it ?? A second Proporting Valve ??  it already has one. !!

Offline dutch

  • Sr. Resident
  • ******
  • Posts: 6944
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #6 on: May 07, 2010 - 01:46:37 AM »
I`ve had to install a adjustable prop valve before to get things right....  especially the 11" drums in the rear tend to have way more stopping power than the prop valve can handle....
Unbelievable dangerous when the rear brakes outperform the fronts  :eek4:
*** Bart ***

Offline Aussie Challenger

  • Resident
  • *****
  • Posts: 3407
  • In Kansas loaded for Drive to West Coast.
Re: Rear Brakes Locked Up Badly in Emergency Stop Today
« Reply #7 on: May 07, 2010 - 02:06:10 AM »
I found this problem on my Australian Dodge Phoenix (Plymouth Fury), I reduced the rear wheel cylinder size to 13/16" and virtually eliminated the problem, I haven't had a chance to check my Challenger but will be looking into doing a similar thing to it when brakes are gone over.   :working:
Dave