Brakes grab really hard

[Carmak 10]

I just bought a 69 302 Mustang. It was restored in the 90's and has been in dry storage the last 5+ year completely unused.

 

The brakes are very grabby.

 

I have had cars before with leaky wheel cylinders and they are grabby also but after a couple hard stops (and some heat) they grab less. This feels different.

 

This is my first Mustang (first Ford other than early 60's T-birds years ago). Is this a chronic thing?

 

Thanks.

Carmak

Riverside, Iowa

[Brian Conway 264]

The Power Disc Brakes on my 69 are sensitive/touchy compared to my other cars. I would not describe them as grabby. If your car has not been driven for a while the shoes will swell. Might want to pull the drums and take a look ? Brian

Edited August 2, 2014 by Brian Conway

[buening 63]

This is typically an indication that the rear brakes aren't working correctly. Does the car try to nose-dive when you hit the brakes hard? If so you either have air in the rear lines or the rear brakes aren't functioning correctly.

[Zipppo 11]

If your car has been sitting for 5 years unused I would spend the money and go through the entire brake system to protect your investment and more importantly yourself and others on the road.

 

Boosters, master cylinders, wheel cylinders, calipers, and fluid sitting unused for that long typically will present with issues. Just go through it all replace,clean flush it etc... Same for fuel system, coolant, oil and filter trans fluid if it is automatic. Belts and hoses typically dry rot as well.

 

No matter the cost even if it is a bit costly I always pose this question.

 

"What is your safety worth to you?"

Edited August 4, 2014 by Zipppo

[manley 13]

Poorly adjusted proportioning valve? Would a master cylinder with too small/large bore cause something like this? Just brainstorming with odd ideas.

[MAD IN NC 21]

I have the same exact problem and wrestling it also. Car while 95% complete has been sitting for a while. Ok - I take it out for ~50 miles per year. This was due to work, family etc... Lately I've been able to focus on cleaning up the past due list, car by car....

 

Today and for the next days all effort is on the stang....

 

Symptoms:

- Extremely touchy brakes (front). Nose would dive. Sensitive... Brake warning light on. Does not pull to right or left...

 

Actions to date:

- Removed front rotors and had them cut. One had .008 taken off to true up rotor. Second rotor the hub (original design where studs/ lugs held hub to rotor) was loose and could not be saved. Purchased new from FLAPS, cut .005 and hung rotors. First drive, brake light off, pedal felt like it should have. No dive!

- Verified Pads all good with less than 1k miles over the last 6+ years.

- Verified no leaks in calipers or rear wheel cylinders.

- Master does not leak and appears good (front and back pressure being applied simultaneously)

- Power Brake Module does not leak air and operating.

- Second drive light came back on... #^%#$ light.

- Jacked up rear, started car and insured that the rear brakes were working. Re adjusted shoes to drum on pass side.. Light still on. #^%#$ light.

 

Next planned steps:

- Refresh Brake fluid and bleed entire system Front and Rear this week.

- Will use a DOT5 silicon fluid as not impacted by water or heat and will not break down if car sits suspended as the cheap DOT3 I have in the car today (Carquest relabel).

- Since pedal feels good/better now (no more diving since front rotors were R&R'd) goal is to flush R&R and work light resolution without wire cutters..............

 

Goals:

- Get brakes back to standard operating with working idiot warning light.

- Find a way to resolve without going to last step of ripping and replacing proportioning valve as it will be a PIA to get to / replace due to other mods.

 

 

 

If resolved in the next week after the bleed I will gladly post results......