[Kirill Catalina]

Hi all. I was wondering why my front brakes lock up every time I hit the brake pedal when I haven't driven my 73 Catalina for a while?

It's not like the brakes are locked up sticking on the rotors. But very, very snappy the first 3-4 brake stops when I hit the pedal. To the point my tires skid the road 🥶

Fronts are disc and backs are drums. Pads and rotors are not worn.

Thanks!

[steve25]

Are fronts and rears looking up?

With rear drum breaks how close the shoes reside from the drum determines pedal feel.

It might just be that the return springs on the rear brakes are not doing there needed job anymore until the shoes cycle back & forth a few times.

And also that where the shoes rest on the backing plate might have no grease left on them and or are worn and grooved up which will hinder the shoes from returning to the backed off adjustment position that you actually have set.

The grease used needs to be a high temp wheel bearing type and no more the a film on the backing plate and the shoes are needed.

Do not use white grease.
It does not have a high enough melting point and will sooner or later get on the linings and drum surface.

[camerjeff]

I have had the old brake flex lines go bad by closing up internally, they start trapping fluid in the calipers, they let the fluid pass thru when you press the peddle, but restrict the return fluid that is not under the same pressure. It go so bad they would not let any fluid return. And I had to bleed off the pressure to release the brakes. This was on the front disc's only. I would test it by raising the car, have someone repeatedly apply the brakes until they start to lock up, then bleed off the pressure and see if they release.

It the hoses are original I would replace them, cheap and easy. Good luck I hope it is that easy

[78w72]

Originally Posted by Kirill Catalina

Hi all. I was wondering why my front brakes lock up every time I hit the brake pedal when I haven't driven my 73 Catalina for a while?

It's not like the brakes are locked up sticking on the rotors. But very, very snappy the first 3-4 brake stops when I hit the pedal. To the point my tires skid the road 🥶

Fronts are disc and backs are drums. Pads and rotors are not worn.

Thanks!

I have the same issue on a front disc/rear drum car after it sits for winter storage, 4+ months. The first time i hit the brakes gently like rolling out of the driveway or coming to the stop sign a few hundred feet away going 1-5mph, the front brakes grab the rotor very firm compared to the light pedal pressure used, or as said they are very "snappy" to the fronts.

This is only the first couple times pushing the pedal very lightly... it goes away & the brakes act normal after just a couple times hitting the pedal... i never gave it much thought, figured it was related to the long storage or maybe pressure built up and took a few pedal pushes to balance back out. The brakes work great after that & all year even after sitting for a few weeks.

The brakes never stay locked up & require bleeding pressure, the snappy feel or brief lock up goes away the instant the pedal is released.

[steve25]

As mentioned in post 3 old brake hoses can make for that issue in terms of the disc brakes especially.

If those 3 hoses are still original then there 30 years overdue in getting replaced even if they show no dry rot cracks on the outside.

[mgarblik]

The first 5 posts give great advice. I would check those items first. Rear backing plates, return springs and the 3 flex hoses. If none of these things solve the problem, here are 3 much less likely but still possible things that can cause this situation. 1. Rear wheel cylinder pistons are sticking. If the wheel cylinders are rusted, when you apply the brakes cold, you are pushing harder than you might think, when you finally apply enough pressure to make the wheel cylinder pistons move and apply the rear brakes, the front brakes are over applied and may lock. 2. The front caliper pistons are sticking. This can be caused by crud and rust collecting inside the caliper pistons over years and the rubber square cut O-ring losing it's memory over many years. When you first apply the brakes, the piston is supposed to move past the seal and the seal is also supposed to twist in it's groove and act like a return spring to very slightly retract the piston when you release the pedal. Just a little, like .010"-.015" . If the groove is full of crap or the seal loses it elasticity, it won't return and locking is possible. 3. Finally, it's possible the combination valve is not working properly. This is very unlikely and I wouldn't condemn this part until everything else has been addressed. Let us know what you find out. Good luck with it.

If you find any of the things I mentioned to be the problem, here is how I would repair. Rear wheel cylinders: just replace them. Front calipers sticking: I rebuild them. Super easy to fix. 2 kits are 10.00. Takes 30 minutes to rebuild a pair. 3. Combination valve: replacement is the only practical repair.

[PontiacHO]

Are you sure that it has a disc-drum master cylinder on it. Drum master cylinder maintains some pressure on the brake lines all the time. Also check to see if the rear brakes are energized when stopping. Proportioning valve could be directing the pressure to the front only.

[Kirill Catalina]

Originally Posted by 78w72

I have the same issue on a front disc/rear drum car after it sits for winter storage, 4+ months. The first time i hit the brakes gently like rolling out of the driveway or coming to the stop sign a few hundred feet away going 1-5mph, the front brakes grab the rotor very firm compared to the light pedal pressure used, or as said they are very "snappy" to the fronts.

This is only the first couple times pushing the pedal very lightly... it goes away & the brakes act normal after just a couple times hitting the pedal... i never gave it much thought, figured it was related to the long storage or maybe pressure built up and took a few pedal pushes to balance back out. The brakes work great after that & all year even after sitting for a few weeks.

The brakes never stay locked up & require bleeding pressure, the snappy feel or brief lock up goes away the instant the pedal is released.

It's exactly this. The rears don't lock up. Only the fronts and just for the first 2-3 times. After this it's all good. The rubber lines aren't that old and pressure is flowing back because it all works fine after a while..

So: it only happens in the beginning after sitting for a while. Instant snappy braking, squealing like hell and skidding the tires. Releasing the pedal, instant releases the brakes. It's just the fronts and all hardware isn't that old.

["QUICK-SILVER"]

With cars that sit awhile, I've had rust film on rotors make for grabby and noisy brakes till the rust film wears off.

Clay

[steve25]

Also you caliper mounting bracket could be worn in the guides causing mayhem.

[Goatracer1]

My cars do it also. My problem is a coating of rust on the rotors with a shiny spot where the caliper was sitting. Like I said on MY cars maybe not yours.

[Formulas]

is there a hold off valve that delays front disc? .... so they are not so grabby ? .... perhaps it needs a bit of exercise to work right

[kyle_blake]

yah my brake pads caused this. ac delco instead of wagner cheap line

might be the same thing ?grease those slider pin locations

[Schurkey]

Originally Posted by "QUICK-SILVER"

With cars that sit awhile, I've had rust film on rotors make for grabby and noisy brakes till the rust film wears off.

Two days ago, I was a hero to my cousins. I "fixed" their 2010 Corolla that had "grinding brakes".

Pulled the front wheels, pads looked like new. Rotors rusted from sitting too long. Drove around the block twice, nailed the brake pedal every hundred yards. Noise was gone after four brake applications, but I was having fun so I kept on going another lap.

Doesn't take much to put enough rust on the rotors to make the brakes grabby.

Yeah, popping the calipers loose and making sure the mounting pins are appropriately greased is a good idea.