Brake Pads Wrong???

[westie47]

My ‘69 Coronet came with manual disc brakes off of a ‘75-76 A Body. I decided to keep them, so I bought new rotors and pads. All of the parts matched the old parts.
When I put the new pads and calipers on, the rotors turned very stiffly, and when the wheels went on, they turned a little bit but rubbed on the calipers then wouldn’t turn at all. I took the outer pad off each side and everything spins and fits just fine.
Are my pads too thick or am I missing something else?
Here’s some pic of the old rotor, new rotor and outer pad.

 

[MoparLeo]

Did you match the part numbers off of the old parts to the new parts or assume that they are the right ones ? Only you have seen both parts so it would be hard for us to guess what happened. You probably had to exchange the calipers but did you keep the rest of the old parts to compare ? Pads don't come in different thickness for the same part number. The inner and outer pads are not usually the same thickness on a single piston caliper system. Hopefully you kept the old pats and your receipt in case you need to exchange something.

 

[493 Mike]

At any rate, looks like you are doing a nice job!
Mike

 

[Don Frelier]

A 1/4" wheel spacer with likely take care of it. Just make sure you have about 6 or more full turns on the lugs. Then recheck the drag on the rotor after you drive it a bit. I suggest synthetic brake fluid.

 

[PRND21]

I’d be curious to see if the dimension from the inner bearing race to the wheel mounting surface of the rotor is the same on the old rotor and the new rotor, also the distance from the face of the rotor to the wheel mounting surface.

 

[bc3j]

Just thinking, is your master cylinder for disc brakes? A drum brake master probably has residual pressure valves which will cause the front discs not to fully release.

Your first photo appears to have the outer pad in contact with the rotor hub. Not sure if your new parts place the outer pad in the same position. In the first photo the tabs on the outer pad are not in the correct position on the caliper. The outer pad needs to have those tabs bend so they are an interference fit on the caliper. That might be the trouble.

 

[Demonic]

The outer pad needs to have those tabs bend so they are an interference fit on the caliper.

That might be it. Supposed to be a snug fit.

https://web.archive.org/web/20160510195150/http://www.moparaction.com/Tech/archive/disc-main.html

 

[bc3j]

That new caliper doesn’t look like it’s machined right. Looks like the corner is missing the recess. Those bottom areas locate and position the outer pad.

 

[westie47]

Did you match the part numbers off of the old parts to the new parts or assume that they are the right ones ? Only you have seen both parts so it would be hard for us to guess what happened. You probably had to exchange the calipers but did you keep the rest of the old parts to compare ? Pads don't come in different thickness for the same part number. The inner and outer pads are not usually the same thickness on a single piston caliper system. Hopefully you kept the old pats and your receipt in case you need to exchange something.

I didn't match the actual part numbers but I compared and matched the new parts to the old parts, everything was the same aside from the worn pads.

 

[westie47]

A 1/4" wheel spacer with likely take care of it. Just make sure you have about 6 or more full turns on the lugs. Then recheck the drag on the rotor after you drive it a bit. I suggest synthetic brake fluid.

Where would I find a wheel spacer? Never heard of that.
The car rolled fine when I picked it up, but like I said, with the new pads on, the wheel rubs on the caliper for a bit then stops turning. It has to be an adjustment I am missing...

 

[westie47]

I’d be curious to see if the dimension from the inner bearing race to the wheel mounting surface of the rotor is the same on the old rotor and the new rotor, also the distance from the face of the rotor to the wheel mounting surface.

The rotors were identical, I checked and compared the new ones carefully. I did have some issues getting the right wheel bearings from the parts store though...had to go back a couple times.

 

[westie47]

Just thinking, is your master cylinder for disc brakes? A drum brake master probably has residual pressure valves which will cause the front discs not to fully release.

Your first photo appears to have the outer pad in contact with the rotor hub. Not sure if your new parts place the outer pad in the same position. In the first photo the tabs on the outer pad are not in the correct position on the caliper. The outer pad needs to have those tabs bend so they are an interference fit on the caliper. That might be the trouble.

I will try that. I didn't realize the tabs were supposed to be bent. Should the brake shoe sit snugly in the caliper without falling out then? The old ones just fell out when I pulled the calipers off.

 

[westie47]

That new caliper doesn’t look like it’s machined right. Looks like the corner is missing the recess. Those bottom areas locate and position the outer pad.

View attachment 972940

They are actually the same calipers, I just cleaned, stripped and painted them.

 

[Don Frelier]

The old calipers could be the cause of excessive drag on the rotor.
Were they easy to press in?

 

[westie47]

The old calipers could be the cause of excessive drag on the rotor.
Were they easy to press in?

Do you mean the pistons or pads? The pads went in easy and the piston was easy to press open.

 

[bc3j]

I will try that. I didn't realize the tabs were supposed to be bent. Should the brake shoe sit snugly in the caliper without falling out then? The old ones just fell out when I pulled the calipers off.

The pads should not fall out. The outer pad should snap in with no vertical movement. The inner pad just drops in on the caliper adapter. I bend those tabs trial and error and put the lower part of the outer pad on the caliper first and rotate the pad until the tabs snap over the caliper. Again, make sure there is no vertical movement of the outer pad. Make sure you lubricate the caliper machined surface.

I'm surprised that your caliper looks like that on the lower side. Mine has the recess areas on both sides and holds the brake pad securely in place.

 

[MoparLeo]

Don't use "spacers" to ever solve a problem, just causes another one. If something worked before and doesn't work now, it isn't because you forgot to put the "spacers" back on. Something looked the same but is now different. The caliper is not bolted directly to the spindle mount. It has to move back and forth as the pads wear. Something is binding. Take apart and recheck everything and reassemble slowly, checking fit as you go.

 

[Don Frelier]

What problem would a 1/4" spacer create?

 

[myk r sanchez]

I was always taught that instead of getting a spacer, get the correct part. For example a lot of people run wheel spacers to get a certain "look;" IMO you should ditch the spacers and get the correct backpacking for the wheel and your application. Spacers introduce another component in your suspension that can fail or cause failure; that is dangerous to me...

 

[MoparLeo]

As said above, a spacer is used to band-aid an incorrect fit. Always get the right part, even if it cost you more money than a spacer.