Noise and shaking from brakes?

[Johnny-T]

A few month ago I had some SPAX installed on 967 because my old struts were completely trashed and it was making it hard to control. I was getting some pretty bad steering wheel shaking when high speed braking. The new struts seemed to fix most of the issues. Not long after, I had a new master cylinder put in because my brakes have always been kinda squishy as well. Now that the brakes feel firm, Ive been having some new issues pop up that I'm not sure about.

First thing I noticed after the new MC was put in was a ticking noise coming from somewhere under the car when coasting a slower speeds (25-40pmh). The ticking speed seems to match the rotation of the wheels and is not affected by the engine RPMs. If I brake or speed up the ticking stops. I can hear it the most when I let up off the gas and begin coasting at lower speeds but if I'm just cruising at low speeds I can hear it sometimes as well. (And this ticking is not the speedo/lambda counter.)

Ive also started developing shaking when braking from high speeds again. I dont have any shaking when accelerating or when I'm on the bumpy Vegas freeways at 80+mph. But when getting off at a freeway ramp and coming to a stop, the steering wheel will shake pretty bad. It will also sometimes shake (but not as bad) when stopping from lower speeds if its a more sudden stop.

Both times I was in the shop doing the struts and MC, my brake pads and rotors seemed to be in good condition. What could be causing my issues? Ive had 967 for just over a year now and this is the first time Ive heard this particular ticking noise. And the shaking has me a bit concerned because I thought the new struts had fixed that problem.

Any suggestions on where to start? I use 967 as my daily driver and will probably be ordering a new fuel pump soon so I would like to figure these other things out so I can get any parts I need at the same time and do it all together.

[Jonathan]

The noise could be coming from the rear brake pads. From my own experience, the rear pads are not quite big enough to fill the entire space dedicated for them in the rear calipers and they tend to clack up against the edges of the caliper when you aren't pressing the brakes. And I mean the length of the pads not the thickness. Mine tend to do it more so after I have done some hard braking. That's probably telling me the caliper pistons are sticking a bit. Maybe yours are too.

The clicking noise is not a big deal other than it's annoying. The shaking I would be more concerned with. I would have normally said to see if one or more of your rotors is warped. You said they are fine, so maybe one or more of your caliper bolts is not tight. The ones securing the caliper housing itself to the hub. If something like that was a bit loose, it would cause some shaking when you're braking (hey, that rhymed!).

[Johnny-T]

The noise could be coming from the rear brake pads. From my own experience, the rear pads are not quite big enough to fill the entire space dedicated for them in the rear calipers and they tend to clack up against the edges of the caliper when you aren't pressing the brakes. And I mean the length of the pads not the thickness. Mine tend to do it more so after I have done some hard braking. That's probably telling me the caliper pistons are sticking a bit. Maybe yours are too.

I did have several very hard braking events right around the time I changed my MC. (One of those times was me testing the full speed emergency stopping capabilities of the new firmer feeling brakes.)

Im not very mechanically inclined so forgive me if this sounds dumb, but is there any danger to the calipers sticking and what is the best way to fix it? Will it be something that my local brake guy can handle?

[DMC-Ron]

I found this link very instructive regarding "warped disks", brake pad types, and breaking in new pads/rotors.
http://www.stoptech.com/technical-su...nd-other-myths

Ron

[Johnny-T]

After reading a few older threads on similar subjects, I decided to try the heat test when I got home from work. I drove about 15 miles on the freeway averaging about 80mph the entire way. After I parked in my garage I felt each of my wheels to see how hot they got. They were all reasonably cool except for the rear drivers side. It was almost to hot to touch. Maybe this info can help in tracking down where the ticking is coming from?

Also I want to note that I use my parking break all the time but sometimes it's a little difficult to disengage. Even when it's down and the brake light is off I sometimes feel like it's not fully off and I will pull the handle up and then back down just to double check. My passenger side parking brake cable isn't even connected so the only one working is my rear driver side. Could this be my culprit? Are there separate pads or anything specifically for the parking brake that may be causing the ticking and heat?

[Jonathan]

There is some good information on checking and adjusting the parking brake here:

http://dmctalk.org/showthread.php?34...-Parking-Brake

Chris did a nice job putting the adjustment how-to together and kept it simple and straightforward.

This would be a good task to start with if you are not mechanically inclined. Assuming you would like to be able to sort some of the car's problems out yourself? Start with something easy and work your way up to more difficult issues.

Could a problem with the parking brake be causing the heat and noise issues? Yes. And getting the rear wheels off to see with your own eyes is a good next step. Post some pictures here if you're not sure what you're seeing once you do get that far.

(The regular brake calipers work differently than the parking brake. The regular brakes use fluid pressure to push on a piston inside the caliper which then pushes on the pads which squeeze the spinning rotors and slow your car down. The fluid doesn't seep past the piston because there is a seal in place there. Things can get gummed up there though and if those tolerances get compromised by crud or rust, the piston can have a hard time going back to it's rest position. This is what it means when they "stick" (they are sticking out a ways still and remain pushing the pads slightly into the rotors that are trying to turn, causing noise and heat as it does.)

The parking brake is purely mechanical in the sense that those cables coming from the hand lever physically pull on the contraption attached to each of the rear wheels and pinches the rotor between the parking brake pads to stop the car. The parking brake assembly on each rear wheel is a separate system from the regular brake calipers.)

[David T]

If one wheel is hot it means the brakes are dragging. Since it is a rear it could be a stuck piston in the caliper or a misadjusted parking (E) brake). The ticking can be because the pads are "threading" like a phonograph needle on the rotors. lifting and falling. The shaking is because something is worn and loose, probably in the front suspension.