Rattling/knocking front end

[Christobal]

I replaced the caliper guide pins and have relatively new pads and rotors. Guide pins did not help, new anti rattle clips are there.

I'm getting a light rattle that sounds like the pads moving a bit. No big deal, almost not notable. There is a larger bump when the suspension gets moved by the road. All of these noises go away with light application of the brakes.

The wheel bearings and anything that could be loose that might cause this hammering sound are tight. It's almost as though the piston is bouncing around in the caliper. I don't see how it can be non-caliper/rotor/spindle related if light brake application quiets everything.

Has anyone experienced this or heard of it and solutions?

 

[Anime]

It might be a good idea to jack up the front axles and do a tie rod and wheel bearing check by grabbing the tire on the bottom, and then on the sides, and checking if there is any noise or movement. If the caliper slide pins are greased, and the brake pad clips are the right ones and in good condition, perhaps banging around lightly with a rubber hammer will reveal the source of the noise. It's also possible the suspension is the cause, worn out radius arm bushings or a loose shock would cause a rattle when driving and a clunk when the suspension takes a hit.

 

[Christobal]

Thinking right along with you. I have pulled on the wheels. There is no sign of bearing issues by feel or sound. I have done everything short of smacking stuff with a rubber hammer.

On the piston being held in, I would think I would get a pull to the other side while braking, though I have none. Slight application of the brakes makes the noise go away. It sounds like the right front, though other times it seems like it's right in the center underneath. There are no handling/tire wear issues at all.

The sounds seems like it's being made by something much more dense than a brake pad. This is a strange one.

 

[BP_93explorer]

I have the same rattle. Goes away with the slightest pressure on the brake. Just enough to make the lights come on but not slow down the vehicle. I took it to a shop and they think its actually coming from the back. They looked at the brakes and didn't see anything wrong. This has been going on for about a month and now I feel a slight pulling to the right when I brake. I've been describing it as dragging a chain. It gets that bad at times.

 

[Christobal]

I have the same rattle. Goes away with the slightest pressure on the brake. Just enough to make the lights come on but not slow down the vehicle. I took it to a shop and they think its actually coming from the back. They looked at the brakes and didn't see anything wrong. This has been going on for about a month and now I feel a slight pulling to the right when I brake. I've been describing it as dragging a chain. It gets that bad at times.

I wonder how they explain it going away with brake pressure and sounding pretty obviously as though it's from up front?

A little background, it has 176k on it. Has done some offroading it's whole life. Calipers are original. I don't think it's driveline related. It does it power on or off. Main factor is tire air pressure and how harshly the road moves what seems to be the front wheels, mainly the RF in my case.

I do have what I am 99% sure is a rear main seal leak that is bad enough that it needs to be corrected after I get it smogged. I think the ping issue mentioned in another thread ultimately set that up, due to blowby and extra pressure in the crankcase due to ping. The tranny also plays some games in the 1-2 shift regime when the tranny fluid is at or beyond the high normal side. I don't see any correlation. I also don't believe the issue showed up when changing rotors/pads. Rotors are 2nd on vehicle and changed around 160-165 K IIRC. It has not been abused. Still on original drums out back.

 

[Anime]

You can have problems with the rear drums and still have it sound like the rear isn't where the sound is coming from. It would be worth it to pull the drums off and check out the hardware. Rebuilt calipers are very inexpensive, if it would be worth it to replace them to rule them out as a cause or just in case, for safety.

If banging around with a rubber hammer doesn't yield any possible sources, perhaps you could have a passenger ride along and listen for the sound more closely, out the window, etc. to pinpoint it better.

 

[DeRocha]

How are you Radius arm bushings? When they are worn you will fell bumping under your feet (where the Radius arms brackets are located).. When the brakes are applied it tends to tighten up the Radius arm and stop the noise..

 

[BP_93explorer]

You can have problems with the rear drums and still have it sound like the rear isn't where the sound is coming from. It would be worth it to pull the drums off and check out the hardware. Rebuilt calipers are very inexpensive, if it would be worth it to replace them to rule them out as a cause or just in case, for safety.

Thats what I was going to check next. I did the same thing recently with sticking our heads out the window and now I think its coming from the back. This would be why the sound stops under braking when nothing is wrong with the front brakes.

 

[Christobal]

Thats what I was going to check next. I did the same thing recently with sticking our heads out the window and now I think its coming from the back. This would be why the sound stops under braking when nothing is wrong with the front brakes.

Wow, surprised to hear this. Curious, how much mileage on this set of rear brakes for you?

Try this, sitting still, put firm pressure on the brake pedal, then crank the wheels all the way to one side or the other. When you get there, release the brake and see if it thumps. Do the same for the return trip back to straight. If it thumps, you probably have what I have. This test pretty much rules out the rear brakes, rearend, driveline etc. because the only thing moving is the 'front end'. Give it a shot.

You might ask, well the wheels aren't turning so how could it be the brakes? The wheels due turn a bit due to 'kingpin axis' and hub mounting surface differences and castor etc. They do rotate a bit.

My first guess is something with the calipers.

2nd choice is radius arm issues.

We'll see.

 

[awood]

I'll have to agree with DeRocha on this one. I experienced the same thing with my RA bushings. With light brake pressure, it loads up the suspension just enough to prevent it from slopping around. Have someone go from drive to reverse while you watch the RA bushings (carefully) from the side. I was surprised at how much even the new bushings moved. The heat from the exhaust is especially hard on the right side bushings. You can partially inspect them by just removing the big nut on the aft side and slide out the rear bushing half. With the noise you're describing, I'd be willing to bet you have metal-to-metal contact between the radius arm and the rear bracket.

 

[Christobal]

I'll have to agree with DeRocha on this one. I experienced the same thing with my RA bushings. With light brake pressure, it loads up the suspension just enough to prevent it from slopping around. Have someone go from drive to reverse while you watch the RA bushings (carefully) from the side. I was surprised at how much even the new bushings moved. The heat from the exhaust is especially hard on the right side bushings. You can partially inspect them by just removing the big nut on the aft side and slide out the rear bushing half. With the noise you're describing, I'd be willing to bet you have metal-to-metal contact between the radius arm and the rear bracket.

Very convincing arguement. The fact that with all the ping issues recently, I am sure egt's have been high. It does seem to be from the right side. Just to plan ahead, any good non-dealer sources come to mind for thoes bushings, either oem or something aftermarket?

I'll be looking at it along with cleaning the MAF sensor later today.


Thanks

Chris

 

[Anime]

It's likely the radius arm bushings are original, in which case it's a good idea to replace them anyway, since it makes a BIG difference in handling and braking. You can get replacement MOOG bushings from the parts store, or get aftermarket polyurethane bushings like Engery Suspension. ES part # is 4.7110 for the 4 pc. front set, which does both sides.

 

[Christobal]

Radius arm bushings were toast on the right side. Installed new oem type bushings on that side. Left didn't look great but didn't change for now due to time. The noise went away. Toes was about 1/4" negative after test drive. reset to about straight. I will check again after few miles to see how things are.

Sprayed brake cleaner with directed tube at the two fine elements in the MAF sensor. Blew off with high pressure air from about one foot back to keep from potentially damaging them. The elements appeared bright in color and cleaner. Test drive brought no pinging or engine light. Everything is good in those two areas for now.

Thanks for the input guys.

 

[DeRocha]

Glad to hear you found and fixed the problem..

 

[BP_93explorer]

Wow, surprised to hear this. Curious, how much mileage on this set of rear brakes for you?

Try this, sitting still, put firm pressure on the brake pedal, then crank the wheels all the way to one side or the other. When you get there, release the brake and see if it thumps. Do the same for the return trip back to straight. If it thumps, you probably have what I have. This test pretty much rules out the rear brakes, rearend, driveline etc. because the only thing moving is the 'front end'. Give it a shot.

You might ask, well the wheels aren't turning so how could it be the brakes? The wheels due turn a bit due to 'kingpin axis' and hub mounting surface differences and castor etc. They do rotate a bit.

My first guess is something with the calipers.

2nd choice is radius arm issues.

We'll see.

I've never changed out the back brakes. I've had the vehicle for the past 5 years for about 30,000 miles. Rotors, calipers, and pads changed out 3 weeks ago. RA bushings were replaced a few months ago. I did what you said and didn't hear a thump.

 

[Christobal]

I've never changed out the back brakes. I've had the vehicle for the past 5 years for about 30,000 miles. Rotors, calipers, and pads changed out 3 weeks ago. RA bushings were replaced a few months ago. I did what you said and didn't hear a thump.

Sounds like you may have something in the back end.

Update: My 93 passed smog with ease recently. Above most of the averages indicated in the dyno data readout, but far below all of the allowed maximums. I did not do an oil change before the test, but it had new plugs.

Other than the disappointing intake manifold gaskets, now replaced with much better looking Fel Pro stuff, overall this thing has been very trouble free, durable and reliable. A new rear main seal and I think it will be good to go another 1-200K, only problem getting there, is it's not a primary vehicle any more.

 

[ricklee4570]

I have the same darn noise. Had the brake anti rattle clips replaced. The noise stopped........for about a week. Now it is back and as loud as ever. Stops when I apply the brakes. All the bushings, tie rods, etc. have been replaced.

Very annoying!

 

[Potomac30]

My knocking issues were solved by: 1) new radius arm bushings 2) tightening the sway bar.
My rattling issue was solved by putting a metal strap around the broken catalytic converter heat shield.

 

[ricklee4570]

I have done all the above! Still looking!

 

[Michiganbear]

make sure when you change the ra bushings, you carefully inspect the bracket the go on. if there is metal to metal contact (arm against bracket), you probably will need to change the bracket too. the hole gets elongated, and the bushings wont last but a few days at the most, because they are not seated properly.

good news is, the brackets are pretty cheap, and not really hard to change. a few bolts, and a couple of rivets that need to be cut off.