News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

eldorado rear brake pad clatter

Started by Erik, November 11, 2006, 11:34:28 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Erik

I have a 76 Eldorado with rear disc brakes.  Ever since I bought the car the rear brake pads have clattered at low speed.  I replaced them and they still clatter.  Apparently, the slowly turning (up to 30mph) rotor wriggles the pads against their caliper mount ends, causing quite a ruckus whenever the wheels go over a bump.  My GM chassis manual doesnt mention anything about shims or other spacers.

Does any of you Eldo owners have this problem?  Any suggestions on how to make things quiet?

Thanks
Erik

JIM CLC # 15000

11-11-06
ERIC, I dont have a 76 eldorado but I have had several cars that have had rear disk brakes and I must say that you have a "strange" problem. Check it out by driving a road that you know well and remember the spot where the noise occures.Then drive the road again, at the same speed and "ride the brakes" at the spot where the noise occured (with-out slowing down). If you dont hear anything, most likely the brakes are at fault. If you do hear anything, better start looking for something else.
Good Luck,JIM

Bruce Reynolds # 18992

Gday Erik,

Sounds like you might just have seized caliper piston(s) and the pads might be simply rattling in the caliper.

Have you checked to see if the rear brakes are actually clamping the disc rotors when the brakes are applied?   I know you would have, but only a suggestion.

The way the pads get clearance when the brake pedal is released is by the action of the Disc Rotors "slapping" them back into the calipers as the axle turns.

But, I would be seriously be checking things back there before using the car.   Things like bearings and the like.

Bruce,
The Tassie Devil(le),
60 CDV

Bob Schuman, CLC#254

I dont think you have a safety problem, just a very annoying rattle. I have had the same problem twice, first with a 71 Pontiac, then with a 92 Mercury. GM came out with a kit that used something like wery tough contact paper applied to the back of the brake shoes, which eliminated the rattle. Ford replaced the Mercurys rear shoes and eliminated the rattle.
The rattle results from the disc brake metal shoes being free to move a little when brakes are released. Hitting a bump makes them rattle in the caliper, unless the brakes are being applied.
My suggestion is to ask one or more GM dealers if they know how to fix the rattle, then try independent auto parts stores. The problem is not exclusive to your Eldo-lots of disc brake cars do this, but most owners never open the windows and never hear the noise.
Bob Schuman

Erik

Its definitely the brake pads rattling.  The noise stops the second I apply brake pressure.  Ive had the wheels off and can ever so slightly wriggle the pads to and fro within the calipers.  The calipers and pads are new but it did the same thing with the old ones.  The only thing I can figure out is that that rotors  grab and rotate the pads against the caliper stops whenever pressure is applied, which over time causes a slight gap between the pads and the caliper stops.  If I somehow shimmed them Im afraid the pads wouldnt ease back from the disc when the caliper piston retracts.  Im have to assume that GM must have installed some type of spacers at the factory that have since been lost and that dont come with aftermarket pads or calipers, but even my GM chassis manual doesnt indicate anything.

ERik

Erik

Quote from: Bob Schuman, CLC#254The rattle results from the disc brake metal shoes being free to move a little when brakes are released. Hitting a bump makes them rattle in the caliper, unless the brakes are being applied.

Exactly.  Ill ask my local Chevy dealer (Caddy dealer is far away) if he knows of anything that would fix it.

Erik

Bruce Reynolds # 18992

Erik,

Is there a possibility that someone has left out some "anti-rattle" clips that are common with most Disc Brake assemblies?

I dont have a Workshop Manual that shows the Cadillac Rear Discs, but when the pedal is released, the pistons dont retract of their own accord.   It is the slightly "out of trueness" of the Rotor that "pushes" the pad out of the way, and that in turn pushes the piston back.

Loose Wheel Bearings will do the same thing.

Bruce,
The Tassie Devil(le),
60 CDV

Jerry

Bruce,

I dont believe that there are any anti-rattle clips on the rear disc brakes - the pads are held in place directly to the rotor with a special screw attachment.  

Jim Skelly, CLC #15958

When I got my 77 Eldorado 8 years ago, I had the same problem.  I could only hear the rattle with the windows down.  It only had 7,000 original miles.  I took it to the local Cadillac dealer to check out the rattle and a few other items.  The mechanic couldnt believe that it still had the original brakes, and mentioned that an anti-rattle clip had fallen off.  I dont recall if it was put back in place or if a replacement was put in.  It has been fine ever since.  Get an exploded diagram from the Cadillac dealers parts dept., or call U.S.A. Supply in Virginia.

Erik

So far as I can tell, the pads are held in place only by the two pins that allow the pads glide freely when pressed by the caliper piston, but the clearances arent so precise that they keep the pads from slapping the caliper stops when contacting the rotating discs.  Ive never seen an anti rattle clip but the caliper design would merit one.  A clip that pushes the pads away from the discs makes sense.

Erik

Chip Hodges, #20536

I have exactly the same problem on a 1976 Eldorado that I acquired last July.  The rattling noise seemed incredibly loud with the top down, and it took me a few weeks to realize that there was no rattle when I applied even the slightest pressure to the brakes when hitting a bump.  The rear pads appear to be mounted correctly, but there is substantial movement in them when the brakes are at rest.  At this point I am not certain if there are spacers missing or what, bur I will probably not readdress this problem until after the first of the year.  

Chip  

Dave MacGregor 18998

Not sure of the 76 Eldos, but for the 77s there are no anti-rattle springs on the rear disk brakes.

Three years and just 6,000 miles ago, I did a rear break overhaul on my 77 with rebuilt calipers, new AC brake pads, etc. all because the parking brakes stopped working - a common problem with these cars.  Quiet as a mouse!

What I can tell you is perhaps the tabs on your rear brake pads arent bent at all or arent bent quite enough.  They must be bent into place with a pair of pump pliers or the pads will indeed fit very loosely and cause rattle.  Not sure how bent to tell you exactly, but lets just say the pads shouldnt just freely fall out of the calipers.  They also shouldnt require any effort to remove either.  Sorry if it that sounds vague, but thats as best as I can put it.  The main thing is they should float on the rotor once the whole assembly is in place.

I also never saw and thus never used any anti-rattle goop on them, but for your rear brakes I imagine it wont hurt, but I do highly recommend checking the tabs first.

Good Luck!

denise mccracken 20352


   OK, I have to be the one to ask another pedantic question.  When you had the last brake job done, were the rotors turned?  If they are not true, they could be slapping.

   Also, with the tires on the car, you can feel for wear in the wheel bearings, and spin the tire and listen to how they sound. A loose wheel bearing could cause this issue in the brakes.

   Are there soft shims, or squeal stopper juice that might help?

   And just to tell a funny story that has nothing to do with fan belts, I had a 70 Toro, which is probably a very similar rear axle, which went a thousand miles with a wheel bearing completely missing.  I drove the car all of the way from Baltimore to Portland, OR, and it started making noise before I even got out of Maryland.  Nothing could make me turn back to the East Coast, but the noise kept getting worse.  Somewhere around Utah, I think it was, I jacked up the wheel and found that the bearing had been chewed to pieces and was completely gone.  I stopped in many wrecking yards on my way, but I went all of the way to Portand, OR before I found a replacement hub for it.

Good luck!

-denise

denise 20352


   If this is the GM "floating caliper" design with the two bolts, I seem to recall a clip on one of them that went around the top of the brake pads and tucked in under each bolt.

-denise

Steve Preston 18375

Yall have been in & around the problem. The OUTBOARD pad needs to have its "ear" staked. Page 5-54 of the 76 shop manual states in section d-5; "Clinch upper ear of outbound shoe by positioning 12" pliers with one jaw on the top of the upper ear and one jaw in notch on bottom of shoe, opposite upper ear." It also mentions a picture #5-16 found on page 5-14. It goes on to say, "NOTE: After clinching, there should be no radial clearance between the shoe ears and caliper housing".

This holds true for the front brakes too. Found on page 5-51, section 36-b-10.

When I do my Eldos brakes, I dont use "channel-locks" but instead a large drift and hammer. One or two sharp blows will stake the ear nicely and give you peace n quiet.

Jack

I had this exact same problem a few years ago when I was replacing the rear brake pads.

With new pads I wanted to install new hardware and the store where I bought the pads had hardware kits made by Bendix.

On my car, a 91 Eldo, there is a part called a "shoe retainer." the Bendix part was not the same size as the original- it was looser. But I didnt know this until after assembling the brake back together and noticing the rattle.

I took the brake assembly apart again and compared this part with the original and there was a considerable difference.

So I found a place that had the AC/Delco brake kits and placed this part on the shoe and it was tight. I assembled the brake and took the car for a test ride.

No rattle! What a relief !

So check and see if your car has this "shoe retainer" and if it is tight.

Jack  

Dave MacGregor 18998

Ditto!!!

Thats exactly what I was trying to get at with my post.  There were no and I just looked up in my repair manual, no clips for the rear brakes on my 77.  It never had them when I replaced the original pads a couple of years ago or so.

All I did was similar to what you said, but I did use Channel Locks, but when I bent the tabs, I didnt just squeeze them, I actually did a little pulling down, then pulling up on them to pull the tabs in tighter.  Worked fine for me without extra tools.

I also have to say that I also used genuine GM brake pads instead of 3rd party.

Finally, the front brakes did have and in the manual, specify the use of the clips that everyone is talking about AND the proper bending of the tabs.

Dave

lwarneka

Rock Auto has the anti-rattle clip cheap. I ordered and received mine but, just too lazy to put them in as of yet! They hold the pads against the mount and away from the rotor soi they can not rub or rattle!

Warehouse A   Tracking: 9400110200847101834324
   Quantity   Return Policy
1976 CADILLAC ELDORADO 8.2L 500cid V8
Brake & Wheel Hub : Disc Brake Anti-Rattle Clip
ACDELCO 18K2281 {#19297073} Professional Info
Rear

35-709

 ;D  Well, if anyone is having this problem --- 10 1/2 years after this thread ran its course --- there is some help.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2