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ASE Master Tech 35yrs
ASE Master Tech 35yrs, ASE Master Auto Tech
Category: Car
Satisfied Customers: 2095
Experience:  ASE Certified since 1972,Master Auto tech,Heavy Truck Tech, foriegn and domestic
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Passenger side rear drum brake making a knocking sound

Customer Question

Passenger side rear drum brake making a knocking sound. Only does it going forward. Have installed all new parts and still have the sound. Only does it when applying the brakes. Any ideas?
Submitted: 8 years ago.
Category: Car
Expert:  mr.james replied 8 years ago.
HiCustomer Thank you for asking your question on JustAnswer. The other Experts and I are working on your answer. By the way, it would help us to know:
-What year is your Car?
-What make and model is your Car?
-How many miles are on your Car?
-What type of engine is in your Car?
-What have you already tried?

Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
Customer: replied 8 years ago.
This is on a 2001 Dodge Grand Caravan Sport with 3.3 L V6 and rear drum brakes. Have 96,500 miles and just replaced all I could on the rear brakes. Front brake pads were just replaced. Let me know if you need anything else.
Expert:  mr.james replied 8 years ago.

does it do it while moving or just braking.

can you spin the wheel and here it

is the exhaust tight and not hiting anything


Customer: replied 8 years ago.
Just does it when applying the brakes and since the front pads are new, it won't kick in with the knocking until applying more pressure on the brakes. I cannot hear it when spinning the wheel and nothing else is loose or hitting anything. Surely this has happened to someone and it was still something with the brakes. Like I said, all parts that could be replaced and relate to the brake are now new. What gives....
Expert:  mr.james replied 8 years ago.
Chrysler has a service bulleton about lubing rear wheel cylinder componets
Customer: replied 8 years ago.
First, the cylinders are new and properly lubed. There needs to be other options since this knocking sound happened with both old and new wheel cylinders. And, unless I have the Service Bulletin in front of me, I can't accept that answer.
Expert:  mr.james replied 8 years ago.

NUMBER: 05-004-02

GROUP: Brakes

DATE: Aug. 19, 2002

Rear Brake Cyclic Rubbing Sound


This bulletin involves applying lubricant to the rear wheel cylinder components.



2001 - 2003 (RS) Town & Country/Voyager/Caravan





A cyclic swoosh, squawk, squeak or grunt sound from the rear of the vehicle may be heard during medium to light brake application on vehicles equipped with rear drum brakes. The sound will be related to the speed at which the tire/wheel turns (one sound per revolution of the tire/wheel).


If the vehicle operator describes the subject Symptom/Condition, test drive the vehicle to verify. Perform the Repair Procedure if the symptom/condition is experienced during the test drive.



1.Raise vehicle on suitable hoist.


2.Remove the rear tire/wheel assembly.


3.Remove the rear brake drum.


4.Remove both rear brake shoes from backing plate using the procedures outlined in the appropriate Town & Country, Caravan and Voyager Service Manual.


5.Clean the area around the wheel cylinder boots.


6.Peel back the edge of both wheel cylinder boots to separate them from groove in casting. Remove the boots and attached pistons from the wheel cylinder.




7.Apply lubricant liberally to the surfaces of the pistons and inside the bore of wheel cylinder without disturbing rubber cup seals. Presence of small amounts of corrosion visible inside the bore of the wheel cylinder can be ignored provided there is no evidence of leakage of brake fluid past the rubber cup seals. Do not confuse traces of assembly fluid from the factory with brake fluid leakage.


8.Install the pistons and boots to the wheel cylinder. Make sure that the boots seal properly onto the casting groove all the way around the wheel cylinder. With your fingers, shuttle pistons back and forth in the wheel cylinder bore to distribute lubricant. Do not allow the boots to become dislodged from wheel cylinder casting groove.


9.Insure the wheel cylinder is sealed to the backing plate. If not, seal around the perimeter of the wheel cylinder using a small bead of RTV (p/n 05010884M).


10.Install the brake shoes using the procedures outlined in the appropriate Town & Country, Caravan and Voyager Service Manual.




11.Wipe any spilled fluid from the outside of the wheel cylinder, as well as any other brake parts, including the linings.


12.Repeat step 2 through 10 for other brake assembly.


13.Install the brake drums and rear tire/wheel assemblies. Torque the lug nuts to 135 Nm (100 ft.lbs.).


14.Lower the vehicle.


Reimbursable within the provisions of the warranty.




Expert:  mr.james replied 8 years ago.

have also seen if lube not put where shoes touch on backing plate

trying to get close since you already replaced everything.

please dont accept untill your satisfied

Customer: replied 8 years ago.

That is great, but I did in fact lube the pistons in the wheel cylinders. In fact, I greased everything that I could grease to ensure I had no other sounds to worry about. Like greasing the back plate where the shoes rub against it as well as the self adjusters and so on. Don't worry, I did not grease the shoes or the drum and cleaned everything with brake cleaner. Again, this happened with the old wheel cylinder as well and it may have actually been fine anyway. Also, the knocling is only coming from one side. I cannot say that the wheel cylinders are the issue here. What else do you have?

Expert:  mr.james replied 8 years ago.

the only thing else i can think of backplate loose, shock movement inside tube which is normaly just 1 knock.

wheel bearing which normal constant growling noise.

rubber bushings in springs.


Customer: replied 8 years ago.
Can we get some other input? Everything is solid, no other sounds with bearings or bushings. What if one of the new drums that I bought is out-of-round or warped somehow? What do you think?
Expert:  JD replied 8 years ago.

HelloCustomerand thanks for choosing!



I see you are in need of further opinions about your issue.


Honestly, doesn't sound like it's the brakes causing this, as you would probably have issues parking it on a hill with the handbrake. I suggest inspecting bushings, either shocks or suspension components bushings. When you brake you are mainly using your front brakes. The rears only come on slighly to help stop the back end from overtaking you. Also when you brake, all the weight of the car goes forward putting less pressure on the rear suspension. Try tapping the brakes and see if you get repeated knocking as the weight shifts back and forth making your suspension lift and lower repeatedly at the back. See if your shocks are leaking or if any of the bushings are rotten, worn or just gone. Also bounce the car up and down while the assistant is inspecting the shocks/suspension to help him/her pin point where the problem may lie. Let me know how the inspected parts look and I will follow up.

Customer: replied 8 years ago.

I just finished checking the bushings and suspension and found no knocking noise. Some bushings are looking old but still functioning. Shocks are not leaking, and bouncing does not generate the knocking sound. Again, the knocking is clearly coming from the passenger side rear wheel. Still only when applying the brakes and rolling down the road. Even when roadway is very smooth (new parking lot nearby). I tested the handbrake and it does hold. Please check with someone to see if an out-of-round or warped drum could be the cause before I go ask for a new one.


Expert:  JD replied 8 years ago.

A warped drum could indeed cause it but it is just highly unlikely that both the old and the new drum would have both been warped.

Customer: replied 8 years ago.
Actually, the knocking sound started after the initial brake repacement-- with new drums. Old drum was worn, not warped.
Expert:  ASE Master Tech 35yrs replied 8 years ago.
I have seen this many times and usually the cause can be cured by turning the drum at a slow speed. I always turn new drums due to that fact that they are stacked high in the parts room can can become warped just sitting there for too long. I have seen if the drum was turned at a faster speed, it causes the grooves in the drum to be too far apart and the brake shoes contacting it will follow the groove causing the knocking sound that you hear. Turn your rear drums and this will solve the problem.
Expert:  JD replied 8 years ago.
You stated at first that the knocking occured BEFORE drum replacement and that replacing the drum and brake hardware did not did the knocking occur BEFORE or AFTER drum replacement??
Expert:  ASE Master Tech 35yrs replied 8 years ago.
He never stated that the knocking was there before the new drum, he said it was there with the old wheel cylinders. He replaced the wheel cylinders and lubed pistons per technical service bulletin in an effort to solve problem.
Customer: replied 8 years ago.
Knocking started after new drums. Also, how does this work if I was the first to say the the drum was at fault. I could get the drum turned and see if that helps. Maybe I will just go to the parts store and exchange the bad one for another new one. They have been very good with returns. Also, that would save me the $15 minimum I would have to pay to get the new drum truned.
Expert:  mr.james replied 8 years ago.
you could try moving drum to other side ,if knock moves with it i would take drum back and save a buck.
Expert:  JD replied 8 years ago.
"Passenger side rear drum brake making a knocking sound. Only does it going forward. Have installed all new parts and still have the sound. " ...
Expert:  ASE Master Tech 35yrs replied 8 years ago.
You could try exchanging the drum and maybe you'll get lucky but I always turn new drums when I do a job so I don't have to take them off again. Time is money to me. Of course there is a possibility that the drum they gave you was the wrong one for the application, perhaps boxed wrong. Check your drum for any shinny marks where the backing plate may be rubbing on it. Also check your backing plate for the same. If you can find a problem there, it may or may not be the drum but a problem with the backing plate. Check to make sure both drums are identical as well. It's been my experience that if it only happens when the brakes are applied, that the problem lies in the fact that the drum is warped or has been turned too fast on the lathe in the manufacturing of it.