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Old 03-23-2018, 09:32 PM   #1
SteveR.
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Default “Clunk” when I hit the brakes

If I do more than slowly apply the brakes, I get a “clunk” sound from the brakes, like the shoes or associated parts have some play in them. This is probably something simple, any tips on where to start would be appreciated.
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Old 03-23-2018, 09:58 PM   #2
larrys40
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Default Re: “Clunk” when I hit the brakes

Steve. It could be a number of thinks.. from brake rods binding, hitting something, loose backing plate ( typically on front) etc.

I would inspect the brake rods and look particulaly at the area where the rods are near the shock arms if they are installed. See if the rod is touching or bent in that area. Wheels up off the ground and grab backing plates and see if there's any rotational movement. Also check your cross shaft for bind and signs of issues there.

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Old 03-23-2018, 11:38 PM   #3
Tom Endy
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Default Re: “Clunk” when I hit the brakes

It is very common to find that the four nuts and bolts on the rear backing plates have bottomed out on their threads without holding the backing plate tight against the axle housing flange. The force of braking and accelerating will rock the backing plate fore and aft and eventually elongate the bolt holes. When sufficiently worn there can be a clunk not only when braking, but also when accelerating.


About the only thing you can do, unless you are an experienced welder, is to replace the rear backing plates with some that are not worn, and insert spacers under the rear grease baffles in order to allow the bolts and nuts to hold the backing plates tight.


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Old 03-24-2018, 05:44 AM   #4
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Default Re: “Clunk” when I hit the brakes

May also pay to check the rear axle nuts. They may be loose and you might also have a damaged axle key way.
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Old 03-24-2018, 06:09 AM   #5
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Default Re: “Clunk” when I hit the brakes

Check the cross shaft on the frame.
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Old 03-24-2018, 07:29 AM   #6
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Default Re: “Clunk” when I hit the brakes

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Hi Steve,
I found wear in kingpin bushes caused the ‘clunk’ in my Pickup. Lift the wheels off the ground and have someone apply the brakes. Then try to rotate the wheels one by one by hand. The slightest fore and aft rotation could be the cause of the clunk.
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Old 03-24-2018, 10:12 AM   #7
BillCNC
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Default Re: “Clunk” when I hit the brakes

Quote:
Originally Posted by Wick View Post
Check the cross shaft on the frame.
BINGO, ...

This seems to be what happens when the engine and trans mounts need replacing. It causes the engine and trans to sit lower in the car. Mine was like that until I fixed all the mounts. If this is indeed the case, you will see a wear mark on the speedometer cable side of the cross member as the speedometer cable nut rubs the cross shaft when the brakes are applied.

One other spot to look at is the Wishbone to Bellhousing joint. Check if the ball is loose, shim with cups if needed.

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Bill

Last edited by BillCNC; 03-24-2018 at 10:17 AM.
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Old 03-24-2018, 04:47 PM   #8
SeaSlugs
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Default Re: “Clunk” when I hit the brakes

Quote:
Originally Posted by BillCNC View Post
BINGO, ...

This seems to be what happens when the engine and trans mounts need replacing. It causes the engine and trans to sit lower in the car. Mine was like that until I fixed all the mounts. If this is indeed the case, you will see a wear mark on the speedometer cable side of the cross member as the speedometer cable nut rubs the cross shaft when the brakes are applied.

One other spot to look at is the Wishbone to Bellhousing joint. Check if the ball is loose, shim with cups if needed.

Regards
Bill
Was just gonna suggest the wishbone ball. Everything else above id also check as well. Might have to get each wheel up in the air - someone spin each one at a time and you apply the brake like you normally would and see if they spot anything.
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Old 03-25-2018, 06:28 PM   #9
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Default Re: “Clunk” when I hit the brakes

As a few have already suggested, check the wisebone. I run into a lot of my customers cars were the wisebone isn't assembled properly leading to the cluck noice you described.
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Old 03-25-2018, 07:44 PM   #10
Mark DeRoseau
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Default Re: “Clunk” when I hit the brakes

PatrickTA what is the going rate to properly assemble the "wishbone" that you've found issues with in your customers cars.
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