Sometimes knocking sound when braking.

[Ovally]

Early Oval, same hydraulic brakes as a Zwitter.
Sometimes there is a slight knocking noise when braking.
The sound comes from the right rear brake.
I removed the drum and everything looks good.
The drums are checked for ovality.
The entire braking system was renewed not long ago.

I think I have this problem.
Someone who is familiar with these types of washers / spacers?
They look square.
A picture with dimensions would be welcome.
VW part number is 11 609 161

Thanks and regards.
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VW Bug Oval 1953
VW Bug 1200 D motor
Porsche 911S MFI 1970
Mazda 929 Hardtop 1977
Mercedes SLC 180 Roadster 2018

[VW_Jimbo]

I found that loose shoes can knock or slap the drum on the trailing edges, after a brake job when the drums are new or turned. I believe it to be the cause of the additional friction between the new shoes and fresh surface area in the drums. They are seating. The additional friction “grabs” onto the leading edge and causes the trailing edge to “slap” the drum.

So, are the shoes adjusted correctly? To a light drag. I typically adjust out till the wheel locks up then back off three clicks. Go pump the brake pedal, 3 or 4 times. That recenters the shoes. Then go readjust for slight drag on each shoe.

Should take care of your noise, if it is what I believe it to be. This same noise can be made to disappear when you slam on the brakes. During that hard braking. The shoe never is allowed to relax, it is continually being forced into the drum with very high pressure.

Hope that’s it!
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Ovally]

[0nebadbug]

Not sure if when you say "knock" if it might be chatter...

We had this just after rebuilding everything (in the rear). We also thought a few clicks back from locked up to not touching the drum & also got an errant chatter. After a few days of head scratching trying to figure it out we came up with the same fix as outlined by Jimbo above. Soon as we had some light friction, it immediately went away... And then after 100 miles of driving, readjusted & it's been smooth sailing ever since...

Now, if you were saying "knocking" and were hearing it upon acceleration as well them maybe you might check the axle splines or the drum spline axle holes for wear then, possibly.
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::: Slowoval ::: LaDawri Sebring ::: '61 Creampuff ::: Dust Storm '66 :::

[Ovally]

[VW_Jimbo]

[quote="Ovally"]

[Ovally]

[VW_Jimbo]

[Mr. OGPaint]

Do you have original rear wheels /lugnuts? Is the axlenit tight/torqued to spec and are the drum splines in good condition and not “undercut”?
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https://instagram.com/mr.ogpaint
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Patrick Hall

[Ovally]

[Ovally]

I have re-checked and adjusted both rear brakes and the handbrake mechanism.
I noticed that the right handbrake cable sometimes did not come all the way back.May have been the cause.
To exclude other things, I replaced the brake shoe levers(12), the brake shoe push bars(13) and the upper and lower return springs(9,10) on both sides with VW NOS parts that I had collected as spare parts.

Drove the car a few times, braked gently and so far everything seems to be fine.

Regards.
_________________
VW Bug Oval 1953
VW Bug 1200 D motor
Porsche 911S MFI 1970
Mazda 929 Hardtop 1977
Mercedes SLC 180 Roadster 2018

[VW_Jimbo]

Sounds like you got it!
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Ovally]

[VW_Jimbo]

I would disagree with installing fully with the car on the ground. I would speculate that the original car was assembled on a production line and those seals were installed before there was a load on the suspension. I have always installed them while the vehicle was in the air. Never have had an issue.

I use a light smearing of silicon grease on the inner and outer surfaces to allow the bushing to slip in rather than drag into place. When fully seated. I bounce the car, using the rear bumper before final tightening. Drive it around a few hundred loosen the bolts back up a few turns and retighten them.
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Ovally]

OK thanks, will do it that way.

Regards.
_________________
VW Bug Oval 1953
VW Bug 1200 D motor
Porsche 911S MFI 1970
Mazda 929 Hardtop 1977
Mercedes SLC 180 Roadster 2018