Bent drive shafts, is this normal?

[John Alves]

Hi all

I have 3 air-cools bought at various stages of my life all with the same problem, all came with the pulsating brake syndrome.
58 Ghia, 68 buggy, 68 bug, after skimming drums and replacing shoes, the
pulsating is still there on all of them, Ive just learned to live with it, I presume its a bent shaft,
is this common or am I just unlucky with my purchases?

[Haans]

Bent shaft,.....neverheardof it,...but then again I am a baby in VW's

Let's hear what the ghurus say??........could it be that the "skimmer",........equipment needs an "update"

I've heard that once a drum is out of 'true',......you have a difficult job to get it back

Maybe you drive too slow,......speed it up. Man!!!!

Haans

[fig]

Pulsation on the brake pedal is usually an out of round drum. Most commonly it would be a rear drum and the cause is usually because the handbrake was applied to very hot drums, which then get pulled oval as they contract onto the extended brake shoes when they cool.

I know people who never use the handbrake because of this. I'm careful about not using the handbrake when the brakes are hot.

If your brakes are getting hot all the time, it may be that the flex hoses are decomposing inside and acting as a one-way valve. This will get worse over time, until your brakes start binding noticeably while driving.

If you have a bent axle you'll get a lot of vibration and weird tyre wear, not pulsation on brakes. Bent axles are unusual and almost always the result of collision damage.

[retrovan]

I totally agree with Fig,

but if you say you had them skimmed, and it still does it,

then your brake man has just sand papered them and not cut them

I think Haans is onto something here, if your brakes are cut by the same guy, that will all do the same thing.

Maybe his equipment needs to be repaired.

Test it by putting some carbon dust om your brake shoes,

Turn your wheel slowly and apply brakes very lightly till you feel the brake just holding the turning wheel on the high spots.

Then remove, and if you find your black spots are on one place only, your drums have been cut off center.

if its on two opposite spots, the drum is oval, and has only been sandpapered.

Herman

[John Alves]

Thanks for replies

The pulsating did improve after skimming, but did not disappear completely, I send them to cbf in Diep River CT
they are recommended by everyone I talk to. Is there a way of skimming them (reversed on the shaft with the motor running) on the car?

[73type2]

Did you double check to make sure that all your brake parts (shoes, springs, cylinders, etc) inside the drum are installed properly?

[Terry Phillips]

Check all your steering ball joints and there is no play the wheel bearings.Make sure your leading edges on the brake shoes are the right way round and they have a chamfer on the leading edges.

[John Alves]

Did you double check to make sure that all your brake parts (shoes, springs, cylinders, etc) inside the drum are installed properly?

yes all is correct

[calooker]

Your bearings? or the bearing landing on the sideshaft could be out of round. Never seen side shafts that are not true.

[John Alves]

Your bearings? or the bearing landing on the sideshaft could be out of round. Never seen side shafts that are not true.

how do I determine this? should I just replace bearings anyway, I'm sure they still the originals

[calooker]

Bearings are not expensive so I would change them, and you can check if landings are not out of round.

[John Alves]

thanks, will do on all my rides

[John Alves]

I went and bought bearings from Beamish buggies and ended up having a chat with Alan (Owner)
He is convinced that its bent drive shafts rather than out of round drums, Ive decided to replace bearings anyway and see.

[fig]

I went and bought bearings from Beamish buggies and ended up having a chat with Alan (Owner)
He is convinced that its bent drive shafts rather than out of round drums, Ive decided to replace bearings anyway and see.

It's easy to exclude bent side shafts.

Jack up the rear of the car and spin the wheels by hand in neutral. If the axle is bent you'll see a wobble. Do this with the wheels on, and again with wheels off, this time looking for a wobble on the drums.

While you have the car jacked up with wheels on, have an assistant apply the brakes just a little (or partially apply the handbrake) and then turn each wheel to see if you can feel the brakes binding anywhere. The resistance should be constant. If not, drum is not round.

[retrovan]

If I had 3 cents to rub together, I would still bet it is oval drums.

To have 3 cars by the same owner, with the same brake guy, have the same problem, points to drums, not bent shafts.

This is possible but never heard of someone having that problem.

Good luck with your investigation.......

Herman