Update - Help! 72 SB Brake Question

[Revias]

It's always a brake issue with these cars, isn't it?

Front wheel bearings were grinding bad so I took them off to replace and while I was there I noticed uneven wear on the shoes. The bottom 2/3 of the shoes were worn down halfway, and the top 1/3 was completely untouched!

I had the wife press the pedal and I watched the wheel cylinders on both sides. On the RF the only one piston moved, but it moved well. First question: Does the first piston and shoe need to engage before the second piston moves or do the move simultaneously?

On the LF brake, both wheel cylinder pistons moved weakly when the pedal was pressed. I am assuming a bad wheel cylinder on both sides? Car does stop, and pedal has pressure, I don't see any signs of a fluid leak. MC was replaced 3 years ago properly by a professional.

Any ideas? I am going to replace the shoes naturally but want to know your guys' thoughts before doing a full overhaul of the front brakes and replacing the wheel cylinders.
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"DAMN MILLENNIALS!"

Proud owner of a '72 Super

I'm down with fat chicks

[Q-Dog]

I would measure the inside diameter of the drums and compare them to the maximum wear specification in your service manual.
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Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[grandpa red]

Flush the brake fluid first if not done recently.

Replacing the wheel cylinders is not expensive and if they have not been replaced recently might as well go new.

Also clean the backing plates and inspect for wear where the sides of the shoes rub.

Clean the hardware.

Turn the drums replace if out of spec and try to have the shoes arced.
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'72 Beetle

[calvinater]

Don't forget the soft brake lines.
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"Albatross"!

[baldessariclan]

Definitely replace the wheel cylinders w/ new ones, both sides.

Uneven shoe pad wear may also be due to inner diameter of brake drums not matching outer diameter of the brake shoes. You can either get some new drums (which should be close to diameter of new brake shoes), or get the current drums turned and then have the brake shoes arced to match (older brake shops usually know how to do this).
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1971 Standard Beetle — fairly stock / driver

baldessariclan -- often in error, never in doubt...

[Revias]

[johnnyvw164]

I recently acquired a 69 standard Beetle. All the brakes were entirely redone by the owner before the person I bought it from, who maybe put 100 miles on it in 10 years. After sitting for 10 years, all the wheel cylinders had at least one frozen piston from sitting for so long, even though they were brand new. And a few of them were leaking past the seals as well. Cars do not like to sit unused....

[volksworld]

whatever part of the cylinder has the least resistance will move first ...yes f&r should move simultaneously...if you stuck a screwdriver between the shoe and backing plate on the side that is moving to prevent it from moving odds are the other side will now move...if not that half of the wc could be frozen....if you grab the slotted end and try to spin it , it should turn freely...new cylinders are just cheap insurance anyway...unevenly worn shoes are usually due to adjusters that dont have the deep part of the slot facing up...but shoes worn at the bottom is not usual...a lot of stupid stuff can happen to a car in 40 or 50 years...its possible someone had (or still has) the shoes on upside down...the squared off end goes into the wheel cylinder...the end thats cut on an angle goes into the adjuster....on a dual circuit master the front and rear brakes are independent hydraulic systems from each other so you only need to bleed the front...it wouldnt hurt to bleed the rear while you're at it but just do the front and make sure everythings ok first cause if something goes wrong you wont know which end to blame

[Revias]

[Revias]

I replaced both front wheel cylinders and shoes, and went to bleed the front brakes. Bled them using the bottle method, filled a bottle 1/4 with new fluid, stuck a hose in it, stuck the other end on the bleeder screw after just cracking it open. Right side bled well, lots of bubbles that eventually turned to just fluid. Capped off that side and moved to left front. Repeated process, but got FAR fewer bubbles. Pumped brakes for a good while and still got no air. Capped that side and tested brakes.

Petal then went to the floor! No pressure, no wheel cylinder movement. I admit I did not bleed the back brakes, but I was told with the dual circuit I only needed to do the front.

So I pumped the brakes for a while and got no change in resistance I did however hear some odd squealing/hissing from the MC area, kind of like a kettle going off. Not good. So I then tried to re-bleed the right front and I could get NO fluid or air movement from the bleeder screw.

What the heck is going on? Did I blow something in the MC? Does not bleeding the back really affect the whole system in a dual circuit MC? I have stainless hard lines on the entire car so it's not a hose collapse. MC was new 4 years ago. Did not have petal stiffness problems at all before, only dug into the brakes because of half working wheel cylinders.

What am I doing wrong? I am a rookie, I admit. Trying to learn so I can work on these brakes myself. Any help is appreciated.
_________________
"DAMN MILLENNIALS!"

Proud owner of a '72 Super

I'm down with fat chicks

[Pruneman99]

Did you leave the rear circuit dry?

[Revias]

[Lingwendil]

check that the connections at the master cylinder are nice and tight. Also check that you have adequate freeplay at the pedal pushrod, and that it is not fouled with carpet or debris that could keep it from fully returning.
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73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[volksworld]

first off...are the fronts adjusted correctly? be aware that the 2 adjusters on each wheel turn in opposite directions to tighten them....tighten one till the wheel wont turn, then force the adjuster tighter till you cant turn the adjuster any more without breaking something...then back it off till you canturn the wheel but you can feel it dragging a bit...now do next adjuster same way...once you know they're adjusted right (and you're going to go back over them after its driven) you can bleed...dont use bottle method...open bleeder, have someone push pedal straight to floor...close bleeder...have person release pedal SLOWLY...like a5 or 10 second count...re-open bleeder...push to floor, close etc...repeat till no bubbles or foam...if the hoses connecting the master to resevoir , or the grommets where the resevoir tubes go into the master are dried out they can suck in air while they are sucking in new fluid from the master...if you had a pedal before you started you should have one now, masters usually dont fail in the middle of bleeding the brakes

[Revias]

[Revias]

Did the traditional bleed method, I like that a lot better. Got some air out of the lines, but no change in pedal hardness.

Wife noticed that while she was holding the pedal down and I released the rear bleeders the pedal went all the way to the floor (as opposed to 1in or so from floor).

When I did the front bleeders while she had the pedal down, there was no change in the pedal, it did not go to the floor.

All 4 bleeder screws let fluid out well. I am stumped. Why the difference between front and rear circuits?

Any idea? I am desperate.
_________________
"DAMN MILLENNIALS!"

Proud owner of a '72 Super

I'm down with fat chicks

[vernonc]

It's because, in a 'dual circuit' system, you should always bleed the fronts first and then the rears.

I suggest, now, that you run a tube from one of the rears into a jar of fluid and open the valve. Then bleed the fronts. When the fronts show no more air, pump, hold and bleed the rear that you left open.

There's several posts on the bleeding of dual circuit systems and some explain why the 'front first' method is required.

Hope this helps.

ol' mort
_________________
"Those who don't read newspapers are un-informed. Those who do read newspapers are mis-informed." Will Rogers

'69 sedan, low mileage, all original.....currently being 'freshened-up' for road trips and daily driving...just not every day

Freshening-up link http://www.thesamba.com/vw/forum/viewtopic.php?t=617386

[Revias]

[vernonc]

Quote:
"So am I correct in assuming if I am getting some pressure, fluid moving at every bleeder, and no previous problems that my MC is fine?"

I'd say, there's a very good chance that your Master Cylinder is okay. I assume that you have checked the 'pedal to cylinder' rod for correct adjustment. (I think it's about 3/16 to 1/4 inch of 'free play' at the pedal.)

Don't forget to do a final brake adjustment........full tight then back off 2 or 3 clicks...........you should re-check after driving a few days.

Hope this helps.

ol' mort
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"Those who don't read newspapers are un-informed. Those who do read newspapers are mis-informed." Will Rogers

'69 sedan, low mileage, all original.....currently being 'freshened-up' for road trips and daily driving...just not every day

Freshening-up link http://www.thesamba.com/vw/forum/viewtopic.php?t=617386

[johnnyvw164]

Try this...first, stop pumping the brakes. Start at the farthest wheel from the MC. Crack the bleeder screw, and have someone slowly push down on the pedal. Have it held down while you tighten the bleed screw back down, then have the pedal released. Repeat until no more bubbles. Go on to the next further wheel from the MC and repeat, then third closest, doing the closest last. This is the method I learned a long time ago in vo-tech school, and I've never failed to bleed brakes unless there was an actual problem.