Super Beetle drum brake adjustment question

[beanlover]

I just replaced the wheel cylinders on both front wheels and put in new shoes.

My question is, is there a way to make sure the brakes all around the car engage at the same time? It seems like my front right brake engages the fastest and hardest. Yesterday I had to hit the brakes pretty hard and the front right wheel locked up while the others did not (top was down so I could hear pretty clearly). It seems like I need to adjust the brakes so that the rest of them engage as much as that one does (or pull that one back...or a mix of those two things).

Is there a trick to doing this other than adjust, drive, evaluate, repeat until all seem to engage equally? The only thing I can think of is to adjust and spin the wheels until they all seem to drag equally on the shoes...but I thought I did that the first time. With also replacing the cylinders in the front I am guessing the fluid has also caused a shift in adjustment as they began to be used and the fluid "settled in" after being bled and the cylinders being used for the first time...but this doesn't really seem like something that should happen so I'm a bit confused.

Additionally the car pulls to the right when I hit the brakes...telling me those shoes touch first and are getting the most use/wear.

[Cusser]

[VW_Jimbo]

Yes!

You need to pump the brake pedal to center the shoes. Turn the adjuster till it locks up the wheel then 3 clicks back. Now do the other adjuster. Go pump the brakes. Same adjusting till locked up then back off till slight drag. SLIGHT! Now listen to the noise the shoes makes when rubbing as you spin the wheel. Go pump the brakes. Now adjust the rear adjuster on that same wheel, the same way! Slight drag.

Typically, I pump the brakes and hit all 4 wheels. Go back and resented the shoes by pumping and go back through all 4 wheels. Making sure the drag sounds and feels the same at each wheel. I turn both sides as if the car was going forwards. Seen a lot of guys have issues due to turning the opposite side the opposite direction. I do not think the wear on the drum is the same and always has a tone difference on the drag, to me! So, I make sure to spin all four as if they where flying down the road forwards.

After you think you got it all done. Go for a test drive. If you feel a pull, get the car back up off the ground and spin the wheels. Sometimes the shoes reset and you will need to readjust them. Several variables at play on that one. Then repeat till everything is 100%! If you cannot obtain a good braking vehicle, you need to take it to a mechanic BEFORE DRIVING IT!

Good luck and know it is a feel thing and a listening thing!
_________________
Jimbo

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

[beanlover]

Thanks guys! That is great information.

This gives me motivation to clean out my garage so I can actually do this without freezing my fingers off haha. It also gives me an excuse to pull the distributor and send it off to be rebuilt while I do these things.

I have new flex lines...I will put those on as I bleed the brakes...might as well go all around and have all new fluid while I'm at it.

I ordered a "fuel smell" kit too so that'll need time and attention...as well as messing with the fuel sender...gonna pull my old one from the other bug and see if it works better...PO replaced the one in here and it doesn't work right as you probably could have guessed.

[goober]

This may or may not be relevant.

Remember we have two independent circuits. If you leave more clicks on one circuit it may engage slower or maybe not as much as the other. I now adjust to 4 clicks after the wheel barely moves from drag.

I've always found the rears to be more troublesome with excess drag after the clicks than the front. To avoid what I thought was 'too much drag' I'd end up doing more clicks on the rears. With too much difference between the circuits I suppose you could eventually end up having the fronts locking up while the rears wouldn't.

Someone on Samba in a post (wish I could remember who) suggested ignoring the 'too much drag' on the rears and just leave 4 clicks. He then said to take it out for a short ride, jack up the rear wheel and check to see if the 'too much drag' after the clicks didn't disappear.

I never heard that before. I tried it. He was right. Gotta love The Samba.

[beanlover]

[beanlover]

Ok...I've changed 3 of the flexible brake lines...the driver-side rear was already replaced recently by the PO it seems (much cleaner than the rest of the hoses...could read the words on the hose). I adjusted the shoes as described above. My brake pedal STILL is at the top of it's travel after driving it around for a few miles...progressively getting worse and worse until the brakes are engaged all the time. This time it's on both passenger side wheels and not just the front...so at least I can see that my adjustments were fairly accurate haha. When I first took it out I even checked to make sure it was coasting "freely" after using the brakes the first few times and it seemed to be...as well as easily maintaining 55+ mph. By the time I got home I couldn't even put it into 4th gear unless I was going down hill because it couldn't overcome the brakes and would decelerate.

I know the master cylinder is a "two circuit" system...I always assumed that was front and rear were each circuit. Is it right and left instead? That would make sense given what I seem to be experiencing. I drove it back with the brakes really giving me fits...my wife was in the driveway and asked, "Am I supposed to be able to smell your car?" The smell of hot brake shoes was in the air for sure. I felt the warmth coming off the rear passenger and front passenger...but the other side was normal smelling and heat-wise.

Is there anything else I should try before replacing the master cylinder? When I replaced the hoses I made sure to bleed the brakes a lot so that the color looked light. There was a lot of dark color fluid coming from the passenger side rear hose (that hose was in the worst shape as well...see pic below). I then proceeded to bleed at each wheel after I replaced the hose...so the only one I didn't bleed was the driver-side rear...but that's not the side that is giving me issues.

[VW_Jimbo]

How much free play is there at the brake pedal?
_________________
Jimbo

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

[beanlover]

[modok]

The hydraulics should apply equal force to both left and right, if it's working right.
The brake shoe star adjusters do not make any difference in that either, just adjusts the amount of play, not the amount of force.

But how the shoes fit the drum, and how the shoes sit on the abutments can make a considerable difference to how braking you get compared the the pedal force.

I think you still need to iron out some more hydraulic problems before you can start to look at that tho.
The brakes being stuck on could be a problem where brake fluid can't get back out again, like there was a one way valve. Could be a problem with the master cylinder, not enough free play, could be a bad hose.

[beanlover]

[modok]

Did you check the pedal free play? pebble stuck under the pedal?
Sometimes if the brakes are stuck on from hydraulic pressure, opening the bleeder will release that pressure and you will know what was causing it.
Could it be the master? maybe, but WHY is it one side not the other?

The "dual" master cylinder is split front and rear.
There is only one brake line going to the rear, so it cannot be split left and right or diagonally.

It would be unlikely and very ironic if the new hoses are causing the problem but it's not not totally impossible.

[VW_Jimbo]

Sounds like the freeplay is incorrect, or you have a wonky master cylinder.

All this is in the Orange Bentley manual.
_________________
Jimbo

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

[beanlover]

[beanlover]

[beanlover]

Definitely seems like the "compensating ports" are under suspicion. Both trouble shooting points (5 and 7) list that as the first reason for the issue. It also seems like the push rod adjustment can affect that...so I'm going to check into that tomorrow. Thanks for talking through this with me!

[sjbartnik]

This is 100% an incorrect push rod length situation.

You MUST have 1mm free play between the end of the pedal push rod and the master cylinder piston when the pedal is at rest.

You cannot measure this directly.

The pedal ratio is about 6:1.

So, a movement of the pedal of 5-7mm before the push rod contacts the piston is how you measure it.

We are NOT talking about "movement of pedal until brakes work." We are talking about movement of pedal before the push rod contacts the piston. This is very hard to feel using your foot. Get your head in the footwell and get your hand on the brake pedal and move it with your hand. You will feel when the push rod contacts the piston.

Either your pedal stop is adjusted incorrectly, or your brake pedal push rod is adjusted incorrectly.

What is happening is that the push rod is not backing off the piston fully, not allowing the piston to return to its rest position. This blocks the compensating ports, which doesn't allow fluid to expand back to the reservoir as it heats up.

This means that as the fluid heats up due to brake use, it has nowhere to expand to. The only thing that can happen is that it expands and gradually applies the brakes. The hotter it gets the harder it applies the brakes which makes it hotter, etc. Nice feedback loop.
_________________
1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[beanlover]

[VW_Jimbo]

Nope. That releasing of the pressure using “bleeding as the means” is not a good choice. The amount of fluid in the system is static. It is either under pressure or is not under pressure based off of the master cylinder piston position. That’s it!

So, just get your wrenches down on the lock nuts on the rod. Loosen those up and spin them several full rotations closer to the bulkhead wall. Then rotate the pushrod into the pedal cluster until you get the correct free play at the pedal. That will release the pressure. Get it?

After the initial adjustment, pump the brake pedal and readjust the pushrod. Then tighten it up. Then check the free play.

Be sure to go back through your brake adjustment. As the pistons being locked, may have set the shoes out too far when you previously adjusted them.
_________________
Jimbo

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

[beanlover]