To adjust the brake pushrod or not?

[Coreymillia42]

I know, NEVER adjust the pushrod even if your life depends on it. And also, it may be necessary to adjust the pushrod if the MC has been replaced...

At least that is what I have come across.

A while back in my other bug I had a problem with the brakes locking up one day, after a lot of messing with everything finally noticed the brake pushrod lock nut was on the wrong side. Meaning it was just loose and adjusting itself. It had been a while since we did the MC, but I don't remember ever messing with it. So, what I finally did was while the breaks were locked up backed the push rod out, till the pressure released. I went back and forth a bit to see how the breaks reacted. Then did my best to adjust the freeplay and left it at that. That was a year ago.

Recently I got a 1966 bug, the guy I got it from replaced the MC and the 4 wheel cylinders, I don't think he did the lines. I noticed the grommet leaking so replaced that and adjusted the brakes, and then bled them. About 30 times each wheel. The pedal still goes to the floor, and now pumps up immediately, whereas before it probably took about 10 pumps. Then goes down after about one second after releasing my foot. The e brake goes all the way up, and barely works. One thing is that when the e brake is on the foot brake feels okay.

I still think there is possibly some stubborn air in the lines, so I am going to bleed it some more. As well as I ordered a power bleeder, though I have heard some better and worse things about them, mostly better.
I sent him a message asking if he removed the foot pedal assembly and am pretty sure he would have. However, it did not look like it. Assuming trying to slide that forward would be the first thing to try?

The reason I wanted to ask as adjusting the pushrod will be the last resort, is because when I feel the brakes in my '71 I can feel pressure on the MC, while in this '66 I can move the brake pedal and feel no pressure till it taps the MC.  

So I am wondering, how many people have had to adjust it? Did not seem like that big of a deal as some make it out to be.
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1971 Super Beetle. Owned 25 years... And now the owner of a 1966 Beetle. Plus, a 1967 bus that doesn't run.

[rcooled]

[EVfun]

You must have some clearance between the pushrod tip and the inside of the piston in the master cylinder with the pedal up. If not it will likely block the bleeder port and the brakes won't easily bleed. If you succeed the brakes will likely drag in use.

The VW approved correct way to adjust the pedal free play is to move the stop bolted to the floor. Since these cars are all 45+ year old now that may be solidly rusted in place. Instead, it is not uncommon to adjust the pushrod length to get a little free play. The catch with this is you don't want the pedals resting positions to be too low, you may not be able to move enough fluid to stop if you have a partial brake failure. So if you need a shorter pushrod it would be best if you could do it the VW way.
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[KTPhil]

Adjusting the pushrod without finding what caused the issue in the first place is Russian roulette, not only with your life but the lives of your passengers and other drivers. To me that is a "big deal."

Do the rest of us a favor: if you do this and ignore the good advice on how to systematically troubleshoot the problem, at least make sure your horn in functioning and LOUD.
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Current Fleet:
'71 Fastback
'69 Westfalia
Retired:
'67 Beetle
'65 Beetle (x2)
'65 Bus
'71 Squareback

[sjbartnik]

The trick is to understand when you should and when you should not adjust the push rod.

It should almost always be the last thing you touch.

The first thing you should look at is the pedal stop which is bolted to the floorpan. This serves as a limiting stop for both the brake and clutch pedals and it should be adjusted so that both pedals are basically standing vertical and even with each other. If you make an adjustment here, you may have to re-adjust your clutch free play afterward.

There is also an important spec in the Bentley that tells you how much distance you must have from the pedal (in resting position) to the front bulkhead. If you have insufficient distance, it may prevent you from fully applying the brakes in the event that one of the brake circuits fails. So that's a big safety issue.

Once you have your pedal stop adjusted and your resting pedal is the prescribed distance from the bulkhead, then you may consider adjusting the push rod as necessary to meet the spec.

You need 1mm clearance between the tip of the push rod and the piston inside the master cylinder. You can't measure this directly, but knowing that the pedal has a 6:1 ratio, you can measure the clearance indirectly by measuring the pedal travel before you feel the push rod contact the piston. You should have 5-7mm of pedal travel before the push rod contacts the piston.

Important note! This is not 5-7mm until you feel braking action! You will not have braking action until the pedal is pushed much further. This is really hard to feel by foot so you need to get in there, put your hand on the brake pedal, and very gently move it so you can feel when the push rod makes contact with the piston.

If you have too much clearance, pedal travel and feel will suffer. If you have too little clearance, you will block the compensating ports in the master cylinder and the brakes will eventually lock up on you while driving as the fluid heats up and can't expand back into the reservoir.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[viiking]

[mukluk]

[Coreymillia42]

[Coreymillia42]

[Cusser]

[KTPhil]