The Speedster that I recently bought has zero brake pedal. The previous owner said that the entire system had just been rebuilt. The pedal feels like it's not even pushing on the master cylinder piston at all. To check and adjust the rod, do I access it from inside the car, under the car, or do I have to remove the gas tank? If it's OK, then I guess it's bleed, bleed, bleed, and more bleed.
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Access from inside the car ... Usually you don't need to adjust the rod but first start here. If the brakes have not been bled, then the pedal will feel like it has minimal resistance against the M / Cylinder piston. To begin, make sure that there is a slight amount of free play when the pedal is at full rearward "rest" position.... Depending on what has been done you may also have to adjust the floor pedal stop position. Confirm all lines fittings and hoses are tight, fill the reservoir and bleed the system starting at RR, then LR , RF and lastly LF.... make sure you keep the fluid topped off as you bleed the brakes.
I think the pedal stop on the floor only affects the clutch pedal.
The length of the rod going to the master cylinder is adjustable. That is how you adjust free play.
I would not touch the master cylinder rod adjustment until after going through the bleeding process described above by Allen on post #2. Unless you know why you are adjusting the rod, you can set yourself backwards by just guessing and fooling around with it.
During the bleeding process, you will know immediately if the master cylinder is functioning: If fluid is being pushed through the lines and out the bleeder, you'll know it is being plunged through the master cylinder via the rod. So at least that much of your question will be answered.
As a footnote: I don't know what kind of MC you have, but I had (successively) three of the Chinese 'Girling' style MC with the aluminum screw cap reservoir. The reason I went through three of them is because after a year or two they would stop working. Like it felt as though the pedal went through an empty space before any pressure and by then didn't have enough stroke to get any pressure. So I changed the MC, which fixed it -- until next time.
The real problem was (my theory) is the MC plunger in the aluminum bore was 'sanding' the bore which observably discolored the fluid black, within a year. The black 'sediment' accumulated in the reservoir and eventually settled on the bottom of the reservoir and plugged the MC relief port. When that happened, fluid no longer circulated through the MC.
By the time I was on the third MC, when it happened once again after a few years; I cleaned the bottom of the reservoir by stirring it up with a Q-tip. Then I bled the brakes and was back in business. Thereafter, as a rule, every year I would stir up the MC reservoir with a Q-tip and bleed it clear through the length of at least one of the rear brake lines.
Never had the problem again.
Edit 1/26/23 Correction alert: See correction on 14th post down.
"I think the pedal stop on the floor only affects the clutch pedal."
I have mine apart right now. The floor pedal stop affects BOTH clutch and brake.
It is used to adjust those two pedals versus the accelerator pedal. Adjusting that floor stop won't affect how the brake or clutch feels.
The brake hits the floor stop with a substantial tab as part of the pedal casting. The clutch hits the stop with a 1/8" thick tab as part of the bottom of the pedal. That tab is what you bend to make both pedals even when at rest against the floor stop.
I agree that any adjustment of the brake pushrod should be done only after all wheels have been bled and, even then, very carefully.
Interesting tip, I'll add then one to the " Book "... thanks !
By the time I was on the third MC, when it happened once again after a few years; I cleaned the bottom of the reservoir by stirring it up with a Q-tip. Then I bled the brakes and was back in business. Thereafter, as a rule, every year I would stir up the MC reservoir with a Q-tip and bleed it clear through the length of at least one of the rear brake lines.
That's a good point. The reservoir is plastic but it seems that some sort of crud always finds its' way in there over the years. Danny P's turkey baster tip for draining the reservoir works well to get that junk out of the bottom of the tank. If you can see it move when swishing a Q-Tip around the bottom, then suck it all out with the baster and bleed with the new fluid.
I am a little concerned about fiber from the q-tip getting into the system.
Recently, there have been articles about a place where older people go to listen to live music and dance. The people are called q-tips.
Q-Tips, Cotton Tops, Gray Heads, White Heads, Silver Heads (me), Coffin Dodgers, they’re all the same and we are slowly becoming them.
Some of us a lot faster than others……
The black crap happens from the steel piston, aluminum M/C, rubber, and moisture from the air. That's why I bleed/flush at least every two years. Always before a race weekend on race cars.
If your fluid is black after a year, it sounds like the cap may not seal well. Sounds like moisture intrusion to me. Or, you live by the seaside.
The other "symptom" that I failed to mention. If I try to use the brake pedal all the way (to the floor) without pumping it, it will stay there, and I have to toe it back up.
@DickJ - How comfortable are you with diagnosing brake issues and correcting them?
If you're not mechanically inclined on early VW Beetles and feel that this is beyond your comfort zone, I would find a way to get it to a competent mechanic who can make it right. It's your life on the line here, you know?
To answer your question, if you have a massive air leak somewhere, like if one of the brake bleeders was left cracked open or a line fitting is leaking and you stepped on the pedal with one long stroke, then sometimes, on some master cylinders, the piston will try to go back to neutral but the vacuum/suction in the lines will hold the piston/pedal in place fully down for a while.
If you wait a while (and the brake pedal return spring is strong enough) the pedal might return to neutral. If not, it's probably something a bit more serious like a leaking wheel cylinder or caliper seals or line fitting, but I would look at leaking bleeders and fittings first.
Or your mechanic.
It could also point at a failing master cylinder. New doesn't matter - There's a lot of aftermarket junk out there and many of us have gone through two or three master-cylinder or wheel cylinder replacements before finding one that works OK.
Agree with Gordon but to add, I would disassemble and start from the beginning as more than likely there is multi issues.
@DickJ posted:The other "symptom" that I failed to mention. If I try to use the brake pedal all the way (to the floor) without pumping it, it will stay there, and I have to toe it back up.
Dick, you have described what is probably a jaw-dropping red-tag situation or condition when read by some of us. I also suggest you follow the cautions of Gordon and Alan and consider handing your brake issues off to professionals if you are not totally confident in your mechanical abilities. Just about any national tire & brake store can go through your system completely and fix whatever is wrong, certainly faster and probably cheaper than you can do it yourself.
There are an infinite number of things for you to tinker with, modify, rebuild, upgrade, take apart and put back together again on your speedster that can provide literally decades fun and satisfaction; if you are of the 'mechanical persuasion'. But the symptom you have described might not be your best first-bite-of-the-apple.
For one thing, the brake pedal has a return spring (presuming you have a stock VW pedal set). The brake pedal springs back to 'up' independently, regardless of whether or not it is hooked up to the master cylinder. For another thing, the master cylinder has internal return spring, so unless the internals of the master cylinder are defective, the master cylinder piston will return home in the bore after being depressed, regardless of whether or not fluid is in the system.
In short, both those things MUST work100% reliable, EVERY TIME or; there are good odds you could die or kill someone else. In your case, according what you have posted, those things are not working.
So I'd say at this point; if you haven't already figured out exactly what is wrong and exactly how to fix it, and you aren't positive you have ability and tools to do it, then take it (tow it) to a brake shop.
Error admission alert: The Madonna came to me in my sleep last night and said "Idiot, what were you talking about in the 4th post on this thread when rambling-on about the black-gunked-up master cylinder. You fool, don't you remember that problem was with your clutch master, not your brake master; and that Dick probably doesn't even have a clutch master, and that the brake master is not aluminum bored?". In a cold sweat panic I awakened eyes-wide and proclaimed "Oh ****, that's right!".
I apologize for posting what might be misleading information, especially on a safety-critical topic. My memory is obviously not improving with age. Sorry.
I understand, my friend. And know this, as you get older, the Madonna will bring these epiphanies to you more and more often.
When I first read RS-60 mark's post I thought it was Madonna, not The Madonna that came to him in his sleep. I found that very interesting to imagine.
@DickJ posted:I understand, my friend. And know this, as you get older, the Madonna will bring these epiphanies to you more and more often.
I could look forward to that, except when the Madonna appears she never starts out with "nice job, you are a good boy". It always starts with "you idiot . . . . ".
As far as the 'other one', the Material Girl; that's a different visual all together.
FYI: VW manual has a spec for the length of the brake MC push rod as used on the Beetle pedal set and it's very near 5 7/16 inches (but in metric so not exactly 5 7/16 inches). There is much Achtung messaging surrounding this to the effect of "get this pushrod length out of spec and you could have problems."
And so passed down to the tinkerers and thinkerers of our hobby.
This is probably very applicable to any pan-based car and to those running the stock pedal mechanisms, perhaps it is less relevant to aftermarket pedal sets. I don't know.
Most of the older VW based projects I've had someone has fondled the master cylinder push rod or bent the crap out of the floor pedal stop as their way of adjusting the pedals...... This is my way of doing the pedal stop - master cylinder rod adjustment. Set and snug the floor mounted pedal stop first, the elongated slot in the stop allows for some vertical positioning of the pedals & by rotating the stop a few degrees counter- clockwise, you can even up the clutch pedal pad even with the brake pad and clutch pad. I adjust the push rod by installing it loose, adjust it until there is zero play then back in about 1/2 a turn, this allows the master cylinder piston to completely return and have zero pressure. Correctly adjusted the push rod to master cylinder contact has a physical click of 1mm free play to at rest. Then snug the 13mm nut on the push rod and recheck. Hope this helps ~
