Is this how the brake pedal should feel?

[ryans88gt]

I just replace the whole brake system. MC bench bled, new disks up front, new wheel cylinders out back. Adjusted the drums to ver little play. Bled the while system starting at the back and did it three times. Verified the free play at the master cylinder. No air bubbles. The brake pedal goes down about 2" before getting firm leaving about 4-5" of pedal travel. So i am not worried about stopping the car, but it is a bit weird having that 2" of travel. Is that normal? It is basically how the brakes felt before. I am used to a firm pedal from tip in with modern cars , not having to press the pedal in a few inches before braking starts.


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[Marc]

You say you've verified the M/C freeplay, but it sounds as though there may still be a problem there. If there's not enough to uncover the compensating ports on the M/C, fluid will be blocked from flowing in from the reservoir on the upstroke and make it hard to accomplish the in-place bleed. Also, when the fluid heats up under driving conditions it'll expand with nowhere to go and the brakes will start to drag. So bear with me, there're some basics to rule out before looking downstream of the M/C.

The pedal stop on the floorboard is supposed to be adjusted so that the underside of the pedal is ~8" from the bulkhead. Over time they can shift, bend, or wear to the point that the pedal comes too far back yielding excessive master cylinder pushrod freeplay.
The pushrod itself is adjustable for length, but that's set at the factory and normally doesn't require tampering - you should be able to leave it alone, and adjust the pedal stop so that there's 1mm of pushrod freeplay (that's about ¼" at the pedal).

Soak the pedal stop bolt with penetrating oil for a day before you try to loosen it (it's no fun to drill out if it breaks). If the bolt does break, or you decide that the stop plate needs to come out for straightening or replacement, there'll be nothing to keep the clutch pedal from flopping back against the floorboard which allows the cable to come unhooked inside the tunnel. So, unless you're planning to remove the pedal cluster for rebuilding you'll want to rig a tether to the clutch pedal (from the slot in the bulkhead or from the steering column) to limit its travel before you start.


If the pedals are both back too far, you'll also want to slack off the clutch cable adjustment a bit so you aren't fighting the return spring as you adjust the pedal stop.

[ryans88gt]

As I said I verified and adjusted the MC pushrod free play to 0.040" or roughly 3/16" at the pedal. I did this before I bled the brakes. The pushrod is not touching the MC when the pedal is at rest. There is about 8.5" between the pedal and the front bulkhead.

The problem if it is a problem is I can feel the plunger engage the MC, but I do not get pedal pressure for about 1-2" of pedal travel... which on any other car I would associate with air in the system, but I rebled this 3 separate times with no change (2 man brake bleed). This isn't the first or fiftieth time I have bled brakes, so I am pretty sure of my abilities here and all of the parts are new...

leading me to believe that either this is the way the MC is supposed to perform or that I still have air in the MC some how. I am leaning towards the first since it is about how the brakes performed before I changed anything... but it just doesn't feel right to me.

[Marc]

I kinda figured you knew what you were doing, just seemed like a good place to discuss that for the benefit of someone searching the topic in the future.
If you've got all of the air out you should be able to feel the M/C starting to push fluid almost immediately after taking up the freeplay (stroking the pedal with your hand).
I'm assuming this is on your `71 Standard Beetle. IIRC the residual pressure check valves had been dropped from the OEM M/C by then; both the factory-installed and 113 611 015BD replacement M/Cs just have restriction drillings so they're compatible with disc brakes. The earlier dual-circuit M/Cs had discrete check valves that screwed into the casting (also acting as a thread adapter) - those need to be gutted, at least the two front ones, when installing discs.
Can you tell if the front & rear brakes are both applying at approximately the same time? If the car's not on the road yet, get it off the ground and have a helper push the pedal by hand until you can feel drag at one wheel, then hold the pedal still while you check the others.
If the rear circuit's not working right, the pedal will sink until the rear piston makes physical contact with the front piston...usually this is accompanied by some external fluid leakage.
A bad seal in the front circuit won't cause any external leakage, but the rear brakes won't apply fully until the front piston quits moving forward. So far this seems like the #1 suspect.
You might also try adjusting the rear shoes hard-up to rule out a mechanical issue there. A common fault on `65-up drum brakes is having the adjusting screws upside-down (so the angled slot doesn't match up with the angled end of the shoe frame). Causes the shoes to catch on the screws resulting in a false/erratic adjustment.

Flex hoses can "balloon" and cause delay in brake application, but it's not a common failure mode - more often they decompose internally and restrict flow, which would've been evident when you bled the brakes.

[ryans88gt]

I did check to see if both front and rear engage at the same time and they do. Furthermore, I took a drum off the rear to see when the wheel cylinder actually starts to move and it isn't until the pedal goes past that first inch or two of travel and then the wheel cylinder starts to expand.

The front hoses are steel braided and the rear hoses were replaced in 1999 according to the tag on them and they looked pretty solid with no cracking so I didn't touch them.

I am wondering if there is an air bubble in the rear circuit since the line is on the side of the master cylinder... but I bled A lot of fluid and was getting no air bubbles out the back... :/

The MC is a regular dual circuit with no residual valves and looks identical to the one I replaced... also functions identical... I had the same 1-2" of free travel with the old brakes and MC.

I guess I can bleed some more maybe after driving a bit.

[Marc]

Initially you reported "about 2 inches" which I consider excessive...but around one inch isn't cause for alarm on non-power brakes.

Question, when the rear brakes were adjusted were the e-brake cables backed off? If the cables are too tight you'll be adjusting against them instead of against the wheel cylinders.

[ryans88gt]

Yep i made sure the e brake cables had slack when adjusted. Maybe i will borrow a vacuum bleeder just to double check.


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[Marc]

...Maybe i will borrow a vacuum bleeder just to double check.

That'd be good. Sounds like it should be safe to drive as-is until you can get your hands on one.

[Ol'fogasaurus]

If you are using drum brakes, I now highly recommend locking up the brakes on all four corners then bleeding the brakes after which you back off on the adjusters until when you spin the wheel you hear a slight drag. Also, make sure that the backing plates are clean and, if required, there is lube in the proper areas.

Also make sure that the rod going from the pedal to the MC has the proper end play.

Also check the soft lines for their condition as they are notorious for swelling and other nasty things.

Brakes can drive you crazy trying to find the faults.

Lee