tunnel brake line replacement

I used some emery cloth wrapped around and just polished it up, then greased it (I used white-lube but I'm sure any grease is fine). It just pushes against a cup type of plunger so there's no critical tolerance.

Thanks, that is a big relieve. Thought I might have to order one. Tomorrow looks like a good day to get it in.

Hi Jeff and Leonard,



That shouldn't be a problem. Looks pretty easy to make a new one using the old one as a pattern.

Gary Hammond,

When you release the pedal the bleeder valve should be closed .
So it cannot suck the air back in .
Open on the down stroke and closed on the release of the pedal .
It is a 2 person operation, unless you are using a power bleeder.
Just replaced my bug's master , Oh did I say I hate bleeding brakes.
Good Luck Leonard , wish I was there to help you out .
Steve

I've had all my kids and the wife pumping pedals at one time or another.

Nope...need to compress all the air bubbles and open and close the bleeders.

Yes this will work.
As will pump/hold/open bleeder/close/release

Bench bleeding the best way
The most common problem customers face when installing master cylinders is improper bleeding procedures. In the past, CARDONE supplied a bleeder kit that consisted of plugs with holes. Tubes pressed on to the holes in order to bench bleed the master cylinder. Although this kit was successful when used properly, it was not the best process. One of our goals in Technical Services is to improve every process. We found a better way.

The new bleeder kit comes with solid plugs to bench bleed the replacement unit.

The advantages of the new process are:

More efficient to bleed the master cylinder.

No mess or fluid dripping when bench bleeding or when installing the unit on the vehicle.

Proving the unit is functional during bench bleeding. If the piston is firm when bench bleeding and not on the vehicle when bleeding, the brake system is at fault, NOT THE MASTER CYLINDER.

The following process is supplied with each CARDONE replacement master cylinder. You can help our customers by stressing the importance of following every process we include with our parts, to prevent warranties and increase sales.

1) Transfer proportioning valves, switches or other components to the replacement master cylinder (as applicable).

2) Tighten bleeder plugs into ports (bleeder plugs may be in parts kit or master cylinder reservoir).

3) Support the master cylinder in a vise in a level position. Never clamp onto the body of the master cylinder.

NOTE: Units with remote reservoirs should be bled on the vehicle. It is VERY IMPORTANT that the body of the master cylinder be kept level during the bleeding process.

4) Fill reservoirs halfway or until reservoir ports are covered. Always use new brake fluid from a sealed container as specified by the vehicle manufacturer.

5) Install reservoir lid so brake fluid does not spray from reservoir during bleeding process.

6) Using a blunt tool or dowel (brake pedal if mounted in vehicle), SLOWLY press in and release the master cylinder piston using short strokes of 3/4” to 1”. NEVER STROKE PISTON MORE THAN 1”. Repeat this step until resistance to piston movement is firm and less than 1/8”.

IMPORTANT NOTE: On step-bore master cylinders, WAIT 20 SECONDS BETWEEN STROKES. This will allow air trapped in the quick take-up valve to rise into reservoir. MASTER CYLINDER BODY MUST BE LEVEL.

7) Install master cylinder on vehicle. DO NOT remove bleeder plugs until brake lines are ready to be installed. This prevents air from entering the unit and brake fluid leaking out.

8) Remove one bleeder plug at a time from the master cylinder and connect the proper brake line to that port. Repeat this step for remaining brake line ports. Be sure fluid level is maintained during installation of brake lines and that all fittings are clean before installation. Bleed brake system according to vehicle manufacturer’s procedures and specifications.

9) Verify proper pedal action before moving vehicle. Do not road test vehicle until correct pedal feel and travel are obtained.

NOTE: If firm brake pedal action results using bleeder plugs, but becomes soft after installation in vehicle, the problem is not the replacement master cylinder.

How much travel is in the pedal BEFORE it contacts the master? If it is 1" as you say, that is too much. Also in relation to an analog clock, what position are your front wheel cylinders at?


Brake Pedal Free Play
Adjustment Procedure

This is one of our many "school of hard knocks" experiences!
See also our discussion of Brake System Pressurization.

The brake pedal must have about 1/4 inch (5-7 mm) of free play, measured at the top of the pedal.

~~~
Some Background

Brake pedal freeplay is the amount of pedal movement before the pushrod touches the piston inside the master cylinder, before the piston starts to move. It's quite a distinctive feel on the brake pedal, but you I have to use your hand to feel it properly.

The brake pedal free play adjustment is very important. The 5-7 mm of free play at the top of the brake pedal translates into 1 mm of play between the end of the push rod and the piston in the master cylinder. This distance is critical to assure that after braking the piston comes back far enough that it does not block the transfer port to the reservoir, allowing the pressure built up during braking to return to the reservoir and relax the system.

This brake pedal freeplay is very light and shouldn't be confused with the "take up distance" that the piston inside the master cylinder bore has to move before your brake lining engages with the drums/rotors; that is, the distance the pedal travels before braking action actually occurs. Excessive "take up distance" can be eliminated by bleeding air out of the lines and adjusting the brakes at each wheel. You usually have to readjust your brakes every oil change when new until they fully seat with the drums (sometimes even more often than that).

Note: It took us a long time to figure this out -- lesson learned (the hardest of hard ways). Bottom line: VERY CAREFULLY set the free play (as measured at the top of the brake pedal) to between 5 - 7 mm by adjusting the length of the push rod. Be careful and take your time -- this adjustment is very critical. If it's not right, you can very easily ruin your brakes.

~~~

Free Play Adjustment Procedure

Note: Unless you are VERY certain that the pushrod length has been tampered with, messing with the length of the pushrod is very risky and must be done with great care. VW recommends that the length of the push rod NOT be changed -- it must be a certain length (precisely 5.433" long plus or minus 0.019") and that's it.

1.

To change the length of the push rod, first loosen the 15mm lock nut on the push rod (furthest rear) with an open-end wrench.

2.

Carefully turn the 15mm nut on the push rod until it feels like its flush up against the piston in the master cylinder (no free play).

3.

Turn the rod back about half a turn and check the free play at the top of the brake pedal.

4.

Repeat until the free play, as measured at the top of the brake pedal, is EXACTLY within the range of 5-7 mm, then tighten the lock nut.

Not understanding what we were doing, we (that is, Dave) tried adjusting the free play by changing the length of the push rod, and we had a "school of hard knocks" pressurization experience as a result. If the transfer port to the reservoir is blocked, the braking pressure cannot be released, the brakes bind up, get hot, then the heat is transferred to the "trapped" fluid, thus pressurizing the system even more. This can bring your Bug to a complete stop, and heat up the brake drums to a point that you'll burn your fingers if you touch them. If you tow the car with this problem, you'll ruin the drums and shoes, as we did. :-( Once again, see our Brake System Pressurization Article for more discussion of this hard-learned lesson.

We received an interesting note about this from Sharkey's Garage -

I really wish an old VW engineer would explain to me why the master cylinder pushrod should be precisely 5.433" long (plus or minus 0.019"). If this measurement was *that* critical, why make the d**n thing adjustable in the first place? A few others would agree with me, including a couple of actual certified and factory-trained ACVW technicians I know. The best response that one of them provided when somebody started going on and on about never adjusting the pushrod went as follows:

VW could not have foreseen that these cars would still be around decades after the factory manuals were printed. VW was very prideful of their products and the more you asked them "why", the more they tightened their sphincters and said "because". He gave plenty of reasons why adjustment of the pushrod may, in fact, may be required:

*

Loose tolerances (using OEM parts with crappy Mexican master cylinders);

*

Swapping single circuit master for newer dual circuit master;

*

Substituting pedal assemblies from cars with different years;

*

Worn or bent pedal stop;

*

Decades of wear on the pushrod tip and pin eyelet (which still has the crusty factory grease and has never been lubed since).

There has been debate in our correspondence regarding the adjustable stop on the floor behind the brake pedal with regard to brake pedal free play adjustment. The Haynes Manual says -

Reposition the brake pedal stop plate so that the brake pedal has 5 - 7mm freeplay. This will produce the specified clearance between the pushrod and the piston recess.

Others say -

The mysterious sliding metal pedal stop in front of the pedals has nothing to do with the way the brakes operate. It is there to keep the brake pedal from returning too far back (toward the driver)...

The Bottom Line: What is being affected here is the at-rest distance beween the master cylinder push rod and the piston inside the master cylinder. This distance must be 1mm, which translates to 5-7 mm of free play as measured at the top of the brake pedal. Don't drive the car unless the brake pedal free play is absolutely correct!]


Look here for lots more info
www.vw-resource.com/index.html

Pads should have a slight drag.

I asked you above "Also in relation to an analog clock, what position are your front wheel cylinders at?" If they are at 3 and 9 instead of 12 then you still have air in the top half of the cylinders.


Follow the master bleeding procedure I posted. It will let you know if the master is good or bad.

Yes, unbolt the backing plate, turn it to 12 oclock, slip the drum back on and re bleed. The shoes do not have to be tight to the drums. You will notice a big improvement and the pedal will get hard instead of spongy like it is now.

Pedal travel seems OK, but it puts a little to the right. Maybe some more air in the right front line? I had the rubber lines changed about 10 years ago, so it shouldn't be bulging. It's not bad, just enought to know it pulls. I wouldn't want to put on the brakes without having a hold of the steering wheel.

When I returned the bad MC, the guy at the shop asked If I had gotten any fluid on the drum. Very well could have, and it might grab a little. I will try to burn it off by dragging the brake and see what happens.

I have now cleaned my brake shoes and drums with brake fluid cleaner, Roughed up the shoes with a wire wheel, bled the right front brake line and removed the wheel cyl on the right side and bled it. BTW, it did have air in it, so it is necessary to do this. The pedel did come up to where it is supposed to be, but it still pulls to the left. My next step would be to replace the right wheel cyl and rubber line. That is all I can think of to do with this problem.