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Helpful Brake Hint.

2268 Views 21 Replies 3 Participants Last post by  ORCoaster
T'was the day before Christmas, and low and behold I lost a wheel Cylinder... No worries I had a spare.
Getting it off took a little creative effort, as one of the Allen bolts Stripped.

Remove the backing plate, left-handed drill bit and it's out. Run to my Favorite Hardware store to get a few, and missed it by 10 minutes...Closed @ 1 Christmas Eve.
No worries off to the Parts store and my Shoes didn't make it to the store... Okay now I have to wait.

But I did have time to clean it all up, and discover that the Acorn bolt that holds the front seat rail is a M6X1.0 Allen that is a direct fit.

So if you ever need an Allen for that Cylinder, you have a Spare in the Drivers or Passengers seat Be sure to use something to keep the seat from sliding off the rails in it's place.

So now I have to wait for Wednesday Morning to get 4 new Allens, and my shoes.

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Have you discovered the virtues of a vacuum pump for bleeding brake lines?
Have you discovered the virtues of a vacuum pump for bleeding brake lines?
Have a home made power bleeder that works like a champ 10 minutes and all Brakes are bleed.

But I have also discovered that the Rear Wheel Cylinder that O'Reillys sells are badly manufactured, and will not bolt up to the Backing plate.
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I have had good luck with the O"Riely brake cylinders. Have you ever had a master cylinder engage the front discs without activating the back cylinders. I tried to tighten down the master cylinder this afternoon and the front brakes went crimp on the rotors and the rear tires could still turn freely. Might be time to replace the MC??

Tried to adjust the clevis pin under the dash but 1981 vintage car so nothing there but a solid rod and a cotter pin.

Not sure what the fix on this should be at this point.
If they worked before you changed the M/C, then you are looking at a bad M/C still or, your Proportional Valve may be the issue.
My issue with the wheel cylinders was that the bolt holes for the Allens were about 1/16 off, you couldn't bolt them up with both screws they were going in at an angle and binding. The replacements I bought at Napa didn't have any issues and bolted up to the backing plate straight.

Another issue I have had was when replacing the M/C you have to take the nuts down equally that is 5 spins left then 5 spins right.
If you try to take one side down first you can cause the booster pin to bind the Booster Pin and force it out of the Booster fingers.
So you don't get a complete throw of the rod Possible ruining the booster.
I always walk the nuts equally on things like that. I held it in place and threaded the nuts on as far as they would go. Then only a few cranks with the wrench and it was tight.
there's a regulator mounted to the left front fender that all four lines tie into---on pickups there is another unit mounted near the rear axle--maybe one or the other isn't doing it's job
there's a regulator mounted to the left front fender that all four lines tie into---on pickups there is another unit mounted near the rear axle--maybe one or the other isn't doing it's job
I have an 81 Pickup and they did away with the rear unit on that one. They went to a different setup. I ordered a new MC as I could pump up the brakes and hold my foot on the pedal and it would just collapse pretty steady to the floor.

Going to remove it tomorrow as AutoZone just shipped the MC today. I need to beat the rain.
there's a regulator mounted to the left front fender that all four lines tie into---on pickups there is another unit mounted near the rear axle--maybe one or the other isn't doing it's job
I have an 81 Pickup and they did away with the rear unit on that one. They went to a different setup. I ordered a new MC as I could pump up the brakes and hold my foot on the pedal and it would just collapse pretty steady to the floor.

Going to remove it tomorrow as AutoZone just shipped the MC today. I need to beat the rain.
That was a load sensing proportional valve, the more weight in the rear it opened a little bit more, Very common on large vans as I had one on my 92 Caravan that was part and parcel of the right rear leaf spring, you had to replace the Spring to replace the Valve... ok caught me, my 92 dodge had electronic braking that failed, and every time it was 400 bucks to repair it..(dealer only). So Since they discontinued the experiment in late 93, I went and got all the parts off a 94 (Calipers) Leafe Spring Brake lines, Vacuum Booster, and back to MC to replace, and for the next 150K I never lost my brakes.

VW did the same thing on Trucks and Cabriolets, the Caveat is that in 81 US Caddy's didn't have this installed...Late 83 and up I think did. They aren't that expensive
Just a Pain in the Keister.

On a side note my son called and said the Brakes were very spongy......... Validated that my MC was Warrantied, but opted to bleed them again, and found that my ho-made bleeder broke in the Middle of the First bleed... (the trigger broke and the valve didn't fully work....ok, 14 dollars later) and a re-bleed couldn't believe the amount of air I sucked out of the opposite side that I really repaired, so I suppose it broke between the switching from left front/ right rear, to right front/left rear....

So he has great stopping power now again....
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So he has great stopping power now again....

Stopping power needs to exceed acceleration and top speed.

I pulled the MC off the Caddy today and tore it apart looking for bad seals or scored cylinder walls. Found neither so not sure why I am getting loss of pressure.

Will check for debris in the lines to the back when I get a break in the rain again. New MC didn't arrive yet anyway.

After driving the Caddy I jumped in the Rabbit the other day and about did a face plant on the windshield. So I know I needed better brakes on the Caddy.
Don't discount the rubber hoses, they can deteriorate, and I have replaced all mine on my Cabbies. His has the SS Jacketed ones that don't balloon at all
Finally got the new MC installed and bled the lines. Bench bled the MC first.

Problem now is that the pedal is near the floor before kicking in and when it does the brakes are very grabby.

I know this is not the way it should be but the only adjustment I see is the little nut on the end of the shaft going into the MC. Anyone ever had success getting that to extend or contract?

I am also wondering if the proportional valve is messed up. Isn't there a way to keep it from engaging when bleeding the rear brakes so that you get more volume of fluid per pedal stroke? Seems there was a way to clip it or set it so it didn't move the pistons inside and limit the flow so badly.

Looking for ideas that I have run out of for the time being.
no it isn't normal. That is the Freeplay adjust and you may have to adjust it.
Also it isn't unusual for a new mc to blow the seals out of the rear wheel cylinders....
I would wait a day and re-bleed it. I made a home made power bleeder out of a 2 quart pump up sprayer.... works really good.

google home made power bleeder.... All you will need is a Spare m/c cap.
you might try bleeding each line at the master cylinder one at a time--that's where the air rises to if there's air in the line---I'm assuming you know the rear brake cylinders aren't leaking---you'd have to take the drums off to find out
I haven't taken the drums off but I don't see any liquid dripping down from them and it has been parked in the same spot for a week. I replaced the wheel cylinders when I did the brakes about 4 mths ago so I am hoping they held up ok with the new MC.

I was going to reverse bleed the lines as that might get the air out of the MC if indeed there is some there. I used a Mighty Vac system to pull a vacuum from the wheel cylinders the first time I bled them. Had a heck of a time getting fluid through them. That is why I was wondering if I could do something other than one of those plastic nuts that replace the switch on the proportion valve. I used to have a car that had a little bit of a stem that stuck out of that valve and you would pull it out a bit and slip a clip on a slot and it would hold it full open.

I had my wife do the pump and close as a second try at bleeding the air out but it really didn't do the job. I know from experience that sometimes the orientation of the car makes a difference or the position of the MC relative to the level of the brake fluid can make air get trapped in and no amount of bleeding can get it easily.

I was also thinking of starting with the lines at the MC as suggested here. Why not try the easy button first eh?

Thanks for the confirmation and hints. No brakes are preventing me from putting the turbo on at this time.
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2 person bleeding is how I used to do it, my mantra to the wife was pump 3 times and hold it If it sinks to the floor good just keep it there and don't let off till I tell you, then when the bubbles stopped coming out of the vinyl tube over the bleeder I would close it and let the wife pump up again.... Left rear/right front, left front/right rear...Do the rears first them the fronts.... on a mity vac you have to wrap the bleeder ports (politically correct) with teflon tape so you don't pull are in from the threads. I usually remove the bleeders and wrap them from the threads to the end and back up, then poke a hole where the point of the nipple is..They will never rust seize.

Since I made the power bleeder bleeding is really really easier now.
Rain let up enough to get out a tarp and get under the offensive truck. First however I used a 2 oz syringe and made sure all the air was out of the MC by squirting a couple of shots through the extra 2 ports that are blocked off with nuts supplied by MC manufacturer. I did see some bubbles out of that work.

Then I crawled under to the rear brakes. I used the Mighty Vac system there and really didn't think I had much of a difference. I collected about an inch out of each cylinder and it felt like I had a good solid pedal after that. I couldn't pump it up and hold it much higher than the initial first step down on it.

So I fired it up and took it for a short trip around the block. Brakes did not heat up or grab more so in the front than the rears. But the pedal does go to the floor on the initial step and my vacuum gauge drops considerably when that happens.

I jacked the rear end up in the drive and then started the truck. I could spin the tire by hand enough to then step inside the truck and push on the pedal. It would go nearly half way down before I would see the tires try to slow down.

So I think it is the free play in the booster that needs to be adjusted. If I make the shaft longer then there will not be as much travel on the pedal before it hits the pistons. That is what I think is happening.

Any other opinions out there? Would love to hear them. Just hoping I get another break or two in the rain tomorrow. This inch or two a day stuff makes not having a garage a real pain.
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I would bleed the brakes one more time first, as it still sounds like you are pushing air. I have always done all 4 wheels when bleeding of any type of replacement or exchanging fluids as in old for new. When I last changed a wheel Cylinder on the rear of my Green Cabby, I bleed all 4 and couldn't believe the air I got out of the fronts.

Yep I can remember the days of my youth, no garage, just a Gravel pad, and we made a wooden swing set out of sawhorse brackets to raise or lower engines, and then wrapping it with plastic sheathing to keep the Rain/Snow off.... I will agree it ain't fun.

When my father decided to Build a 3 car garage, it was a whole different game. I have since had the pleasure of always having a Carport, or Garage ever since I moved out.
I have been looking into several proportioning valves that might replace the one on the truck. Doesn't seem to me that there are any with the right combination. Mine has the two lines coming out of the different bowls on the Master Cylinder and then two lines out to the back. In between the valve is actually two functions in one. First it has the switch on top to show me if one side of the system is doing more work than the other. It kicks a piston over one side or the other and the switch turns the BRAKE light on the dash on.
There are two pistons with O rings and what look to be rubber washers and a spring in each cylinder. I have read someplace that these pistons regulate the bias or amount of fluid to the rear brakes to keep them from locking up on a hard stop. Hence proportioning the fluid between the rear and the front discs. I have read and don't exactly know that it is true that these same devices keep a little bit of pressure built up on the rear cyclinders so that your foot doesn't travel as far to the floor when you first step on the brakes after not using them for a bit.

Can anyone verify that is the case? I know there are after market valves that keep a bit of pressure like that but I am not sure that is the case for our VW's.

I have found several Wildwood valves in the aftermarket area but I don't think they will do all the jobs that the original is designed to do. Then there is the issue of controlling both rear wheels and having the switch work.

I think rebuilding what I have is the only way to fix my brake pedal travel problem. That will require cutting the lines from the back of the car as there is just no way to work in that area on the fender. I already tried that and didn't like the result. I would just detach the lines going to the top of the valve from the MC as those already are loose. I then will need to splice the rear lines back together after rebuilding or replacing the valve.

Might be time to invest in stockpiling those valves. I bet most folks scrap their cars with them on. They are NLA. And no good aftermarket subs either.
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The standard Westy build has a single proportional valve on the inside fender to the right and below of the master.
It takes the 2 lines and splits them off 4 ways IIRC.

The purpose of the proportional valve is to reduce pressure to the rears so they don't lock up on braking.
As far as I know they don't hold any residual pressure, and are a Spring loaded valve arrangement.

You can upgrade to the 22MM MC off of a Cabriolet, and that has 2 proportional valves on the MC itself, where the Brake Pressure light is controlled through a Brake Fluid is Low sender in the cap of the res.

The res is different as well as the MC has 4 Brake lines attached to it.

Some of the Tween versions have a Load Sensing Proportional Valve located on the rear axle that accomplished the same thing but based on the load on the rear axle.

With the advent of the Cabriolet later 83 they went to the larger MC, Vented Rotors. Which decreased Brake Fade and better wear of the pads on the front.

The rears and the fronts are on diagonal Circuits so that you can brake straight, they are left front right rear, and right front left rear, it isn't that they are one for the front and one for the rear. So don't get conflicting information. You can do away with them sort of by using separate proportional valves from the Cabriolet in-line with each rear, but you still would need to diagonal the circuits.

typical mc set up with the load sensing at the bottom, and the proportional valves for that set up are still avail overseas.
Pricey: may have a Westy proportional valve as used, but I have heard mixed things about them. It would be best to email them first.

84 Golf

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