Brake repairs -- hydraulic side


Jean

New member
My brake pedal on a 1990 Westfalia is very soft.
My local garage changed my front disks and pad. A couple of months later, I forgot my hand brake on and heated my rear wheels. The drums turned blue and had to be changed but since then, my pedal is soft.

If I pump the pedal, it does not improve. The rear wheels won't block even if I slam the brakes.

No leakage at the wheels or the master cylinder.
I asked 3 times to bleed the lines. No results. If they bring the rear bads closer to the drums, the van will brake properly for a couple of weeks only.

I went to the VW dealer accredited for Westfalia and I had to show the young mechanics where the brake fluid tank was located. He bleeded the brakes and when I asked him if the van was braking properly, he told me that he did not know because he had never driven such a vehicle. That was a big help.

I just had my master cylinder changed, still no changes. I am about to change the "proportional valve" balancing the front and the rear of the van, but before I do, I would like to understand why the valve could solve the problem.

Here's my concern:
If the proportional valve does not work, the rear wheels are not braking, so no hydraulic fluid is going to the rear. This should make my pedal stop higher than normal but yet I already reach the floor today. If I change the valve, more fluid will go to the rear wheel, lowering my pedal even more.

When I asked for a new master cylinder, my assumption was;
1- If I had air in the lines, by pumping my pedal a few times, it would go up, but it does not.
2- If the proportioanl valve was the "bad actor", I would have enough pressure on the front wheel to block them.

So, my conclusion was that the master cylinder does not deliver the pressure or enough fluid to push all 4 brakes. Obviously, I was wrong because I now have a new cylinder and got no noticable changes.

Help me understand what's going on. I am going on vacation next week-end with my family on a scenic road with steep hills.
 
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CGOTTS

New member
Couple of questions need to be asked - when the hand brake was left on, I assume that they replaced the drums? If so, did they also replace the shoes, wheel cylinders, brake springs, wheel adjusters, etc.? The first thing that comes to mind is when a brake gets so hot that the drum turns blue, then a number of other parts should also be replaced, due to the heat that transfer over to other parts. It is possible that they never replaced the wheel cylinders and are not operating properly, they should be replaced! You mentioned that if you adjust the brake shoe closer to the drum, it only lasts a couple of weeks - do you back up the vehicle every so often to allow the adjuster to automatically readjust the shoe distance? Another question needs to be asked, may not be related, but do the front brakes brake the same as you remember, before the pad change? If not, then it is possible the vacuum connection to the power booster has a leak, of the hose has come off of the intake pleunem. But then you would also notice that your engine idle would be bad. It could be the proportional valve - and the best way to check is to test it via the instructions in the Bentley Manual, section 47.9. You basically are to have a pressure guage on the front caliper, and one on the rear wheel cylinder. If you don't get the proper readings, then it needs to be changed. According to my book, when you have the brakes pumped to 1450 psi, the fronts should get the full amount, but the rears are to get 798-943 psi. Another thing that needs to checked is the condition of your rubber brake hoses - I have seen them expand when you step on the brakes, to a point where you aren't getting the full pressure. I hope this helps in answering your questions - good luck. CGOTTS
 

Capt. Mike

Moderator
One additional thing to consider during "bleeding" is that the clutch is hydraulic and gets its fluid off the brake master cylinder. Theoretically, they are independent thereafter, but I bleed the clutch along with every brake bleeding job. I've seen air get into one system after repairs to the other so it surely won't hurt, and may help.

There is a thread on brake fluids under the TIPS forum, that also has hints on bleeding.
 

Capt. Mike

Moderator
Transferred from another post to consolidate similar topics.

Spongy brake pedal on '72

JiveTurkey, Junior Member, 03-04-2001 05:47 PM

I have a 1972 Westy with a spongy brake pedal. If I pump the pedal 3 or 4 times they work fine. If not the pedal hits the floor, stays there and the brakes stick. In October the front brake rotors, pads, seals, right caliper and two lines were replaced. Also, the rear drums were machined and shoes replaced. Everything was lubed, adjusted and all the hardware was replaced. The brakes worked fine until a couple weeks ago when this problem arose. After bleeding the brakes with no improvement, I replaced the Master cylinder and bled them again as described in Bently's. Still no improvement. Any ideas or suggestions that could help these symptoms would be greatly appreciated. I would dig stopping my bus when I need to.
 

Capt. Mike

Moderator
The first thing that rings a warning bell is the "brake drums were machined". This has become such an overused brake job padder, it often creates more problems than it solves. Drums should only be turned for specific reasons (out-of-round and surface damage) and then only within very narrow limits. Brake drums new are 252 +/- .2 mm. The wear limit is 253.5 mm. So you've only got 1.5 mm to turn off without putting the drum oversize and making the brake cylinders and associated hardware work outside its designated range.

Another possibility is a '72 had a pressure regulator. (Bentley 5.2)

However, all that said, that your pedal hits the floor and then pumps up leans very heavily to a master cylinder or blown seal. I can sympathize that you've just replaced the master cylinder, but a defect or contaminated fluid (dirt) can damage a new one's seals quickly. You're going to have to pull the wheels looking for leaks there first, then go back to a master cylinder check-out.
 

Capt. Mike

Moderator
Transferred from another post to consolidate same topics.

Is it the brake booster?

johnandliz, Member, 05-14-2001 11:00 AM

86 Westy

When starting up, I back down our driveway, which is probably a 10 degree grade. I can press the brake pedal right down and do not stop. I slow to a stop, but do not stop. Is this the brake booster? I have (with mechanic) looked at the discs, drums and replaced the master cylinder in previous visits, and all are good. When the ignition is off I pump up the pedal, I hold my foot on it and start the motor, the pedal goes down, but very minimally. I am wondering how far it is supposed to go down and how noticable this depression should be?

I hope I have made my brake booster question(s) clear. Thanks all.

John
 

Capt. Mike

Moderator
When a brake pedal 'goes to the floor' it indicates either the fluid is leaking, the fluid is blowing by a seal, or a brake mechanism in a wheel is able to move beyond limits.

The P/B booster assists in exerting pedal pressure but is NOT part of the hydraulic system. That it helps the pedal at start up indicates it's probably OK.

The master cylinder is a dual chamber system. It's possible for a blown seal to allow fluid to pass from one area to another, drastically reducing brake effect and letting the pedal bottom out, without showing a visible leak. It's also possible for it to leak into the booster chamber but that should show up as a drop in the resevoir.

You could have a wheel cylinder or caliper leak that you have not yet notices in terms of fluid loss. The rears leak into the brake drum and may not be running out (yet).

See the post on this forum about changing brake fluid. That a master cylinder is new does not mean that it could not get a damaged seal from improper bleeding practices. All indications point that way.
 
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Capt. Mike

Moderator
Transferred from another post to consolidate same topic.

Brake problem (new owner)

Ward Junior Member # 2498 posted 10-05-2001 03:30 PM

A day ago, I noticed my breaks were not as tight as they have been. Today, they were almost gone completely. I noticed I didn't have any brake fluid, so I put some in. Still, no breaks. I checked the fluid and it was completely empty. I just filled it up fifteen minutes before this? I checked for some lose fittings, but all seemed tight. The front left tire is wet, and seems to be coming from the inside of the breaks or something? What could this be?

wild bill Junior Member # 2378 posted 10-05-2001 04:38 PM

Sounds like you may need some help doing this! Try checking the flex lines for weather cracking and or the caliper leaking you can get rebuild kit for them that's a lot cheaper.

Ward Junior Member # 2498 posted 10-07-2001 12:53 PM

Much appreciated !! I'll check it out.
 

Capt. Mike

Moderator
jswank Junior Member posted October 02, 2002 10:49 PM

Hello, I am in the process of replacing my brake fluid in my 1991 Westfalia. According to the Bently manual, prior to bleeding the brakes or changing the brake fluid, I have to push a lever on the brake pressure regulator and disconnect the vacuum hose/check valve from the brake booster.

For the life of me I cannot find this device. I assume that it is in the front behind the dash.

Any guidance/help would be greatly appreciated.

Thanks,

James
 

Capt. Mike

Moderator
The brake pressure regulator function is to proportion the front & rear brakes. Therefore it must be located between the feed from the front brakes to the rear. Location along that route is not critical though attitude (angle of mount) is.

My '90 4WD has the regulator mounted to the inside right frame near the rack & pinion steering gear and fairly close to the RF caliper line.

My version of the Bentley doesn't call for those steps you cite and for a straight change of fluid, seem like overkill. The idea of changing fluid is just to flush new, clean fluid thought the lines until old, contaminated fluid is dispelled. The brake bleeding topic in this forum describes a working home method well, including some precautions.

Since the regulator proportions by angle and the bleeding is (should be) done on the level, both ends get even flow without these steps. Also, since the master cylinder feeds from the top, it will pull the old, dirty fluid first. Without the engine running, there is no vacuum (after the first couple of strokes) so disconnecting the vacuum line doesn't materially affect the process.

Testing of the regulator is not easy and requires special tools per Bentley 47.8 & 47.9. The regulator is angle sensative (to detect nose-dive) and then limits rear brake pressure to reduce the possiblity of lock-up when the rear end gets lighter from weight transfer during braking. Repairs are not possible. If you are getting normal even braking and not experiencing rear wheel lock-up, especially in downhill braking, chances are the regulator is OK.
 

Capt. Mike

Moderator
Transferred to consolidate same topic.

masone Member posted April 02, 2003 02:40 PM

Here's a question I think I know the answer to but would like a second opinion. On my 78 westy I am able to push the brake pedal almost to the floor before the brakes engage. If I pump them a few times they "tighten up" a bit, but as soon a I release the pressure on the pedal they go back to the way I first explained. In other words I have to pump them each time if I want to get max braking power. When the brakes are engaged weather fully depressed or pumped, the pads and shoes seem to stop the car fine. Here's my question: Does the master cylinder need replacing? And If it does will that clear up the "pumping the brakes" dilemma that I have. And If I replace the master cylinder , do I also need to replace the servo unit as well. What if I just put new pads and shoes on? Will that change anything?

thanks for any help
 

Capt. Mike

Moderator
Answered above: you may just have air in the system and rebleeding is all that is required (unlikely). See "Brake Fluid Changes" topic as well.

Most likely is the master cylinder needs rebuild/replacement. No, the servo does NOT need replacing; the two are independent of each other hydraulicly. Changing pad & shoes will have no effect.
 

mr.rocksteady

New member
Help finding the brake fluid reservoir

Earlier today I was driving myself mad trying to find the brake fluid reservoir on my '85 Westy. Just so everyone knows (the manual and Bentley's tell you, but not as clear as I am about to tell you), the brake fluid reservoir (which needs to be opened to allow you to push back the circle pistons in the calipers so new pads can be installed --see my post in mechanical side) is actually located BEHIND the instrument panel. To get there...you sit in the driver's seat and reach out to the base of the windshield and you will find 2 notches in the dash. just pull those up and out and the whole plastic piece of dash surrounding the instruments will pop out. Viola! There is the brake fluid reservoir.

Thanks. TP
 

Capt. Mike

Moderator
Transferred to consolidate same topic.

azmav Junior Member posted July 09, 2003 01:12 AM

I have 74' Westy, bled the brakes cuz they were going to the floor and had to pump em to stop. They dont go to floor but still soft, not stopping powere they should be, I figure seals are bad in master cylinder considering the gunk that came out during the bled. Once the resevoir was off with cylinder, I fould A LOT of black sediment. I assume that fluid has not been regularly changed. Is there any method for flushing out the metal lines without removing them or replacing them, will they be ok or can I expect more sediment in the lines? Should they be replaced?
 

Capt. Mike

Moderator
Reexamine your sediment. There are basically 4 categories.

1. Moisture induced. Brake fluid is hygroscopic and will draw moisture out of the air. When there are other contaminates, this moisture will appear as a whitish tinge or streak in the drained fluid jar. When it's reached this stage -- since the fluid absorbs most moisture -- you need a major flush and all new fluid.

2. Rust. This is from either the metal lines, fittings or brake cylinders themselves. Brown or black but a gritty feel. Does not 'float' but quickly settles out. If from the cylinders, they must be replaced as they will now be pitted and just tear up new seals right away.

3. Hose deterioration. Black, can actually appear gummy or sticky. This indicates the inside of the hoses is breaking down. Replacement required immediately as further breakdown may cause major failure without notice.

4. Oxidation -- the most common. Combined with its hygroscopic nature, the brake fluid will loose color (if originally colored like DoT 5 or Ate "Blue". Most clear or amber will darken with age. It may appear cloudy. No cylinder is 100% tight and as the piston expands, it rides onto the sleeve area that has previously been exposed, picking up brake dust and dirt. It also picks up moisture. This will usually flush out with the first bleeds.

If changing good brake fluid on schedule, removing the major portion from the master cylinder, refilling with fresh and just pumping through until clear, new is comming out is sufficient. If the fluid has been changed every two years, it's not critical to get all of the old.

If flushing a system or changing types of brake fluid, you may disconnect the brake lines and flush with denatured alcohol. Allow to dry after blowing out all excess. The best 'flush' is still new brake fluid.

With your symptoms, replacing the flexible lines and overhauling/replacing all cylinders is prudent.

Replacing metal lines is a tough call. They corrode because of moisture in the fluid settling in pockets around low points. When you break the metal lines at their fittings, look inside at the seal points of the fitting and as far as you can into the line to see if the corrossion is all external from road salts and weather, or if it looks like it's gotten inside. That and what you got in your flush are the only guidelines; replace if in doubt.
 

hugor

New member
Hi,

I have an 86 Westy, 2.1L Auto.

When I stomp on the brakes (only when i need to of course), the van seems to pull to the right and the rear drums howl. Not squeal, howl. There is no recognizable pull during regular braking.

I went to my local brake shop, and they wanted to turn my drums and service the shoes. When inspecting the shoes, there was only wear near the very top of the shoes. I assumed this was because the drums had probably already been turned a few times and were now too big??

For the same price as the servicing, I bought new drums and shoes, and plan to do that job this weekend.

My real question is: The brake shop said the reason that the van was pulling was not mechanical, it was hydraulic. They said that the front flex hose was probably collapsed. Does this sound right? I am planning to replace this hose myself, but can't find anything in the bentley on brake hose. There is a little "clip" assembly where the flex hose attaches to the metal hose coming from the master cylinder, but it's so rusty/dirty that I can't figure out what to do with it.

Please help. Thanks.

Hugh.
 

icarus

Moderator
Not directly related to the above but if your shoes were only warn on the ends, make sure you have the shoes "arced" to your drums. By grinding the new shoes to the arc of the drum, makes sure they contact the drum evenly. I have glazed more than one set of shoes in the old days by not arcing them. Check the hoses as well.

Does anyone ever do this any more?

Icarus
 

Capt. Mike

Moderator
Pulling due to a single hydraulic line failure is relatively rare. The deterioration of hoses is more likely to cause a brake to not retract when released. See above posts. However,if the hoses are showing any signs of deterioration such as soft spots, overall hardness, cracks & damage, replace the set together.

Brake pulling only during panic stops is more like a case of either front caliper problems -- possible leaking around the seals -- or misadjustment of rear shoes for whatever cause.

Since you've already got a rear drum/shoe problem, start there with your full overhaul. I'd suggest you replace all the hardware while replacing shoes -- they are sold as a kit by VW and are worth it. Since rear shoes last so long anyway, it's a nominal extra expense.

Good time to consider installing a 2nd viewing port for the rear shoes per that topic already posted.
 

hugor

New member
Thanks Capt. Mike for all your help.

I spent Sunday replacing the front flex hoses, rear wheel cylinders, shoes and drums with a friend of mine who has done it before on his westie. One thing we didn't do was disconnect the parking brake cable while working on the rear brakes. We bled the system and all seems well. I am waiting for the shoes/drums to wear in a bit before I test the "panic stopping". The howling is gone now, the brakes seem solid. If everything was done correctly, should i expect that the brakes will lock now? or do westies just have weak brakes?
 
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Capt. Mike

Moderator
Westies rarely lock on pavement unless the equalizer is not working properly. Brakes are good though not their strongest point; rears are relatively trouble free and last forever. Fronts take most of the work. It still takes some pretty extreme mountain driving to ever get one to fade. Don't make the mistake of using hard or metalic pads -- they will increase stopping time & distance for what I believe is marginal improvement in mileage.
 

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