Brakes binding, help needed please.....

OurPoorBus · Post by **OurPoorBus** » Fri May 09, 2003 1:10 pm

Hi, we have a 1973or4 VW bus, 1800, I will have to re-verify the age, we took her in to have the brakes checked and fixed awhile back as they were binding badly [how we bought her] and when driving you could see the rear hubcaps actually sticking and not turning. They did the repairs, made up a brake pipe that was history, replaced the handbrake cable etc. We took her home and she went a bit better but not much, the guy at the brake place said it would loosed up on its own after a bit of driving, I was driving behind the kombi and the hubcaps were all going round fine.
Next day we took her for a drive and after driving about a 100m she started binding again, 1st, 2nd and 3rd gear are fight and go and 4th gear is impossible to get as she totally binds up. So now we are a bit lost, the company that did the brakes are supposed to be reputable but I am reluctant to take her back to them. Alternatively could this be some other problem. We are busy doing major body repair work on her and we have to move her around a bit to get into the workspace, I am worried that we are damaging something while moving her.
The brake drums at the back were replaced with good seconds as new parts are impossible to find, The rear wheels are the ones with the hub that does not come off.
Any help is greatly appreciated.

Bucko · Post by **Bucko** » Fri May 09, 2003 1:22 pm

If the drums are good (I'd have them tested for round-ness), the next step is to see if the brake shoes are correct. If they are correct, could a previous owner have replaced the rear drum parts (backing plates, etc)with that of a different year, and the brake shop put on what they thought were the correct parts, but are not because someone swapped out/installed parts from a different year?

You did say that parts are hard to come by, so I suspect that this could be the case.

Then again, it could be wheel bearings freezing up on you.

OurPoorBus · Post by **OurPoorBus** » Fri May 09, 2003 2:04 pm

Its quite possible that the previous owner swopped out parts, he said the 'brakes' had been giving hassle for a while, could be the reason why he sold her, I have put a pic in under my signature, not too clear but maybe you can see from there what year she is, hmmm, having searched a bit I now see I took pictures of her data plate, guess I should go and see what it all means. There did seem to be a bit of confusion when I went round looking for 2nd hand drums, the one guy told me that I had the wrong year, but I took the old one with me so they just matched it.
Let me get back to you on what year she is and that may help a bit.
Thanks for the reply.

OurPoorBus · Post by **OurPoorBus** » Fri May 09, 2003 2:35 pm

I put a picture of her here http://www.thesamba.com/vw/gallery/inde ... +82832.jpg
if you would like to take a look.

raygreenwood · Post by **raygreenwood** » Fri May 09, 2003 3:21 pm

There are a handful of things to check. First: after sitting still, do the brakes unbind?
Things to check: Look for leaking wheel cylinders. If fluid gets on the shoes, they will swell and bind when they get hot.
Check the torque on the rear hub. If its too loose, the drums can grind on the backing plate, when cornering.
Check for proper brake cable adjustment. It is also possible, that the shoes were adjusted too tight upon installation. Geneally, they will wear in pretty quick....but not all brake material is the same , especially the newer non-asbestos stuff.
Check for proper brake pedal freeplay. If your brake pedal stroke was adjusted, and the pedal has been moved too far in, the compensating ports can be covered and all of the pressure may not be coming off the line.
Also, if the fluid has been replaced with a DOT 5 synthetic (silicone), it will cause seal binding in one or more circuits, as well as the wheel cylinder seals. It is not compatable.
Lastly, check to see if your brake system has a pressure compensator in the rear. It may be rusted and sticking. Ray

OurPoorBus · Post by **OurPoorBus** » Sat May 10, 2003 7:02 am

Ray, thanks for the reply.
Yes . they do release on their own after a while.
When we bought the kombi the guy said that the only problem was the brakes binding, but he also said that she had been standing for quite awhile near the beach, [ex surfers kombi]. He bought her from the surfer and I don't think he drove her much or knew too much about her.
The brake pedal does not go hard when she binds, it stays soft, like a normal pedal. The handbrake cable was replaced but it only takes at the very end, and then only faintly.
Did the 74 kombi have the wheel hub that was removable or the solid one. Ours is solid, brake drum has the 2 little adjusting screws diagonally opposite each other, now removed for the rims to fit. Our other kombi [which is a parts one] has the removable hub.

OurPoorBus · Post by **OurPoorBus** » Sat May 10, 2003 7:03 am

Sorry I meant to also say that I think they would have used Dot 4 brake fluid, as its the most common one available here.

OurPoorBus · Post by **OurPoorBus** » Sat May 10, 2003 7:59 am

I must be getting old, forgot to ask this question as well.

"Lastly, check to see if your brake system has a pressure compensator in the rear. It may be rusted and sticking"

What does it look like and where would I find it?

raygreenwood · Post by **raygreenwood** » Sat May 10, 2003 8:14 am

The book says the regulator was introduced in 1973. It should be mounted on the frame of the body, just inside one of the rear wheel wells. Trace the brakelines forward from the rear wheels until you come to a device about the size of your fist with one bleeder screw.

Why is your handbrake so slack? Is it becasue the cable is slack? Or possibly because the shoes have way to far to move to meet the drum. If its a show distance issue, you could be leaking fluid . Ray

OurPoorBus · Post by **OurPoorBus** » Sat May 10, 2003 8:27 am

Thks Ray, if it would just stop raining I could check, but its coming down in buckets, who says the sun always shines in Africa

This poor kombi has been standing under cover for awhile, been busy working on the cougars and she got a bit neglected, but seeing as we now have a blown/cracked head on the one cougar and unresolved issues with the other one we thought we would turn our attention to her for awhile. She went in for the brakes about 2 or 3 months ago, when we discovered that she still had brake problems we decided to wait till we could give her our full attention before doing anything, so nothing was really checked out at the time. Its the classic case of having no space to do anything, and now, we have the space but don't want to move her out of cover cos' of the rain. Can't work on her where she is cos' we can barely move round her, let alone under her. But, will get back to you on the handbrake problem as soon as we can.

raygreenwood · Post by **raygreenwood** » Sat May 10, 2003 10:23 am

The main overriding cause of brake binding ...when all else seems normal...is a blocked compensating port. The compensating port is the small hole across from the larger hole...that is under the rubber grommet where the plastic elbow for the fluid supply pipe plugs in. Technically, the compensating ports are also the ring of holes under the brass flap valve that is under the primary cup in each circuit. The primary cup is the one closer to the bottom of each circuit. On the outer circuit...its the cup right before the spring. On the inner circuit...its also at the bottom near the spring. When you put pressure on the pedal...the brass flap valve under the cups is pressed flat, sealing against the "drain holes" in the piston. The cup expands and you get pressure. When you let off the brake...the cups collapse, the brass flaps lift off the holes in the pistons and fluid travels from the space between each cup in the piston...allowing the piston to replenish, and also to move through the fluid and allow pressure to drain off....without forcing fluid into the wrong places.
When the piston comes to rest...it must be in avery specific spot in relation to the small vent hole and the larger supply hole under the rubber grommet that I spoke of earlier. If not...pressure will not bleed off andthe brakes will drag. here are some things that will cause this condition:
(1) blocked compensating port from rust or grease. The compensating ports under the grommet are only about .030-.040" in diameter. They can plug from having crud in the fluid tank. They can ge cleaned with air or with a small piece or wire or plastic
(2) Blocked compensating port from the piston being in the wrong place in the bore whn the pedal is at rest. This can either come from using an after market cylinder replacement with different dimensions...and not adjusting the stroke rod, or from misadjusting the stroke rod, or from rebuilding the cylinder and using the wrong piston kit. They are very specific. It is common mistake when rebuilding a cylinder for instance tgo use an ATE kit with an FAG cylindre or vica versa. The pistons have different compensating port spacing. They will fail in this manner.
(3) Blocked compensating port from swelling of piston cups. This is either caused by ancient cups, defective cups, or improper fluid/rubber combination. If your fluid is black in the resovoir...somewhere in your system, the rubber is worn out. That is where the black color comes from.
(4) lastly, if this is a dual circuit brake cylinder and it was rebuilt or disassembled for any reason and the intermediate piston (which is the one at the bottom of the bore) was not properly compressed on its spring when the lock screw that screws in from the outside of the cylinder and holds the pistons down in the bore was installed, it will dent theedge of the piston. This causes it to drag and stick in the bore. It does not allow the cup to come to rest in the right place. This blocks the compensating port.
For he record, I try to avoid the newer brazilian cylinders that havee no outer lock screw. They are relying on proper spacing of the pistons via correct spring pressure to keep from blocking compensating ports. Asthe cylinder ages, this position cannot be kept...so the cylinder malfunctions, Hope this helps. Ray

OurPoorBus · Post by **OurPoorBus** » Sat May 10, 2003 5:33 pm

Thanks again Ray, that should keep me busy, when it stops raining that is.

amskeptic · Post by **amskeptic** » Sat May 10, 2003 7:13 pm

Based on your tiny tiny little picture, that is a '74 Bus if there is no fuel filler door. Volkswagen changed the width of the rear shoes and drums mid-model year of 1973, not the usual August model year change. They also changed the emergency brake cables and pull yoke.
The pressure regulator Ray mentioned was introduced in 1971 with the advent of front disk brakes.
Binding rear brakes can be caused by those aforementioned compensating ports, a vacuum servo pushrod that is too long, later brake shoes in earlier drums, collapsed brake hoses that run from hub carrier to above the diagonal arms, emergency brake cables jamming inside of their sheaths due to rust.
These cars have excellent footbrakes and powerful emergency brakes.
By all means get to the bottom of this. That emergency brake should lock the car up at the sixth click of the handle and be fully released at the second click. Good luck!
Colin

raygreenwood · Post by **raygreenwood** » Sat May 10, 2003 7:56 pm

I never knew about the different shoes. Thanks for the info! Ray

OurPoorBus · Post by **OurPoorBus** » Sun May 11, 2003 12:31 pm

Thanks Colin for all the info, still raining here, good for the farmers I know, so can't complain too much, not good for us backyard mechanics tho'. Interesting info on the brakes, and I would take a good guess that something wrong has been put in the system somewhere along the line.
I am also certain its a 74, based on what info I can find from the data plate, also the fact that she is an 1800, they were only introduced in 74.

Colin I did put a pic on the Samba site, at the link in my previous post, its one picture of 4 pictures of her, front, side,back, interior dash, if you want to have a look. She has a round metal fuel cap, no door.