Brake bleeding problems

How are you bleeding? If you don't have a bleeder tool (pump), then you need a mate/helper:

Open bleed screw. Push pedal down and hold it. Close bleed screw. Release pedal.

Repeat

Speedy Jim

Yes. That is how I did it. The pedal operator was though my daughter. She did as I told and we did like you describe above. I cannot say about the speed that was used to push the pedal down and released. Is there any limitations? To push slowly or "normally" or something else?

Could the raised front be a problem? Or the handbrake being engaged?

The raised front and handbrake shouldn't affect it.

Try this test: Adjust the front adjusters (starwheels) so tightly that the wheels won't spin. See if the pedal is high and firm now. If it *is*, then the problem is brake shoe clearance to the drum, not air in the system.

Jim

I will try that after I try to bleed the brakes once more.

For curiosity - How could the shoe clearance have changed while I changed the hoses? The brakes were functioning perfectly before I changed the hoses and I have not touched the adjusters. The car passed MOT just before the repair (the MOT checker told me about the cracked hoses) and the brakes were dynoed. They were better than ever before.

I had the same question in mind :) Don't have an answer.

As an aside, I'm sure you were careful to keep the fluid reservoir filled, were you not?

Yes. The level has been max 1 mm below the "seam" in the reservoir (ie. about 75% full).

Ok. Back from garage. Adjusted the brakes. I think it had been a while since I lest did that. The shoes might have been a bit far from the drums at least in the front. Now the pedal is feeling again more normal. Not taking from as top as it has some times after the adjustment, but feels normal and the brakes are back.

But. How on earth there has been excellent brakes, taking more or less from the top, working ok, feeling normal, performing excellently in the dyno... And then after replacing the front rubber brake hoses they are completely different and the pedal goes to the bottom. Were the hoses clogged? Could that cause this? Or is my master cylinder faulty somehow?

I'm taking it for a test drive tomorrow. Better to start carefully...

I would also adjust the rear shoes as that will affect pedal height as well.

There is probably nothing wrong with the M/C.

Jim

Ok. I was unclear. I already adjusted all four wheels. The back ones were ok'ish and did not require much adjustment to bind the drum. The front ones required more. The front brakes are more involved in normal braking and probably wear more.

I would suspect the brake hoses were possibly collasped internally. This possibly allowed the brake shoes to stay close to the drums due to pressure still remaining at the wheel cylinders. THEN when you installed the new brake hoses the fluid could easily return to the master.

Your mileage and power might >> Speedy Jim wrote:

: >>> The raised front and handbrake shouldn't affect it. : >>>

: >>> Try this test: : >>> Adjust the front adjusters (starwheels) so tightly that : >>> the wheels won't spin. : >>> See if the pedal is high and firm now. : >>> If it *is*, then the problem is brake shoe clearance to the drum, not : >>> air in the system. : >>

: >> I will try that after I try to bleed the brakes once more. : >>

: >> For curiosity - How could the shoe clearance have changed while I : >> changed the hoses? The brakes were functioning perfectly before : >> I changed the hoses and I have not touched the adjusters. : >> The car passed MOT just before the repair (the MOT checker told me : >> about the cracked hoses) and the brakes were dynoed. They were : >> better than ever before. : >>

: >> --- : >> Olli : >

: > I had the same question in mind :) : > Don't have an answer. : >

: > As an aside, I'm sure you were careful to keep the fluid : > reservoir filled, were you not? : : Ok. Back from garage. Adjusted the brakes. I think it had been a while : since I lest did that. The shoes might have been a bit far from the : drums at least in the front. Now the pedal is feeling again more normal. : Not taking from as top as it has some times after the adjustment, but : feels normal and the brakes are back. : : But. How on earth there has been excellent brakes, taking more or less : from the top, working ok, feeling normal, performing excellently in the : dyno... And then after replacing the front rubber brake hoses they are : completely different and the pedal goes to the bottom. Were the hoses : clogged? Could that cause this? Or is my master cylinder faulty somehow? :

If the rubber in the hoses was bad INSIDE as well as outside there could be peddle with limited but enough break action to fool the inspection. BTDT

Once pulled a '27 Model A in for inspection and was rejected for leaking break fluid. (for those who've not worked on A's: A's have 100% mechanical breaking.)

On old master cylinders, the last part of the piston bore that isn't normally used, can be corroded and rusty or dirty. Then when you bleed the brakes by pumping the pedal, you make the pedal go to the floor... the piston enters the less used area and gets stuck there. The pedal returns, and in dual circuit master cylinders the other piston might still come back out and you would not see any slack (grown rod clearance). usually it's the furthest/deepest piston that gets stuck at the end of the bore - front circuit in vw's.

On old cars, pressure bleeding is a better way to bleed, less risk of getting pistons stuck or seals damaged from driving the piston through rusty cylinder walls.

Well, not quite, I think. The amount of fluid needed to actuate is dependent only on the diameter of the wheel cylinders and the travel of the cylinder pistons. The diameter of the hoses/tubes does not affect this volume and thus the amount of fluid needed is the same.

The swollen hoses would however restrict the fluid flow so that there feels more resistance in the pedal while it is going down. And the smaller diameter could restrict the flow back from the wheel cyls so that the back pressure caused by the brake shoe springs is not enough to fully return the wheel cyl pistons.

Olli Lammi wrote: >

Went past the parts store today and popped in to get new hoses for the back also. I will change them all, if the front ones were bad.

The brake hose replacement show has reached the point where I have to replace the brake line that goes from the left side of the tranny (the T-piece) to the right side on the back. The right back hose connection to the line would not open without such force that the line connection went round.

The question is: how should the line be routed? Are there some clips or such on top of the tranny in the firewall? The line disappears there in the dirt and comes out on the other size. Parts manual states that the line is 650 mm of length. Will I be able to take the line out just by pulling and without breaking any clips etc? Or is the line attached to the firewall somehow? I cannot really see where the line goes there.

I've lost track of what car this is on, but here's a pic (from Samba) of an early IRS:

HTH

It is a standard (swing axle) Beetle 1300 year model 1973. The line disappears in the seam in front of the transmission. That picture with the IRS might show the location, though the line is not straight. That "clip" there in the IRS picture holding the line might be similar that is holding my line also there.

However to me it seems that I can get the old one off there by force, but putting a new one in and routing it exactly as the old one might be a bit of a problem without removing the engine and transmission first. And that I do not want to do.

In the swing pictures there (they are rather small), it might be that the line has been routed just in the empty space over the transmission and not bent to go behind that clip. Do you think it is safe to do so? That it will not cause for example vibration to the line that would be a problem?

Few pictures of the situation. I have cut the line end off the right side (visible in the picture). The left side is off the T-piece. The break line "disappears" under that lip there and comes out on the other side in quite similar way.

Left side:

As a bonus I noticed that the transmission ground strap had seen its best days. Replaced that. The old one was about to go (a blurry picture, sorry):