Std Beetle drums and MC.

[ZeroAxe]

Ok, I am officially pissed! And I am not referring to being drunk

I followed the instructions in this link, but for the life of me, I cant get this spunge feeling out of the system. I have to pump 4 times before having brakes!!!! So, my question is this:

1. If you have done this before, please show me your setup, that you have 'designed' to help bench bleed the master cylinder(ie. bottles, tubes, the whole thing!)
2. What do you do/how do you go about taking your newly bleed MC to your car, and what do you do/go about preventing ANY air getting back into the MC?

YOUR help is needed because MY life is in the scale here(I have no choice than to use this car in this state.....)

Thanks in advance!

[forcecooled]

Hi
Forget about bench bleeding. it seldom works as there is always air lurking in all the corners of the system.
1- fit the master cyl to the car
2- check that all the bleeder nipples on the drum back plates @wheel cyls are clear - unscrew them and wipe off and blow thru with a bit of pipe to make sure they are open.
3-refit the bleeder nipples
4- fill the the master cyl fluid container to the brim
5- find a bit of clear plastic tube that fits over the bleeder snugly
6- get a small clear bottle and fill it with about 1cm of fluid
7-have your assistant sit in the car and pump the pedal ONLY when you say so -when you say PUMP he must SLOWLY push the pedal all the way down, release it SLOWLY, taking his foot just off it every time and going again and again. When you say HOLD he must hold the pedal down while you tighten the bleeder you are working on
8- fit the tube over the furthest bleeder from the master cyl. , place the other end in the bottle with it under the level of the fluid ,open the bleeder,and ask your asst to PUMP -when you see dirty fluid and air coming out , things are happening!
DONT FORGET TO STOP AND HAVE YOUR ASST FILL THE CARS FLUID CONTAINER OFTEN - IF THE CONTAINER RUNS DRY, YOU WILL HAVE TO START OVER, AS AIR WOULD HAVE BEEN DRAWN INTO THE SYSTEM .
9- when there is no more air bubbles coming out, only clear fluid, ask him to HOLD and tighten the bleeder.
10-Do all the wheels like this. --there should be lots of hard pedal developing at this stage
11- Bleed all of the wheels again, as the air has a habit of lodging in the corners of the system while the process is going on.
if you are content with the results , nip up the bleeders, wash any spilt fluid away with plain water, top up the container and road test

There are quite few auto bleed systems available for you to do the job single handedly, and are simple to use.

If you still have a problem with spongy pedal, there can be a few reasons other than air in the system to cause it, including some dangerous mechanical defects.

defective brakes are killers. so if you dont sort the problem this way, GET HELP

Cheers
Bill

[calooker]

One main reason for spoungy brakes are the old flexable brake hoses that tend to swell and contract more than they should, if you are replacing the master cylinder I would do the pipes and the slave cylinders as well, no use doing a patch job, or you will be doing it again in no time, the shoes also need to be in good condition without any previous contamination from leaky seals, drums too, need to be round and true oval drums give you a odd feeling @ the pedal. A lot of the brake parts have been on your ride for more than likely 30 years and more, that should be pleny reason to change them, drums will also have suffered and have probably been machined so many times that the next time they heat up they warp. Check and replace where needed. No need for a bench bleed.

[fig]

Follow Bill's advice above and you should have no problems.

And Rui's point about the flexible brake lines is also important. They will often look good on the outside, but are perished inside, which can lead to binding brakes or total brake failure.

Bleed the brakes starting with the drum furthest from the MC, then work your way to the closest one.