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Rear drum brake diagram??
by
tkisling
on 07 Jun, 2010 20:52
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Hi there again.
I was wondering whether anyone could post a diagram of the drum brake assembly on a 1981 Rabbit diesel L. I'm having a heck of a time figuring out how everything goes together.
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#1
by
Baron VonZeppelin
on 07 Jun, 2010 22:00
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I just did a full makeover on my 81 rear brakes, and took pics.
Should be easy to see details since everything is new/clean.
PM me your email address and i can email a couple/few pix.
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#2
by
Baron VonZeppelin
on 08 Jun, 2010 00:59
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Your profile has email addy, i'll send some pix to that.
I can't post pix to forum because my ISP doesn't cooperate with pic webhost sites. But you can post them here when you get them, if you are able.
The Germans have their own way on drum brakes, first time is a true learning curve. Golden Rule is to leave one side assembled so you can use it as reference on the other side = until you are veteran-ized.
#1 ordeal is that most aftermarket shoes pay no attention to detail on the bend on the emergency brake arm. I had to check 3 different brands/offerings before finding shoes with right bend on e-brake arm. AdvanceAuto and Oreilly failed. AutoZone was right, and so was Carquest.
The stuff will not go together right AND function right - if that bend doesn't allow the shoe/eBrake arm/crossbar to all fit with right clearance in right areas.
Make note that AdvanceAuto has New 180mm Drums for $8 each, if you need them. But i needed 200mm (truck).
Shoes were $14 at AutoZone ($25 Carquest)
Wheel cylinders (Wagner) $10 each Carquest
Spring kit was $4 or $7 at AutoZone
O'Reilly turns drums for $10 each
National bearings and seals $30 for all at AdvanceAuto
The spring colors of my parts may not match your colors, but use my color references in conjunction with my pictures, compared to your physical spring shapes.
Step #1 is to position the notched tabs/ears of the wheel cylinder pistons so that they are to the outside of the vehicle. This keeps the shoes from trying to walk out towards the outer edge of the drum.
Step #2 is to loosen your e-Brake cables to the full limit of the threads, this will make getting the spring end of the cable back onto the e-brake arm of the shoe 500 times easier. At the spring end - pull out the cable slack you created. The cable end will now have freedom from the spring and slip right into place on the eBrake arm of the shoe.
Step #2 is to take the shoe with the eBrake lever, and attach the cable properly to the lever. Do not attach the shoe to the backing plate - leave it free.
Step #3 is to position the crossbar properly over the eBrake lever, and onto the shoe. Then attach the Blue spring to the crossbar, and to the shoe. Let that shoe and crossbar hang together free for now.
Step #4 is to attach the Yellow spring to the other shoe, then position that shoe into the crossbar, and attach other end of yellow spring into crossbar.
Step #5 is to position your shoes/crossbar assembly onto the backing plate. Start by compressing the wheel cylinder pistons in - and manuever the upper section of shoes into position on the wheel cylinder.
Then spread shoe/crossbar assembly apart by hand at lower extremities, and set the lower ends of shoes against the lower stop.
Then attach the hold-down pin/spring/cup to each shoe.
Step #5 attach lower Green spring.
Step #6 with a medium flat blade screwdriver inserted into the crossbar slot where the Blue spring attaches - pry the screwdriver against the brake shoe and open some room to slide the funny little self adjuster tab into place.
Make sure the little 'knob' sticking out on the backside of the self adjuster tab - is facing towards the backing plate - NOT facing towards you. This 'knob' keeps the tab from falling through the crossbar later into the lifespan of the brake shoes.
Position the self adjusting tab so that the top of it is about even with the top of the brake shoe.
Attach Purple spring to bottom of self adjuster, and into brake shoe.
Double check that you still have the brake cylinder piston "ears" facing towards outside of vehicle.
If you aren't positive about the operation of old wheel cylinders, have someone mash the brake pedal now while you watch for their action moving and releasing the shoes.
Center the shoes/assembly up on the backing plate by eye to the best of your visual perception. So that the drum will hopefully just plop right back on without interference.
Tighten wheel bearing nut with a wrench just beyond hand tight enough to set everything into place. Then loosen the nut back, and hand tighten. Go just a tiny bit past hand tight with a wrench.
Be sure to use a new cotter pin.
Drive car and do full stops in forward and reverse.
About 10-15+ times in forward and reverse.
Jack vehicle back up, and verify that wheels still turn freely.
Hearing "some very slight" brake rubbing is usually normal and will wear in quickly. So long as wheel turns pretty freely.
If all that checks out proper, now you can adjust your emergency brake and fine tune it to your liking. Engage and disengage the eBrake numerous times after adjustments and check for equal amount of grab on both wheels at certain numbers of clicks.
Adjust as necessary.
Standard setting is 4-5 clicks up on handle and you shouldn't be able to turn wheels any by hand. But that can be to your own taste, tighter or looser.
After final eBrake tuning, re-check that wheels still turn freely with eBrake disengaged. And you're done with it.
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#3
by
tkisling
on 08 Jun, 2010 13:40
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Thanks so much for the info. This is really going to help since I don't have a bentley manual. I bought the Wagner brand shoes, wheel cylinder, and spring/hardware kit from Oreilly's so I hope this all works. <:/
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#4
by
Baron VonZeppelin
on 08 Jun, 2010 19:07
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If you went with Wagner shoes instead of their house brand, you should be in great shape.
You can tell ahead of time by fitting the crossbar into shoe that has the eBrake lever on it. If it all fits in the crossbar flush, and has clearance for the eBrake lever travel - you're good to go.
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#5
by
tkisling
on 13 Jun, 2010 19:52
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#6
by
Baron VonZeppelin
on 13 Jun, 2010 20:06
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Did you get the pix i emailed to you ?
I can't view your pix, imageshack refuses to jive with my ISP in any form. But you can send them to my email.
Read back through step #6 another time or so, and check the pix i sent. Might help sort it out.
The goofy lil adjuster fits in a "slot" in the crossbar, it wedges between the brake shoe and crossbar. Its an odd design, but simple. And evidently works about 95% of the time.
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#7
by
tkisling
on 13 Jun, 2010 22:11
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I did receive your pics just fine. By the "slot" do you mean the angled, open section of the crossbar the long blue spring passes through?
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#8
by
Baron VonZeppelin
on 14 Jun, 2010 11:02
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No, the slot for the blue spring is on Outer side of the brake shoe.
The slot for the eBrake adjuster wedge is on Inner side - behind the brake shoe. It slips in right behind the upper metal part of the brake shoe.
Take note again of inserting a flat screwdriver into the small slot where the blue spring actually attaches - then leverage the screwdriver against the brake shoe applying mild force to open the gap for the adjuster to slip into - on backside of the brake shoe.
If you can:
download the pix i sent - to your computer - then open them with your picture viewing software - then enlarge/explode the view of picture numbers DSC02099 and DSC02102.
Those pics show the adjuster location pretty good - considering most of the adjuster is hidden. That should help you tremendously if you can enlarge those pics.
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#9
by
600K
on 14 Jun, 2010 15:34
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I would use caution if you have someone "just mash the brake petal" to see if the wheel cylinders are working. Flooring the brake petal without the drums on is usually a great way to push the plunger out of the cylinder, drenching everything with brake fluid and usually necessitating replacing the wheel cylinders and shoes. ask me how I know this.
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#10
by
tkisling
on 14 Jun, 2010 20:38
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Well, me and my dad finally got both rear drum brake shoes and new wheel cylinders installed, it wasn't easy, but we got er' done in the end. Now I am faced with the original problem before I started all this, my system has no pressure. I am assuming I need to bleed the brakes. But I do not know the specific process of brake bleeding a system with two new cylinders. Can anyone help me finish this saga?
ps. Big thanks to "Baron VonZeppelin" for all his advice and the complete instructions, it really helped.
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#11
by
neimis
on 15 Jun, 2010 00:38
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#12
by
rs899
on 15 Jun, 2010 07:32
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#13
by
Baron VonZeppelin
on 15 Jun, 2010 11:21
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I am assuming I need to bleed the brakes
Yep, probably 100 diffy ways to do it.
If you don't want to make or buy a device, there are other ways.
What you will likely find - since you had bad cylinder(s) already - is that the lines leading up to them will have rusty'ish brake fluid and some corrosion from the air and moisture that was drawn back into them over time. You need to get that mess out.
I would NOT want to pump that garbage through my new cylinders to get it out of the system. I would disconnect the lines from the cylinders (both) before pumping/bleeding the lines - which would send the garbage through the cylinder(s) otherwise. If you only disconnect one at a time - the other will be getting the stuff run into it.
So i would disconnect both and do an initial Flush of both lines.
I used a MightyVac hand pump vacuum tool on mine to flush them until clear fluid was coming out each line - before connecting the lines to the new cylinders. And then pressure bled them.
Another method would be to run lengths of (old/new) vacuum or fuel hose or clear vinyl tubing from each brake line (something that fits tightly over the line nipple - not the line nut). Enough hose so that both hoses can meet near the middle of the car. Clear vinyl tubing is ideal - but not required.
Have a catch pan/jar/jug to catch what comes out.
Have a helper to work the brake pedal in car, and he will also refill the brake fluid reservoir as needed.
Wear some type of rubber/vinyl/latex gloves - hold both hoses into catch container.
Have helper push down brake pedal with medium pressure to the bottom. He holds it there. Then you cover the hoses with a gloved finger - and tell him - OKAY. He lets the pedal up - and says OKAY back at you when its back up completely.
You let your fingers off the hoses and tell him - OKAY. He pushes pedal down again to the bottom and says OKAY. You put fingers over hoses and tell him - OKAY, and keep repeating that process until you get clean fluid coming out both sides. It takes good teamwork and communication - and you can use more words than just okay.
You want the hoses to be covered anytime the brake pedal is going up - so that you hopefully don't draw air back into the lines. Its not the end if you do slip a couple few times - you're just flushing for now. About every 3-4 flush pumps - check/refill brake fluid level.
This was a guidline. You can do something like this many different ways and you can modify anybodys instructions to fit your needs.
You "might" be able to pump the brake pedal some with your finger over it in the very beginning - but as it gets fluid built up and pressure increasing - i doubt you will be able to do more than one pedal push at a time.
After all that is completed to satisfaction - you can re-connect the brake lines to the wheel cylinders and start the pressure bleed operation. It is pretty similar to the flush operation. Takes teamwork and voice commands.
With the brake lines securely fastened into the wheel cylinders - and the bleeder screws on backside of wheel cylinders run in snug on both sides - put a box end wrench (7mm-8mm) on passenger side bleeder screw and then connect one of your flush hoses over the bleeder screw nipple. Run hose into a container.
Have helper pump brake pedal smoothly about 10 times.
He holds pedal down and gives voice command - you loosen the bleeder screw about a half turn while he pushes pedal to floor and holds.
He gives voice command - you tighten bleeder screw.
Then you give voice command and he lets pedal up.
Then he pumps pedal again .... continue doing this until you get full fluid - no air - coming out of the hose.
Then tighten the bleeder screw snugly.
Remember to keep an eye on brake fluid level every few bleeds, the rear capacity is less than the front and it runs out quickly.
Then do driver side rear.
Then do passenger front.
Then do driver front.
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#14
by
tkisling
on 15 Jun, 2010 14:45
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I have all the tools to bleed the brakes now. But whenever I go to bleed the brakes i can't get any pressure to build up in the system before I loosen the bleeder screw and it appears that the master cylinder level is constant. Do you think my problem is the MC?