Guide: Rear drum brake overhaul

Guide: Rear drum brake overhaul - Printable Version

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Rear drum brake overhaul - 306Puggy - 09-08-2013

Right, this is a guide for rebuilding the rear drum brakes. In this guide we are gonna replace the shoes, retaining springs and wheel cylinders. This is a common failing point for MOT tests so this guide will hopefully keep more 306s on the road! You don't have to do all the parts you can just choose the ones that are applicable to you. To do all of it, it will take about a day allowing for plenty of hold ups and tea breaks and bleeding a good amount of fresh fluid through. First things first, let's make a tool list:

1/2 inch breaker bar
1/2 inch extension
32mm socket
molegrips
needle nosed pliers
picks
3/8th inch ratchet
3/8th extension
10mm socket
13mm spanner
11mm spanner
6mm spanner
jack
axle stands
wire brushes

Parts:

sandpaper (80-200 grit)
brake cleaner
brake fluid (obviously if you have DOT 5.1 then you need DOT 5.1 otherwise just DOT3/4)
Wheel cylinders (obviously)
brake shoes (obviously)
brake retaining spring kit (obviously)

That's all of it. Some advice about the items, brake shoes last a very long time so look up on them as an investment, if you get good quality ones they will last you for years to come. The same goes for the retaining springs; on the other hand brake cylinders tend to leak after 2-3 years so are almost a consumable (I found moisture behind the dust seems of mine which were only 4 years and 2 1/2 years old!). The wheel cylinders are also side specific but if you get two the same side you MIGHT still be able to get the pipe in with a bit of bending. You can of course elect to renew the brake drums as well, but as long as the drums have not gone oval, they should be fine with just a sand down, as we will do in this guide. As a note, all brake friction components should be renewed in pairs. It is also recommended that the brake union nuts are soaked in plusgas/diesel at least once before attempting to undo them. I found the new brake shoe springs on eBay, I think it would be very unlikely to find them in a motorfactors so bear that in mind before you start.

Right, let's get down to it:

1. Jack the car up and support it correctly on axle stands (refer to Dum-Dum's guide for this). Release the handbrake, remove the centre console and back the adjuster nut all the way off. Remove the rear road wheel off the side you are working on and remove the dust cover from the drum. This will expose the hub nut which you use the 32mm socket to undo. Grab some cling film from the kitchen, double layer it and place it over the master cylinder fluid reservoir and tighten it down loosely. This will create a vacuum and stop you from loosing more brake fluid than necessary.

2. With the drum off, prise the handbrake cable out of the handbrake lever on the rear brake shoe. If the spring is too compressed you need to slacken off the handbrake cable more. The easiest way to remove the brake shoes is as a unit, to do this all you need to do is twist the retaining pin on the backing plate so that the head goes through the slot on the retaining washer, pin pictured below:

Once the two washers are off and handbrake cable are off, you must prise the brake shoe assembly from the backing plate. To remove the wheel cylinder, first slacken the union nut which is either a 13mm or 11mm. Once you have slackened this off, remove the two 10mm bolts holding the wheel cylinder to the backing plate. Finish removing the brake union nut and withdraw the wheel cylinder.

3. Using brake cleaner, spray the backing plate and brush with a stiff wire brush.

Clean the threads on the wheel cylinder bolts and the brake pipe union nut, remembering to smear some brake fluid between the pipe and the union nut to prevent it from seizing next time you want to undo it. Remove the self adjuster assembly from the old brake shoes, clean with brake cleaner/wire brush and lightly grease the threads of the ratcheting mechanism with anti seize, taking care to remove any excess.

4. Find a clean work area and begin building up your new brake shoes. They should be as below:

I found the best way to do it was to begin with the self adjuster (wedged between the front shoe and the handbrake lever) and top spring (the long part should be over the adjuster mechanism) and then squeeze together the bottom to put the bottom spring in:

(Edit: I have got the spring the wrong way around in the picture)

Adjuster mechanism components:

To get the spring for the adjuster mechanism in, hook it to the adjustment lever first, then, using the hook pick, hook the other end of the spring into the slot on the brake shoe, the same slot that the lower retaining spring goes into.

Make sure that the slot on the self adjuster fork is on the handbrake shoe side, otherwise it won't work:

Now the brake shoes will be ready to go back onto the car.

5. Before refitting the new brake shoes, refit the wheel cylinder and tighten the union nut so that no brake fluid spills on the new shoes. Once the wheel cylinder has been refitted, slot the brake shoes into position over the retaining plate at the bottom. The easiest way was to do one side and then stretch the shoes to get them over the other side, as below:

6. Arguably, the hardest part of the whole job, fitting the brake shoe to back plate retaining springs and washers. I used a combination of needle nosed pliers and molegrips adjusted to the correct width for the washer. You have to get the head of the pin through the washer slightly off centre as below:

Once you have done that all you have to do is twist the retaining pin around, so that the head sits in the grove in the washer. This part took me about an hour to do one side, it is very fiddly! Once done, take a minute to sit back and admire the shiny.

7. Using the sandpaper, lightly scruff the surface of the brake drum and then clean away any debris with brake cleaner and kitchen roll. Replace the brake drum, remove the film from over the master cylinder and proceed to bleed the brakes. For non ABS vehicles this should be done from the furthest from the master cylinder to the nearest. Two wheel ABS is left rear, right rear, left front, right front, then your hydraulic modulation assembly must be bled as well. Four wheel ABS is left front, right front, left rear, right rear.

8. With the brakes bleed up, pump the brake pedal a few times to activate the self adjusters (this probably won't work, as mine didn't). If the self adjusters are not working then you have to adjust them manually until they just scrub slightly, by tapping the ratchet wheel round with a screwdriver on the steeper end of the teeth.

Once you have done this, check the handbrake to make sure it doesn't come up too far, adjusting the adjuster nut at the back if necessary. Remove the drums, check for a tight fit and any fluid leaks (sometimes you need to nip up the union nuts a couple of times for them to seal).

Once the above has been completed, you will need to allow for the brakes to bed in, a series of sharp stops from 50-60 miles per hour should have the desired effect, ensuring to apply progressive pressure to the pedal. Make sure there is no traffic behind you when you do this.

After doing this, I only found the brake efficiency to go up by 3%, so it probably does take a few hundred miles of driving to get the shoes bedded in properly. Luckily it put me over the pass rate for the MOT but only just. As long as your front calipers/pads/discs are okay then it should at least scrape a pass.

RE: Rear drum brake overhaul - Mattcheese31 - 09-08-2013

the cylinders aren't sided....they're the same and there's better ways of doing some of that, i'll help tomorrow when i'm not on my phone Smile

RE: Rear drum brake overhaul - Piggy - 10-08-2013

not a bad guide there.
worth mentioning that you will want to back off the internal adjuster to get the drums off.
the handbrake cable nut inside the car should only be used to remove slack from the cables, not to adjust the shoes....so dont touch it till you have adjusted the shoes in the drum first.
the adjuster wheel/mechanism is real easy to do if you have someone put there foot on the pedal while with a thin screwdriver and torch you adjust the wheel through one of he wheel bolt holes in the drum.
when someone puts their foot on the brake you can visually see how much adjustment is needed AND it takes the pressure of the assembly and makes it easy to adjust.

and a little dremel comes in handy to take the drum 'lip' off. no harm in that Smile

cant see how the cling film does anything, I always use proper brake line clamps.

otherwise a nice guide chap.

if kept on top off though and adjusted, I have never known rear drums on 306s become inefficient. even when theres no shoes left!

(if you have no 'someone' to put foot on pedal, a 2×4" against the pedal/seat works a treat)

RE: Rear drum brake overhaul - 306Puggy - 10-08-2013

(09-08-2013, 11:35 PM)Mattcheese31 Wrote: the cylinders aren't sided....they're the same and there's better ways of doing some of that, i'll help tomorrow when i'm not on my phone

Okay, thanks. I always seem to miss the obvious ways!

(10-08-2013, 05:49 AM)Piggy Wrote: not a bad guide there.
worth mentioning that you will want to back off the internal adjuster to get the drums off.
the handbrake cable nut inside the car should only be used to remove slack from the cables, not to adjust the shoes....so dont touch it till you have adjusted the shoes in the drum first.
the adjuster wheel/mechanism is real easy to do if you have someone put there foot on the pedal while with a thin screwdriver and torch you adjust the wheel through one of he wheel bolt holes in the drum.
when someone puts their foot on the brake you can visually see how much adjustment is needed AND it takes the pressure of the assembly and makes it easy to adjust.

and a little dremel comes in handy to take the drum 'lip' off. no harm in that

cant see how the cling film does anything, I always use proper brake line clamps.

otherwise a nice guide chap.

if kept on top off though and adjusted, I have never known rear drums on 306s become inefficient. even when theres no shoes left!

(if you have no 'someone' to put foot on pedal, a 2×4" against the pedal/seat works a treat)

I agree about the internal adjuster but where did I say to adjust the handbrake nut before adjusting the brake shoes? Heh, a dremel is too expensive for me at the moment! Sandpaper is much cheaper! The cling film creates a vacuum, it is a well known trick.

Interesting what you said about the drums not becoming inefficient. I think some brake fluid got onto my old shoes which reduced their efficiency slightly. But when I failed the first MOT I cleaned everything up and they still only got 49% so I thought I should replace them so as not to risk failing another MOT.

RE: Rear drum brake overhaul - Piggy - 10-08-2013

if brake fluid gets on ya shoes, yeah its a good idea to change them, you did the right thing.

cling film is a new one on me.

and for once Puggy, try not to pick at everything any one says!

RE: Rear drum brake overhaul - 306Puggy - 10-08-2013

I am not picking at everything you say. If I had said to adjust the handbrake nut in order to make the handbrake stiffer then please point out where I have said that so that I can edit the article. Okay? Stop being paranoid Tongue

RE: Rear drum brake overhaul - Piggy - 10-08-2013

Point 8 bud...
you say to pump brakes to make self adjusters work (which yours didnt and TBh none do properly, so its not just yours! lol)
then you move on to the adjuster nut at the back, I assume you mean the one behind the handbrake

RE: Rear drum brake overhaul - 306Puggy - 10-08-2013

Yes, yes I did. I'll change it, thanks. It was on the assumption that the self adjusters were going to work, that's why.

RE: Rear drum brake overhaul - Piggy - 10-08-2013

I have NEVER known self adjusters work properly...on any car, and on any age of car!
they should just have made it easier to manually adjust!

RE: Rear drum brake overhaul - Tom - 10-08-2013

You guys are so cute when you get along <3

RE: Rear drum brake overhaul - ConorTRG - 11-08-2013

Good enough wee guide, but braking hard from 50/60mph isnt the best way to bed in brakes imo.

RE: Rear drum brake overhaul - Piggy - 11-08-2013

(11-08-2013, 01:48 AM)ConorTRG Wrote: Good enough wee guide, but braking hard from 50/60mph isnt the best way to bed in brakes imo.

I agree for sure but wasnt guna mention it all at one time for fear of waking the beast TMI

RE: Rear drum brake overhaul - 306Puggy - 11-08-2013

(11-08-2013, 01:48 AM)ConorTRG Wrote: Good enough wee guide, but braking hard from 50/60mph isnt the best way to bed in brakes imo.

Well, feel free to offer an alternative then.

RE: Rear drum brake overhaul - Piggy - 11-08-2013

well its a good way to ruin your new brakes.
or any age of brakes from cold really.

drive slowly, I would say 15/20mph with little left foot braking for a couple hundred yards then some loooong but firmer stops from about 30mph. then try avoiding sharp stops for 100-200miles or so

RE: Rear drum brake overhaul - 306Puggy - 11-08-2013

Well, I must have read the wrong thing then. Like I said all I get my info from is google when I don't know. I have read that continuous light application of the brake pedal causes the material to glaze over. Maybe I'll just change it to say "bed the brakes in using your preferred method".

RE: Rear drum brake overhaul - Piggy - 11-08-2013

hard stops from 50/60 will either glaze the brakes or warp them

if thats your preferred method, be my guest!

RE: Rear drum brake overhaul - 306Puggy - 11-08-2013

I didn't say it was my preferred method Rolleyes

I can only go off what I read from google.

RE: Rear drum brake overhaul - Niall - 11-08-2013

(11-08-2013, 01:48 AM)ConorTRG Wrote: Good enough wee guide, but braking hard from 50/60mph isnt the best way to bed in brakes imo.

On a disc setup, id normally agree but with rear drums, they do no more than 20% of the braking so you wont get enough heat into them to damage the shoes or drums like you could with a new front disc setup.

Just FYI, the school of thought i go with for bedding in front brakes is lots of slow gentle stops and then as soon as you come to a stop, release the brake pedal. You are tying to leave a layer of the brake pad material on the disc. When you see sort of an imprint of a pad on a disc, this is where someone has got them red hot then stayed on the brakes after stopping. This leads to having disgusting feeling brakes!

RE: Rear drum brake overhaul - 306Puggy - 11-08-2013

I have nothing to add.

RE: Rear drum brake overhaul - Jonny81191 - 11-08-2013

(11-08-2013, 05:56 PM)306Puggy Wrote: I have nothing to add.

Then don't say anything? lol

RE: Rear drum brake overhaul - Mattcheese31 - 11-08-2013

i do . . .the brake cylinders aren't sided . . . did i already say that? . . . lol

. . .did you just copy and paste half of this? . . Wink

RE: Rear drum brake overhaul - 306Puggy - 11-08-2013

lol cheeky git. I spent ages writing this up and collecting photos.