Components and Assembly
Rear Suspension & Brakes.

1 Brake Drum
2 Locking Screw ( SFS 8.8.)
3 Shock Absorber
4 Rear Spring
5 Rear Exhaust hanger
It is important to use the correct tools when working on components , bolts and star drive screws are notoriously difficult to remove once they have been damaged.

The W168 A class is a car full of surprises as Earnie found out when he ventured the check and change his brake shoes .
Where one would normally expect to find a Torx securing screw he did not have one. Instead he had what looked like a location pin.
In this case one would expect to pull the drums off the studs and pin rather that having to release a Torx screw
I have never heard nor seen one before or since so this, this is just one more variation that can catch owners out when doing their own maintenance.

Part no, MA 001 990 38 50 Nut.

When replacing with a New stub axle nut, it is only necessary to secure one tab..
Before attempting removal of nuts already fitted, it is necessary to swage this locking tab A away from the stub axle using a suitable tool. Take care not to damage the stub axle end and threads,
The unsecured section B of the nut can be then used on the next occasion the nut is removed which allows the nuts to be used twice following hub /drum removal. These nuts MUST be locked or you may well loose a rear wheel complete with brake drum and bearings.

Note that you will require a 30mm socket to remove the nut 7 Shows the used nut which having been used twice is now scrap.

Having now fitted the new rear brake pre-assembled kits as sold by Mercedes-Benz Parts, although they will will cost you more I strongly advise using these brake kits apart from the the kit which consists of two pre-assembled brake shoe kits as well as new pins clips and grease only the wheel nuts have to be purchased. If you are aware the hubs have never been off then you won't even need those as one tab should have been left unused.

Replacing just the brake shoes would in my opinion be far more difficult and unless you have a ref such as this site or my CD on which there is even more detail then you are unlikely to get the springs etc correctly positioned which could dramatically effect the operation and efficiency of the rear brake's and hand brake. Fitting the the pre-assembled units is easy and takes approx 30 mins per side taking your time and cleaning as you go.

I changed mine at just under 50000miles but in truth there is at least another 10-15000 miles left in the shoes removed. I have cleaned and serviced these and may well in years to come re-use them or pass them to any future owner as they are still very serviceable.

The space between the back plate and the drum when fully housed is fractionally under 3mm this space 1 should be even all-round the drum.
Remember before you can withdraw the drum you must release the handbrake and remove the locking screw. If the drum still fails to come off, a tap with a hammer either side of the drum will normally do the job. The drum should pull off by hand.

Where the retaining screws are stubborn and won't undo it may be necessary to use and impact screw driver. Ensure the correct size 'Torx' bit is used. If the screw head is damaged replace as soon as convenient. Do not over tighten when re-placing <

1 Brake Shoe
2 Wheel Cylinder
3 Return Spring
4 Back
5 Stub axle Cap

Rear brake components in situ

Lower Brake Shoe locator & showing location of securing/ retaining spring.

These two photos give a very good idea where and how the brake shoes are installed Normally a lot of what you can see is hidden behind the wheel flange which in this instance has been removed for purposes other than dealing with the brakes. The red arrow is pointing to the auto adjuster which in some instances has to be slackened before the drum can be removed.

The toothed wheel A is part of the auto adjust mechanism, this can be accessed though any of the five wheel bolt holes, If having fully released the handbrake, the drum cannot be removed, rotate the drum striking the drum as it is turned this normally assists with it is removal. If it still can't be removed rotate the toothed wheel towards the back plate, this reduces the adjustment on the auto adjust spindle and will allow the drum to be removed.

Note the positioning of the brake shoe retaining clips and layout of the springs, It its always good practice when dealing with brakes to remove and replace one side at a time . This then enables you to inspect to untouched side for reference if you do lose your way and with brake springs its easy to get it wrong. Note that there is a hand brake adjuster at the front of the rear suspension cross member (NOT SHOWN) this will enable you the adjust the cables to get the best from your brakes .
Even with New brake shoes , your rear wheels should turn with ease, if they are binding on the drums they will overheat and unnecessary where will be caused to the shoes.

Replacing Brake shoes. When the need arises for the brake shoes to be replaced due either to wear or contamination from fluid (due to leaking wheel cylinders)then you will have to decide whether to purchase Mercedes Genuine Parts A168 420 03 20. or compatible parts from other sources.
The cost will vary considerably, GSF for instance are less than half the Price of Mercedes genuine parts. However history has shown that you do not get all of the components that are contained within the rear brake kit supplied by Mercedes Parts.
It is also interesting to note that the brake assemblies supplied by Mercedes Parts are pre assembled ready to place on the back plate as a complete unit and do not therefore need assembling on the car.

When purchasing the Mercedes rear brake shoe pack you will receive two sets of components pre-assembled as in the photograph.
this is the o/s brake set as seen from the front.
It is worth pointing out the difference in thickness of the two shoe linings . The one that is operated by the hand brake cable is 3mm thick while the other is 5mm thick.
When I inspected my brake shoes some months ago I noticed that there was not a lot of braking surface left on one of the shoes, I have therefore purchased a rear brake shoe kit in readiness to fit when the weather improves. However it my well be that when I measure the thickness of the remaining lining that they can remain in service for considerably longer than was first thought. So make sure your not mislead by the unequal thickness of the linings.

This is the same kit as seen from the back plate.
In addition to the two assemblies you will have a packet containing 4 clips and 4 retaining studs as well as to small sachets of special grease

Procedure for changing rear brake assemblies. (Shoes A160 2002)
Please do not confuse these with and shoes only for hand-brake parking, as fitted on 'A' Class fitted with rear disc braking

A and B Show the self adjuster from the front and the rear, which is fitted into the rear brake assembly. If the mechanism is working correctly then the auto-adjust is achieved when the hand-brake(parking brake)is applied.
Please note there are situations where it is difficult to remove the brake drum. In such situations the auto-adjust toothed wheel, should be slackened off through one of the wheel stud holes in the drum, when the wheel is removed.

If your car has done a high mileage then ensure the brake drums are not badly worn. When new the drums are 180mm - 180.2mm The max wear factor is 1mm so if your drums measure more than 181.2 mm they should be, according to Mercedes-Benz replaced.

1. Where possible work on a level surface.
2. Using the information on my page 4 ensure the wheels of the vehicle are chocked and that the jacks are secure. Please also read page 25 before starting this job. It will I hope clear up and questions or doubts you have before starting.
3. Slacken the wheel nuts of the wheel on which you intend working.
4. Jack up the wheel and remove.
5. Remove the grease cap from the wheel hub ( tap the rim of the cap evenly until it is withdrawn)
6. Replace the wheel and hand tighten the wheel nuts, lower the vehicle to contact the ground.
7. Undo the centre Hub nut and remove. (30mm)
8. Ensure the wheel chocks are wedged tight on remaining wheels, fully release the hand brake
9.Raise the vehicle and remove the wheel.
10. Remove the brake drum retaining screw. Remove the brake drum.
11. Withdraw the wheel flange from the stub axle.
12. Slacken the handbrake cable, forward of fuel tank, remove cable end from brake wheel assembly
13. Remove the brake shoe retaining pins and clips. & remove old brake assembly from back plate.
14. Clean the brake shoe back plate as required.
15. Inspect the wheel cylinder for leaks. Replace as necessary.
16. Fit new brake assembly. Replace all other components in reverse order. Remember to refit handbrake cable and re-adjust
17. Follow assembly procedures as outlined on page 26 ensuring the stub axle nut and wheel nuts are re-torqued.
18. Ensure that the hand & foot brake are working correctly before road testing
19. Enter rear brake service in your service record file

It is advisable to retain old pins, clips, & springs that are in a sound condition, to overcome any future problems, as some of these parts are not available without buying the complete brake kit.

This E-Mail was received from a fellow owner who owner a LWB ( long Wheel base) A160 W168 A class which is fitted with rear disc brakes and an integral drum for the hand brake:-
Hi Lofty
I've just put a set of rear disc pads in my wife's 2001 A160 LWB auto and thought you may be interested in the process.
Firstly, the pads I put in were Textar pattern ones from GSF cost at less than 35.00. The only reason for this, is that GSF is closer than MB to where I live. In the box are four pads, four spring clips, and two bolts with a 12mm head.
The first thing obviously, is to get the car up in the air safely, and remove the wheel. Once this is off, the caliper can be released by removing the bottom bolt with 12mm head, and swing the caliper upwards. There is no hand brake linkage to worry about as in other makes, so this part is simplicity itself. With the caliper held up, you can retract the piston.
Once again another simple exercise as this just pushes back in so you do not need a tool to screw it back. I just used a woodworking clamp and slowly but steadily pushed the piston back. The old pads can be levered out with a screwdriver, and the same can be done with the spring clips. Replace the clips in reverse to the old ones coming out, this bit is a bit fiddly, but is quite easy, just a bit of patience here.
Once these are in the new pads can be clipped into them not forgetting a bit of copper-slip on the backs to prevent future squealing.
Place the caliper back over the new pads and put in the new 12mm bolt as supplied, tighten it up then give the brake pedal a good pump to settle everything in.
Replace the wheel then test drive the car. Total time taken to replace both sides 1 hour. These must be one of the simplest cars to change rear pads, so hopefully some of your readers can save some money here.
Sorry there's no pics, but old brake dust and cameras do not mix!

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