With the weather being so bad in the UK at the moment I have best avoided doing any maintenance tasks until it gets a little warmer. However a sight rear parking brake imbalance on the Vito was beginning to bug me, and the the day in question was sunny and dry although bitterly cold – I was going to have a quick look and adjust the shoes to balance the parking brake.
Its a simple enough task to drop the rear wheels off and click the adjusting spur wheel round a few notches through a wheel-bolt hole, bringing the shoes into contact with the drum – then back it off a noted number of clicks until the wheel rotates without binding, repeat on the opposite wheel and job done ! Simple….
As I dropped off the rear passenger wheel on the Vito (111 W639 2008) to make the shoe adjustment I noticed that there was a lip forming on the outer edge of the brake disc. As this is some thing that I usually like to remove when servicing the brakes myself, (dealer did it last time !) Thinking I would just drop off the disc and run around it with the grinder, I backed off the adjuster through one wheel-lug hole, removed the caliper completely by undoing the two 18mm securing bolts and then took out the single torx retaining bolt from the front face of the disc/drum. The assembly then pulled directly off the hub to reveal the parking brake mechanism/shoes.
Gulp! … Now being so glad that I had not just blindly adjusted the parking brake shoes to obtain best balance and just continued to drive the vehicle, I was met by a very unpleasant sight inside the drum that needed urgent attention – serious corrosion of the actual brake shoes and back plate. (These were genuine Mercedes shoes, with stamped logo and OEM part no.6394200220 ) Honestly never seeing anything quite like this ‘rotting’ of the shoes in my many years of mechanics, additionally so on such a modern vehicle with a documented service history (2008) was to say the least, a tad disturbing.
A quick phone round to source replacement shoes was a total waste of time as it was Easter Sunday and the places that were open had no stock – So I decided to strip both sides and do a ‘proper job’ in readiness for the new shoes ordered online to be fitted in the next day or two.
All the time I was working on the vehicle cleaning up the parts that were in very poor condition, I reflected how fortunate I was to have made the decision to remove the disc/drums to take a look inside. This was further underlined when the friction lining totally de-laminated from the steel shoe support on its removal. What a mess !
Having stripped the back plates and cleaned them up with a wire brush and in places used a Dremel grinder, paying special attention to the raised surfaces where the shoes slide during actuation, as any rust here would for sure hinder their smooth sprung return when in use.
Cleaning the inside of the drum revealed little wear and only the slightest lip to be removed with a file so that refitting and future removal would be made a lot easier without snagging the shoes as it slides off the hub. Lips were removed from the outer and inner edges of the disc area with careful use of a grinder and finishing with a file, they were then treated to the same paint coating as the back plates – all awaiting fitment of the new parts. New parking brake shoes were purchased from here, super quality German manufacture and fast delivery – above all excellent value. I also bought a set of new DELPHI springs and retainers from here, again fantastic value and truly fast delivery. The job was done for less than £35.00 !! MB want over £100.00 for the shoes alone, seeing how the original OEM parts had deteriorated I have little problem in using parts sourced from an alternative manufacturer.
My advice to anyone contemplating blindly adjusting the Mercedes Vito parking brake is DONT ! Unless you can personally vouch for the condition of what lies inside, I recommend having at least a look inside first, just to see what condition it is all in.
Better to be safe than sorry!