Health check questions

[amwebby]

Had a health check done on my car by MB Romford when they fitted the new cats, which they've just sent me.

They said the rear brake pads were beginning to get low but noted the minimum wear sensor was not yet activated. 4,000 miles later the minimum wear sensor is still not activated. How long have I got before these need doing?

They also noted the offside track rod end had some play and recommended replacement of the pair. 4,000 miles later I haven't noticed any knocking. How long have I got before these need doing?

Finally they noted that the rear prop shaft coupling is beginning to crack. I haven't noticed any clunks when pulling away after 4,000 miles. What's the consensus on this one? How long have I got before this needs doing?

I'm hoping to spread the cost of attending to these problems over the next three months as my wife's illness is a continuing drain on finances. Any ideas as to the order of urgency I should apply to these items?

 

[grober]

FIRST PRIORITY
Worn track rod ends are a common MOT failure since they are associated with the steering. Cars with power steering tend to wear them due to the loads imposed moving the wheels while the car is stationary. In theory the cars toe in (tracking) should be checked after they are replaced ( always best to replace both at the same time) but careful measurement before removal can often retain the previous setting. Best to use bona fide mercedes parts or lemforder from ECP. It sounds as if they arn't too bad at the moment and would pass the test OK


SECOND PRIORITY
Rear brake pads don't play a major part in braking so can last quite a long time. There is a minimum thickness and the best way to predict remaining pad life is to measure the existing pad dimensions and compare them to the dimensions when new. This way you can get an idea of the wear rate. Having said this some people advocate changing pads when they reach about 1/2 worn since this means there is less chance of the caliper pistons "cocking" or corroding leading to jamming? Unlike front brakes the problems that beset rear brakes are due to not being used e.g. rear disc corrosion being common. What also happens is corrosion on the brake pad backing plates and the sliding surfaces of the caliper/pins causing them to jam. When pads are installed these surfaces are coated with high temperature grease but this is gradually burnt/washed off leading to possible seizure. During a brake service the pads should be removed the calipers and pins cleaned and regreased before being put back to ensure their continued effective action. This means the labour costs of operations involved in replacing the pads is done anyway so it makes sense to renew them if they are not too expensive. To sum up since I'm starting to ramble- summarising --due to differing wear rates --- I would say front brakes replace by wear ---rear brakes by time interval .

FINAL OPERATION
The cracked rear propshaft coupling can probably be ignored in short term.

P.S. If you are stretched for cash all these repairs can be easily tackled successfully by a mercedes specialist or competent independent garage using MB parts.