Bedding in parking brake shoes

[paulcallender]

I've just replaced brake pads all round and the parking brake shoes too. I understand that it takes around 100 miles for the brakes to 'bed in' and work to full efficiency. How do you do this too for the parking brake?

While the parking brake is much better (7 clicks holds the car stationery while in D or R), its not that powerful, for example even a firm application won't lock the wheels while moving - other cars I've had, do this (I never actually do that, its simply to test the efficiency of the parking brake). Should it be better? ie. would it get better once 'bedded in'?

Or don't you need to 'bed in' shoes, just pads?

 

[stwat]

Im not sure what merc you have but isnt 4 clicks usualy the norm for the handbrake? You might need to adjust it up some more.

Stu

 

[paulcallender]

Its a 1990 W124 230TE. The 'handbrake' is operated by the foot, on a pedal. The Haynes manual said 7 clicks.

 

[stwat]

I seeeee. Il get mi coat :Oops:

Stu

 

[mlc]

I assume that these brakes shoes work in the same way as my 350 SL 107, that is that they are quite small and operate on the inside of the main rear brake disc.

If this is the case then they will never bed in themselves, because used correctly you only apply the handbrake on a stationery vehicle, so they dont actually ever get to rub against the metal surface.

Dont know what the official way of handling this is but what I have done is driven for short distances with the handbrake on, not to much so that they dont get too warm. This worked perfectly and my handbrake holds well. At my last MOT the tester commented how good the handbrake was "cos its normally crap on Mercs".

Mark.

 

[SLinKyjoe]

one of my rather less than good collegues has a 1988 190.

he was rather annoyed when he came to work one day with smoke billowing out of his rear wheels. he had left his handbrake on and when he had it recovered to the fixerpeople he was very upset at the bill to have them repaired. his comments however, were that he did not know he had left the brake on and that it didnt make any noticeable difference to performance. this would suggest that the brake is really only for holding the car and designed with the power to be used as braking for the car. which is probably why you have 2 different systems on the rear!

he leapt all over my first slk to explain the situation about mercs and crap brakes to me in a look down your nose manner. i smiled politely until i cracked up when he realised that slk's dont have this system....he went off in a huff.



so my view is that you wont need to bed them in, but if you do as the previous post suggests, which seems to have a benefical effect, dont forget to remember you have left your brake on. and try not to repeat the unfortunate situation my idiot collegue did.


ps. he is an idiot and we all laughed that he has trouble with his car....we dont like him very much. not mercedes owner like i know, but he is a buffoon.

 

[shaggy]

is all i did on my 300d (w124) and my c220d (w202) was run the car a few days and then took them back to the happy mechanic who took the back wheels off and 'backed' them off then adjusted them back up with a screwdriver through the hole in the disc mine has 6 clicks and work perfectly if yours are the same i wouldnt worry about 'bedding in' the handbrake as you dont use them when braking

 

[Derm]

Just thought it's important to mention there is a cable adjuster just behind the Cat on these cars the cable should be slack when the shoes are adjusted otherwise the parking brake will not be effective. adjust cable after adjusting shoes if required
230TE 1991

 

[mlc]

Whilst I always agree with everything my learned friends say I cant agree that you can ignore the handbrake.

The handbrake is effectively the emergency brake, although it is not counted as such for the MOT. Brake systems do fail and you can end up relying on the mechanical brake. For the MOT the handbrake has to achieve 16% of gravity retardation - on a big merc that would mean more braking effort than the service brake on the back of lots of little hatchbacks.

I still recommend the manual bedding in process described earlier.

Mark.

 

[SLinKyjoe]

Whilst I always agree with everything my learned friends say I cant agree that you can ignore the handbrake.

The handbrake is effectively the emergency brake, although it is not counted as such for the MOT. Brake systems do fail and you can end up relying on the mechanical brake. For the MOT the handbrake has to achieve 16% of gravity retardation - on a big merc that would mean more braking effort than the service brake on the back of lots of little hatchbacks.

I still recommend the manual bedding in process described earlier.

Mark.

so would this mean that if they were bedded in that they may not hold the car? I assumed by your previous post that yours worked more efficenlty than normal but i would think that as they are not used for stopping but holding, bedding in wouldn't make as big an impact.

altho i do agree with making sure you handbrake works. nothing worse then finding a nice gap where your car was when you left it early, and a lovely merc shaped indentation in someones Mondeo at the bottom of the hill.


and, does anyone here get annoyed about those who insist on yanking up the handle (On the cars what still have this atiquated device) without pushing in the button so as at 4am when the iltiterate over the road with his n reg escort comes home he wakes everyone up with the rachet racket?

and what about them who pull it up so hard on steep hills they have no room left for releasing it and you see them pulling and grunting and then the car bounce a bit when they finaly realease it?

 

[davidsl500]

bedding in ensures that the maximum amount of friction material is in contact with the drum and also cures the material. I would presume that the friction material is much softer than on normal shoes since they are used at low speed or stationery. There are worse systems on the maket - the early Jaguar XJ6's used tiny handbrake pads on inboard discs - an absolute pain to get set up properly to pass the Mot.

Actually Brake Friction material scores pretty lowly on the friction scale - its the ability to dissipate the massive heat produced from braking without disintegrating that is its main property.

My SL has a handbrake warning tone if you leave it on whilst trying to drive off would have thought that would be common to all pedal handbrake vehicles?

 

[paulcallender]

Funny thing is, the old shoes weren't that bad condition. And, they were a right pain to change. But I'd bought all the bits in preparation and I was fitting new discs/drums too, so hence I changed them. No doubt if I'd left the old shoes on, I'd have to have 'bedded' them into the new drum.

Like many others, I don't use the parking brake to stop the vehicle, but it gets tested for the MoT, which is my main concern. I can feel its better than the old parking brake, so hopefully it will not be a problem. Also, its fairly obvious your parking brake is on, you can feel the retardation and see the red light on the dashboard.

 

[SLinKyjoe]

Also, its fairly obvious your parking brake is on, you can feel the retardation and see the red light on the dashboard.

this is why we fell apart laughing out our golden nugget employee.

 

[190]

Did you degrease the drums first and did you slacken the cable adjuster off and adjust the rear shoes then adjust the cable If you have done all this and the cable is not seized your hand brake should be Ok. As for bedding them in a quick way is to put the parking brake on until you feel a slight drag when you try to move off then drive about half a mile then let the brake off and your shoes should be bedded in.

 

[Mark-R]

The shoes would then need readjusting after bedding in as the excess lining which has burnt off will allow the shoes to move too far before gripping.

When all is said and done, even once 'bedded in' the hand brake shoes do not have as much lining in contact with metal than a vehicle which uses the same shoes for it's foot brake. Therefore it cannot possibly work as efficiently. My 190E comes up 4 notches and holds on a hill or in drive or reverse unless I give it some throttle.
Out of interest, does anyone else have trouble with the retaining clips breaking up?
I suspect it could be due to overadjusting the shoes, but not sure.

 

[paulcallender]

Retaining clips? Where are the retaining clips in the brake mechanism?? I never saw any clips when I did the work!!!

 

[190]

The retaining clips are like springs one on each shoe you will probably find it?s not the clip that?s broke but the back plate that?s rotted where the clips fit into.

My 190D,s handbrake comes up 3 notches and locks the rear wheels.

here,s a pic of the handbrake cable adjuster

 

[paulcallender]

Aaaah those springs! They were fine, although they were a right pain to remove and replace. the backplate that they hook into was in good condition, bearing in mind the age of the car (1990). The caliper bolts were covered in underseal paint, so I don't think the parking brake shoes or the disc/drum had been replaced in 15 years....

 

[paulhipwood]

I replaced my pads, discs and brake shoes this week end. Fiddly but not too difficult. The friction material on the old shoes had broken up, so not too sure why the handbrake was working at all!!!

I did not bed em in as advised in the other posts - sounds as if they were trying to wear them out!!!!

The parking brake works ok, theoretically there should be no movement between the brake shoes and the disc, so they will not bed in in normal use as there is no relative movement. Speaking theoretically that is.

Who cares anyway as long as it works and passes the MOT - which mine has!!!!

regards

paul

 

[OlafMaxwell]

Having had two brake failures where the pedal went straight to the floor I regard handbrakes as very very important. I must admit to trying its efficiency and I was not impressed and the MOT tester was not impressed either. I have to use a lot of pressure on the footpedal to get it to hold the car on any kind of a slope. I know, it stays in Park and locks up the wheels but you don't have that protection if you are driving and have to use it to stop the car when your brake system suddenly decides to pump your brake fluid from both circuits all over the road.