R230 Handbrake not fully releasing

[Ronnie]

I have a R230 55 Reg.
The handbrake is not fully releasing.
The foot pedal is releasing fully.
Don’t actually feel any drag when driving and no alert on dash but rear wheels overheating, which is how I identified the problem.
Local garage had a quick check and advises it’s an electrical problem and he does not have the expertise.
Just wondered if this could be right as I thought it was a mechanical operation ?
Any advice on the likelihood of it being an “electrical” issue would be much appreciated

 

[OneForTheRoad]

It can't be electrical if you apply with a foot pedal and release by pulling the handle , chances are your rear caliper slide pins are binding or the handbrake shoes have moved inside the brake disc assembly.

 

[Dodipops]

Turnbuckles seized, guaranteed

 

[Ronnie]

Turnbuckles seized, guaranteed

Now that’s what I call a positive diagnosis

 

[Ronnie]

It can't be electrical if you apply with a foot pedal and release by pulling the handle , chances are your rear caliper slide pins are binding or the handbrake shoes have moved inside the brake disc assembly.

Thanks Onefor..that’s what I thought.
Not too clued up on the mechanics but the operation of the handbrake gave me the impression it was totally mechanical with no electrics involved ..

 

[OneForTheRoad]

Thanks Onefor..that’s what I thought.
Not too clued up on the mechanics but the operation of the handbrake gave me the impression it was totally mechanical with no electrics involved ..

Your handbrake is separate from the rear brake . Your handbrake shoes sit inside the rear brake disc, your rear brakes are external pads within the caliper .

 

[Ronnie]

Your handbrake is separate from the rear brake . Your handbrake shoes sit inside the rear brake disc, your rear brakes are external pads within the caliper .

So we are where that no electrics involved whatsoever..even sensors that may not be working properly ?

 

[Trickythemerc]

The only electrical bit will be the warning light on the dash. As previous posts suggest it will be something seized on the park brake mechanism.

 

[Ronnie]

The only electrical bit will be the warning light on the dash. As previous posts suggest it will be something seized on the park brake mechanism.

Thanks for your help and advices

 

[OneForTheRoad]

So we are where that no electrics involved whatsoever..even sensors that may not be working properly ?

Sounds like the garage you used doesn't want to take the job on and blew some smoke up your anal glands .

 

[zipdip]

Suggest you never use that local garage as stated it cannot be electrical,on the w221 S mercedes you do have electrical problems with the hand brake,because owners instead of putting the hand brake on electrically they hit the park button on the gear change stalk that just puts a prawl into the gearbox,and so the gear that puts on the rear brakes stops working .

 

[Petrol Pete]

If your parking brake is made up of shoes inside the drum within the rear discs (as most MB's of this vintage are) you could be either very lucky or in dep doo doo.

First thing is get the back wheels off the ground and try spin the wheels by hand , there is no adjustment on the foot pedal it is shared by the cable splitter and the 'star' turn barrels inside the drum , adjustments are made with the road wheels off the car.

Having completely re built this system myself on my 54 plate C class I can tell you it's not rocket science , just a PITA.

You don't mention the mileage of the car ?

The worst part of the brake design is that the (critical) shoe holding springs attach to the disc 'stone' shield which rusts and the spring has no where to hold on to. Replacing the shield is usually a 'hub off' task unless you are able to cut them to fit .

Most garages will not cut them .

Here are a few photos.

This hole rusting out is never a good thing.

This is not 'worse case scenario' ....this is . Splitter box return spring snapped , not fun to replace.



PS as far as I am aware there are no sensors other than the switch on the parking brake pedal itself , all that does is put the light on the dash.

I too did not feel any drag when all this happened and in fact the car had passed MOT shortly before, BUT I did experience one disc/drum getting hot and a kind of brown dust that was hard to clean off the wheel. I do not suffer from drake dust on this car as it is fitted with ceramic carbon brake pads so the 'brown' dust was more noticeable and was obviously one of the shoes breaking up in the drum.

If your car does not have the above system please accept my apologies for scaring the $hit out of you.

Let us know what you find.

 

[Ronnie]

If your parking brake is made up of shoes inside the drum within the rear discs (as most MB's of this vintage are) you could be either very lucky or in dep doo doo.

First thing is get the back wheels off the ground and try spin the wheels by hand , there is no adjustment on the foot pedal it is shared by the cable splitter and the 'star' turn barrels inside the drum , adjustments are made with the road wheels off the car.

Having completely re built this system myself on my 54 plate C class I can tell you it's not rocket science , just a PITA.

You don't mention the mileage of the car ?

The worst part of the brake design is that the (critical) shoe holding springs attach to the disc 'stone' shield which rusts and the spring has no where to hold on to. Replacing the shield is usually a 'hub off' task unless you are able to cut them to fit .

Most garages will not cut them .

Here are a few photos.

View attachment 160381 View attachment 160382 View attachment 160385 This hole rusting out is never a good thing.

This is not 'worse case scenario' ....this is . Splitter box return spring snapped , not fun to replace.

View attachment 160386 View attachment 160387

PS as far as I am aware there are no sensors other than the switch on the parking brake pedal itself , all that does is put the light on the dash.

I too did not feel any drag when all this happened and in fact the car had passed MOT shortly before, BUT I did experience one disc/drum getting hot and a kind of brown dust that was hard to clean off the wheel. I do not suffer from drake dust on this car as it is fitted with ceramic carbon brake pads so the 'brown' dust was more noticeable and was obviously one of the shoes breaking up in the drum.

If your car does not have the above system please accept my apologies for scaring the $hit out of you.

Let us know what you find.

That is absolutely brilliant information…many thanks.
The car has done just under 90k
Just a bit of info that may assist in determining the most likely cause of the problem.
The outer lip of the handbrake release arm snapped some months ago,so whilst I was able to pry it out with a screwdriver and pull it out, I have been lazy and had not been applying the handbrake, just putting it in park.
However, after some months of not applying it I do recall doing so a couple of weeks before detecting problem…
Now when I apply it and try to disengage it, the foot pedal does come up but there is nothing else physically happening…normally u feel and hear it disengage
Does this help point in any other direction ?

 

[colinallcars]

That is absolutely brilliant information…many thanks.
The car has done just under 90k
Just a bit of info that may assist in determining the most likely cause of the problem.
The outer lip of the handbrake release arm snapped some months ago,so whilst I was able to pry it out with a screwdriver and pull it out, I have been lazy and had not been applying the handbrake, just putting it in park.
However, after some months of not applying it I do recall doing so a couple of weeks before detecting problem…
Now when I apply it and try to disengage it, the foot pedal does come up but there is nothing else physically happening…normally u feel and hear it disengage
Does this help point in any other direction ?

Is it actually applying?

 

[Ronnie]

Is it actually applying?

The pedal does stay depressed, other than that there are no telltale signs it is actually applying the brake.

 

[OneForTheRoad]

The pedal does stay depressed, other than that there are no telltale signs it is actually applying the brake.

Try pulling away .

 

[colinallcars]

The pedal does stay depressed, other than that there are no telltale signs it is actually applying the brake.

Jack it up, gearbox in neutral and see if the rear wheels turn. You’re going to have to work through this logically; eliminating the possibilities along the way.

 

[Petrol Pete]

Try pulling away .

Depends on the engine , I know from experience my 5.4 V8 will happily pull away with the handbrake applied !

Not recommended , ask me how I know

 

[Ronnie]

Try pulling away .

Not sure what you mean by “pulling away,
there is nothing noticeable and nothing showing on the dash..only thing flagging a problem is the rear wheels are overheating

Try pulling away .

Depends on the engine , I know from experience my 5.4 V8 will happily pull away with the handbrake applied !

Not recommended , ask me how I know

sane here, nothing noticeable at all, although notice it did appear to decelerate quicker than normal but this is now only with hindsight

 

[OneForTheRoad]

Try pulling away .

Depends on the engine , I know from experience my 5.4 V8 will happily pull away with the handbrake applied !

Not recommended , ask me how I know

Well it would wouldn't it .

I'll word it differently for the infidels.

Try putting the car into drive on a flat road and see if the car will move off in drive with little revs or does it hold and creak , even doing this won't be conclusive as your rear caliper could be sticking. Get it up in the air and spin the wheels ,as per instructions. Remove the rear pads, if the wheel still won't turn then yes it's handbrake related.