Brake advice

[Funkyboy]

Looking to change my front disc and pads on my w212 E250. Had a look at the set up today only thing that looks a problem is the caliper bracket holder. I am doing it jacked up from the floor so not much leverage to undo the bolts. Any tips from you guys that have done it before?
Thanks

 

[190]

Looking to change my front disc and pads on my w212 E250. Had a look at the set up today only thing that looks a problem is the caliper bracket holder. I am doing it jacked up from the floor so not much leverage to undo the bolts. Any tips from you guys that have done it before?
Thanks

I did mine on a W204 very recently which I expect are similar. Pads are easy but yes the main caliper bolts are tight. I also found they were a non preferred size at 18mm and had to go out and buy a new socket. I got better access by turning the wheels to full lock. You might need to slip something on the end of the ratchet or use a breaker bar to gain more leverage and make sure there are blocks of wood in place under the car in addition to being raised on a trolley jack.

One disc securing screw came out reasonably easily but the other torx screw slipped and got damaged. It was very easy to drill the head off with a sharp drill bit. With the disc off there was enough of the screw shank proud to remove it with mole grips.

 

[AMGeed]

I've found using a trolley jack under a breaker bar never fails to crack the caliper retaining bolt free.

 

[IanW]

I've replaced the front discs on the CLK a few times now.

non preferred size at 18mm and had to go out and buy a new socket

Definitely this - and make sure that it's a 6 sided socket rather than the more common 12.
Occasionally the disc sticks to the hub even after the screw has been removed - re-insert the caliper bolts without the caliper & use them to push the disc off the hub.
Make sure that the hub is spotless & absolutely flat before the disc is replaced. I always use a dial gauge to check run-out on the disc before replacing the caliper. I re-insert the wheel bolts to clamp the disc against the hub while checking, using a large stack of M12 washers as spacers. Checking posts on the forum, you'll see lot's of messages about warped discs, often blamed on poor fitting.
Ian.

 

[johnsco]

I've found using a trolley jack under a breaker bar never fails to crack the caliper retaining bolt free.

That's the way I loosened the rear caliper retaining bolts when I last changed the rear discs on the E280.
They were lock-tighted and were as tight as hell !

 

[optimusprime]

Funkyboy Use the best socket , or ring spanner, you have . And use a small jack to fit under the spanner jack it up to break it lose ..I had the same problem when i replaced my discs .

 

[OneForTheRoad]

Use a new ring spanner and shock the nuts loose with a 4 lb hammer.

 

[W1ghty]

I use an 18” breaker bar on the caliper bolts when I change mine

 

[optimusprime]

No good when you have very little room .The jack never failed me so far. Thats when the bolts are locked up solid .

 

[W1ghty]

No good when you have very little room .The jack never failed me so far. Thats when the bolts are locked up solid .

True , but you only need the breaker bar to move the bolt a couple of millimetres, then swap to a normal ratchet .
I’m only working on the drive with axle stands and it has always worked without issue .
The Jack option is always there for me if the breaker doesn’t work .
You also need enough space to get a decent sized torque wrench in there when you refit the calipers

 

[OneForTheRoad]

True , but you only need the breaker bar to move the bolt a couple of millimetres, then swap to a normal ratchet .
I’m only working on the drive with axle stands and it has always worked without issue .
The Jack option is always there for me if the breaker doesn’t work .
You also need enough space to get a decent sized torque wrench in there when you refit the calipers

Turning to full lock allows alot more access too. Soak with wd40 the night before and have a gas blow torch to hand , all help.

 

[johnsco]

Turning to full lock allows alot more access too. Soak with wd40 the night before and have a gas blow torch to hand , all help.

WD40 will help
But - It's not the best penetrating oil.
Plusgas is better.
I use Unilease - Brilliant penetrating fluid - Sadly no longer available, as the firm went out of business some years ago.
I bought a couple of cans when I knew they were on the way out.

 

[Petrol Pete]

Loctite 8040 freeze spray is my 'go to' . failing that , PlusGas.

WD40 ? Only if you have nothing else to hand.

 

[Funkyboy]

I use an 18” breaker bar on the caliper bolts when I change mine

Can you do this from the ground with car on jack? Do you have enough room

 

[Funkyboy]

True , but you only need the breaker bar to move the bolt a couple of millimetres, then swap to a normal ratchet .
I’m only working on the drive with axle stands and it has always worked without issue .
The Jack option is always there for me if the breaker doesn’t work .
You also need enough space to get a decent sized torque wrench in there when you refit the calipers

What is the torque spec please

 

[AMGeed]

What is the torque spec please

The front caliper retaining bolts are 180Nm. Use some threadlock if you are reusing the bolts.

 

[W1ghty]

Can you do this from the ground with car on jack? Do you have enough room

You mean axle stands ? Don’t be under a car on just a Jack .

 

[jasonh]

If removing the front caliper carrier the straightforward way is to use a 6 sided socket (18mm) a long breaker bar and put the steering on full lock. Sometimes you need a short extension bar on the socket to clear obstructions. Doing it this way you can almost always apply force from beside the car, rather than under it. I've done this many times. It also allows you access to torque the bolts back up afterwards.

Sometimes caliper carrier bolt heads aren't the full depth, they are also tightened to a high torque spec, so you want the socket on square.

 

[Bellow]

When space is tight and breaker bar and 6 sided socket is being used, be aware that by removing and refitting the socket on the breaker bar after turning it 90 degrees you change the orientation of the socket's flats to the bolt head.