Caliper Mounting Bolts Seized (i think)...what to do?

[golden1245]

So I put aside the entire day to start replacing my brakes and rotors on my w202 c230k. Everything is going well, caliper comes off, pads come off, spray everything with brake cleaner.

Now I'm about to unscrew the big caliper mounting bolts to get the rotor off and the damn things won't budge...at all. I spent a whole hour in every imaginable angle in order to get some muscle into breaking it loose, even tried using a toggle nut wrench but I didn't want to strip the hex.

I didn't use what they would call a breaker bar, but either way I think they might have seized, it's been 5-6 years since i've last had a rotor/brake change.

what do I do? Just follow the the remedy I see every where on the internet regarding stubborn bolts? spray with penetrating fluid and heat with propane torch, repeat until loose? or is that not a good idea for this car? Please help! Thank you in advance for reading.

 

[carat 3.6]

Give the bolt heads a good smack with a hammer, or if that dosent work heat them up with the gas bottles.

 

[DRBC43AMG]

Penetrating oil and patience. It should work. If not, worse car scenario would be a sheared bolt. Are you using a good quality hex socket? Tap it in "gently" to make sure it goes fully in and then get the pressure on a good wrench and eventually a breaker bar as last solution.

 

[andy27168]

Hi,
Make sure you have a good fitting six sided socket and it is properly fitted to the bolt, to minimse rounding the head of the bolt off, and a good power bar.
Be careful where you heat, only heat where the thread of the bolt is as you could end up making it tighter if you heat the wrong area.

 

[wilsodg]

My (non-MB) locking wheel-bolts had seized when I went for a tyre change last week. Worried that the pins on the locking socket might break, one of the guys applied pressure with a socket bar whilst the other hit the end with a copper mallet. It did the trick - the combination of shock and torque freed the bolts.

You'll probably will end up with a combination of all these ideas - just be careful not to ruin the bolt head. A good impact (6-sided) socket as suggested by Andy is most important.

 

[WOODYTHEWISE]

If you can lay your hands on an impact wrench, give it a try, have shifted a fair few bolts/nuts with one in my time. Plus all of the above.

 

[Sp!ke]

These bolts shouldnt sheer. Ensure you have a good fitting socket and a decent length (24"+) breaker bar and it'll be a breeze.

Forget trying to undo them with a standard ratchet.

 

[StevenN]

I had a tight bolt on one of mine.
I used a bottle jack under the ratchet so the weight of the car was my turning force.
Just had to keep everything in line while I raised the jack.

They do have thread lock on them so they will need a bit of a shock to break the seal

 

[golden1245]

Hmm, I'll get a breaker bar, as well as the penetrator and torch for good measure.

seems like most the responses don't advocate the use of a propane torch. Is using a propane torch dangerous/will ruin the bolt?

(i didn't quite understand what Andy said because I can't see the threads when it's completely screwed in, just the head. I was thinking about spraying the penetrator and then heating up just the head of the bolt as I've seen in most youtube videos...on non mercedes though)

I'd like to re-use the bolts if possible, none of the online stores sell them so i'd have to drive down to the dealership to get them.

Thanks for the all the responses so far

 

[artyman]

Don't force it.... use a bigger hammer

 

[golden1245]

um, hit the bolt with a hammer?

Not sure about using an impact wrench, doesn't seem like it'll fit even if the wheel is completely turned to.

Well, thanks for the responses so far. I ordered some "Kano Kroil" which is supposedly the absolute best penetrating oil they sell in the USA. Gonna tackle this next week with a combination of Kroil, a 24 + inch breaker bar, some metal pipe for extra length and a a torch.

If I do get the bolt out, is it reusable, or am I better off getting some new ones and loctite as well?

 

[DRBC43AMG]

I would get new ones and blue loctite then torque down to correct level. Mine where a little hard getting off, but then the loctite seal broke, they where a breeze after.

 

[grober]

You want one of these if it will fit :- Clarke CEW1000 Electric Impact Wrench - Machine Mart
The pros in a garage would normally give the bolts a "tweak" with an air impact wrench to slacken em off

 

[Sp!ke]

You want one of these if it will fit :- Clarke CEW1000 Electric Impact Wrench - Machine Mart
The pros in a garage would normally give the bolts a "tweak" with an air impact wrench to slacken em off

I dont think you'll be able to get an impact wrench on those bolts without a few wobble bars.

That is a good tool though - have one myself although I find myself using the battery powered one more frequently.

 

[jonc78]

Are you changing the front or rear discs? The reason I ask is that I've just changed the front discs and pads on my w202 and had exactly the same problem as you are having. I found that I couldn't get enough leverage on the socket or enough space to put a pipe on the socket to give me extra leverage. After a bit of googling I found the solution was simply to turn the steering wheel so the disc turns outwards enabling you to get at the bolts. I then slipped a pipe over the end of the socket for extra leverage and they came off easily. I think my discs were the originals, so had been on there 14 years!

 

[DRBC43AMG]

I thought that turning the wheel to the outside so as to better expose the rear of the caliper was obvious. Guess not, but I did proceed like this and when reading this thread I completely forgot that detail

 

[golden1245]

Kano Kroil penetrate won't come in until next weekend, so I'm going to wait till then.

I don't even know what i'll do if the rear caliper bolts are seized like this, there's no way to turn them to get leverage.