Stuck -- What Would You Do?

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
OK, so I'm trying to do the brakes on my wife's Mercedes ML320. It's a pretty simple job, almost exactly like a Disco II, but no rust! Technically, this should take me about 20 minutes per wheel. But I've gotten stuck on trying to remove the caliper bolts. Not the guide pins, the bolts that hold the caliper frame to the wheel hub. These are 21mm standard bolts.

I broke my first socket. Then tried heat. Then heat and Liquid Wrench. Then WD40. Then a 6-sided impact socket on a 21" breaker bar. Then an impact wrench. Then I got insane and I actually lowered the car down onto the breaker bar to try to use it's own weight to loosen the bolt. Now I have a new, newly bent breaker bar, but the bolts still won't budge. I've been at this for 3.5 hours now.

So the only thing I think I can do is to clean it up real well, put it back together with the old pads, then get it towed if there are any faults, or if the braking seems off in some way. I'm at a loss.

Any ideas?
 

SARTech

Well-known member
Sorry but I'm going to ask an obvious question.
Are they left hand threads?
Mike

Same as what Mike said. What I would do is confirm the thread orientation and then get a good quality 6 point socket, and a long piece of pipe to put over the breaker bar and show those bolts who is the boss.
 

javelinadave

Administrator
Staff member
Did you heat it with a mapp torch? Way hotter than a propane torch and get it nice and hot to soften up the locktite.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Heated it pretty well. I'm afraid to do too much because of the CV boot and bushings in the area.

I have tried both directions. But yeah. After dinner, after it has soaked. I'll try both ways again.
 

chris snell

Administrator
Callsign: NW5W
Staff member
Also, here's the thing about penetrating oils like Liquid Wrench: sometimes you have to soak them for days. Soak them every morning before you head out and again at night. Do this for days, trying with the wrench each day. Give the bolt a light tap on the head with a hammer after you apply the oil, to help it soak in.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Well, fail. I put it all back together and gave it a test Drive to make sure it was not dangerous now. I did think of a better way to access the bolts. With wheels still on, I can actually get a clearer shot at them if I raise the suspension and put it up on rAmps. This should allow me to get at it with an air hammer gun without having to hold the caliper out of the way while twisting my wrist around just to hold it on the bolt before I even pull the trigger. So I'll try again tomorrow.
 

Dan kemper

Founding Member
Callsign: KK6ECF
Plus it is amazing how much easier a job is when you step away and come back at it with a fresh perspective.
 

rovercolorado

Well-known member
Plus it is amazing how much easier a job is when you step away and come back at it with a fresh perspective.

I second that, I had a Mustang that gave me fits when I was in high school and I was young and thought i could solve anything with brute force. Starting over on the next day made all the difference. I bet they used the wrong loctite as noted above.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
New angle to approach it tonight. Beer in the fridge. Whisky in the cupboard. Dictionary of dirty idioms at hand.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I just used a 1000lbs impact wrench on it... nothing. Tried both ways, just to be sure.
 

RDavisinVA

Technical Excellence Contributor
In younger days, would move up to the 3/4" breaker bar and long galvanized pipe, but am not so sure that is the best approach.
I would try the soak down heat em up approach.
Have had overly rusted or overly tightened bolts that would loosen only when they were glowing red hot.
When they would cool down below glowing red they stop turning and needed to be red again before they would move.
Best of luck!
 

nas90tdi

Well-known member
Maybe a stupid question, but what kind of air pressure are you running to your impacts? If you aren't getting 150-175 PSI to them, you aren't getting their advertised torque.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
No, the air pressure really isn't enough. I'm only getting about 2 seconds of full throttle. I'm going to give it one more try tomorrow by going to a neighbor's house with a big compressor.
 

nas90tdi

Well-known member
Hope it pops right out for you with some pressure. Good Luck!
Robert nailed it with the 3/4 breaker and a piece of pipe. I don't go that route anymore either, but I have torn some stuff up doing it in the past.
 
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