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MG MGB Technical - Caliper hose stuck

I've tried all the heat, cold, oil tricks I know, but I can't get the flexible hose off my caliper. The problem is using an open end wrench/spanner, because there's not enough clearance to get a box end on the fitting. It was a good fit to start with, but now I've rounded off the flats.
Does anyone have a secret for getting a box end or socket on the fitting? I'm about ready to give up on rebuilding the calipers and buying new ones!

C Crews

Now that's one nasty looking caliper! Just what kind of "heat" did you try? Propane or oxy/acetylene? Propane won't get it hot enough. You'll need to cut off the hose section and try getting a thin walled six point socket over the remainder of the fitting. This is the only way to apply enough torque, on the fitting, to get it off. I recently had the same problem with the power steering hose on an '84 GMC conversion van. I had to cut off the line just above the fitting and use a six point impact socket to remove the impossible to remove fitting. Once I had the socket on the fitting, it came off with very little resistance. RAY
rjm RAY

As Ray notes, cutting the flex line and driving a six point, thin walled socket onto the hexagonal portion is the best, and most common method. Vise grips (Mole grips?) can, sometimes, be used but do not provide as much working surface as the six point socket. A good penetrating oil (not WD-40, something like PB Blaster) can be of help, but may take several days of application, soaking in, and reapplication before the end of the hose will release. Lightly tapping around the hole, using a soft faced hammer, can provide a minor vibration which may help break the rust bond and allow the penetrating oil to soak in further. One other tip would be to make sure the caliper is held, firmly, either on the car or in a vise, so that all of the torque applied to the end fitting on the hose goes directly to the joint between the hose and the caliper. Trying to hold the caliper on the ground and twist results in wasted force.

Les
Les Bengtson

I had to resort to using a large chisel and with the caliper in a heavy duty vise I attacked the hex side in direction of removal and with two healthy hits it moved.No damage to the caliper body.
Sandy
DARNOC31

If you can get a flank drive socket on, they are fantastic because they don't rely on the "corners" of the hex but drive on the flats. If not enough room open out the spot facing with a burr, Dremmel etc.
Allan Reeling

May have to use a grinder to thin the walls of your socket.
Art Pearse

Yes, chisel with alternate blows on opposite sides - shock and twist in one go.
Paul Hunt

I tried all the tricks suggested and let it sit over night. First thing this morning, it came undone. I think it was a combination of all the heating, cooling and tapping that finally got the PB Blaster down the threads.
I also learned a valuable lesson regarding the amount of pressure the brake caliper pistons can exert with compressed air. I was trying to get the pistons out and one kept coming out first, so I held it with my finger while blowing air in the fluid hole. OMG! Both pistons clamped on my finger with such force I couldn't get the pistons to retract and I had the weight of the caliper hanging from my hand as I walked around trying to find a screwdriver to pry the pistons apart. Wow, that hurt!
Thanks for all the suggestions. Now I'm ready for the other side of the car.
C Crews

Hmm.... 50 psi x 3 square inches = ouch!
Art Pearse

"I had the weight of the caliper hanging from my hand as I walked around trying to find a screwdriver to pry the pistons apart."

LOL
Paul Hunt

There is a point when reman calipers become a bargain. Cold beverage helps with the swelling and the attitude.
Dan Craig

Always place some sort of a block between the pistons when applying compressed air to move caliper pistons. Never, ever put your fingers between the pistons while using compressed air! You're very lucky to still have the use of them. Also, depending on the type of caliper that you are working on, it's very easy to launch a piston across your shop if you don't contain the piston. Usually, a shop rag will suffice. RAY
rjm RAY

Thanks for all your comments!
Regarding the danger of the moving pistons, I noticed while applying the compressed air that the pistons were moving slowly towards each other. However, when the pressure built up, the pistons took off. Up to this point they had not moved very fast. Seeing that they were moving slowly, I thought I could hold them back with my fingers, but that was not the case. They were just moving slowly because they were stuck.

The second caliper was a whole different story. I had figured out, with everyone's help how to get the things apart and how not to hurt myself in the process.

I do have a recommendation regarding removing stuck pistons. I tried heating the caliper, oiling the rubber/piston interface and applying compressed air with no progress. What finally did the trick was to use a little circuit tester spray on the inside of the piston to shrink it while applying compressed air. Both pistons popped right out without issue.
C Crews

Some people swear by this penetrating fluid - 50% ATF and 50% acetone - mix it fresh as the acetone can evaporate if you leave the mixture lying around.
If all else fails you can resort to a set of left hand drills and gradually work up in size!
Mike
Mike Ellsmore

Conventional drills working up size by size can often result in the last bit unscrewing normally because of the heat and vibration generated, BT, DT. However I'm not sure I'd want to drill the hose connection without making absoutely sure every bit of swarf had been removed from the piston chambers and passageways afterwards.
Paul Hunt

This thread was discussed between 25/10/2013 and 02/11/2013

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