Splitting AP Calipers
Discussion
Im in the process of refurbishing some AP CP6600 callipers, and am trying to remove the bolts that mate the two halves together, but they are literally impossible to remove. Ive tried tried heating the caliper body, impact wrenches, breaker bars. They literally will not budge, and amazingly the hex bolts used are so strong that they're even rounding the flats on my Hex keys!!
My next approach will be to mill the heads of the bolts to release some pressure. I believe the bolts are only partially threaded, with the thread going in to the caliber half furthest from the bolt head. Anyone see any big issue in this. Its driving me nuts..
These have external fluid pipes so theres no issue with separating the halves.
My next approach will be to mill the heads of the bolts to release some pressure. I believe the bolts are only partially threaded, with the thread going in to the caliber half furthest from the bolt head. Anyone see any big issue in this. Its driving me nuts..
These have external fluid pipes so theres no issue with separating the halves.
I appreciate that as they are two piece it may not be possible but I've serviced a few monoblock calipers and its not really difficult. If the piston isn't too deep and will come out I'd do that.
The way I do it is to cable tie the pistons I don't want to come out and push out each one I do in turn. Getting at the dust / pressure seals isn't much of a pain. This was on motorbike calipers which are of course much smaller.
The way I do it is to cable tie the pistons I don't want to come out and push out each one I do in turn. Getting at the dust / pressure seals isn't much of a pain. This was on motorbike calipers which are of course much smaller.
m4tti said:
Apparently AP use loctite 620.
I see. That definately won't be helping.Have you tried a manual impact driver, the ones you hit with a hammer? Might just give a slightly bigger shock to break the seal.
Mangaling the caliper body is of course a concern when the bolts are so tight.
m4tti said:
I want to completely strip them, powder coat, and replace all fixings with new, rather than the original weathered items.
Does that actually require you to split the calipers? I don't see how splitting the housing lets you do anything useful.I remember reading advice from AP Racing that their calipers were not designed to be split after manufacturing and there was a risk of expensive damage due to the high bolt tension; you would also need to obtain the right very high grade of bolt and do it up to the correct very high torque to reassemble, which would bring its own risks.
There's not really much risk in splitting them. It's a steel bolt with thread lock applied. I like to do things properly and painting calipers with the bolts in situ looks a bit shoddy. The wear plate screws are easier to remove once split.
I know for example Godspeed brakes split these to refurb. That's still an option... give them the stripped caliper to split and powder coat.
I know for example Godspeed brakes split these to refurb. That's still an option... give them the stripped caliper to split and powder coat.
Edited by m4tti on Sunday 12th February 17:44
Loctite starts the holding job, ally corrosion finishes it - I've had it a few times with calipers, the only thing that seems to do it is plenty of heat on the other side of the body and slowly rocking the bolt back and forth to break the corrosion out. Once you crack it a little leave them submerged in some penetrating oil overnight.
Rippthrough said:
Loctite starts the holding job, ally corrosion finishes it - I've had it a few times with calipers, the only thing that seems to do it is plenty of heat on the other side of the body and slowly rocking the bolt back and forth to break the corrosion out. Once you crack it a little leave them submerged in some penetrating oil overnight.
Thanks for this. I have tried heating the things but to no avail.On further investigation the tech sheet on Loctite 620, it recommends the local application of heat to 250c to break the bond. This stuff isn't like a normal thread locker, its more of an epoxy. Taking this into consideration I think I may well leave the halves together, remove every single other component and repaint as a single it. Annoying.. but I'm losing interest now
Realise I am reviving this thread from a long time ago but I snapped two H8 hex bits, impact gun wouldn’t touch it nor a breaker bar with added scaffold pole for leverage and all the heat my Rothenberger could throw at it before I resulted to google and found this thread.
They are definitely built not to be split!
They are definitely built not to be split!
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