david@st ives

i have just purchased new rear brake disks for my c4 the trouble is the bolts holding the calipers are extremely tight. do i just use brute force to remove them or am i more likely to round the allen bolts i am annoyed i might have to take my car to a garage for what should be a simple job
any ideas
cheers
dave c4 90

craig001

Your first mistake was using the phrase "simple job" in the same sentence as the word Porsche. It seems like every time I start a project it just grows in scope.

If you have new bolts handy you could try an impact wrench or driver or whatever it's called with the allen head socket. The only problem is you'd probably ruin the socket and bolts.

Tom W

Spray them with WD40 and let them sit a while before you use a socket with a long handle to get good leverage to loosen them with 'brute force'

springer3

Don't be discouraged by stubborn fasteners. It is just a matter of gradual escalation until either it lets go, or it breaks. Most of the time, it can be persuaded to let go. The worst thing that happens is you break the bolt, and need to drill out the carcass. That is just part of the job, and even professional mechanics accept that it has to be done sometimes. Here are some tips learned from disassembling a somewhat rusty early 911 among other restoration projects:

Most important, get professional quality tools. Take the job to a professional if you are not willing to invest in good tools. Stripped fastener heads are invariably caused by cheap tools that are too soft, worn out, or out of dimensional tolerance. I have not rounded a single fastener since purchasing a set of Snap-on wrenches (no affiliation, etc, etc). My previous tools were Sears Craftsman, and they are junk. The warranty is great, but it does not cover skinned hide, busted knuckles, damaged fasteners, or the unnecessary frustration and delay in completing your projects.

Spray the bolt heads and any accessible threads with penetrating oil. I use PB Blaster, and it works miracles (no aff....). Tap the bolt head with a hammer. Wait overnight if you can. An impact wrench is often a magic bullet - not because of the torque but because shock and vibration really help when loosening things. If you don't have an impact wrench, pull on a standard wrench at about 75% of what you think will strip the head, and tap the area with a hammer (carefully, of course). If that does not work, use a propane or oxy-acetylene torch to heat things up. Remember you want thermal expansion to increase the thread bore, and minimize the thermal expansion of the bolt threads. Heating the bolt head is good, because it releases the pressure surface, and helps the bolt loosen by thermal elongation of the shank. Never hold the heat on one spot too long - keep moving or you will damage something. I'll bet you can get them out without drama.

Remember you are working on brakes - no shortcuts, and get the torque correct on every fastener.

Bill Gregory

When dealing with allen hex heads that don't want to budge, first, clean them out. Use something long with a sharp point, in the case of the lower rear bolts. That will maximize contact with the hex tool to minimize the chance of stripping it. Others suggested some good ideas for loosening the bolts. The tightening torque is around 62 ft lbs or 85 Nm, so while tight, they aren't like the rear strut to lower control arm of 147 ft lbs or 200 Nm!

david@st ives

thanks for the fast response and ideas
i will have a good attempt this weekend and let you know how i get on

dave c4 90