Caliper Bolt head rounded

So went to change the front brakes tonight and one side done then the very last caliper bolt head has rounded. Other than drilling and easyout is there any other option? Any tips other then heat and plusgas?

A last resort for me would be an easy out with a bolt so long. I would be trying to heat the hub and hammer the next size allen key in if possible, next I would try to weld a nut on the end but it all depends on your facilities. Plusgas/WD as much as possible for as long as possible too. Some people have had to drill them out and Helicoil

Would try the next size up Allen hex socket - drive it in with a decent hammer and soak it overnight with a release fluid. Then use an impact driver/wrench. Good luck!

It`s a metric hex bolt, I would try a slightly larger imperial allen key, sometimes I use Torx bits and hammer them in, they all have to be decent quality though :grin: I think the torque on the bolt is 90Nm, so it isn`t going to come out easily :sad:

I have had this happen before on another car... would echo the sentiments above (bang in a good quality large size torx bit), but would also add: put the other caliper bolt back in and torque it up, it may only be in my head but anything that can help to ease the tension on the bolt you are undoing can only be a good thing right? also I gripped the outside of the head at the same time with a good quality pair of molegrips, and aligned them so that you undo both the mole grips and torx bit at the same time to apply more power. I would also try doing it up first as that often helps as odd as it sounds. Best of luck

Thanks, all suggestions are what I was thinking. Just wondered if anyone had had more success than others. Ive ordered 4 new bolts to replace them. To be honest the discs are okay so Im going to change out pads and then I plan to replace all suspension arms and have a set of coilovers to fit over winter so I'll sort it then. I'll have plenty of other sized bolts to deal with then!!! :lol:

Yup my first thought when I saw this was try to hammer in a section of imperial allen key and apply a spot mig weld to keep two together then use an imperial socket on the allen key stub to remove the offending item. I appreciate you may not have mig welding facilities but you could fit the allen key and take it to a local garage/welder and progress from there... :?: Good Luck.

Any of the above but regardless of the method, definitely douse it in penetrant and even put a heat gun on it. Also, if it won't loosen, try to turn it in the tighten direction a tiny tiny bit just to break the torque. Bear in mind it is a steel bolt in aluminum so you don't want to over tighten. I'm talking about 5-10 degrees here. Also, after dousing in penetrant, clean the threads sticking out of the housing. These are normally rusted up. The rusted crud is sometimes hard enough to rip out the aluminum threads in the housing as you unscrew the Bolt. Good luck

Graham Have you got a set of Irwin nut / bolt detractors Heat + plus gas + Irwin

Ive got Irwins but there isn't enough room for them on the head. MOT in about 2 weeks, if it fails then its coming off the road so I'll do it then. If not then it will be a couple of months yet.

I would try and undo using a Torx socket .. to be fair that's what i normally use on these allen head bolts .. T55 or T50 i think .. not sure. Failing that i would try and weld a nut on or just drill out the head , slide the caliper off and then deal with what's left .

Another good option as above, remove the bolt head and get a stud extractor on whats left of the bolt, I have removed head stud with one of these plus you can get some penetrating fluid right to the start of the threads with no caliper there.

Lol, every time I suggest drilling a bolt out, every body insisits that we should throw some fire on it instead :grin: :joker:

^^ :grin: Good luck Graham. If you end up needing to helicoil/timesert it then be careful. Craig had a loud annoying creak on his car for a while a couple of years back. Turned out that a previous owner or mechanic had had to helicoil the hub carrier for exactly your problem and they hadn't managed to keep it square. When Craig was breaking the calliper was actually flexing as the pads pulled it square to the disc. Remedy - new hub carrier. :nooo:

Drilling is fine .. as is welding .. it's down to what equipment you have .. I will say welding will burn the paint on the caliper so drilling might be the better option. Mechanics are lazy anyways .. we go with the easiest option lol .