Balls!

rossnunn · Post by **rossnunn** » 03 Sep 2006, 21:25

A friend of mine has a Xantia LX. It has been suffering from the common squeaky rear calipers, so today we decided to do something about them.
After removing the rear wheels he took out the rear pads to show not only have they worn at a angle but they have a nasty ridge around the outer edge.
After some faffing we got the two main caliper bolts out & found that good old corrosion has set in.
I cleaned the back of the caliper & surface off, added some copper slip & went to reattach them, I asked if he had bought some new bolts. "Nope" came the response.
mmmm
So anyway I managed to get the bolts back in & tightened down, I then went for a pee.
When I came back he was muttering expletives. In his wisdom he ran around the two bolts 'one more time' with the whizzy gun - he sheared a bolt! Well at this point I nearly battered him.

We've taken off the caliper again but the bolt has broken off flush with the rear arm. I've tried to drill out the bolt but nothing will touch it, its almost like they are hardened steel??

Personally I think its a rear arm job, what do you guys rekon? If so thats a major pita right?

AndersDK · Post by **AndersDK** » 03 Sep 2006, 21:43

Yes they are hardened steel.

Only options :
1) get the remainings out - welding a nut to the remainings. Or use a high quality plated drill bit (the "golden" type). The standard HS drill bits wont stand up to such a job.
2) replace the arm

Will you please tell your friend that - however much he loves to play with his wizzy gun - he should NEVER fool around with his toy this way

Its so easy to overdo bolts and nuts to such an extent - you can never get them off again with the same wizzy gun. If you dont believe it - try it on the wheel bolts

rossnunn · Post by **rossnunn** » 03 Sep 2006, 21:57

yes we've had words, I ran them on by hand & cracked them up good, he went for 'one more go' just to be sure fool!
The remains won't be easy to get a weild on. Personally I think a new arm, this mucho pain? I've never done one.

AndersDK · Post by **AndersDK** » 03 Sep 2006, 22:07

Replacing the rear arm is a "major pita".

Have you tried the latest generation titanium hardened drill bits ?
They are much better drilling holes in hardened steel than the standard HS types.
Difference is amazing.

citronut · Post by **citronut** » 03 Sep 2006, 22:43

try useing a good center punch now the bolt has sheered of there should not be any load on the thread of the remaining stub of the bolt,you should be able to chase it round if you catch it right with the punch,or is there any bolt patruding at the rear of the arm you might be able to undo it with a decent pair of grips,otherwise its not that bad a job to replace the rear arm,if you end up with the last option do not try removeing theABS sensor from the arm as you will destroy it,just unplug it and remove it completly with the arm
regards malcolm

Kowalski · Post by **Kowalski** » 04 Sep 2006, 10:05

AndersDK wrote:Replacing the rear arm is a "major pita".

Have you tried the latest generation titanium hardened drill bits ?
They are much better drilling holes in hardened steel than the standard HS types.
Difference is amazing.

The gold bits you get are TiN coated, they're a normal HSS drill with a titanium nitride coating on the outside, the coating makes the outer edge of the drill harder so its eroded more slowly than the inner material of the drill, in theory this means that they don't blunt so quickly. There are good an bad quality TiN drills available, the coating is not a guarantee of anything.

If you're dealing with hardened steel, you need a drill specifically for hardened steel, a cobalt steel drill is the thing to use. You have to be a bit careful with cobalt steel drills because if you snap one off in a hole and get it stuck, you'll not have anything hard enough to drill it with....

jeremy · Post by **jeremy** » 04 Sep 2006, 10:20

I'd expect a bolt stub to come out quite easily as the tension would be between the head and the thread - so remove the head - no tension.

If it won't budge it suggests that either the end has got onto a rusty or damaged bit of thread or has bottomed in a captive hole or hit something immoveable behind.

If its hit something immoveable it may be possible to cut that bit out with a grinder. If its hit rusty thread - lubricants like Plus Gas may help or even heat if its available (Careful) - and if its bottomed - you've got problems - unless the back of the casting could be cut off - which is probably not safe in this context.

Post by **Sir Clive** » 05 Sep 2006, 08:27

The bolts aren't actually hardened but they are high tensile steel (10.2)
Don't try to replace them with a standard bolt! Your mate must have given them some welly

I've just done the same job on the C5 and one of the bolts had to be 'persuaded' out with an 18" Stillson wrench.
As the other posters have said, once the bolt is sheared it should be not too bad a job to get the remains out.

jeremy · Post by **jeremy** » 05 Sep 2006, 10:15

I would emphasise what Sir Clive has said and that tensile bolts should be replaced with tensile - not the soft ones which are more generally sold. There are specialist bolt suppliers who will hold stock. (yellow pages)

Overtightening stretches bolts and can produce a permanent change in shape. Its quite common to find that bolts have 'Waisted' (gone thin in the middle of the shaft) when they have been overtightened. - This means that if a bolt has been overtightened but not snapped it is not necessarily sound.

steelcityuk · Post by **steelcityuk** » 05 Sep 2006, 13:48

I always put a couple of blobs of thread lock on caliper bolts. Usually suggested in the Haynes BOL.

Steve.

rossnunn · Post by **rossnunn** » 05 Sep 2006, 19:34

TBH I think the reason the bolt snapped - other than my mate being a prat is they had probably been weakened with the caliper being pushed out of alignment.
We will be repalcing all 4 bolts with ones from Citroen at £2.64+ it hardly seems worth replacing them with anything else.

exect · Post by **exect** » 05 Sep 2006, 21:34

Hi
Have you thought of grinding a slot across it and using a screwdriver?
Regards
Exect

Post by **philhoward** » 05 Sep 2006, 21:58

jeremy wrote:I would emphasise what Sir Clive has said and that tensile bolts should be replaced with tensile - not the soft ones which are more generally sold. There are specialist bolt suppliers who will hold stock. (yellow pages)

Also Sir Clive...

I've found that hex head bolts are found in either 4.8 (only good for flatpack furniture) or 8.8. 10.9 is available occasionally, but most decent cap head (allen key) bolts tend to be 10.9 or 12.9 - Unbrako is one of the more common brands (yes, bolts do have recognised manufactures - not just a shed in China somewhere!).

pete@co.uk · Post by **pete@co.uk** » 10 Sep 2006, 13:41

hi

im going to keep watching this post to see how your going to get the bolt out or have you already done it if so how.

pete.............................

rossnunn · Post by **rossnunn** » 10 Sep 2006, 18:58

right just got back from him today.

We've managed to drill out the old bolt & have re-tapped the leg but my tap is a size too small, so I've got one that I'll pick up tomorrow then we should just be able to re-tap it again & we're done - hopefully