Stripped bolt removal - HELP!

[Dad]

Help! As I was replacing the rear calipers on the IRS I managed to shear off one of the mounting bolts and now there is a stripped bolt shaft left stuck in the brake mount. It's really inaccessible, but thankfully one of the most accessible of all the caliber bolts.

I *REALLY* don't want to have to disassemble the entire IRS to remove the brake mounts to be able to drill out the bolt shaft, so any technical wizardry suggestions would be really, really welcome.

Many thanks.

Dad

P.S. Before everyone assumes I'm a complete muppet, I can say with absolute honesty that I really didn't torque the bolt all that hard and it is the proper grade bolt

[christopher storey]

I have to say that I am not especially hopeful of an easy way out of this . Can you e mail me a pic so that I can see what we are talking about. Is the IRS in or out of the car ? Are we talking about a large caliper setscrew ( about 7/16 UNF ) which secures through the eye of the caliper direct to the axle casing, or do you mean a small one which secures the wheel cylinder to the caliper mount ? ( S1 only usually ) And what exactly has stripped, or are you using this as a synonym for sheared ? If there is any of the shaft left protruding , then if it is a small bolt it may be possible to unscrew it again with pliers , possibly of the needle nosed variety. If it is a big bugger, however, and the head has come off, then it might be better to try and file 2 flats on it to try and get some purchase on it with an adjustable . Failing that, you could try mole grips if you can get access

[kingzetts]

If you were in the process of reattaching the caliper, I would expect that the bolt would be screwing in reasonably easily and should not have been excessively tight in the threaded hole. If that was the case and the shear occurred when the bolt was tight, then you may be lucky if you can get hold of a left-handed drill and try drilling a relatively small diameter hole in the centre of the bolt using a power drill set to go in reverse, or by drilling with a conventional drill and then using a stud extractor of the type which looks like a somewhat tapered twist drill (carefully).

If, however, the bolt was tight in the hole (maybe cross-threaded) and sheared before the head was snug against the caliper boss, then this will probably not work and I'd be surprised if you could accomplish much without being able to accurately drill the broken stub.

[Dad]

Yes - sorry - sheared. It's one of the small bolts that secures the wheel cylinder to the calliper mount. No protruding shaft. Will attach a pic in a min[/img]

[Dad]

Not going to post an image, as it would appear you need a host site to do so(!). In summary, it is a small bolt that holds the caliper cylinder assembly on the brake mounting block. Thankfully it is one of the pair closer to the outside of the IRS than the inside, and the IRS is deteached and away from the car. The main issue is accessibility. If this was something I could slap on the work bench and drill, it would be easy. I'm hoping for a crafty way of getting it out in place, without having the remove the calibre mounting block (bracket?).

[christopher storey]

A picture is worth a thousand words . If you have a pic, just e mail it to me,as I said first time ! My e mail is given below my posts ( click on the e mail button ) and is cstoreyqc@aol.com

[neil4444]

Hi,

Is the shear flush with the face of the piston or somewhere further inwards ?
If the former then at least you will have something to grab with molegrips. The problem is going to be getting to all the other 3 bolts holding the piston on. My IRS is out of the car at present and even then it's hard to get to them. From recollection the o/s caliper is worse (virtually impossible to get to the upper rear bolt due to the diff case being wider this side).

It may seem daunting but I think I'd prefer to remove the IRS. If one bolt has sheared are the others in dodgy condition too ?

Regards,

Neil

[abowie]

I'm assuming that what has happened is that you have been installing the piston and cylinder assembly onto the body of the caliper and one of the 4 mounting bolts has broken off in the caliper. If this is on the side of the caliper facing outwards removing one or both shock absorbers may improve your access to the snapped bolt. This is relatively easy to do.
Personally unless you have good straight access to the bolt I'd bite the bullet and remove the caliper first. PITA I know but it will probably take you about the same amount of time as trying to drill the bolt for an extractor. Depending on which model you have there are holes in the disc which allow you to get a socket on the caliper mounting bracket bolts.
The good thing is that at least it has broken off during reinstallation so you know the threads aren't totally seized.

[Dad]

IRS is out. Piston assembly is off and thankfully it's one of the outermost bolts on the more friendly side of the rear diff. It's the most accessible bolt of any holding the piston assembly on, but still not accessible for (e.g.) a handheld drill. I do have a cunning plan I plan on trying tonight (going to try to light g-clamp the sheared off bolt against the sheared bolt to see if I can very gently turn it to get a tiny bit protruding so I can grab it with a wrench). If that doesn't work, I'll have to remove the piston mount.

Bummer, but that's how it goes sometimes. Could be worse.

[neil4444]

I had similar issue once and managed to cut a slot in the remaining stud with a dremel & then used a flat blade screwdriver (or flat blade socket if limited access) to unscrew.

[Dad]

I was thinking I'd try exactly the same thing! Many thanks. Good to know it worked for someone else.

[Dad]

Dremmel plus flex attachment and a crafty high speed cutting bit allowed me to create enough of a channel in the sheared bolt head that I could get a custom tool (sacrificed/shortened stubby screwdriver) in and very carefully, gradually turn the bolt shaft and eventually get it out. Closest thing I've done to neurosurgery on a car.

This classic car business certainly does wonders for the art of patience.

Many thanks to all who posted helpful hints.

[abowie]

The piston retaining bolts, because of their odd size, don't get replaced and so do break. If perfect originality isn't your concern replace them with high tensile Allen headed setscrews.

The ones I have are 1" long 1/4 UNF and fit a 3/16 Allen key. I have removed them now but I believe they were fitted with spring washers.

[paulsco]

Does the broken bolt protrude enough to get a flat washer over it and is there enough room to get in there with a MIG welder?

I have used this tip with success:

Place a washer over over the broken stud; make sure the hole is no bigger than the broken bolt (you don't want to weld the washer to the casting) and with a relatively high setting plug weld the washer to the broken bolt through the hole.
Make a depression in the washer to touch the bolt if necessary.

Then weld a nut to the washer. Hopefully you can then get a spanner or mole grips on it.
loosen it a little at a time then tighten it up a little to gradually back it out. The heat of the welding should help.

Paul

[Dad]

All good - got it out by cutting a notch in the top with a very crafty Dremmel flex hose attachment, cutting a screwdriver down so it would fit in the gap, then a lot of very careful but forceful persuasion.

Many thanks for all the great advice!