406 brake disc screws removal problem

You should have used an impact screwdriver instead of just going at it until you'd destroyed the screws. To destroy one and then repeat the exercise on the other tells me you don't learn from your mistakes very quickly. Now you'll have to drill them out but if you're a cack handed sort of person anyway you might scrap the hubs or disks in the process. There's an article on removing stubborn fixings on my website. Maybe it'll help you to not repeat the same mistakes in the future.

-- Dave Baker - Puma Race Engines

Sounds like you tried to remove them with a Torx screwdriver. A better tool is an impact driver. The simple type used with a hammer. One might still work even though the screw heads are a little chewed up. Worth a try. An impact driver is only a few quid and a useful tool to have in your toolbox. After you get them out, and buy some new screws. A tip. When you replace them, put a light coating of copperslip on the threads and under the head, and only very lightly nip them up. They don't need to be tight at all. They're only there to stop the a disc or drum falling off when a wheel is removed. As long as their heads are below the surface before the wheel is fitted, loose or tight doesn't matter. The wheel nuts/bolts do all the work of holding the disc in position. It also makes any subsequent removal so much easier. :-) Mike.

They start out heat treated hard & then they get heat cycled & soften. It's easier with an impact wrench but for now just drill the heads out carefully, it's not as if they do anything usefull, except make it easier to get the wheel bolts lined up.

I've never come across soft Torx screws. Sure they are Torx and not allen?

However, if they're that soft they'll drill out easily, and Torx gives a decent centre for the drill. Just drill deep enough for the head to come off, and you should have enough of a stump left to remove with a Mole grip.

Don't know whether it's worth a mention Dave, but Makro were selling a 50W impact gun with a range of bits for £9.99 plus Vat, dunno if might be useful for smaller jobs such as this?

Dave, off topic for this thread, but I've got a question regarding porting heads, is it ok generally to remove any protruding section of a valve guide inside the ports to aid gas-flow? - Does this depend on the engine? - Does this greatly shorten engine life?

Andy

Never used one of these but my experience of impact drivers has been mixed; limited success when I used a normal hammer, complete success when I used a 4lb lump hammer.

**COPIED FROM alt.autos.Peugeot***

I had the same issue with my 98 406 2.1TD - I only have one screw on them ATM cos Peugeot where all out of them at the time I did my disks, I also had to replace - Callipers, Back Plates, Disks, Pads, Full 3 part handbrake cable, shoes and a handbrake fitting kit and the hand-brake lever! - About £300,000,000 from Peugeot....

I couldn't believe there prices, £90 for two backplates, there only a bit of pressed tin for gods sake... I won't tell you what they wanted for a handbrake lever, needless to say I got one from the scrappy.

Andy

It's generally a very bad idea for various reasons. It makes it very difficult to remove the guides in future if they wear out because there is now no square end to use a drift against. It obviously reduces guide life depending on how much was ground off and in most cases it doesn't even improve flow. It can make it harder to cut the seats properly depending on whether the valve cutting system needs a square top to the guide to register the pilot against. Sadly too many porting 'specialists' do this because it's faster than removing the guides, porting the head properly and fitting the guides back again.

Look at it this way. If a significant portion of the guide's length sticks into the port then shortening the guides by that much would be a bad idea. If only a small proportion of the guide's length protrudes then grinding it off won't help flow. However you slice it it makes little sense to do it.

-- Dave Baker - Puma Race Engines

Hmmm, I see, ta for that, it's just I have been trying my hand at a few old

8V heads to get an idea for where water channels are etc... - Having fun with grinders etc. I was reading a book on engine tuning by a chap called 'Alexander Graham Bell' - very interesting. I had no idea early Porsche engines where so badly flowed, trouble is he concentrates a lot on V8's and I cannot afford to run one :(

Andy

They are just std temper c/sk screws, and they stay that way. That part of the disc never gets hot enough to alter the temper or hardness of the screws. Mike.

Ok, maybe the corrosion takes the edges off, they always appear to be buggered whenever I try & remove them. & I've yet to have anyone explain why you'd ever want to put them back.

Eh?

Hello, Just to be completely clear to everyone- These screw heads were VERY SOFT. Absolute minimum force had been applied to them with a small ratchet with a properly fitting Torx55 head (properly seated in the screw). at no point was there any feeling of resistance to the turning force. Once again- they felt like they were made of lead!! The reason I managed to do the same to 2 screws was that I convinced myself that the first screw must have had some rare metalurgical problem and the second screw would most likely be ok (but not so, as it turned out).

Bottom line (please take my word for it)- Excessive force played NO PART in the failure of these screws.

Michael.

A Torx 55 is huge. That's the sort of size you get on 11mm or 12mm cylinder head bolts. A disk retaining screw is usually 6mm or at most 8mm. I'd expect no bigger than a Torx 35 for one of those.

(properly seated in the screw). at no point was

Fair enough. Maybe they were from a bad batch but it's most unlikely with modern bolt manufacturing techniques.

It's a non starter. It would need temperatures of several hundred C to do anything to steel screws and brakes don't get anywhere near that hot down at the hub.

Any other

I can't imagine why but it's pretty academic. You'll still have to drill them out and get new ones. At least if they're that soft it should be easy to drill them. I would suggest a 4mm drill to start with and go right into the shank of the screws with that. Then work up to a size just big enough to remove the screw head where it joins the shank. i.e. a drill bit about the same size as the shank. Once you've removed those and the disks you can screw a left hand spiral easy-out into the 4mm hole you started with and remove the shanks with that if there isn't enough sticking out to get mole grips on. Forward planning you see :)

However if you give the screw heads a thorough hammering to shock them loose you might get them undone by hammering an allen key into the heads and save yourself a drilling operation. Another good plan is to put the wheel bolts back on first to clamp the disk down hard and take the tension off the screws. However gentle you thought you were being with them I can pretty much guarantee that an experienced engineer would have had them off without breaking them by using such techniques.

-- Dave Baker - Puma Race Engines