Brake disk bolts

[osx]

Was planning to change front disks but when I removed the first wheel I saw that both torx screws (think they are T30) that hold the brake disk in place were in bad condition and stripped. I've sprayed them both with WD40 and will have a go tomorrow. They will definitely need replacing.

Will these https://www.ebay.co.uk/itm/115718856367 ... R_bAndDiYQ do (or anything from Halfords, ECP etc)

or these

https://www.amazon.co.uk/Alpha-Rider-St ... on+2.0+HDI

work?

Shaft diameter: 5.7 mm
Thread length: 10.5 mm
Head diameter: 11.6 mm

[Lenny]

I've just bought some of these for the new discs I'll be bunging on soon:

https://www.ebay.co.uk/itm/183666055465 ... 1154720783

I'm usually quite a fan of stainless bolts (along with some copper grease) but I find the smaller allen sizes tend to round off too readily so I've gone for high tensile this time. These might be too long but I'll chop a couple of mm of if they are.

[bobins]

Personally, I'd avoid stainless as they may end up being too soft when it comes to 'the next bloke' who has to remove them.

[MattBLancs]

I'd agree on not stainless.

Normally countersunk M6 is all you need. It's worth remembering these are only to hold the brake disk until the wheel is put on. So no necessity for strength.

I've bought countersunk M6 set screws from Screwfix previous that work fine (as it happens ones I bought are 50mm long as bought principally for another job, so I'd to junior hacksaw them to length for use as as disk retaining screws.

And yes, loads of copper grease is good insurance to help guarantee they'll come out ok next time.


Also recommend a Torx bit in a manual impact screwdriver as generally successful way of getting these out. Think T30 is correct. If mangled, sometimes hammer and next size up (T35 or T40) can get you back on track.

[Jay-Bruce]

Remember that the screw is only holding the disk in place to stop it from wobbling or spinning on the hub and occluding the wheel bolt holes when the wheel is off. It's actually the wheel and it's bolts that clamp the disk to the hub, so the disk screws do not need to be gorillad up. My BMW uses m8 screws for the discs, rather than the m6 screws on a C5, but the torque for the BMW m8 bolts is only 16nm, it will be even less for the C5's smaller m6 threaded disc screws, meaning even stainless ones shouldn't chew up under those torques.

Also, when removing brake disc screws, use something like this:

https://www.amazon.co.uk/Teng-Id515-Pie ... B0001P0VXU

...it's called an impact driver, not to be confused with a power tool used to drive in decking screws, or the air/battery powered gun for driving sockets. You put the appropriate hex/torx/screwdriver bit in, whack it the handle with a hammer, it hammers the bit in and simultaneously twists the bit a couple of degrees, thus preventing "camming out" of the screw head as it only twists the screw when the bit is getting hammered into the screw.

I've used those very screws before, albeit from a different seller, I recognise the markings. Get the stainless screws, use your antiseize compound of choice such as copperslip on the threads, don't gorilla them up, and you'll be golden. If you're worried about getting the discs off later to do a wheel bearing or a drive shaft gaiter or such like, get one of those impact driver things, just make sure it's twisted to the loosen position so when you push down on it the chuck turns counterclockwise.

Those tools are are also handy as they have a 1/2" square on them like a ratchet or breaker bar, can be a godsend for corroded fasteners, as you whack it with the hammer, your simultaneously forcing your socket onto the mangled bolt head, and twisting it, helps prevent the socket slipping off and rounding the bolt head.

edit - the phrase "tw_t it with a hammer" triggered the expletive filter

[Estately]

If the torque insert is truly not going to undo the screw, you can bash it undone by rotating it with a small sharp punch.

The new disc set should include new screws and as already said grease the thread and only nip the screw up.

You may want to use some abrasive, dry wet and dry for instance, to clear any rust off the hub/disc mating surface and when bright, a light smeer of grease/copperslip.

Hope that helps.
Andy.

[CitroJim]

Jay, that little impact driver - from my days of spannering Japanese motorcycles - is definitely my go-to tool for disc retaining screws... Never failed me yet!

[MattBLancs]

Yes, same thing I was describing. I'd call it a "manual impact screwdriver"

Oh, we all missed an important detail

Hit it with a BIG hammer, a little toy thing will bounce off more so definitely in nice big wallop territory.

[MattBLancs]

Torx bits

This is the Torx bits set I got to use with my impact screwdriver.

Reminded me: note it is 8mm hex, not the smaller 1/4" (6.35mm) hex commonly used for screwdriver bits.

My impact driver is an old but decent one - Sykes Pickavant from memory. But given the simplicity of the actual device I don't know why a cheap one would be measurably worse??

[myglaren]

Teng tend to be rather expensive but very good tools.
Impact driver £46 from Screwfix, £26 from Amazon. Not identical kits though.

Bahco were always excellent quality tools but pricey. Their stablemate Teng are equally expensive but better, in my limited experience.

[Jay-Bruce]

I've got to admit, I was somewhat surprised how cheap the teng one was off Amazon, I thought it was a safe link. Having said that, the Halfords one is OK, and great value at £15, even better as it's on offer at £12 the how. I actually own both, I loaned my Teng one to a mate, who went offshore, then I needed to use one myself, so I bought a Halfords one just to get by, both are decent enough.

[osx]

The bolts must have been rusty. They snapped when I tried to remove them so at the end I drilled them out. They don't seem to do much as they don't need to be tightened much. Interestingly the inner brale pads were very worn but I didn't get any brake alerts - sensor and cables are ok.

[CitroJim]

Hit it with a BIG hammer, a little toy thing will bounce off more so definitely in nice big wallop territory.

Oh yes, nothing less than a 4 lb club hammer!

[Jay-Bruce]

The bolts must have been rusty. They snapped when I tried to remove them so at the end I drilled them out. They don't seem to do much as they don't need to be tightened much. Interestingly the inner brale pads were very worn but I didn't get any brake alerts - sensor and cables are ok.

Glad to hear you got the screws out, the screws main purpose is to stop the disk flopping about or spinning on the hub occluding the wheel bolt holes whenever the wheel is off. They are only 15nm for the m8 screws on my BMW, so it'd have been a lot less torque on the m6 screws on a C5.

[Doo]

I recently experienced gorilla stupidity when helping a friend with her BMW Mini (T50 torx were chewed no end ).

This prompted me to buy a torx/Allen equivalent to the Irwin sockets (the flats are replaced with a screw type surface which grip the damaged bolt head) which have a screw shape to bite into the damaged torx or Allen insert. They cost almost £60 so I'm expecting decent results.

NEVER understood these absolute MORONS who get a spanner and a 30ft scaffold pole (well, you'd "think" that was how they applied torque) to do up nuts & bolts